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Evidence-Based Guideline: Evaluation, Diagnosis, and Management of Congenital Muscular Dystrophy


Report of the Guideline Development Subcommittee of the American Academy of Neurology and the Practice Issues Review Panel of the American Association of Neuromuscular & Electrodiagnostic Medicine

Peter B. Kang, MD1,2; Leslie Morrison, MD3 ; Susan T. Iannaccone, MD, FAAN4 ; Robert J. Graham, MD5 ; Carsten G. Bönnemann, MD6 ; Anne Rutkowski, MD7 ; Joseph Hornyak, MD, PhD8 ; Ching H. Wang, MD, PhD9,10; Kathryn North, MD, FRACP11; Maryam Oskoui, MD12; Thomas S. D. Getchius13; Julie A. Cox, MFA13; Erin E. Hagen13; Gary Gronseth, MD, FAAN14; Robert C. Griggs, MD, FAAN15
  1. Division of Pediatric Neurology, University of Florida College of Medicine, Gainesville, FL
  2. Department of Neurology, Boston Children’s Hospital and Harvard Medical School, Boston, MA
  3. Department of Neurology, University of New Mexico, Albuquerque, NM
  4. Departments of Pediatrics and Neurology & Neurotherapeutics, University of Texas Southwestern Medical Center, and Children’s Medical Center, Dallas, TX
  5. Division of Critical Care Medicine, Boston Children’s Hospital, and Department of Anaesthesia, Harvard Medical School, Boston, MA
  6. Neuromuscular and Neurogenetic Disorders of Childhood Section, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
  7. Cure Congenital Muscular Dystrophy (Cure CMD), Olathe, KS, and Department of Emergency Medicine, Kaiser Permanente South Bay Medical Center, Harbor City, CA
  8. Department of Physical Medicine & Rehabilitation, University of Michigan, Ann Arbor, MI
  9. Departments of Neurology and Pediatrics, School of Medicine, Stanford University, Stanford, CA
  10. Department of Neurology, Driscoll Children’s Hospital, Corpus Christi, TX
  11. Murdoch Childrens Research Institute, The Royal Children’s Hospital, and University of Melbourne, Parkville, Victoria, Australia
  12. Neurology & Neurosurgery, McGill University, Montréal, Québec, Canada
  13. Center for Health Policy, American Academy of Neurology, Minneapolis, MN
  14. Department of Neurology, University of Kansas School of Medicine, Kansas City, KS
  15. Department of Neurology, University of Rochester Medical Center, Rochester, NY Practice
Guideline American Association of Neuromuscular & Electrodiagnostic Medicine Page 2 Address correspondence and reprint requests to: American Academy of Neurology guidelines@aan.com

Approved by the AAN Guideline Development Subcommittee on July 13, 2013; by the AAN Practice Committee on May 26, 2014; by the AANEM Board of Directors on December 24, 2014; and by the AANI Board of Directors on December 17, 2014.

This guideline was endorsed by the American Academy of Pediatrics on September 12, 2014; by the American Occupational Therapy Association on August 1, 2014; by the Child Neurology Society on July 11, 2014; and by the National Association of Neonatal Nurses on April 5, 2014.

AUTHOR CONTRIBUTIONS

Peter Kang: study concept and design, acquisition of data, analysis or interpretation of data, drafting/revising the manuscript, critical revision of the manuscript for important intellectual content, study supervision.

Leslie Morrison: study concept and design, acquisition of data, analysis or interpretation of data, drafting/revising the manuscript, critical revision of the manuscript for important intellectual content.

Susan Iannaccone: study concept and design, acquisition of data, analysis or interpretation of data, drafting/revising the manuscript, critical revision of the manuscript for important intellectual content.

Robert Graham: study concept and design, acquisition of data, analysis or interpretation of data, drafting/revising the manuscript, critical revision of the manuscript for important intellectual content.

Carsten Bönnemann: study concept and design, acquisition of data, analysis or interpretation of data, drafting/revising the manuscript, critical revision of the manuscript for important intellectual content.

Anne Rutkowski: study concept and design, acquisition of data, analysis or interpretation of data, drafting/revising the manuscript, critical revision of the manuscript for important intellectual content.

Joseph Hornyak: study concept and design, acquisition of data, analysis or interpretation of data, drafting/revising the manuscript, critical revision of the manuscript for important intellectual content.

Ching Wang: study concept and design, acquisition of data, analysis or interpretation of data, drafting/revising the manuscript, critical revision of the manuscript for important intellectual content.

Kathryn North: study concept and design, acquisition of data, analysis or interpretation of data. Maryam Oskoui: analysis or interpretation of data.

Thomas Getchius: study supervision.

Julie Cox: drafting/revising the manuscript.

Erin Hagen: study supervision.

Gary Gronseth: study concept and design, acquisition of data, analysis or interpretation of data, drafting/revising the manuscript, critical revision of the manuscript for important intellectual content, study supervision.

Robert Griggs: study concept and design, critical revision of the manuscript for important intellectual content.

STUDY FUNDING
Funding for this publication was made possible (in part) by grant DD10-1012 from the Centers for Disease Control and Prevention. The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention. The remaining funding was provided by the American Academy of Neurology.

DISCLOSURE

Dr. Kang has received funding for travel from the American Academy of Neurology (AAN), the American Academy of Pediatrics (AAP), and Sarepta Therapeutics; has received consulting fees from Third Rock Ventures, Sarepta Therapeutics, and C1 Consulting for work unrelated to continuing medical education; has received honoraria for continuing medical education lectures from the AAN, AAP, American College of Medical Genetics, and HealthmattersCME; and has received research support from the National Institute of Neurological Disease and Stroke (NINDS) of the National Institutes of Health (NIH) and the Muscular Dystrophy Association (MDA).

Dr. Morrison has received funding for travel from the AAN; currently receives funding from the NINDS/NIH and the University of New Mexico (UNM) Myotonic Dystrophy Foundation; has received support from the UNM La Tierra Sagrada Foundation; and serves as director for the pediatric MDA Clinic at UNM, for which she receives annual support.

Dr. Iannaccone has received funding for travel from the AAN, Cure CMD, the GBS/CIDP Foundation, and NINDS/NIH; has received research support from the NINDS/NIH, Isis Pharmaceuticals, PTC Therapeutics Inc., Santhera Pharmaceuticals, and GlaxoSmithKline; and serves as director of the MDA Clinic at Children’s Medical Center Dallas (for which she receives annual support) and as medical director for the Dallas MDA Summer Camp.

Dr. Graham has served as a one-time, paid consultant for Hoffmann – La Roche Ltd for a Pulmonary Advisory Panel on investigations pertaining to spinal muscular atrophy (SMA).

Dr. Bönnemann has served on the scientific advisory board of CureCMD and CMD-IR, without any compensation; has received funding for travel from BioMarin (for scientific advice, no personal compensation), Novartis (no personal compensation), and the Third Rock Ventures (no personal compensation); has served as editor in chief of the Journal of Neuromuscular Disorders; sees patients with congenital muscular dystrophy (CMD) and performs muscle ultrasound on patients with CMD; has received intramural funds from the NINDS/NIH and National Human Genome Research Institute of the NIH; and has received a research grant from MDA, PI.

Dr. Rutkowski has received funding for clinical research from Kaiser Southern California Permanente Medical Group.

Dr. Hornyak has received funding for travel from the AAN.

Dr. Wang reports no relevant disclosures.

Dr. North has received funding to attend a CMD workshop hosted by CureCMD; has received clinical trials funding from PTC Therapeutics and GSK Prosensa; and has received funding from the Australian National Health and Medical Research Council (for research into congenital myopathies, dysferlin-related muscular dystrophy, and the effect of αactinin-3 deficiency on skeletal muscle performance), from the Australia Research Council (for research into α-actinin), and from the US Army Department of Defense (for a clinical trial on lovastatin for the treatment of cognitive deficits in neurofibromatosis type 1).

Dr. Oskoui has received funding for travel from the AAN and Isis Pharmaceuticals; has received fellowship funding from the Spinal Muscular Atrophy Foundation; has received research support from Grifols (GuillanBarré syndrome), Isis Pharmaceuticals (SMA), and SickKids Foundation (cerebral palsy); and is a member of the Canadian Pediatric Neuromuscular Group and the Canadian Neuromuscular Disease Registry and Network.

Mr. Getchius, Ms. Cox, and Ms. Hagen report no relevant disclosures.

Dr. Gronseth reports no relevant disclosures.

Dr. Griggs receives support for service on data safety monitoring boards from Novartis, PTC Therapeutics, and Viromed; consults for Sarepta Pharmaceuticals; consults and has received research support for Marathon Pharmaceuticals and Taro Pharmaceuticals; receives royalties from Elsevier for Cecil Textbook of Medicine and Cecil Essentials of Medicine, and from Oxford University Press for Evaluation and Treatment of Myopathies, Second Edition; receives a stipend from the AAN for editorial work; has received grants from the NINDS/NIH, the MDA, and Parent Project for Muscular Dystrophy; and chairs the Executive Committee of the Muscle Study Group, which receives support from numerous pharmaceutical companies.

ABBREVIATIONS
 
AAN:  American Academy of Neurology
AANEM: American Association of Neuromuscular & Electrodiagnostic Medicine
B3GALNT2: β-1,3-N-acetylgalactosaminyltransferase 2
B3GNT1: β-1,3-N-acetylglucosaminyltransferase 1
CK: creatine kinase
CMD: congenital muscular dystrophy
CMDs: congenital muscular dystrophies
COL6A1: collagen 6α1
COL6A2: collagen 6α2
COL6A3: collagen 6α3
DAG1: α-dystroglycan
EVID: statements supported directly by the systematically reviewed evidence
FHL1: four-and-a-half LIM domain 1
FKRP: fukutin-related protein
FKTN: fukutin
FVC: forced vital capacity
GMPPB: GDP-mannose pyrophosphorylase B
INFER: An inference from one or more of the other statements
LAMA2: laminin α2
L-CMD: LMNA-associated CMD
LGMD: limb-girdle muscular dystrophy
LMNA: lamin A/C
MD: muscular dystrophy
MDCs: merosin-deficient CMDs
MDs: muscular dystrophies
POMGnT2/GTDC2: POMGnT2
PRIN: an accepted axiom or principle
RELA: statements supported by strong evidence not included in the systematic review
SD: standard deviation
SEPN1: selenoprotein 1
SGK196: protein-O-mannose kinase
TMEM5: TMEM5


ABSTRACT

Objective. To delineate optimal diagnostic and therapeutic approaches to congenital muscular dystrophy (CMD) through a systematic review and analysis of the currently available literature.

Methods. Relevant, peer-reviewed research articles were identified using a literature search of the MEDLINE, EMBASE, and Scopus databases. Diagnostic and therapeutic data from these articles were extracted and analyzed in accordance with the American Academy of Neurology classification of evidence schemes for diagnostic, prognostic, and therapeutic studies. Recommendations were linked to the strength of the evidence, other related literature, and general principles of care.

Results. The geographic and ethnic backgrounds, clinical features, brain imaging studies, muscle imaging studies, and muscle biopsies of children with suspected CMD help predict subtypespecific diagnoses. Genetic testing can confirm some subtype-specific diagnoses, but not all causative genes for CMD have been described. Seizures and respiratory complications occur in specific subtypes. There is insufficient evidence to determine the efficacy of various treatment interventions to optimize respiratory, orthopedic, and nutritional outcomes, and more data are needed with regard to complications.

Recommendations. Multidisciplinary care by experienced teams is important for diagnosing and promoting the health of children with CMD. Accurate assessment of clinical presentations and genetic data will help in identifying the correct subtype-specific diagnosis in many cases. Multiorgan system complications occur frequently; surveillance and prompt interventions are likely to be beneficial for affected children. More research is needed to fill gaps in knowledge with regard to this category of muscular dystrophies.

The congenital muscular dystrophies (CMDs) are a group of rare muscular dystrophies (MDs) that have traditionally been defined as having symptom onset at birth. CMDs are distinct from congenital myopathies, which are characterized by different pathological features and genetic etiologies.e1 Epidemiologic data are sparse. The prevalence has been reported to be 6.8 x 10-6 in 1993 in northeast Italye2 and 2.5 x 10-5 among children aged 16 years and younger in western Sweden,e3 data which suggest that at least in European populations, the prevalence is likely to be in the range of 1 in 100,000 people. The genetic origins of many cases of congenital muscular dystrophy (CMD) have been discovered,e4 and genetic testing is now a valuable component of the diagnostic evaluation; however, many affected individuals remain without a genetic diagnosis, an indication that novel genes have yet to be identified. Clinical genetic testing through Sanger sequencing is available for virtually all genes known to be associated with CMD. Although the diagnosis remains essentially a clinical one, especially for the classical subtypes defined below, genetic discoveries have expanded the recognized phenotypic spectrum of these disorders, and precise genotype-phenotype correlations will become increasingly important in the future. A recently published set of algorithms will help with the diagnostic process for these patients.e5

Traditionally, symptoms of CMD were expected to be present at birth or soon thereafter, as the term suggests. However, owing in part to recent genetic advances, a broader phenotypic spectrum is now recognized for CMD, e5 and the exact age at onset may be difficult to define in some cases, especially for the milder variants. One study found that the mean age at onset of symptoms for Ullrich CMD is 12 months, suggesting that many cases of certain subtypes may have onset of symptoms later than was previously thought.e6 Thus, MDs with onset in the first 2 years of life, especially during infancy (the first year of life), are now commonly considered to be CMDs, although this expanded range raises the possibility of overlap in age at onset with other MDs such as limb-girdle muscular dystrophy (LGMD). One lingering nosological question is whether a later-onset disease that is allelic to a CMD should be classified as a CMD or a different disease. In the case of several dystroglycanopathy genes, most notably FKRP, the CMD and LGMD phenotypes were established before it was evident that the relevant subtypes of these 2 disease categories shared the same genetic etiologies. Thus, at present, the later-onset diseases are generally categorized differently, but this may change as characterization of all of these diseases improves.

Progressive skeletal muscle weakness and hypotonia are the cardinal clinical manifestations. Serum creatine kinase (CK) levels are typically but not invariably elevated. As with other MDs, the CMDs share characteristic muscle biopsy findings: necrosis, regenerating fibers, fiber size variability, and increased perimysial and endomysial connective tissue. In contrast with most other MDs, certain subcategories of CMDs are frequently associated with brain and eye malformations. The range of structural and functional CNS outcomes is broad in CMDs; many patients, especially those with dystroglycanopathies, often have severe brain abnormalities, whereas many others have completely intact cognition throughout their lives.

Three major categories of CMDs are commonly recognized, each of which has distinct, welldescribed phenotypic features: (1) collagenopathies (also known as collagen VI-related Page 10 myopathies), including Ullrich CMD and Bethlem myopathye7,e8; (2) merosinopathies (also known as merosin-deficient CMDs [MDCs], laminin α2 [LAMA2]-related CMDs, and MDC1A); and (3) dystroglycanopathies (also known as α-dystroglycan-related MDs), including Fukuyama CMD,e9 muscle–eye–brain disease, and Walker–Warburg syndrome. A broad spectrum of dystroglycanopathies exists that also includes rare variants such as fukutin-related protein (FKRP) and LARGE-associated CMDs, as well as mild phenotypes that fall within the phenotypic spectrum of LGMD. There are other rare CMDs that do not fit into any of the classic categories, including rigid spine muscular dystrophy (MD), which overlaps with multiminicore disease and has been associated with mutations in selenoprotein 1 (SEPN1) and four-and-a-half LIM domain 1 (FHL1),e10,e11 lamin A/C (LMNA)–associated CMD (L-CMD),e12 and diseases that share features of both CMD and congenital myopathy, such as early-onset myopathy, areflexia, respiratory distress, and dysphagia (caused by mutations in MEGF10).e13-e15 Rigid spine syndrome associated with FHL1 mutations may be associated with reducing bodies on muscle biopsy.e11 Tables e-1 and e-2 list these CMDs with their associated genes and clinical phenotypes. More recently, several other genes have been associated with CMDs, including GTDC2, e16 TMEM5, e17 B3GALNT2, e18 SGK196, e19 B3GNT1, e20 GMPPB, e21 and DAG1. e22

CMDs are most often autosomal recessive, but some cases have been found to follow autosomal dominant patterns, by direct inheritance, spontaneous mutations, or mosaicism. Emery-Dreifuss MD is generally not classified as a CMD, and thus no X-linked forms of CMDs have been described to date. Suspected founder mutations have led to clusters of certain mutations in discrete populations, such as POMGnT1 mutations causing muscle–eye–brain disease in Finland,e23 FKTN mutations causing Fukuyama CMD in Japan,e24 and FKTN mutations causing Walker–Warburg syndrome in the Ashkenazi Jewish community.e25,e26 Other clusters are likely to be found in the future.

Whereas the genetic, pathophysiologic, and pathological features of the CMDs have become better understood in recent decades, optimal diagnostic and therapeutic approaches remain unclear. This evidence-based guideline reviews the literature on the evaluation, diagnosis, and management of patients with suspected CMD. Duchenne MD, LGMD, myotonic dystrophy, and facioscapulohumeral dystrophy are not included in this guideline, as they are or will be discussed in other guidelines (one published,e27 the others forthcoming). We assessed the efficacy of various screening and diagnostic procedures and therapeutic interventions for the management of patients with suspected or definite CMD. The guideline seeks to answer the following clinical questions:
 
1. For children with suspected CMD, how accurately do the
a. geographic location and ethnicity
b. clinical features
c. brain imaging findings
d. muscle imaging findings
e. muscle biopsy findings predict the subtype-specific diagnosis?
 
2. How often does genetic testing confirm a diagnosis of CMD?  
3. How often do patients with CMD experience cognitive, respiratory, and cardiac complications?   
4. Are there effective treatments for complications of CMD, including scoliosis and nutritional deficiencies?  

Appendix e-1 provides a brief glossary of common terms related to genetics and genetic sequencing, and appendix e-2 lists resources for genetic testing.

DESCRIPTION OF THE ANALYTIC PROCESS

This guideline was developed in accordance with the processes outlined in the 2004 and 2011 American Academy of Neurology (AAN) process manuals.e28,e29 In July 2010, the American Academy of Neurology (AAN) Guideline Development Subcommittee and the American Association of Neuromuscular & Electrodiagnostic Medicine Practice Issues Review Panel (appendices e-3 through e-5) formed a panel of pediatric neurologists, a pediatric physiatrist, a pediatric critical care specialist, a patient advocate who also is a physician, and an AAN evidence-based medicine methodologist, selected to represent a range of expertise in CMDs. The panel searched the MEDLINE, EMBASE, and Scopus databases for relevant, peer-reviewed articles in humans and in all languages (see appendix e-6 for full search strategy and terms). The initial search identified 2,008 abstracts. Of those, 811 articles were selected for full-text review. An updated search of Medline in June 2012 and EMBASE and Scopus in August 2012 yielded an additional 1,090 articles, 70 of which were selected for review. Two panel members working independently of each other reviewed each of the 881 selected articles. Seventy-eight articles were selected for inclusion in the final review. Two panel members rated each of those articles, using the 2011 AAN criteria for classification of therapeutic and screening articles (appendix e7). Questions 1, 2, and 3 are screening questions, and question 4 is a therapeutic question. A third panel member arbitrated any differences in article ratings.

We included articles in the review if they pertained to any of the following conditions: CMD, Ullrich disease, Bethlem myopathy, merosin deficiency, Walker–Warburg syndrome, muscle-eye-brain disease, Fukuyama CMD. Case reports were excluded. Class I, II, and III studies are discussed in the text. To target the specific treatment questions listed previously, we limited the search methodology to the CNS, myocardial dysfunction/arrhythmias, and respiratory complications (e.g., recurrent infections from presumed aspiration, hypopnea, hypoxemia, restrictive/neuromuscular insufficient lung disease).

The panel formulated a rationale for recommendations based on the evidence systematically reviewed and stipulated axiomatic principles of care. We explain this rationale in a section which precedes each set of recommendations. From this rationale, we inferred corresponding actionable recommendations. We assigned a level of obligation to each recommendation using a modified Delphi process that considered the following prespecified domains: the confidence in the evidence systematically reviewed, the acceptability of axiomatic principles of care, the strength of indirect evidence, and the relative magnitude of benefit to harm. Additional factors explicitly considered by the panel that could modify the level of obligation include judgments regarding the importance of outcomes, cost of compliance to the recommendation relative to benefit, the availability of the intervention, and anticipated variations in patients’ preferences. Appendix e-8 presents the prespecified rules for determining the final level of obligation from these domains. We indicated the level of obligation using standard modal operators. Must corresponds to Level  A, very strong recommendations; should to Level B, strong recommendations; and might to Level C, weak recommendations. Appendix e-9 indicates the panel members’ judgments supporting the level of obligation for each recommendation.

ANALYSIS OF EVIDENCE

Question 1 focuses on clinical features, question 2 on genetic diagnosis, question 3 on complications, and question 4 on treatments. The literature review yielded significantly more articles relevant to diagnostic questions than to ones involving complications and therapeutic issues. Thus, for the purpose of analysis, we divided question 1 into 5 subquestions.

We found only a few large studies and a number of smaller studies, most likely because of the rareness of CMD and the fact that the available studies oftentimes focus on specific subtypes. The panel decided to include at least some smaller studies so as not to miss what likely would be a significant number of valuable data, and thus set a minimum sample size of only 2 unrelated families for inclusion and a minimum evidence level of Class III for either diagnostic or screening criteria. In the end, many of the smallest studies were excluded because they provided only low levels of evidence (Class IV); however, a small number of these studies contributed data that were not readily available in studies that were rated Class III or higher, and thus were included in the analysis.

Clinical features.

Question 1a. For children with suspected CMD, how accurately do the geographic location and ethnicity predict the subtype-specific diagnosis?

One Class I article, 4 Class II articles, and 1 Class III article were identified. In the Class I article, screening of the Japanese population with clinical Fukuyama CMD revealed that 87% carry the retrotransposal founder mutation in FKTN, with an additional 9 nonfounder compound heterozygous mutations identified, leading to the severe phenotype.e30 Carrier frequency for the founder mutation in Japan is 6/676.e24,e30 The Class III article found FKTN mutations in 9 of 12 patients with α-dystroglycanopathy in Korea.e31 In the first Class II article, 4 Ashkenazi Jewish patients with Walker–Warburg syndrome were identified as having a founder mutation in FKTN, c.1167insA, with a carrier frequency of 2/299.e26 The second Class II article reported that an A200P haplotype in the POMT1 gene was found in 5 Turkish patients, all presenting with a similar clinical phenotype based on an early age at onset (1–3 years), age at onset of ambulation (3–4 years), the presence of calf and thigh hypertrophy, developmental disability (IQ 50–65), significant elevations in the serum CK level (> 20-fold over normal), and a lack of structural brain abnormalities on CT and MRI scans.e32 The next 2 Class II studies found that LAMA2 mutations were common in children with biopsy-confirmed merosin deficiency in Europe, North Africa, and Korea (see Question 1e, discussed latere33,e34). Merosin deficiency has been reported to be a common subtype in several populations, including in Brazilians (see Question 1ee35).

Conclusion. In children with suspected CMD, founder mutations exist in the Japanese, Ashkenazi Jewish, and Turkish populations. Other founder mutations likely exist. Thus, the geographic and ethnic background of children with suspected CMD may help predict the specific subtype when published information is available for the population of interest (1 Class I study,e30 4 Class II studies,e26,e32-e34 1 Class III studye31).

Question 1b. For children with suspected CMD, do certain clinical features accurately predict the subtype-specific diagnosis?

Eight articles addressed this question: 1 Class II article and 1 Class III article for collagenopathies, 1 Class II article for merosinopathy, 1 Class II study and 3 Class III studies involving dystroglycanopathies, and 1 Class III study involving L-CMD.

Distal joint hyperlaxity is a characteristic clinical feature of collagenopathy. In the Class II study of collagenopathies, 4 patients were described with a congenital presentation of marked distal hyperlaxity and diaphragmatic paralysis. They were found to have homozygous or compound heterozygous mutations consistent with the diagnosis of Ullrich CMD. e36 In the Class III study of collagenopathies, 3 patients shared common features: congenital hypotonia, joint contractures, high-arched palate, prominent calcaneus, scoliosis, hyperhidrosis, normal intelligence, and normal serum CK levels. EMG was myopathic. Muscle biopsy demonstrated variation in muscle fiber diameter with increased connective tissues. These patients were diagnosed with Ullrich CMD. e37

A hallmark of merosinopathy is a pattern of white matter abnormalities of the brain in conjunction with congenital weakness. In a third Class II article, 13 patients with merosin deficiency were found to have congenital weakness, elevated serum CK levels, and white matter signal abnormalities on brain MRI. The MRI findings did not include cortical malformations such as lissencephaly and pachygyria. These patients were found to have merosin deficiency on immunohistochemistry of their muscle biopsy tissue, and partial deficiency correlated with a milder phenotype than complete deficiency.e38

The dystroglycanopathies in their syndromic forms are typically characterized by muscle weakness, structural eye abnormalities, and cortical brain abnormalities, this last often associated with migrational defects. Fukuyama CMD tends to be milder in phenotype, and muscle–eye– brain disease is generally moderately severe. Walker–Warburg syndrome often carries the most severe structural and functional abnormalities as well as the shortest life expectancy. In the fourth Class II article, 31 of 92 patients (34%) with a suspected clinical diagnosis of dystroglycanopathy were found to have mutations in associated genes.e39 The second Class III Page 14 article identified a cohort of 26 patients with clinical features of muscle–eye–brain disease who were found to have mutations in POMGnT1. e40 The third Class III article found that patients with the clinical features of muscle–eye–brain disease tend to have necrotic and regenerative fibers on muscle biopsy during infancy, whereas fat infiltration becomes more prominent when the muscle biopsy is performed later in childhood. Secondary merosin deficiency was a common finding.e41 In the fourth Class III article, patients with clinical features of Walker–Warburg syndrome, characterized by severe weakness at birth, accompanied by severe structural abnormalities in the brain and eyes, were found to have mutations in POMT1, a known causative gene.e42

The fifth Class III study examined the clinical features for various MD forms associated with LMNA mutations and found that L-CMD is strongly associated with neck extensor weakness.e43

Conclusion. In children with suspected CMD, clinical features may predict specific subtype diagnoses and may in some cases predict the causative genes (3 Class IIe36-e38 and 5 Class III articlese39-e43).

Question 1c. For children with suspected CMD, how accurately do the brain imaging findings predict the subtype-specific diagnosis?

Two Class II studies and 1 Class III study addressed this question. The first Class II study identified characteristic white matter abnormalities on brain MRI suggestive of a merosinopathy diagnosis and found that these imaging results correlated with merosin deficiency on muscle biopsy.e44 In the second Class II study, two specific cerebellar abnormalities were found to be strongly correlated with the diagnosis of Fukuyama CMD: disorganized cerebellar folia (found in 16 of 25 cases) and intraparenchymal cysts (found in 23 of 25 cases).e45 The Class III study examined 4 patients with dystroglycanopathy confirmed by clinical, histologic, and radiographic criteria and found that all 4 demonstrated polymicrogyria, white matter lesions, pontine hypoplasia, and subcortical cerebellar cysts.e46

Conclusion. Abnormal findings on brain imaging studies can predict the subtype-specific diagnosis in some cases, especially in merosinopathy and some dystroglycanopathies (2 Class II studiese44,e45 and 1 Class III studye46).

Question 1d. For children with suspected CMD, how accurately does muscle imaging predict the subtype-specific diagnosis?

There were 3 Class I articles and 1 Class III article. In the first Class I article, children with suspected neuromuscular disease underwent qualitative muscle ultrasound. Ultrasound distinguished normal from diseased muscle with a sensitivity of 81% and specificity of 96%. A highly characteristic central shadow pattern for Bethlem myopathy, one of the collagenopathies, Page 15 was identified.e47 In the second Class I article, ultrasound and EMG successfully aided in the classification of infants as those with neurogenic disorders, those with myopathic disorders, and those with no neuromuscular disorder.e48 In the third Class I article, lower-extremity MRI showed specific patterns in patients with collagenopathy (34 of 40 patients) and SEPN1-related myopathy (12 of 13 patients) that indicated the subtype-specific diagnosis.e49 The Class III study compared muscle CT findings of 14 patients with confirmed Ullrich CMD or Bethlem myopathy with the findings of 13 patients with confirmed EmeryDreifuss MD, and found that CT muscle imaging could distinguish reliably between the 2 groups.e50

Conclusion. Skeletal muscle imaging in children with suspected CMD using MRI, ultrasound, and CT often demonstrates signal abnormalities that suggest subtype-specific diagnoses. This has been most extensively documented in CMD subtypes associated with rigidity of the spine, such as collagenopathies and SEPN1-related myopathy. These conclusions are based on 3 Class I articlese47-e49 and 1 Class II article.e50

Question 1e. Do children with specific muscle biopsy findings have specific CMD subtypes?

Three Class II articles and 1 Class III article addressed this question for merosinopathy, 1 Class III article for laminopathies, and 1 Class III article for CMD in general. The 3 Class II articles found that merosin deficiency on muscle biopsy correlated strongly with mutations in LAMA2 in a cohort originating primarily from Europe and North Africa,e33 a Japanese cohort where 1 in 40 children was found to have merosinopathy,e51 and a cohort of 35 Korean patients wherein 8 (23%) had merosinopathy.e34 The Class III article involving merosin deficiency examined 46 patients with immunohistochemistry. This study found that merosin deficiency correlated strongly with genetic mutations in LAMA2 and that the patients in whom merosin was absent were more likely to have a severe phenotype as compared with the ones with partial deficiency.e52 The Class III article involving CMD in general studied a Brazilian cohort of 59 patients with suspected CMD and found that 32 had merosin-positive CMD, 23 had merosindeficient CMD, 1 had Ullrich CMD, and 3 had Walker–Warburg syndrome. In this cohort, partial merosin deficiency did not predict a less severe phenotype than complete merosin deficiency. A deficiency of α-dystroglycan on muscle biopsy predicted a severe phenotype.e35 A Class III article examining children with early-onset myopathy with signs of inflammation on muscle biopsy identified heterozygous LMNA mutations in 11 of 20 patients.e53

Conclusion. In children with suspected CMD, muscle biopsy findings predict the subtypespecific diagnosis for merosinopathy most reliably and can detect the likelihood of dystroglycanopathy in general with the exception of the specific dystroglycanopathy syndromes. The data are insufficient to draw conclusions with regard to collagenopathies. These conclusions are based on 3 Class IIe33,e34,e51 and 3 Class III articles.e35,e52,e53

Genetic diagnosis.

Question 2. How often does genetic testing confirm a diagnosis of CMD?

With respect to screening characteristics, 1 study met Class II criteria and 44 studies met Class III criteria. The selected studies included 2 for CMD in general, 13 for collagenopathies, 9 for merosinopathy (including 2 prenatal studies), 16 for dystroglycanopathy (including 7 general studies, 4 focusing on Fukuyama MD, 2 on muscle–eye–brain disease, and 3 on Walker– Warburg syndrome), and 5 for extremely rare CMDs. The selected studies were each assigned a diagnostic rating of Class III or IV, with 2 exceptions: one prenatal merosinopathy study met the criteria for Class II (diagnostic), and one Fukuyama MD study met the criteria for Class I (diagnostic).

One large Class III screening study screened multiple genes across the major CMD categories in 101 patients from Australia. The study included patients with collagenopathy, merosinopathy, and dystroglycanopathy and found genetic confirmation of the diagnosis in ~20% of cases.e54 Another large Class III study screened 214 patients from the United Kingdom who had been evaluated for possible CMD between 2001 and 2008. Of those, 116 were determined to have CMD, and genetic diagnoses were found in 53 of the 116. The distribution included 19% with collagenopathies, 12% with dystroglycanopathies, and 10% with merosinopathies.e55

The Class II collagenopathy screening study examined 49 patients with the clinical diagnosis of Ullrich CMD, Bethlem myopathy, or an intermediate phenotype and found mutations in COL6A1, COL6A2, and COL6A3 in all of them.e56 Among the 12 Class III collagenopathy screening studies, 5 studies with sample sizes greater than 10 were found. In the first Class III study, COL6A1, COL6A2, and COL6A3 were screened in 79 patients with Ullrich CMD and Bethlem myopathy, and mutations in 1 of these 3 genes were identified in 62% of patients.e57 In the second Class III study, 34 patients with CMD with complete or partial collagen deficiency on immunohistochemistry were screened for the 3 collagen VI genes, and mutations were identified in 26 (76%).e58 The third Class III study, on 14 patients with Bethlem myopathy, found collagen VI mutations in 8 of the 14.e59 In the fourth Class III study, examining 25 patients with a clinical diagnosis of collagenopathy, 15 patients were found to have collagen VI mutations.e60 The fifth Class III study used comparative genome hybridization array technology to search for unusual mutations in 14 patients with Ullrich CMD and Bethlem myopathy who did not have collagen VI mutations on Sanger sequencing, and found 1 novel mutation in this manner. e61 In these 5 studies, heterozygous mutations were most common; homozygous mutations tended to occur in some cases of Ullrich CMD and when complete deficiency of collagen was seen on immunohistochemistry. The other 7 Class III studies all had sample sizes smaller than 10 and generally found high rates of mutation detection,e62-e68 including 1 that documented large genomic deletions in 2 patientse62 and another that identified compound heterozygous COL6A2 mutations in 2 unrelated patients with an autosomal recessive form of Bethlem myopathy.e63

Among the 7 Class III screening studies examining genetic diagnosis rates in merosinopathy, the 2 largest studies focused on patients with complete deficiency of merosin in muscle tissue. The first study identified LAMA2 mutations in 26 of 26 patientse69 and the second study in 21 of 22 patients.e70 Most of the patients in these studies had compound heterozygous mutations, whereas a few had homozygous mutations or single heterozygous mutations. The other 5 studies had smaller sample sizes with a variable rate of mutation detection.e33,e71-e74 Of note, 2 of the smaller studies that included a majority of patients with partial merosin deficiencye73,e74 showed a lower mutation detection rate overall relative to the larger studies that primarily included patients with complete merosin deficiency.e69,e70

Two studies examined the accuracy of prenatal genetic testing in fetuses at risk for merosinopathy. One large, international, multicenter study genetically screened 102 fetuses and found 27 with 2 disease alleles, 52 heterozygous carriers, and 23 with no disease alleles (Class II diagnostic / Class III screeninge75). Among the 27 fetuses predicted to be affected, 10 had immunohistochemical testing on muscle tissue after the pregnancies were terminated and were confirmed to be affected. No false-positive or false-negative results were found. A smaller Class III screening study screened 1 fetus each from 3 women and predicted 1 affected child, who was confirmed postnatally to have merosinopathy on the basis of genetic testing of blood leukocytes and clinical phenotype.e76

Seven Class III screening studies, 3 of which were large studies, examined genetic diagnosis issues in dystroglycanopathies across multiple phenotypes. The first large study screened 81 patients for all 6 known genes (POMT1, POMT2, POMGnT1, FKTN, FKRP, and LARGE) and identified mutations in 53% of those patients.e77 The second large study screened 92 patients in whom FKRP had previously been excluded for the other 5 genes.e39 In the third large study, 61 patients were screened for POMT1 and POMT2 only, and mutations were found in 30%.e78 The studies determined that mutations in POMT1 and POMT2 were the most common overall, whereas POMGnT1 and FKRP were less common. The prevalence of FKTN mutations was generally lower outside of Japan, but clusters of FKTN mutations were identified in 2 studies outside of Japan, including 1 in Korea.e31,e39 Among children with dystroglycanopathy, mutations in LARGE have been described but are rare. Another study also found a low prevalence of LARGE in dystroglycanopathies.e79 A study of 65 histopathologically confirmed fetal cases of cobblestone lissencephaly found that 66% had mutations in POMT1, POMT2, POMGnT1, LARGE, FKTN, or FKRP. e80 A cohort of 33 patients with dystroglycanopathy was screened for mutations in WWP1, with no mutations identified.e81

Among the 4 studies on Fukuyama CMD that met Class III screening criteria, 1 study also met Class I diagnostic criteria. This study screened 18 patients with Fukuyama CMD in Japan and identified mutations in all 18, primarily the common retrotransposal insertion.e30 The other studies confirmed the high rate of the retrotransposal insertion among affected individuals in Japan, with a lower rate of other mutations in FKTN. e24,e82,e83 The carrier frequency in Japan has been estimated to be 1/88.e24  

Two Class III screening studies on muscle–eye–brain disease indicate that mutations in POMGnT1 were associated with a high proportion of cases. One study identified POMGnT1 mutations in all 26 families examinede40 and the other in all 8 families tested.e84

Three Class III studies addressed the question of genetic diagnosis in Walker–Warburg syndrome. The first study screened 40 families for POMT1, POMT2, POMGnT1, FKTN, FKRP, and LARGE and found mutations in 40%.e25 The study identified four genes—POMT1, POMT2, FKTN, and FKRP—as being associated with Walker–Warburg syndrome. The second study also found that FKTN mutations were a cause of some cases of Walker–Warburg syndrome.e85 Two of the studies found that POMT1 mutations are less commonly associated with Walker–Warburg syndrome than previously thought.e25,e86

Some rare CMDs share features of both CMDs and congenital myopathies. These include SEPN1-related myopathy (rigid spine MD/multiminicore disease), integrin α-7 deficiency, lamin-associated CMD, and a CMD with mitochondrial structural abnormalities. Two small Class III studies found associations between SEPN1 mutations and patients with multiminicore myopathy.e87,e88 Another Class III study demonstrated that ITGA7 mutations are a rare cause of CMD. e89 Two children with dropped head syndrome were found to have LMNA mutations.e90 Another unusual CMD is associated with early-onset muscle wasting, intellectual disabilities, and enlarged mitochondria that accumulate at the periphery of muscle fibers. Fifteen cases of this CMD were found to be associated with mutations in CHKB.e91

Conclusions (genetic diagnosis).

The mutation detection rate for CMDs in general ranges from 20% to 46% (2 Class III studies).e54,e55

In children with collagenopathy (Ullrich CMD or Bethlem myopathy), COL6A1, COL6A2, and COL6A3 genetic testing possibly has a high likelihood of detecting causative mutations (1 Class II study,e56 5 large Class III studies,e57-e61 and 7 small Class III screening studiese62-e68).

In children with complete merosin deficiency on muscle biopsy, LAMA2 genetic testing has a high likelihood of detecting causative mutations (2 large Class III studies).e69,e70 In children with partial merosin deficiency, the likelihood of detecting causative LAMA2 mutations is less consistent (2 smaller Class III studies).e73,e74 Prenatal genetic testing is highly accurate (1 Class II diagnostic / Class III screening studye75 and 1 Class III studye76 ).

Genetic testing can detect causative mutations in many children with dystroglycanopathy in general (7 Class III studies), and detection is estimated to be 30% to 66% in those reports (percentages vary in part because the exact genes and the selected cohort vary from study to Page 19 study).e31,e39,e82-e86 However, it is clear from these data that a high proportion of affected children are not likely to have mutations in any of the known genes. In Fukuyama CMD, FKTN mutations are detected in as many as 100% of patients (1 Class I diagnostic / Class III screening studye30 and 3 Class III screening studiese24,e82,e83). In muscle–eye–brain disease, POMGnT1 mutations may be detected in 100% of patients (2 Class III studies).e40,e89 In Walker–Warburg syndrome, only 40% of patients have mutations in the known genes (1 large Class III studye25 and 2 smaller Class III studiese90,e91). These studies did not include ISPD, DAG1, and DPM3, genes that have been recently described and may also account for dystroglycanopathy.

Complications.

Question 3. How often do patients with CMD experience cognitive, respiratory, or cardiac complications?

Numerous reports highlight a wide spectrum of complications in children and young adults with CMD. Among the studies, 1 Class III article examined the diagnostic utility of polysomnography, 1 Class II study examined rates of cognitive impairment, 8 Class III studies examined complication frequencies and risk factors, 2 Class IV studies examined structural and developmental brain complications, and 2 Class IV studies examined echocardiographic abnormalities in patients with CMD. See the clinical context section for discussion of further consideration of associated complications, including but not limited to aerodigestive issues (dysfunction of the throat, esophagus, or stomach, or a combination of these, leading to airway, breathing, or swallowing dysfunction, or a combination of these), growth issues, and musculoskeletal complications (e.g., scoliosis and joint contractures).

Structural brain malformations have been identified in children with a variety of CMD subtypes, as described previously in the diagnostic section. However, functional CNS complications have not been as thoroughly documented. The Class II article examined 160 patients with CMD in Italy and found that 92 (58%) had cognitive impairment.e92 In 1 of the Class III articles, a cohort of Japanese children with Fukuyama CMD was reported to have a high incidence of seizures, findings in many cases supported by EEG abnormalities, during a 10-year observation period.e83 Another Class III article reported that 2 girls with dystroglycanopathy had epilepsy associated with unusual EEG findings.e93 In 1 of the Class IV studies, 2 patients with merosinopathy were found to have no correlation between brain MRI abnormalities and cognitive outcomes.e94 Another Class IV study identified 2 patients with Walker-Warburg syndrome complicated by hydrocephalus and seizures; the hydrocephalus was stabilized by ventriculoperitoneal shunting procedures.e95

The current literature does not identify specific diagnostic tools for the development of acute and chronic respiratory complications in children with CMD, although 1 small study examined the utility of polysomnography. One of the Class III studies, which examined 102 patients with CMD, found an overall respiratory complication rate of 12%; however, 13 additional patients Page 20 who had died were not included in the analysis, an indicator that the true complication rate may be higher.e96 In another Class III study, 13 patients with Ullrich CMD found that forced vital capacity (FVC) was < 80% predicted in all patients by age 6 years. An annual average decrement of 2.6% (SD 4.1%) in FVC was reported. Mean age at onset of noninvasive ventilation support was 14.3 years (SD 4.7). Although not focused on treatment, the study also reported that the use of noninvasive ventilation or scoliosis surgery was not associated with improved FVC.e6 Another Class III study examined the use of polysomnography for the diagnosis of sleep-disordered breathing in 2 patients with CMD and 2 patients with rigid spine syndrome and found that all subjects experienced nocturnal hypoventilation and hypoxemia.e97 Cardiac manifestations and complications occur but are not consistent across CMD subtypes. One of the Class III studies previously mentioned noted an overall cardiac complication rate of 6% in a cohort of 102 patients with CMD. e96 Three Class III studies examined echocardiographic measurements of myocardial and ventricular dimension in children with CMD but did not correlate these findings with clinical symptoms. An estimated 8% to 30% of patients with merosin-positive CMD had significantly depressed cardiac function based on shortening and ejection fraction on echocardiography. Structural or valvular abnormalities were not identified.e98-e100 The currently available data are not sufficient to study correlations between cardiac complications with age or the clinical course for the various CMD subtypes. One of the Class IV studies, a case series, detected a higher incidence of echocardiographic dysfunction in merosin-negative CMD vs merosin-positive CMD. e101 Another Class IV series, examining 9 patients with rigid spine syndrome, found that 5 had mitral valvular abnormalities, which have not been identified in other CMD subtypes.e102

In a Class III study of 14 children with merosinopathy, the families of all 14 reported that their children had feeding difficulties; the study showed that all but the youngest child (a 2-year-old) had abnormal swallowing on videofluoroscopy.e103

Conclusions (complications).

Various CNS, respiratory, and cardiac complications have been identified in children with CMD. There is insufficient evidence to draw comprehensive conclusions as to the risk factors and frequency of these complications in the various subtypes. However, seizures are common in Fukuyama CMD and respiratory complications in Ullrich CMD. These conclusions are based on 1 Class II study,e92 9 Class III studies,e6,e83,e93,e96-e100,e103 and 4 Class IV studies.e94,e95,e101,e102

Treatments.

Question 4. Are there effective treatments for complications of CMD, including scoliosis and nutritional deficiencies?

Review of the treatment literature identified no prospective intervention studies for contracture treatment, scoliosis prevention, or nutrition optimization for children and young adults with CMD. A single Class III study of spinal fusion demonstrated correction and prevention of progression of scoliosis and pelvic obliquity over 2 years, resulting in improved or stable balance and sitting posture. The impact on respiratory status and other complications is unclear, as pulmonary function declined after surgical intervention, a finding which may be related to disease progression.e104

Conclusions.

Because only 1 Class III studye104 was identified that specifically addressed this question, the evidence is insufficient to determine whether surgical correction of scoliosis results in stabilization of skeletal abnormalities, sitting, balance, respiratory status, and longer-term outcomes. In general, due to the absence of prospective interventional studies, the evidence is insufficient to support or refute use of specific therapeutic interventions to prevent nutrition related complications, contractures, or scoliosis.

No data are available to support the use of gastrostomy in children with CMD.

PRACTICE RECOMMENDATIONS
Given the lack of literature directly relevant to CMDs for some of the clinical questions, some of the recommendations below are based in part on evidence from other neuromuscular disorders of childhood.

Section AA. General recommendations.
CMD is a category of rare, complex genetic disorders with multiorgan system complications, and the various subtypes display a wide spectrum of phenotypes (EVID). These patients may develop various combinations of cardiovascular, gastrointestinal/nutritional, neurologic, ophthalmologic, orthopedic, and pulmonary manifestations (EVID). Multidisciplinary teams are recommended in the care of patients with complex neuromuscular conditions such as amyotrophic lateral sclerosis,e105 and are thus widely believed to be effective in the care of children with complex medical needs such as those with CMD, despite regional variability in the composition and availability of such clinics (RELA). Neuromuscular specialists, particularly child neurologists and physiatrists with subspecialty training, are key members of such teams, as are physicians from other specialties (e.g., cardiology, gastroenterology, neurology, ophthalmology, orthopedic surgery, pulmonology) and allied health professionals with relevant expertise (e.g., dieticians, genetic counselors, nurses, nurse practitioners, occupational therapists, physical therapists, and speech-language pathologists) (PRIN).

Recommendations.
 
AA1. Physicians caring for children with CMD should consult a pediatric neuromuscular specialist for diagnosis and management (Level B).
AA2. Pediatric neuromuscular specialists should coordinate the multidisciplinary care of patients with CMD when such resources are accessible to interested families (Level B).
AA3. When genetic counselors are available to help families understand genetic test results and make family-planning decisions, physicians caring for patients with CMD might help families access such resources (Level B).

Section A. Use of clinical features, MRI, and muscle biopsy in diagnosis.
Many children and adults with CMD may present with subtle features and milder clinical severity with later onset (EVID). However, patients with some of the classic CMD subtypes, including collagenopathies and dystroglycanopathies, have distinct phenotypic features that may help focus the diagnostic process (EVID). Serum CK levels may be helpful in identifying potential cases (RELA).e106-e109 Recognition and evaluation of clinical features characteristic of CMD can be difficult in atypical and late-onset cases (PRIN).

Recommendation.
 
A1. Physicians should use relevant clinical features such as ethnicity and geographic location, patterns of weakness and contractures, the presence or absence of CNS involvement, the timing and severity of other organ involvement, and serum CK levels to guide diagnosis in collagenopathies and in dystroglycanopathies (Level B).

Interpretation of muscle biopsy findings, especially in children, is heavily dependent on technique and the experience of the pathologist or neuromuscular specialist who interprets the studies. Proper interpretation of these studies requires knowledge of the clinical context as well as availability of advanced testing capabilities such as immunohistochemistry and electron microscopy. In the proper setting such as a multidisciplinary neuromuscular clinic with access to sophisticated muscle pathology resources, muscle biopsy is often a valuable component of the diagnostic process and may facilitate genetic diagnosis and genetic counseling. Even in cases where a genetic diagnosis cannot easily be obtained, the knowledge obtained from a muscle biopsy may help families and providers better understand the disease process affecting specific patients (PRIN).

Recommendations.
 
A2. Physicians might order muscle biopsies that include immunohistochemical staining for relevant proteins in CMD cases for which the subtype-specific diagnosis is not Page 23 apparent after initial diagnostic studies, if the risk associated with general anesthesia is determined to be acceptable (Level C).
A3. When muscle biopsies are indicated in suspected CMD cases, they should be performed and interpreted at centers experienced in this test modality. In some cases, optimal diagnostic information may be derived when the biopsy is performed at one center and interpreted at another (Level B).

Typical brain MRI findings of white matter abnormalities in merosinopathies can be found consistently above the age of 6 months,e77,e110 and the structural brain abnormalities that often accompany the dystroglycanopathies are well documented (EVID). These neuroimaging findings however, may be misinterpreted by adult neuroradiologists or radiologists who are not accustomed to the myelination patterns of infants and toddlers, and by those who are unfamiliar with the patterns observed in patients with rare genetic disorders such as merosinopathies (PRIN).

Muscle ultrasound and MRI studies can help distinguish neurogenic from myopathic disorderse48 and show pathognomonic patterns for specific CMD subtypes such as Bethlem myopathy (EVID).e47 Muscle MRI studies likewise can help identify CMD subtypes, including collagenopathies and SEPN1-related myopathies (EVID).e49

Recommendations.
 
A4. Physicians should order brain MRI scans to assist with the diagnosis of patients who are clinically suspected of having certain CMD subtypes, such as merosinopathies and dystroglycanopathies, if the potential risk associated with any sedation is determined to be acceptable and if a radiologist or other physician with the appropriate expertise is available to interpret the findings (Level B).
A5. Physicians might order muscle imaging studies of the lower extremities for individuals suspected of having certain CMD subtypes such as collagenopathies (ultrasound or MRI) and SEPN1-related myopathy (MRI), if the risk associated with any sedation needed is determined to be acceptable and if a radiologist or other physician with the appropriate expertise is available to interpret the findings (Level C).

Section B: Genetic diagnosis.
Causative genetic mutations have been found in the majority of cases of CMD, and the remainder of cases likely also harbors such genetic mutations (EVID). Targeted genetic testing often identifies causative mutations in the classic CMD subtypes, such as Ullrich CMD, Bethlem myopathy, merosin-deficient CMD, Fukuyama CMD (specifically in Japan), muscle–eye–brain disease, and Walker–Warburg syndrome (EVID). However, the cost of traditional Sanger Page 24 sequencing for some of the larger associated genes, such as COL6A1, COL6A2, COL6A3, and LAMA2, presents an obstacle to universal application of such sequencing, even though the testing is readily available (RELA).e111 Genetic diagnoses are beneficial to the patient, as they often enable physicians to provide more accurate prognoses and facilitate genetic counseling and family-planning discussions, and may enable patients to become more aware of future clinical trials for which they may be eligible (PRIN). A substantial proportion of patients with CMD remain without a genetic diagnosis because of lack of access to genetic testing resources in some cases and unidentified causative genes in other cases, although this proportion is expected to decline over time (EVID). Prenatal genetic diagnosis is accurate in fetuses at risk for merosinopathy and is likely to be accurate in other CMD cases in which the familial mutations are known (RELA).e75,e76 Ethical issues may arise when a family is considering prenatal diagnosis for severe neuromuscular conditions, as has been discussed for Duchenne MD (RELA).e112

Recommendation.
 
B1. When available and feasible, physicians might order targeted genetic testing for specific CMD subtypes that have well-characterized molecular causes (Level C).

The analysis also indicates that a large number of patients with CMD do not have mutations in one of the currently known genes (EVID). The cost of next-generation sequencing (whole-exome and whole-genome sequencing) is dropping rapidly, to the point where these technologies are now readily available to many researchers who seek novel causative disease genes (RELA).e15 Several medical centers and commercial genetic-testing companies have begun offering nextgeneration sequencing on a clinical basis (RELA).e113 These technologies have the potential, not only of facilitating the identification of novel disease genes, but also of identifying mutations in myopathy genes that were previously associated with different phenotypes (PRIN). This option will become increasingly accessible, accurate, and cost-effective over time, and may largely supplant traditional Sanger sequencing in the future (INFER). The percentage of individuals affected by CMD who have molecular diagnoses is expected to rise steadily over the next decade as next-generation sequencing becomes widely used on a clinical basis (INFER).

Recommendation.
 
B2. In individuals with CMD who either do not have a mutation identified in one of the commonly associated genes or have a phenotype whose genetic origins have not been well characterized, physicians might order whole-exome or whole-genome sequencing when those technologies become more accessible and affordable for routine clinical use (Level C).

Section C. Complications and treatment.
Patients with CMD experience a broad spectrum of respiratory, musculoskeletal, cognitive, and cardiac complications with variable tempo between individuals (EVID). This reflects variations Page 25 among CMD subtypes and interventions, although the literature review did not identify specific risk or mitigating factors (EVID). In the absence of immediate evidence-based practice, neurologists and other providers may, in appropriate circumstances, extrapolate from early-onset neuromuscular and neuromotor diseases for which consensus guidelines have been developed on the basis of both established principles of care and limited outcomes and intervention trials (RELA).e114-e118 There are currently no curative CMD subtype-specific interventions (EVID). Thus, all complication screening and interventions are intended to promote growth and potential development, mitigate cumulative morbidities, optimize function, and limit mortality while maximizing quality of life (EVID).e119

Recommendations.
 
C1. At the time of diagnosis, the physician should advise families regarding areas of uncertainty with respect to clinical outcomes and the value of interventions as they pertain to both longevity and quality of life. Physicians should explain the multisystem implications of neuromuscular insufficiency and guide families as they make decisions with regard to the monitoring for and treatment of CMD complications (Level B).

Section D: Respiratory complications.
Patients with respiratory failure from neuromuscular-related weakness may experience conspicuous respiratory symptoms but often do not have symptoms such as dyspnea that precede the onset of respiratory failure (RELA).e120 Noninvasive and invasive interventions are routinely utilized for children with CMD (PRIN). Pulmonologists, critical care specialists, and respiratory therapists with pediatric training and experience with neuromuscular disorders are most likely to offer treatment options that optimize respiratory outcomes and minimize infection risks and complications (PRIN).

Recommendations.
 
D1a. Physicians should counsel families of patients with CMD that respiratory insufficiency and associated problems may be inconspicuous at the outset (Level B).
D1b. Physicians should monitor pulmonary function tests such as spirometry and oxygen saturation in the awake and sleep states of patients with CMD, with monitoring levels individualized on the basis of the child’s clinical status (Level B).
D2. Physicians should refer children with CMD to pulmonary or aerodigestive care teams, when available, that are experienced in managing the interface between oropharyngeal function, gastric reflux and dysmotility, and nutrition and respiratory systems, and can provide anticipatory guidance concerning trajectory, assessment modalities, complications, and potential interventions (Level B).

Section E: Complications from dysphagia.
Patients with neuromuscular disorders often experience dysphagia (impaired swallowing), with implications for growth and nutrition (RELA).e121 Children with severe neuromuscular conditions, including CMD, may have impaired oro-pharyngeal tone and coordination, placing them at risk for aspiration and potentially limiting the beneficial effects of oral nutrition (EVID, RELA).e103,e122 Swallowing dysfunction may thus manifest as failure to thrive given nutritional limitations and abnormally high energy expenditures, and may also increase the risk of admission to critical care units and mortality (PRIN). Dysphagia may be diagnosed through standard multidisciplinary evaluations and radiologic studies (PRIN). Safe and adequate nutrition is necessary for optimal health, and thus the potential benefits of improved nutrition with a gastrostomy must be weighed against the potential risks associated with an invasive procedure (PRIN). Some patients may live far from a pediatric referral center, and thus much of their routine care may be coordinated by primary care providers (PRIN).

Recommendations.
 
E1. Neuromuscular specialists should coordinate with primary care providers to follow nutrition and growth trajectories in patients with CMD (Level B).
E2. For patients with CMD, physicians should order multidisciplinary evaluations with swallow therapists, gastroenterologists, and radiologists if there is evidence of failure to thrive or respiratory symptoms (or both) (Level B).
E3. For patients with CMD, a multidisciplinary care team, taking into account medical and family considerations, should recommend gastrostomy placement with or without fundoplication in the appropriate circumstances (Level B).

Section F: Cardiac complications.
Patients with CMD experience both functional and structural cardiac complications, but the frequency of these for many of the subtypes is unknown.e101,e102,e123-e127 On the basis of more extensive experience with cardiac complications in Duchenne MD and Becker MD, cardiac involvement may be subclinical and evident only on echocardiography or electrocardiography (or both) in the earlier stages; such involvement may be amenable to pharmacologic therapy (RELA).e128-e132

Recommendation.
 
F1. Physicians should refer children with CMD, regardless of subtype, for a baseline cardiac evaluation. The intervals of further evaluations should depend on the results of the baseline evaluation and the subtype-specific diagnosis (Level B). 


Section G: Periprocedural complications.
Patients with neuromuscular diseases are at increased risk for periprocedural complications, including airway problems, suboptimal pain control, pulmonary complications, prolonged recovery times, and complications of bed rest and deconditioning (RELA).e104,e133-e135

Recommendations.
 
G1. Prior to any surgical interventions and general anesthesia in the setting of CMD, physicians should discuss the potential increased risk of complications with patients’ families, as these factors may affect decision making with regard to whether to consent to certain elective procedures (Level B).
G2. When children with CMD undergo procedures involving sedation or general anesthesia, physicians should monitor longer than usual in the immediate postoperative period to diagnose and treat respiratory, nutritional, mobility, and gastrointestinal mobility complications (Level B).

Section H: Musculoskeletal complications.
Patients with CMD are at increased risk of musculoskeletal complications, including skeletal deformities and contractures (EVID). Range-of-motion exercises are straightforward interventions that generally do not involve significant risk to affected children, but the efficacy of such exercises has not been established in the literature (EVID). Such an exercise program may be a component of physical therapy but may also be performed by the patient and family (INFER). Data on the efficacy of bracing are also lacking for children with CMD (EVID). It is generally accepted that orthopedic surgical interventions such as heel cord–lengthening procedures relieve tendon contractures at least in the short term; however, the long-term efficacy is not clear (PRIN). Neuromuscular blocking agents (e.g., botulinum toxin) can cause prolonged worsening of weakness in patients with neuromuscular diseases (RELA).e136-e139

Recommendations.
 
H1. Physicians should refer to allied health professionals, including physical, occupational, and speech therapists; seating and mobility specialists; rehabilitation specialists; and orthopedic surgeons, to help maximize function and potentially slow the progression of musculoskeletal complications in children with CMD (Level B).
H2. Physicians may recommend range-of-motion exercises, orthotic devices, heel cord– lengthening procedures, or a combination of these interventions for children with CMD in certain circumstances (Level B).
H3. Physicians might avoid using neuromuscular blocking agents (e.g., botulinum toxin) in patients with CMD, unless the contractures are determined to cause significantly greater impairment than would any potential worsening of weakness in the targeted muscle groups (Level C).

Section I: Educational adjustments.
Prior to school age, children at risk for developmental delays are eligible for early intervention services as federally mandated. The Individuals with Disabilities Education Improvement Act of 2004 guarantees children with disabilities a free and appropriate public education (PRIN).e140

Recommendations.
 
I1. Physicians should refer children with CMD to special education advocates, developmental specialists, and education specialists when appropriate for individual circumstances (Level B).

RECOMMENDATIONS FOR FUTURE RESEARCH

Despite the advances in genetic knowledge of the CMDs, many patients appear not to have mutations in the known causative genes, an indication that novel CMD genes remain to be discovered. This is especially true for children with Walker–Warburg syndrome or with dystroglycanopathies that do not easily fit in one of the classic phenotypes. Thus, further genetic research is needed.

The clinical presentations of the various CMD subtypes have been well described, and as the genetic knowledge of these diseases becomes more complete, better genotype–phenotype correlations will be made. However, gaps in knowledge remain with regard to the clinical courses of, complications associated with, and optimal treatment regimens for the various subtypes. Standardized outcome measures would also help promote more rigorous research that would help identify complications and optimize treatment in these patients.e141 Further studies with respect to patient safety and quality improvement would be pertinent to the goal of improving the long-term outcomes for these children.

Thus, the following topics merit further research:
1. Gene discovery in CMD
2. Genotype–phenotype studies in CMDs, especially longitudinal studies
3. Frequency and risk factors for various complications in CMDs
4. The merits of various therapeutic interventions for CMDs

DISCLAIMER
Clinical practice guidelines, practice advisories, systematic reviews and other guidance published by the American Academy of Neurology and its affiliates are assessments of current scientific and clinical information provided as an educational service. The information: 1) should not be considered inclusive of all proper treatments, methods of care, or as a statement of the standard of care; 2) is not continually updated and may not reflect the most recent evidence (new evidence may emerge between the time information is developed and when it is published or read); 3) addresses only the question(s) specifically identified; 4) does not mandate any particular course of medical care; and 5) is not intended to substitute for the independent professional judgment of the treating provider, as the information does not account for individual variation among patients. In all cases, the selected course of action should be considered by the treating provider in the context of treating the individual patient. Use of the information is voluntary. AAN provides this information on an “as is” basis, and makes no warranty, expressed or implied, regarding the information. AAN specifically disclaims any warranties of merchantability or fitness for a particular use or purpose. AAN assumes no responsibility for any injury or damage to persons or property arising out of or related to any use of this information or for any errors or omissions.

CONFLICT OF INTEREST
The American Academy of Neurology and American Association of Neuromuscular & Electrodiagnostic Medicine are committed to producing independent, critical, and truthful clinical practice guidelines (CPGs). Significant efforts are made to minimize the potential for conflicts of interest to influence the recommendations of this CPG. To the extent possible, the AAN and AANEM keep separate those who have a financial stake in the success or failure of the products appraised in the CPGs and the developers of the guidelines. Conflict of interest forms were obtained from all authors and reviewed by an oversight committee prior to project initiation. AAN and AANEM limit the participation of authors with substantial conflicts of interest. The AAN and AANEM forbid commercial participation in, or funding of, guideline projects. Drafts of the guideline have been reviewed by at least three AAN committees, at least one AANEM committee, a network of neurologists, Neurology peer reviewers, and representatives from related fields. The AAN Guideline Author Conflict of Interest Policy can be viewed at www.aan.com. For complete information on this process, access the 2004 AAN process manual.e28

picture-e-1.PNG
         e-1-part-2-(2).PNG
See MuscleGeneTable.fr for current information.
Abbreviations: CMD = congenital muscular dystrophy; CMDs = congenital muscular dystrophies. 

table-e-2.PNG
Abbreviations: CMD = congenital muscular dystrophy; CMDs = congenital muscular dystrophies; CNS = central nervous system.

Appendix e-1. Glossary of terms

Congenital: Traditionally refers to diseases in which clinical manifestations are present at birth, including CMD; however, genetic discoveries suggest that patients with similar phenotypes but slightly later onset may have essentially the same diseases, and thus the term congenital muscular dystrophy is now recognized to encompass MDs with onset in the first 2 years of life, especially during infancy (the first year of life).

Founder mutation: Occurs when a population is established by a relatively small number of individuals, with the potential for a specific disease-causing mutation to propagate among a number of families who are not obviously related.

Next-generation sequencing (also known as high-throughput sequencing): Represents the first major advance in DNA sequencing technology since Sanger sequencing (see next) was developed in the 1970s. The key breakthrough was the application of massively parallel sequencing reactions to generate relatively short DNA sequences that could then be matched to the relevant sections of the reference sequence. Variations of next-generation sequencing include targeted sequence capture, whole-exome sequencing, and whole-genome sequencing.

Sanger sequencing: Discovered by Frederick Sanger in the 1970s; made DNA sequencing widely accessible to laboratories and, later, to diagnostic facilities around the world. The fundamental conceptual breakthrough was the use of modified nucleotides to determine the exact sequence of a given DNA strand.

Appendix e-2: Resources for genetic testing

A general resource that is helpful for physicians ordering genetic tests is GeneTests: GeneTests.org. This website lists facilities that offer testing for specific genes in the United States and other countries, and provides links to individual test facility websites.

In the United States, clinical testing for many of the genes discussed in this guideline is available at various facilities, including the following:
  • Baylor College of Medicine, Houston, Texas: www.bcm.edu
  • Claritas Genomics, Cambridge, Massachusetts: ClaritasGenomics.com
  • Emory Genetics Laboratory, Atlanta, Georgia: geneticslab.emory.edu
  • Prevention Genetics, Marshfield, Wisconsin: PreventionGenetics.com
  • University of Chicago Genetic Services Laboratory, Chicago, Illinois: DNATesting.@Chicago.edu

Genetic testing technology is undergoing rapid changes, and it is likely that much clinical sequencing of individual genes will be replaced by whole-exome or whole-genome sequencing (or both) within the next decade. It is not clear yet which facilities will offer the most accurate testing at the lowest cost.

Appendix e-3: 2013–2015 AAN Guideline Development Subcommittee (GDS) members
Cynthia Harden, MD (Chair); Steven R. Messé, MD, FAAN (Vice-Chair); Richard L. Barbano, MD, PhD, FAAN; Jane Chan, MD, FAAN; Diane Donley, MD; Terry Fife, MD, FAAN; Jeffrey Fletcher, MD; Michael Haboubi, MD; John J. Halperin, MD, FAAN; Cheryl Jaigobin, MD; Andres M. Kanner, MD; Jason Lazarou, MD; David Michelson, MD; Pushpa Narayanaswami, MD, MBBS; Maryam Oskoui, MD; Tamara Pringsheim, MD; Alexander Rae-Grant, MD; Kevin Sheth, MD, FAHA; Kelly Sullivan, PhD; Theresa A. Zesiewicz, MD, FAAN; Jonathan P. Hosey, MD, FAAN (Ex-Officio); Stephen Ashwal, MD, FAAN (Ex-Officio); Deborah Hirtz, MD, FAAN (Ex-Officio); Jacqueline French, MD, FAAN (Ex-Officio)

Appendix e-4: Mission statement of AAN GDS
The mission of the AAN GDS is to prioritize, develop, and publish evidence-based guidelines related to the diagnosis, treatment, and prognosis of neurological disorders. The AAN GDS is committed to using the most rigorous methods available within our budget, in collaboration with other available AAN resources, to most efficiently accomplish this mission.

Appendix e-5: AANEM Practice Issues Review Panel (PIRP) members
Yuen T. So, MD, PhD (Co-Chair); Williams S. David, MD, PhD (Co-Chair); Paul E. Barkhaus, MD; Earl J. Craig, MD; Prabhu D. Emmady, MD; Kenneth J. Gaines, MD; James F. Howard, MD; Atul T. Patel, MD; Bharathi Swaminathan, MD; Darrell T. Thomas, MD; Gil I. Wolfe, MD

Appendix e-6: Complete search strategy
The complete search strategy is available as an electronic data supplement to this article on the Neurology® website. To obtain the search strategy, locate the “appendix e-6 search strategy” pdf at Neurology.org.

Appendix e-7: AAN rules for classification of evidence for risk of bias

For questions related to therapeutic intervention

Class I
 
- Randomized, controlled clinical trial (RCT) in a representative population
- Relevant baseline characteristics are presented and substantially equivalent between treatment groups, or there is appropriate statistical adjustment for differences.
- Masked or objective outcome assessment

- Also required:
 
a. Concealed allocation
b. Primary outcome(s) clearly defined
c. Exclusion/inclusion criteria clearly defined
d. Adequate accounting for dropouts (with at least 80% of enrolled subjects completing the study) and crossovers with numbers sufficiently low to have minimal potential for bias
e. For noninferiority or equivalence trials claiming to prove efficacy for one or both drugs, the following are also required*:
 
  1. The authors explicitly state the clinically meaningful difference to be excluded by defining the threshold for equivalence or noninferiority
  2. The standard treatment used in the study is substantially similar to that used in previous studies establishing efficacy of the standard treatment (e.g., for a drug, the mode of administration, dose, and dosage adjustments are similar to those previously shown to be effective)
  3. The inclusion and exclusion criteria for patient selection and the outcomes of patients on the standard treatment are comparable to those of previous studies establishing efficacy of the standard treatment
  4. The interpretation of the study results is based on a per-protocol analysis that accounts for dropouts or crossovers

Class II
 
- Cohort study meeting criteria a–e above or an RCT that lacks one or two criteria be
- All relevant baseline characteristics are presented and substantially equivalent among treatment groups, or there is appropriate statistical adjustment for differences
- Masked or objective outcome assessment

Class III
 
- Controlled studies (including studies with external controls such as well-defined natural history controls)
- A description of major confounding differences between treatment groups that could affect outcome**
- Outcome assessment masked, objective, or performed by someone who is not a member of the treatment team

Class IV
 
- Did not include patients with the disease
- Did not include patients receiving different interventions
- Undefined or unaccepted interventions or outcome measures
- No measures of effectiveness or statistical precision presented or calculable

*Numbers 1–3 in Class Ie are required for Class II in equivalence trials. If any one of the three is missing, the class is automatically downgraded to Class III
**Objective outcome measurement: an outcome measure that is unlikely to be affected by an observer’s (patient, treating physician, investigator) expectation or bias (e.g., blood tests, administrative outcome data)

For questions related to screening (yield)

Class I
 
- Study of a cohort of patients at risk for the outcome from a defined geographic area (i.e., population based)
- The outcome is objective
- Also required:
a. Inclusion criteria defined
b. At least 80% of patients undergo the screening of interest

Class II
 
- A non-population-based, nonclinical cohort (e.g., mailing list, volunteer panel) or a general medical, neurology clinic/center without a specialized interest in the outcome. Study meets criteria a and b (see Class I)
- The outcome is objective

Class III
 
- A referral cohort from a center with a potential specialized interest in the outcome

Class IV
 
- Did not include persons at risk for the outcome
- Did not statistically sample patients, or patients specifically selected for inclusion by outcome
- Undefined or unaccepted screening procedure or outcome measure
- No measure of frequency or statistical precision calculable

Appendix e-8: Steps and rules for formulating recommendations
Constructing the recommendation and its rationale
Rationale for recommendation summarized in the Clinical Context includes three categories of premises:
  • Evidence-based conclusions for the systematic review
  •  Stipulated axiomatic principles of care
  •  Strong evidence from related conditions not systematically reviewed
Actionable recommendations include the following mandatory elements:
  • The patient population that is the subject of the recommendation
  •  The person performing the action of the recommendation statement
  •  The specific action to be performed
  •  The expected outcome to be attained
Assigning a level of obligation
Modal modifiers used to indicate the final level of obligation (LOO)
  • Level A: “Must”
  • Level B: “Should”
  • Level C: “Might”
  • Level U: No recommendation supported
LOO assigned by eliciting panel members’ judgments regarding multiple domains, using a modified Delphi process. Goal is to attain consensus after a maximum of three rounds of voting. Consensus is defined by:
  •  > 80% agreement on dichotomous judgments
  •  >80% agreement, within one point for ordinal judgments
  •  If consensus obtained, LOO assigned at the median. If not obtained, LOO assigned at the 10th percentile
Three steps used to assign final LOO:
1. Initial LOO determined by the cogency of the deductive inference supporting the recommendation on the basis of ratings within four domains. Initial LOO anchored to lowest LOO supported by any domain
  • Confidence in evidence. LOO anchored to confidence in evidence determined by modified form of the Grading of Recommendations Assessment, Development and Evaluation processe154
    • Level A: High confidence
    • Level B: Moderate confidence
    • Level C: Low confidence
    • Level U: Very low confidence
  • Soundness of inference assuming all premises are true. LOO anchored to proportion of panel members convinced of soundness of the inference
    • Level A: 100%
    • Level B: >80% to < 100%
    • Level C: >50% to <80%
    • Level U or R: <50%
  • Acceptance of axiomatic principles: LOO anchored to proportion of panel members who accept principles
    • Level A: 100%
    • Level B: >80% to < 100%
    • Level C: >50% to <80%
    • Level U or R: <50%
  • Belief that evidence cited from rerated conditions is strong: LOO anchored to proportion of panel members who believe the related evidence is strong
    • Level B: >80% to 100% (recommendations dependent on inferences from nonsystematically reviewed evidence cannot be anchored to a Level A LOO)
    • Level C: >50% to <80%
    • Level U or R: <50%
2. LOO is modified mandatorily on the basis of the judged magnitude of benefit relative to harm expected to be derived from complying with the recommendation
  • Magnitude relative to harm rated on 4-point ordinal scale
    • Large benefit relative to harm: benefit judged large, harm judged none
    • Moderate benefit relative to harm: benefit judged large, harm judged minimal; or benefit judged moderate, harm judged none
    • Small benefit relative to harm: benefit judged large, harm judged moderate; or benefit judged moderate, harm judged minimal; or benefit judged small, harm judged none
    • Benefit to harm judged too close to call: Benefit and harm judged to be equivalent
  • Regardless of cogency of the recommendation the LOO can be no higher than that supported by the rating of the magnitude of benefit relative to harm
    • Level A: Large benefit relative to harm
    • Level B: Moderate benefit relative to harm
    • Level C: Small benefit relative to harm
    • Level U: Too close to call
  • LOO can be increased by one grade if LOO corresponding to benefit relative to harm greater than LOO corresponding to the cogency of the recommendation
3. LOO optionally downgraded on the basis of the following domains
  • Importance of the outcome: critical, important, mildly important, not important
  • Expected variation in patient preferences: none, minimal, moderate, large
  • Financial burden relative to benefit expected: none, minimal, moderate, large 
  • Availability of intervention: universal, usually, sometimes, limited

Appendix-9e.PNG
When genetic counselors are available to help families understand genetic test results and make family-planning decisions, physicians caring for patients with CMD might help families access such resources (Level B).

Page-46-a.PNG
Physicians should use relevant clinical features such as ethnicity and geographic location, patterns of weakness and contractures, the presence or absence of CNS involvement, the timing and severity of other organ involvement, and serum CK levels to guide diagnosis in collagenopathies and in dystroglycanopathies (Level B).

Page-46b.PNG
Physicians might order muscle biopsies that include immunohistochemical staining for relevant proteins in CMD cases for which the subtype-specific diagnosis is not apparent after initial diagnostic studies, if the risk associated with general anesthesia is determined to be acceptable (Level C).

Page-46c.PNG
When muscle biopsies are indicated in suspected CMD cases, they should be performed and interpreted at centers experienced in this test modality. In some cases, optimal diagnostic information may be derived when the biopsy is performed at one center and interpreted at another (Level B).

Page-47a.PNG
Physicians should order brain MRI scans to assist with the diagnosis of patients who are clinically suspected of having certain CMD subtypes, such as merosinopathies and dystroglycanopathies, if the potential risk associated with any sedation is determined to be acceptable and if a radiologist or other physician with the appropriate expertise is available to interpret the findings (Level B).

page-47b.PNG
Physicians might order muscle imaging studies of the lower extremities for individuals suspected of having certain CMD subtypes such as collagenopathies (ultrasound or MRI) and SEPN1- related myopathy (MRI), if the risk of any sedation needed is determined to be acceptable and if a radiologist or other physician with the appropriate expertise is available to interpret the findings (Level C).

page-48a.PNG
When available and feasible, physicians might order targeted genetic testing for specific CMD subtypes that have well-characterized molecular causes (Level C).

page-48b.PNG
In individuals with CMD who either do not have a mutation identified in one of the commonly associated genes or have a phenotype whose genetic origins have not been well characterized, physicians might order whole-exome or whole-genome sequencing when those technologies become more accessible and affordable for routine clinical use (Level C).

Page-48c.PNG
At the time of diagnosis, the physician should advise families regarding areas of uncertainty with respect to clinical outcomes and the value of interventions as they pertain to both longevity and
quality of life. Physicians should explain the multisystem implications of neuromuscular insufficiency and guide families as they make decisions with regard to the monitoring for and treatment of CMD complications (Level B).

page-49a.PNG
Physicians should counsel families of patients with CMD that respiratory insufficiency and associated problems may be inconspicuous at the outset (Level B).

page-49b.PNG
Physicians should monitor pulmonary function tests such as spirometry and oxygen saturation in the awake and sleep states of patients with CMD, with monitoring levels individualized on the basis of the child’s clinical status (Level B).

Page-49c.PNG
Physicians should refer children with CMD to pulmonary or aerodigestive care teams, when available, that are experienced in managing the interface between oro-pharyngeal function, gastric reflux and dysmotility, and nutrition and respiratory systems, and can provide anticipatory guidance concerning trajectory, assessment modalities, complications, and potential interventions (Level B).

page-50a.PNG
Neuromuscular specialists should coordinate with primary care providers to follow nutrition and growth trajectories in patients with CMD (Level B).

page-50b.PNG
For patients with CMD, physicians should order multidisciplinary evaluations with swallow therapists, gastroenterologists, and radiologists if there is evidence of failure to thrive or respiratory symptoms (or both) (Level B).
51a.PNG
For patients with CMD, a multidisciplinary care team, taking into account medical and family considerations, should recommend gastrostomy placement with or without fundoplication in the appropriate circumstances (Level B).

51b.PNG
Physicians should refer children with CMD, regardless of subtype, for a baseline cardiac evaluation. The intervals of further evaluations should depend on the results of the baseline evaluation and the subtype-specific diagnosis (Level B).

51c.PNG
Prior to any surgical interventions and general anesthesia in the setting of CMD, physicians should discuss the potential increased risk of complications with patients’ families, as these factors may affect decision making with regard to whether to consent to certain elective procedures (Level B).

52a.PNG
When children with CMD undergo procedures involving sedation or general anesthesia, physicians should monitor longer than usual in the immediate postoperative period to diagnose and treat respiratory, nutritional, mobility, and gastrointestinal mobility complications (Level B).

52b.PNG
Physicians should refer to allied health professionals, including physical, occupational, and speech therapists; seating and mobility specialists; rehabilitation specialists; and orthopedic surgeons, to help maximize function and potentially slow the progression of musculoskeletal complications in children with CMD (Level B).
53a.PNG
Physicians may recommend range-of-motion exercises, orthotic devices, heel cord–lengthening procedures, or a combination of these interventions for children with CMD in certain circumstances (Level B).

53b.PNG
Physicians might avoid using neuromuscular blocking agents (e.g., botulinum toxin) in patients with CMD, unless the contractures are determined to cause significantly greater impairment than would any potential worsening of weakness in the targeted muscle groups (Level C).

53c.PNG
Physicians should refer children with CMD to special education advocates, developmental specialists, and education specialists when appropriate for individual circumstances (Level B).

54a.PNG

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