Myotonic Muscular Dystrophy Type 1
Guidance for primary care clinicians diagnosing and managing children with myotonic muscular dystrophy
Myotonic muscular dystrophy is a multisystem disorder that affects the brain, skeletal and smooth muscles, eyes, heart, gastrointestinal tract, lungs, and endocrine system. The 2 forms, type 1 and type 2, are caused by different gene mutations. Type 2 has no congenital or early childhood form and is not discussed further here. Type 1 can be classified into mild (late onset), classic (adult onset), childhood/juvenile, and congenital forms. The classification describes a continuum ranging from mild to severe disease, which generally correlates with trinucleotide repeat (CTG) length. Myotonic muscular dystrophy type 1 is a progressive condition; repeat expansion and RNA splicing dysregulation increases over time and leads to a gradual worsening in many domains, including cognition, muscle strength, and others.
Key Points
Myotonic muscular dystrophy type 1 may present as global developmental
delay
Early myotonic muscular dystrophy may present as a global
developmental delay in a child with an uneventful birth. The characteristic
myotonia is not present until later in childhood, and the typical facial
features may not be obvious unless the provider is aware of the potential for
this underlying diagnosis in a child with developmental delays.
Assess cardiac symptoms immediately
Any symptoms suggestive of cardiac arrhythmia (e.g., chest pain
with exertion, light-headedness, or palpitations) should be taken seriously.
Manage fatigue
Fatigue is an ongoing problem. Clinically, this is observed in
older children who still need naps to function well. Consider a sleep study for
obstructive or central sleep apnea when fatigue or daytime sleepiness are
present. School accommodations may be necessary for children with fatigue. [Johnson: 2015]
Consider suggesting a disability placard for the family's car to help conserve
the child's energy while out of the house; even if the child is only going to
run around at a park, the child should conserve energy to get to the play
area.
Complications with anesthesia
Individuals with myotonic
muscular dystrophy type 1, even those with mild manifestations, have a higher
rate of complications associated with general anesthesia. Families should be
educated about this possibility and reminded of this during well-child visits.
[Mangla: 2019] See the anesthesia guidelines available at Anesthesia & Myotonic Dystrophy - Risks & Recommendations (MDF).
Medication considerations
Begin any
sedating medications at half the typical dose. These patients are sensitive to
sedating medications and are at risk for associated respiratory depression. Any
medication that prolongs the QT should be evaluated in the context of that
patient's current ECG. Often, pain is myotonia. Rather than traditional pain
medications, consider trying anti-myotonia medications. Statins may lead to
increasing muscle weakness and pain.
Incidence of diabetes
Individuals with myotonic muscular dystrophy type 1 may have
insulin resistance that sometimes develops into diabetes, even in the absence of
obesity.
Bacterial infections
There is an increased risk of pneumonia in the setting of upper
respiratory infections due to weakness of the muscles required for
optimal respiration.
Guidelines
Standard of care guidelines were first published in 2010 and updated in 2018 to include new recommendations on the transition from pediatric to adult care, endocrine management, primary care, and emergency management. No practice guidelines have been published. Guidance based on expert opinion includes:
Lagrue E, Dogan C, De Antonio M, Audic F, Bach N, Barnerias C, Bellance R, Cances C, Chabrol B, Cuisset JM, Desguerre I, Durigneux
J, Espil C, Fradin M, Héron D, Isapof A, Jacquin-Piques A, Journel H, Laroche-Raynaud C, Laugel V, Magot A, Manel V, Mayer
M, Péréon Y, Perrier-Boeswillald J, Peudenier S, Quijano-Roy S, Ragot-Mandry S, Richelme C, Rivier F, Sabouraud P, Sarret
C, Testard H, Vanhulle C, Walther-Louvier U, Gherardi R, Hamroun D, Bassez G.
A large multicenter study of pediatric myotonic dystrophy type 1 for evidence-based management.
Neurology.
2019;92(8):e852-e865.
PubMed abstract
Johnson NE, Aldana EZ, Angeard N, Ashizawa T, Berggren KN, Marini-Bettolo C, Duong T, Ekström AB, Sansone V, Tian C, Hellerstein
L, Campbell C.
Consensus-based care recommendations for congenital and childhood-onset myotonic dystrophy type 1.
Neurol Clin Pract.
2019;9(5):443-454.
PubMed abstract / Full Text
Diagnosis
Presentations
Diagnostic Criteria & Classifications
- Myotonic muscular dystrophy type 1, the most common type, results from an abnormal DNA expansion (CTG) in the DMPK gene on chromosome 19, causing mis-splicing of mRNAs, affecting all organs.
- Myotonic muscular dystrophy type 2 arises from an abnormal expansion of DNA (CCTG) in the first intron of CNBP (cellular nucleic acid binding protein). Unlike myotonic muscular dystrophy type 1, where the number of repeats is roughly correlated with the severity of the disease, there is no correlation between phenotype and repeat length.
Genetics & Inheritance
Prevalence
Differential Diagnosis
Comorbid Conditions
Prognosis
Age of onset and severity of symptoms are variable. Mild presentation can involve cataracts and mild myotonia. Severe presentation can involve breathing issues, swallowing problems, or life-threatening cardiac arrhythmias. While no cure or treatment slows myotonic muscular dystrophy's progression, early intervention can reduce or eliminate some complications.
Treatment & Management
Although children with myotonic dystrophy often seem to be doing fairly well, a survey performed in the US and Canada revealed that children with myotonic dystrophy are concerned about communication and hand/finger problems. Parents were also concerned about their child’s communication but also noted that fatigue was a major problem in daily functioning. [Johnson: 2015] [Hagerman: 2019]
Knockdown of the toxic repeat expansion may be possible using antisense oligonucleotides. A clinical trial (NCT02312011) tested this approach. We expect others to continue to improve on this approach in the near future. Gene therapy for myotonic dystrophy is likely still years away, but adeno-associated viral vector gene therapy is being worked on. [Crudele: 2019]
Since myotonic muscular dystrophy type 1 is a multi-system disease:
- Perform a complete, age-appropriate evaluation in all children. Initiate developmental therapies based on delays. Intellectual disability and other psychological symptoms are seen in more than half of children with congenital myotonic muscular dystrophy. A neuropsychological profile may be helpful.
- Children with MMD require an ECG yearly to screen for progressive arrhythmias, atrial fibrillation, and conduction defects (less commonly cardiac muscle problems). Any detection of an early arrhythmia, most commonly first-degree heart block, requires an urgent evaluation by a cardiologist.
- Consider a barium swallow study for symptoms of dysphagia, drooling, or frequent pulmonary infections that may be due to silent aspiration.
- Ophthalmologic evaluation should be performed at diagnosis. Although cataracts (posterior subcapsular/cortical type) are unusual in young children, strabismus and ptosis are common.
- Children may have thyroid function and diabetes; consider annual screening with a TSH and HbA1c.
- Screen for sensorineural hearing loss, which is present in more than half of individuals with myotonic muscular dystrophy type 1.
- Children should have a sleep study at diagnosis or when new symptoms of daytime sleepiness occur to screen for sleep apnea. Sleep and fatigue are often reported as the most debilitating symptoms of myotonic muscular dystrophy type 1.
Children should be managed within a medical home, with input from the family, unless a multidisciplinary Neuromuscular Clinic (see Neuromuscular Clinics (see OH providers [0])) is available. The goal is to avoid duplication of services or unnecessary appointments while still seeing the subspecialists needed. All screening and interventions are intended to promote growth and potential development, mitigate cumulative morbidities, optimize function, and limit mortality while maximizing quality of life. [Kang: 2015]
Neurology
Development
Musculoskeletal
Rehab/Mobility/Function
Sleep
Cardiology
Gastro-Intestinal & Bowel Function
Respiratory
Communication
Nose, Throat, Mouth, Swallowing
Nutrition, Growth, Bone
Maturation/Sexual/Reproductive
Endocrine/Metabolism
Recreation
Eyes/Vision
Dental
Surgery
Transitions
Services & Referrals
Neuromuscular Clinics
(see OH providers
[0])
Referral to a muscular dystrophy clinic for evaluation and genetic
testing is recommended. Neurology follow-up may be available at specialized
clinics.
Pediatric Orthopedics
(see OH providers
[0])
Consider a baseline visit with follow-up as necessary. Children
with joint contractures and/or scoliosis may be managed concurrently with
pediatric orthopedics.
Pediatric Gastroenterology
(see OH providers
[0])
The medical home should order multidisciplinary evaluations with
swallow therapists, gastroenterologists, and radiologists if there is evidence
of failure to thrive or respiratory symptoms (or both). Consider a referral for
constipation, reflux, and/or failure to gain adequate weight.
Pediatric Physical Medicine & Rehabilitation
(see OH providers
[0])
Consider a referral to evaluate development and recommend
interventions aimed at increasing function.
Physical Therapy
(see OH providers
[1])
Refer when help is needed for muscle strengthening, dealing with
fatigue, or for a stander, walker, or wheelchair fitting. A consultation can
help with school and home adaptations (e.g., the child who wants a bike for a
present, but the parents don't know what to purchase, or the child is interested
in obtaining a sporting wheelchair). Also, refer for range-of-motion exercises,
orthotic devices, heel cord lengthening procedures, or a combination of these
interventions for children as needed.
Pediatric Cardiology
(see OH providers
[0])
Clinicians should refer children with myotonic dystrophy for a
baseline cardiac evaluation. The intervals of further evaluations should depend
on the results of the baseline evaluation. [Kang: 2015] Exercise testing should be
considered.
Medical Genetics
(see OH providers
[0])
A consultation is recommended to help with diagnosis and to help
families understand genetic test results so they can make family-planning
decisions. [Kang: 2015] If the family has further questions about the genetics of
myotonic muscular dystrophy type 1, consider re-evaluation. Genetic counseling
for teens with congenital muscular dystrophy should be offered on a
developmentally appropriate basis.
Pediatric Neurology
(see OH providers
[0])
If an MMD or other muscle disease clinic is not available, the
child should be referred to pediatric neurology and/or genetics, depending on
local expertise, for a baseline exam and periodic assessments as needed and to
monitor weakness and developmental issues.
Pediatric Pulmonology
(see OH providers
[0])
When available, refer to pulmonary or aerodigestive care teams
with experience managing the interface among oropharyngeal function, gastric
reflux and dysmotility, nutrition, and respiratory systems and providing
anticipatory guidance concerning trajectory, assessment modalities,
complications, and potential interventions. [Kang: 2015]
ICD-10 Coding
G71.11, Myotonic muscular dystrophy
ICD-10 for Myotonic Muscular Dystrophy (icd10data.com) provides further coding details.
Resources
Information & Support
Related Portal Content
The Portal provides related general diagnosis and management
information, including:
- Drooling in Children with Special Health Care Needs
- Gastroesophageal Reflux Disease
- Dental and Oral Health Screening
- Feeding Tubes & Gastrostomies in Children
- Mental Health Screening for Children & Teens
- Boosting Calories for Babies, Toddlers, and Older Children
- Intellectual Disability and Global Developmental Delay (FAQ)
- Constipation
- Myotonic Muscular Dystrophy (FAQ)
- Guardianship/Estate Planning
- Management and Prevention of Constipation in Children
- School Accommodations: IEPs & 504s
For Professionals
Myotonic Dystrophy Type 1 (GeneReviews)
Detailed information addressing clinical characteristics, diagnosis/testing, management, genetic counseling, and molecular
pathogenesis; from the University of Washington and the National Library of Medicine.
Myotonic Dystrophy (OMIM)
Information about clinical features, diagnosis, management, and molecular and population genetics; Online Mendelian Inheritance
in Man, authored and edited at the McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine
Myotonic Muscular Dystrophy Type 1 (Orphanet)
Overview of MMD1 (aka Steinert myotonic dystrophy) and links to more information, services, and other resources; from Orphanet,
a French-coordinated consortium involving over 40 countries to provide a portal for information about rare diseases and orphan
drugs.
Myotonic Muscular Dystrophy Type 2 (Orphanet)
Overview of MMD2 (aka proximal myotonic myopathy) and links to more information, services, and other resources; from Orphanet,
a French-coordinated consortium involving over 40 countries to provide a portal for information about rare diseases and orphan
drugs.
For Parents and Patients
Facts about Myotonic Muscular Dystrophy (MDA)
Excellent overview of myotonic muscular dystrophy written for the family and patient; Muscular Dystrophy Association.
Myotonic Dystrophy Foundation
A non-profit that provides adaptive equipment and emotional support to individuals and families affected by any of the neuromuscular
diseases.
Muscular Dystrophy Association
The Muscular Dystrophy Association (MDA) covers many conditions including CMT, Duchenne muscular dystrophy, and spinal muscular
atrophy. More information about these conditions, how to register, and clinic locations can be found here.
Muscular Dystrophy (NINDS)
Information about muscular dystrophy, treatment, prognosis, research, and links to other organizations; National Institute
of Neurological Disorders and Stroke.
Services for Patients & Families in Ohio (OH)
Service Categories | # of providers* in: | OH | NW | Other states (4) (show) | | NM | NV | RI | UT |
---|---|---|---|---|---|---|---|---|---|
Medical Genetics | 1 | 2 | 5 | 4 | 7 | ||||
Neuromuscular Clinics | 1 | 1 | 2 | 3 | 3 | ||||
Pediatric Cardiology | 3 | 4 | 17 | 4 | |||||
Pediatric Gastroenterology | 2 | 5 | 18 | 2 | |||||
Pediatric Neurology | 5 | 5 | 18 | 8 | |||||
Pediatric Orthopedics | 4 | 7 | 8 | 16 | 10 | ||||
Pediatric Physical Medicine & Rehabilitation | 3 | 3 | 3 | 6 | 11 | ||||
Pediatric Pulmonology | 4 | 4 | 6 | 3 | |||||
Physical Therapy | 12 | 9 | 7 | 40 |
For services not listed above, browse our Services categories or search our database.
* number of provider listings may vary by how states categorize services, whether providers are listed by organization or individual, how services are organized in the state, and other factors; Nationwide (NW) providers are generally limited to web-based services, provider locator services, and organizations that serve children from across the nation.
Studies
Clinical Trials in Myotonic type 1 (clinicaltrials.gov)
Studies looking at better understanding, diagnosing, and treating this condition; from the National Library of Medicine.
Authors & Reviewers
Author: | Lynne M. Kerr, MD, PhD |
Reviewer: | Nicholas Johnson, MD, MS-CI |
2023: update: Lynne M. Kerr, MD, PhDA; Russell Butterfield, MD, PhDR |
2020: update: Mary A. Murray, MDCA; Vandana Raman, MDCA |
2016: update: Meghan S Candee, MD, MScR; Nicholas Johnson, MD, MS-CIR |
2013: first version: Nicholas Johnson, MD, MS-CIA; Lynne M. Kerr, MD, PhDA |
Page Bibliography
Bassez G, Lazarus A, Desguerre I, Varin J, Laforêt P, Bécane HM, Meune C, Arne-Bes MC, Ounnoughene Z, Radvanyi H, Eymard B,
Duboc D.
Severe cardiac arrhythmias in young patients with myotonic dystrophy type 1.
Neurology.
2004;63(10):1939-41.
PubMed abstract
Canavese F, Sussman MD.
Orthopaedic manifestations of congenital myotonic dystrophy during childhood and adolescence.
J Pediatr Orthop.
2009;29(2):208-13.
PubMed abstract
Crudele JM, Chamberlain JS.
AAV-based gene therapies for the muscular dystrophies.
Hum Mol Genet.
2019;28(R1):R102-R107.
PubMed abstract / Full Text
Ekström AB, Hakenäs-Plate L, Samuelsson L, Tulinius M, Wentz E.
Autism spectrum conditions in myotonic dystrophy type 1: a study on 57 individuals with congenital and childhood forms.
Am J Med Genet B Neuropsychiatr Genet.
2008;147B(6):918-26.
PubMed abstract
Groh WJ.
Arrhythmias in the muscular dystrophies.
Heart Rhythm.
2012;9(11):1890-5.
PubMed abstract
Hagerman KA, Howe SJ, Heatwole CR.
The myotonic dystrophy experience: a North American cross-sectional study.
Muscle Nerve.
2019;59(4):457-464.
PubMed abstract / Full Text
Ho G, Cardamone M, Farrar M.
Congenital and childhood myotonic dystrophy: Current aspects of disease and future directions.
World J Clin Pediatr.
2015;4(4):66-80.
PubMed abstract / Full Text
Johnson NE.
Myotonic Muscular Dystrophies.
Continuum (Minneap Minn).
2019;25(6):1682-1695.
PubMed abstract
Johnson NE, Abbott D, Cannon-Albright LA.
Relative risks for comorbidities associated with myotonic dystrophy: A population-based analysis.
Muscle Nerve.
2015;52(4):659-61.
PubMed abstract / Full Text
Johnson NE, Aldana EZ, Angeard N, Ashizawa T, Berggren KN, Marini-Bettolo C, Duong T, Ekström AB, Sansone V, Tian C, Hellerstein
L, Campbell C.
Consensus-based care recommendations for congenital and childhood-onset myotonic dystrophy type 1.
Neurol Clin Pract.
2019;9(5):443-454.
PubMed abstract / Full Text
Johnson NE, Ekstrom AB, Campbell C, Hung M, Adams HR, Chen W, Luebbe E, Hilbert J, Moxley RT 3rd, Heatwole CR.
Parent-reported multi-national study of the impact of congenital and childhood onset myotonic dystrophy.
Dev Med Child Neurol.
2015.
PubMed abstract / Full Text
Kang PB, Morrison L, Iannaccone ST, Graham RJ, Bönnemann CG, Rutkowski A, Hornyak J, Wang CH, North K, Oskoui M, Getchius
TS, Cox JA, Hagen EE, Gronseth G, Griggs RC.
Evidence-based guideline summary: 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.
Neurology.
2015;84(13):1369-78.
PubMed abstract / Full Text
Endorsed by the American Academy of Pediatrics in March 2015.
Lagrue E, Dogan C, De Antonio M, Audic F, Bach N, Barnerias C, Bellance R, Cances C, Chabrol B, Cuisset JM, Desguerre I, Durigneux
J, Espil C, Fradin M, Héron D, Isapof A, Jacquin-Piques A, Journel H, Laroche-Raynaud C, Laugel V, Magot A, Manel V, Mayer
M, Péréon Y, Perrier-Boeswillald J, Peudenier S, Quijano-Roy S, Ragot-Mandry S, Richelme C, Rivier F, Sabouraud P, Sarret
C, Testard H, Vanhulle C, Walther-Louvier U, Gherardi R, Hamroun D, Bassez G.
A large multicenter study of pediatric myotonic dystrophy type 1 for evidence-based management.
Neurology.
2019;92(8):e852-e865.
PubMed abstract
Mangla C, Bais K, Yarmush J.
Myotonic Dystrophy and Anesthetic Challenges: A Case Report and Review.
Case Rep Anesthesiol.
2019;2019:4282305.
PubMed abstract / Full Text
Modoni A, Silvestri G, Pomponi MG, Mangiola F, Tonali PA, Marra C.
Characterization of the pattern of cognitive impairment in myotonic dystrophy type 1.
Arch Neurol.
2004;61(12):1943-7.
PubMed abstract / Full Text
Morgan AT, Dodrill P, Ward EC.
Interventions for oropharyngeal dysphagia in children with neurological impairment.
Cochrane Database Syst Rev.
2012;10:CD009456.
PubMed abstract
Norwood FL, Harling C, Chinnery PF, Eagle M, Bushby K, Straub V.
Prevalence of genetic muscle disease in Northern England: in-depth analysis of a muscle clinic population.
Brain.
2009;132(Pt 11):3175-86.
PubMed abstract / Full Text
Peglar LM, Nagaraj UD, Tian C, Venkatesan C.
White Matter Lesions Detected by Magnetic Resonance Imaging in Neonates and Children With Congenital Myotonic Dystrophy.
Pediatr Neurol.
2019;96:64-69.
PubMed abstract
Pratte A, Prévost C, Puymirat J, Mathieu J.
Anticipation in myotonic dystrophy type 1 parents with small CTG expansions.
Am J Med Genet A.
2015;167A(4):708-14.
PubMed abstract
Theadom A, Rodrigues M, Roxburgh R, Balalla S, Higgins C, Bhattacharjee R, Jones K, Krishnamurthi R, Feigin V.
Prevalence of muscular dystrophies: a systematic literature review.
Neuroepidemiology.
2014;43(3-4):259-68.
PubMed abstract / Full Text
Wenninger S, Montagnese F, Schoser B.
Core Clinical Phenotypes in Myotonic Dystrophies.
Front Neurol.
2018;9:303.
PubMed abstract / Full Text
Wheeler TM, Thornton CA.
Myotonic dystrophy: RNA-mediated muscle disease.
Curr Opin Neurol.
2007;20(5):572-6.
PubMed abstract