Home > Diagnoses & Conditions > Myotonic muscular dystrophy type 1 > Initial Diagnosis
Myotonic muscular dystrophy type 1 - Initial Diagnosis
Overview
It is easy to miss the diagnosis of myotonic muscular dystrophy (MMD) in babies unless the diagnosis is kept in mind when considering a child with respiratory and/or feeding problems, hypotonia, and/or global developmental delays without a family history of the disease. When presented with these problems in a newborn or infant, assess the face of the mother (and father) for weakness, ptosis, and hollow temples. To further assess the parents, you can perform percussion myotonia testing on tongue and thenar eminences. Also, have the parent close eyes and fists and hold them tight for several minutes and then ask him or her to let them go suddenly. Individuals with myotonia demonstrate a slow release. An electromyogram in the parent may also demonstrate myotonia associated with MMD if it is not clinically apparent.Presentations
Babies with congenital MMD may be identified at birth with severe hypotonia, positional problems such as club feet and hip dysplasia, and breathing and swallowing problems. These latter two may be severe enough to require ventilation and tube feeding, sometimes for prolonged periods of time. Less severely affected babies may be identified when they fail to meet early developmental milestones. Individuals with classic or mild MMD1 and MMD2 tend to present later, and have less severe disease.Diagnostic Criteria
Diagnosis is made by molecular testing confirming presence of the CTG repeat expansion in the DMPK gene of chromosome 19.Pearls And Alerts
The early presentation of MMD in a child who had an uneventful birth may be only global developmental delays. The characteristic myotonia is not present until later in childhood, and the typical facial features may not be obvious unless the provider is keeping this diagnosis in mind for a child with developmental delays.
Differential Diagnosis
If the possibility of MMD is not considered, many other much less common muscle and nerve diseases may be in the differential. These include distal muscular dystrophies and Dejerine Sottas disease, a type of hereditary motor sensory neuropathy, that would be found during EMG/NCV testing, and hyperkalemic periodic paralysis, which presents with episodic weakness. Because of the intellectual disability associated with MMD, diseases of the central nervous system may also be considered. Metabolic testing is normal in myotonic dystrophy. Although brain MRI is usually normal in individuals with MMD, it may show periventricular myelin changes that could be interpreted as perinatal hypoxic/ischemic injury. [Modoni: 2004]History And Examination
Family History
Ask about a family history of early heart disease or pacemaker use, severe fatigue, early cataracts, learning problems, and distal muscle weakness. Remember to examine the mother who may have undiagnosed MMD.Pregnancy/Perinatal History
Ask about a history of polyhydramnios and decreased fetal movements. Ask about a prolonged or complicated labor. Ask about the presence of developmental hip dysplasia and/or club feet. Ask about breathing and feeding problems near birth, including the ability to breast/bottle feed, and any difficulty learning to eat as an infant or failure to thrive.Medical History
Ask about a history of swallowing problems, aspiration, frequent drooling, respiratory illnesses, fatigue.Developmental and Educational History
Determine when developmental milestones were achieved. Inquire about IQ, learning disabilities, attention, and educational success.Social and Family History
Ask about family members and level of functioning, including learning disabilities and fatigue. Identify resources available to help cope with the diagnosis of MMD in an infant/child.Physical Exam
General
Children with MMD may have decreased facial expression due to weakness of the facial muscles. A high arched palate may be noted. Drooling may be present.HEENT
Children with congenital MMD have facial muscle weakness, leading to a bland expression and an upper lip that comes to a point — known as a tented upper lip. Ptosis may be present. They have a characteristic long face with hollowing at the temples. Adolescent males may have early balding at the temples.Testing
Sensory Testing
Ophthalmologic evaluation should be performed at diagnosis in any child with MMD. Although cataracts are unusual in young children, strabismus and ptosis are fairly common. Hearing problems are also common and hearing testing should also be performed at the time of diagnosis.Genetic Testing
Genetic testing for MMD types 1 and 2 is readily available and fairly inexpensive. See Myotonic dystrophy 1 testing (GeneClinics).Other Testing
Swallow study-Consider a barium swallow study if there are symptoms of dysphagia or frequent pulmonary infections that may be due to silent aspiration.Developmental and IQ testing-The incidence of ID in congenital MMD is 50-60%. A complete evaluation, which will vary with the child's age, should be performed in all children with congenital MMD. Appropiate developmental therapies based on delays present should be initiated.
Subspecialist Collaborations and Other Resources
Muscular Dystrophy Clinics (see Services below for relevant providers)
Referral to an MDA Clinic for evaluation and genetic testing is recommended.
Pediatric Neurology (see Services below for relevant providers)
If an MDA or other Muscle Disease specific clinic is not available, the child should be referred to pediatric neurology and/or genetics, depending on local expertise.
Pediatric Medical Genetics (see Services below for relevant providers)
If an MDA or other Muscle Disease specific clinic is not available, the child should be referred to genetics or pediatric neurology, depending on local expertise.
Pediatric Physical Medicine & Rehab (see Services below for relevant providers)
Consider a referral to a pediatric physiatrist to evaluate development and recommend interventions aimed at increasing function.
Resources
Information & Support
For Professionals
Myotonic dystrophy 1 (GeneReviews)
Myotonic muscular dystrophy (OMIM)
From the Online Mendelian Inheritance in Man site, hosted by Johns Hopkins University, providing technical information for
providers on genetic disorders, links to MEDLINE, and links to other scientific information and sites.
For Parents and Patients
General
Myotonic dystrophy (Genetics Home Reference)
Information for patients/families from Genetics Home Reference, sponsored by the National Library of Medicine
Facts about myotonic muscular dystrophy (MDA)
Excellent overview of myotonic muscular dystrophy written for the family/patient, on the Muscular Dystrophy Association site
(www.mdusa.org).
Services
Muscular Dystrophy Clinics
See all Muscular Dystrophy Clinics services providers (1) in our database.
Pediatric Medical Genetics
See all Pediatric Medical Genetics services providers (3) in our database.
Pediatric Physical Medicine & Rehab
See all Pediatric Physical Medicine & Rehab services providers (6) in our database.
For other services related to this condition, browse our Services categories or search our database.
Helpful Articles
PubMed search for articles on Myotonic Dystrophy in children for the last 5 years.
Schara U, Schoser BG.
Myotonic dystrophies type 1 and 2: a summary on current aspects.
Semin Pediatr Neurol.
2006;13(2):71-9.
PubMed abstract
Lee JE, Cooper TA.
Pathogenic mechanisms of myotonic dystrophy.
Biochem Soc Trans.
2009;37(Pt 6):1281-6.
PubMed abstract
Kaliman P, Llagostera E.
Myotonic dystrophy protein kinase (DMPK) and its role in the pathogenesis of myotonic dystrophy 1.
Cell Signal.
2008;20(11):1935-41.
PubMed abstract
Hsu DT.
Cardiac manifestations of neuromuscular disorders in children.
Paediatr Respir Rev.
2010;11(1):35-8.
PubMed abstract
Angeard N, Gargiulo M, Jacquette A, Radvanyi H, Eymard B, Héron D.
Cognitive profile in childhood myotonic dystrophy type 1: is there a global impairment?.
Neuromuscul Disord.
2007;17(6):451-8.
PubMed abstract
Authors
| Authors: | Jacinda B Sampson MD, PhD, 5/2010 Lynne M Kerr MD, PhD, 3/2010 |
| Content Last Updated: | 3/2010 |
Page Bibliography
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