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Emergency: requires immediate attention
Myotonic dystrophy
Other Resources UpToDate PubMed
Emergency: requires immediate attention

Myotonic dystrophy

Contributors: Andrea Wasilewski MD, Jamie Adams MD, Richard L. Barbano MD, PhD
Other Resources UpToDate PubMed

Synopsis

Myotonic dystrophy is an autosomal dominant, inherited, progressive disorder affecting the muscles. The disorder is characterized by muscle wasting, weakness, and myotonia (delayed relaxation of muscle). Wasting of the temporalis and masseter muscles combined with frontal balding results in its characteristic appearance. Patients have other abnormalities including cataracts, heart conduction defects, dysphagia, excessive daytime somnolence, and mild cognitive impairment.

Myotonic dystrophy type 1 has distal weakness, with myotonia prominent in the hands; type 2 has proximal muscle weakness (also called PROMM or proximal myotonic myopathy). The signs and symptoms of myotonic dystrophy typically manifest in the third or fourth decade, although they can occur at any age.

Congenital myotonic dystrophy can occur in neonates born to affected mothers. These children have a severe phenotype with prominent weakness, hypotonia, skeletal abnormalities, feeding difficulties, and respiratory distress at birth.

Codes

ICD10CM:
G71.11 – Myotonic muscular dystrophy

SNOMEDCT:
77956009 – Steinert myotonic dystrophy syndrome

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Differential Diagnosis & Pitfalls

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Therapy

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References

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Last Reviewed:10/18/2018
Last Updated:01/20/2022
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Emergency: requires immediate attention
Myotonic dystrophy
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A medical illustration showing key findings of Myotonic dystrophy (Classic Type 1) : Distal muscle weakness, Dysarthria, AV conduction abnormality, Eyelid ptosis, Hypotonia, Cardiac dysrhythmia, Dysphagia, Asthenia, Myalgia, Cataract
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