ALTERNATE NAMES

Steinert’s Disease; Myotonic dystrophy type 1

DESCRIPTION

Congenital Myotonic Dystrophy (type 1) is the most severe form of myotonic dystrophy, a rare, inherited neurlogical disorder caused by a mutation of the DMPK gene. Signs and symptoms are apparent after birth. These can include severe muscle weakness resulting in respiratory insufficiency, dysphagia leading to aspiration pneumonia, cardiomyopathy, and failure to thrive. Developmental delays are common. Later complications may include excessive daytime sleepiness, intellectual disability, autism, and ADHD. If the child survives to adulthood, they will start to take on the symptoms commonly seen in adult myotonic dystrophy type 1 as well.

DIAGNOSTIC TESTING, PHYSICAL FINDINGS, AND ICD-9-CM/ICD-10-CM CODING

Diagnostic testing: Congenital myotonic dystrophy is difficult to recognize because there can be multiple causes of weakness and hypotonia in newborns. The diagnosis can be confirmed through:

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  Molecular genetic testing;

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  Electromyography (EMG);

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  Muscle biopsy; and

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  Sometimes-elevated serum CK concentration.

Physical findings: Physical examination shows:

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  General muscle weakness, especially of the face and throat muscles;

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  Difficult or labored breathing (dyspnea);

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  Difficulty swallowing (dysphagia);

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  Ineffective nursing due to weak suck;

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  Slurred speech;

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  Extremity contractures;

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  Developmental delays;

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  Cardiomyopathy;

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  Failure to thrive;

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  Excessive daytime sleepiness;

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  Intellectual disability;

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  Autism; and

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  Attention deficit hyperactivity disorder (ADHD).

ICD-9: 395.21

ICD-10: G71.11

PROGRESSION

For congenital myotonic dystrophy, abnormal muscle weakness and other findings are present at birth. Progression occurs throughout the child’s lifetime; however, the rate and severity may vary, even with family members.

TREATMENT

Currently there is no cure for this disorder. Treatment is supportive and symptomatic.

SUGGESTED PROGRAMMATIC ASSESSMENT*

Suggested MER for Evaluation:

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  Clinical history and physical examination that describes the diagnostic features of the impairment; and

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  Genetic testing.

Suggested Listings for Evaluation:

DETERMINATION

LISTING

REMARKS

Meets

11.13

111.13

Listing-level severity must be documented.

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