ADULT ONSET HUNTINGTON DISEASE

ALTERNATE NAMES

Huntington Chorea; Huntington Chronic Progressive Hereditary Chorea; Huntington’s Chorea; Huntington’s Disease

DESCRIPTION

Huntington disease (HD) is a hereditary neurodegenerative disorder that is characterized by progressively worsening motor, cognitive, behavioral, and psychiatric symptoms. HD is caused by a mutation of the Huntington gene called a “CAG repeat expansion.” The mutation results in gradual neuronal degeneration in the basal ganglia of the brain, and progresses to involve other regions of the brain responsible for coordination of movements, thoughts, and emotions. Neuronal degeneration causes diffuse and severe brain atrophy that is comparable to late stage Alzheimer's disease.

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

Diagnostic testing: The diagnosis of HD is made by:

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  Clinical history documenting changes in motor, behavioral, and cognitive function;

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  Family history of HD;

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  Abnormal neurological exam findings;

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  Abnormal neuropsychological test results; and

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  HD gene test with abnormal results (40 or more CAG repeats).

Brain imaging is optional, but if performed may show atrophy of the caudate nucleus or diffuse brain atrophy.

Physical findings: Clinical presentation of HD may include:

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  Changes in personality, behavior, cognition, speech, and coordination;

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  Random uncoordinated extremity movements (chorea);

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  Rigidity;

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  Leg stiffness;

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  Clumsiness;

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  Slowness of movement;

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  Tremors; and

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  Muscle spasms.

As the disease progresses, concentration on cognitive tasks becomes increasingly difficult, and an individual may have difficulty swallowing and feeding himself. Family history of HD is usually but not always positive.

ICD-9: 333.4

ICD-10:G10

PROGRESSION

The average onset age is around 40, plus or minus 10 years; however, onset has been documented as young as age 5 (see Juvenile HD) and as old as age 90. Death usually occurs at about 15 to 20 years after onset of symptoms, and is due to complications of the disease.

TREATMENT

There is no cure or treatment to stop, slow, or reverse the progression of HD. An individual’s medical source(s) may prescribe medications to manage symptoms. A psychiatrist or behavior management specialist may address behavior disorders. A speech language pathologist may evaluate communication and swallowing problems. A nutritionist may be consulted to address nutritional needs as the disease progresses. Assistive devices such as wheelchairs, helmets, and communication boards may be used for safety, and to improve quality of life.

SUGGESTED PROGRAMMATIC ASSESSMENT*

Suggested MER for Evaluation:

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  Claimant’s medical source(s) records documenting progression of motor, cognitive, and psychiatric symptoms and signs; family history of HD, and abnormal neurological exam findings consistent with HD;

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  Laboratory testing showing a CAG repeat expansion in the HD gene (40 or more CAG repeats);

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  Brain imaging may provide supporting evidence; and

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  Psychological or psychiatric reports including neurocognitive testing.

Suggested Listings for Evaluation:

DETERMINATION

LISTING

REMARKS

Meets

11.17

Equals

12.02