TN 3 (02-10)
DI 23022.500 Spinocerebellar Ataxia
SCA; Infantile-onset Spinocerebellar Ataxia; Autosomal Dominant Spinocerebellar Ataxia (ADSCA)
Spinocerebellar Ataxia (SCA) refers to a group of genetic disorders characterized by slowly progressive difficulties with gait, hand movements, speech and abnormal eye movement. These disorders were previously known as autosomal dominant cerebellar ataxias (ADSCA). People with SCA have progressive damage in the areas of the brain that control movement in the arms, legs, hands, and eyes. When this type of brain damage occurs, the cells in the part of the brain that controls movement degenerate (atrophy) resulting in ataxia. This disorder causes a slow progression of ataxia of gait, stance, limbs, and dysarthria (speech disturbance) with or without oculomotor (movement of the eyeball) dysfunction due to cerebellar degeneration. The prevalence of SCA’s is estimated to be about 1-4/100,000.
TESTING, PHYSICAL FINDINGS, AND ICD-9-CM CODING
Genetic testing and MRI can distinguish genetic from acquired (non-genetic) causes of ataxia.
ONSET AND PROGRESSION
The rate of progression for SCA varies with the gene mutation identified and, in general, is faster with earlier onset or increased length of the trinucleotide expansion repeat in those with this particular genetic finding. In SCA1, 2, and 3, time to becoming wheelchair dependent is 13-15 years and time to death is 20-30 years. The prognosis for SCA6 and SCA11 is less severe with a very slow worsening of symptoms, and persons with SCA8 and SCA11 have a normal lifespan.
There is currently no cure or treatment to slow the progression of SCA. Medications can help manage the symptoms (stiffness, depression, spasticity and sleep disorders). Occupational therapy can be helpful in developing ways to accommodate the individual in performing daily activities such as handwriting, buttoning, and use of eating utensils. Ambulatory aides such as canes, walkers and wheelchairs have been prescribed for gait ataxia. Speech therapy and/or computer-based devices for those with dysarthria and severe speech deficits.
SUGGESTED PROGRAMMATIC ASSESSMENT*
Suggested MER for Evaluation: Molecular genetic testing is diagnostic for the hereditary SCA’s but to evaluate the severity, a clinical neurological examination will be needed. If molecular genetic testing is not available, then a clinical neurological examination may be sufficient to establish a medical equals determination as long as all treatable causes of ataxia have been ruled out. It should be stated that a positive family history supports the diagnosis of a hereditary disorder but does not rule out an acquired, treatable disorder in a particular case.
Suggested Listings for Evaluation:
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* Adjudicators may, at their discretion, use the Medical Evidence of Record or Listings suggested to evaluate the claim. However, the decision to allow or deny the claim rests with the adjudicator.