Juvenile parkinsonism: a patient with possible primary striatal dysfunction.

A 15-year-old boy who initially manifested dystonic features and later developed classic parkinsonism is described. Cerebrospinal fluid homovanillic acid levels were normal or slightly elevated both before and after administration of probenecid. The patient responded favorably to treatment with levodopa and carbidopa. The normal or slightly elevated cerebrospinal fluid homovanillic acid levels contrast with the low levels usually seen in adult parkinsonian patients. The data on this patient suggest direct neostriatal involvement rather than depletion of neurons of the substantia nigra. Juvenile parkinsonism may have at least two distinct pathological forms, but they have similar clinical features and a similar response to treatment.