Progressive dystonia with marked diurnal fluctuation.

Three children, 2 of them siblings, developed a progressive dystonic condition in the first decade of life. The symptoms and signs were milder in the mornings or after a daytime nap but worsened greatly later in the day. One patient became unable to walk by evening. Investigations in 2 patients revealed a reduced concentration of cerebrospinal fluid homovanillic acid. The 2 more severely affected patients showed dramatic and sustained improvement with levodopa therapy. The condition bears a clinical resemblance to some reported cases of juvenile Parkinson's disease but is probably a separate disorder.