Dominant recurrent ataxia and vertigo of childhood.

Four families are described with an autosomal dominant illness characterized by the childhood onset of recurrent attacks of prolonged ataxia, server vertigo, and vomiting. The attacks often begin in infancy. On the average, attacks occur monthly, and last between one hour to more than a week. Variations in severity occur within families. During an attack, consciousness is unaltered, but severe vertigo makes walking impossible and vomiting is frequent and severe. An attack is marked by horizontal and vertical jerk nystagmus, accompanied by vertigo which is sometimes worsened by position; however, there is no muscular weakness. During an attack, blood gases, ammonia, and amino acid studies are normal. Between attacks patients manifest combinations of slight horizontal or vertical jerk nystagmus or mild clumsiness. Cochlear and labyrinthine studies and neurologic investigations were noncontributory. Conventional therapies for vertigo, epilepsy, and migraine were ineffective, but acetazolamide (250-500 mg/day) stopped the attacks.