A dramatic response to acetazolamide in 3 patients with familial paroxysmal ataxia is reported from the Ipswich Hospital, Neurological Centre, Suffolk, England. Case 1 developed mild squint at 3 years and nystagmus at 6 years. Subsequently she experienced episodes of dysarthria, ataxia and vertigo often accompanied by nausea and vomiting and followed by headache and drowsiness. The attacks lasted from 2 to 24 hours and occurred every 2 weeks. When assessed at 26 years of age the attacks were occurring up to 5 times a week. The EEG was normal and an MRI showed atrophy of the superior cerebellar vermis. Acetazolamide 250 mg bid reduced attacks dramatically over an 8 month observation period. Cases 2 and 3, sons of Case 1, developed identical episodes at 1 year and 6 weeks of age, respectively. Both responded to acetazolamide. The father of the index case was ataxic and then chairbound for 13 years and died at age 67. This family was the first described in the U.K. but many may be mislabeled as epilepsy or migraine. 
COMMENT. Provisional diagnoses of basilar migraine and epilepsy had been made initially in 2 of these cases. The accurate diagnosis in 1 individual will often reveal similarly affected family members. Inheritance is autosomal dominant. Acetazolamide is also effective in the treatment of paroxysmal dystonia (tonic seizures) as a presenting manifestation of multiple sclerosis . Koller W et al. have used acetazolamide successfully in the treatment of essential tremor.