[Familial paroxysmal ataxia responsive to acetazolamide].

From their early twenties, a 56 year-old french woman and her 33 year-old son suffered from paroxysmal attacks of gait ataxia, incoordination of both hands, dysarthria and nystagmus. These attacks lasted from one to three hours and occurred at the rate of one to seven per week. On examination between attacks, there was only a bilateral horizontal and upward-beating gaze nystagmus. This was documented by E.O.G. Biological investigations were normal with the exception of a mild elevation of glucose blood level. Treatment with acetazolamide 250 mg daily, completely abolished the attacks in both patients. These cases meet the criteria of familial paroxysmal ataxia, a disorder only described in the United States up to the present. Although rare, this disease should be recognized because of its dramatic response to acetazolamide.