REGULATION OF RESPIRATION IN FRIEDREICHS ATAXIA

Friedreich's Ataxia (F.A.) is a degenerative disease which commonly leads to premature death of cardio-respiratory origin. To explain the early death of these patients, previous investigations have established the existence of I) a cardiomyopathy in nearly 100% of cases, 2) a restrictive pulmonary syndrome of scoliotic origin and 3) a mild hypoxemia associated with slight respiratory alkalosis and a normal oxyhemoglobin dissociation curve. To further assess the cause of early death in patients with such neuromyo-pathy, we evaluated, in eleven FA. patients, the sensitivity of the respiratory centers to hypercapnia, hypoxia, and hyperoxia. Ventilatory (VE, VT, F, VT/Ti) and occlusion pressure (P0.1) responses were taken as indices of the respiratory centers output during progressive hypercapnia (Read's method) and isocarhic hypoxia (Weil's method). We studied lì Friedreich's Ataxia patients and II age, sex, and arm-span matched controls. The responses of patients to hypercapnia were significantly greater than controls hut their responses to hypoxia were similar to controls. Our study establishes that the respiratory centers are functioning adequately in early Friedreich's Ataxia and do not contribute to cardio-respiratory insufficiency in such neuromyopathy. © 1979, Canadian Neurological Sciences Federation. All rights reserved.