Subclinical pulmonary dysfunction in spinocerebellar ataxias 1, 2 and 3

Objectives - Evaluation of pulmonary function in patients with spinocerebellar ataxias (SCA) 1, 2 and 3 without clinical evidence of pulmonary dysfunction. Methods - Thirty patients (F:M = 7:23; age: 35 +/- 11.3 years; SCA1 - 13, SCA2 - 9 and SCA3 - 8) without clinical manifestations of respiratory dysfunction and 30 controls underwent pulmonary function tests. The percentage predicted values of forced vital capacity (FVC), volume of air exhaled during first second of FVC (FEV1), peak expiratory flow rate (PEFR) and maximal voluntary ventilation (MVV), actual values of maximal inspiratory and expiratory pressures (MIP and MEP in mmHg), and ratios of actual values of FEV1/FVC (%) and FEV1/PEFR (ml/l/min) were analyzed. Results - Compared with controls SCA patients had significant reductions of FVC (71.1 +/- 17.5 vs 85.5 +/- 18.7; P < 0.01), PEFR (51.5 +/- 20.7 vs 77.1 +/- 24.9; P < 0.001), MVV (64.4 +/- 21.6 vs 97.2 +/- 22.7; P < 0.001), MIP (27.7 +/- 16.8 vs 50.1 +/- 15.1; P < 0.001) and MEP (38.1 +/- 18.7 vs 74.7 +/- 16.0; P < 0.001), elevation of FEV1/PEFR (10.5 +/- 2.8 vs 7.4 +/- 2.1; P < 0.001), but no significant change of FEV1 and FEV1/FVC. FEV1/PEFR correlated positively with illness duration and MVV negatively with severity of illness. Conclusions - The present study showed subclinical restrictive type of pulmonary dysfunction in SCA, and possible presence of upper airway obstruction. Chest physiotherapy and breathing exercises should be introduced early in management of SCA.