Respiratory impairment in multiple sclerosis: a study of respiratory function in wheelchair-bound patients.

BACKGROUND AND PURPOSE: Respiratory disorders are a major cause of morbidity and mortality in multiple sclerosis (MS). Mainly reported in walking patients, they are poorly explored when walking is severely impaired. To characterize respiratory impairment in patients with advanced MS. METHODS: From 2012 to 2015, patients with MS with an Expanded Disability Status Scale (EDSS) score of ≥7 who were referred for functional and rehabilitation evaluation underwent pulmonary function tests to study lung volumes, cough efficacy and respiratory muscle pressures. RESULTS: Among 73 patients with a median EDSS score of 8 [7.5; 8.5], 72.6% had impaired respiratory function with a mean vital capacity (VC) of 57.9 ± 33.5% of theoretical value. Severe impairment (VC < 50%) was found for 34 (46.6%) patients. Cough was impaired in 45 (61.6%) patients, with a mean cough peak flow of 3.14 ± 1.9 L/s and severe impairment (cough peak flow < 2.67 L/s) in 27 (37.0%) patients. Overall, the results suggested predominant expiratory muscle dysfunction and non-predominant diaphragm impairment. EDSS score was correlated with VC but not with any other clinical data. CONCLUSION: Restrictive respiratory failure is frequent in severely impaired patients with MS, predominantly involves expiratory muscles, does not involve diaphragm weakness and is associated with cough impairments.