Utility of Clinical Assessment of Respiratory Muscle Function

Purpose: The aim of this study was to assess the utility of clinical assessment of respiratory muscle weakness in MS. Thtients and methods: We studied 40 MS patients who performed pulmonary function tests using standard procedures and measures of respiratory muscle strength. Descriptive clinical indices included a history of detailed neurologic findings, including upper and lower extremity weakness, cerebellar signs, and evidence of cerebral lesions and other clinical signs including dependence in activities of daily living, shortness of breath, weak voice, dysarthria and dysphagia. We devised an index comprised of four clinical signs: the patient’s report of difficulty in clearing pulmonary secretions and his report of a weakened cough, the examiner’s observation ofthe patient’s cough, and ability to count on a single exhalation. Reaulis: Mean values of TLC (95 percent± 14) VC (91 percent± 19), and RV (106 percent± 34) were normal. By contrast, MVV (68 percent±20), Punax (74 percent ±27) and PEmax (51 percent± 22) were decreased. Stepwise telectasis, aspiration and pneumonia have long been recognized as terminal events for MS patients.’ Recent studies suggest that when MS patients perform specific tests of respiratory muscle strength, occult respiratory muscle weakness frequently is found in those patients free from pulmonary symptoms or disease.2’3 Since specific tests of respiratory muscle strength are rarely performed in this population of patients, clinicians often are unaware ofboth the time of onset of such weakness and the temporal relationship between the onset ofrespiratory muscle weakness and pulmonary dysfunction. Pulmonary function testing, although routinely performed, is an insensitive indicator of respiratory muscle weakness. Although the performance of the vc maneuver requires both inspiratory and expiratory muscles, severe muscle weakness may be accompanied