IMPAIRMENT OF CENTRAL MOTOR CONDUCTION TO THE DIAPHRAGM IN STROKE

Respiratory complications are common in patients with stroke, but the involvement of the diaphragm in this setting is not completely underst ood. The purpose of this study was to assess corticodiaphragmatic path ways in patients with vascular hemiplegia. Fifteen patients were studi ed, nine with a capsular type of hemiplegia. Seven age-matched subject s served as the control group, and eight healthy young volunteers were studied to validate the methods by comparison with the literature. Di aphragm electromyogram was recorded bilaterally, using surface electro des. Abductor pollicis brevis electromyogram was also recorded. After having checked the integrity of peripheral conduction, corticofugal pa thways were studied using cortical magnetic stimulation, a reproducibl e and patient-independent stimulus. Left and right conduction times to the diaphragm were symmetrical in the control subjects, the young vol unteers, and the six patients with hemiplegia but without capsular les ion (16.5 to 20.1 ms). Conversely, they were markedly asymmetrical in patients with capsular hemiplegia, diaphragm response on the plegic si de being abolished or markedly delayed. Although the clinical impact o f these findings remains to be determined, this study confirms that '' central diaphragm paralysis'' can be present in stroke. It also indica tes that there is no bilateral motor representation of each hemidiaphr agm.