Acute ischaemic hemispheric stroke is associated with impairment of reflex in addition to voluntary cough

Cough function is impaired after stroke; this may be important for protection against chest infection. Reflex cough (RC) intensity indices have not been described after stroke. RC, voluntary cough (VC) and respiratory muscle strength were studied in patients within 2 weeks of hemispheric infarct. The null hypotheses were that patients with cortical hemisphere stroke would show the same results as healthy controls on: 1) objective indices of RC and VC intensity; and 2) respiratory muscle strength tests. Peak cough flow rate (PCFR) and gastric pressure (Pga) were measured during maximum VC and RC. Participants also underwent volitional and nonvolitional respiratory muscle testing. Nonvolitional expiratory muscle strength was assessed by measuring Pga increase after magnetic stimulation over the T-10 nerve roots (twitch T-10 Pga). Stroke severity was scored using the National Institutes of Health Stroke Scale (NIHSS; maximum=31). 18 patients (mean +/- SD age 62 +/- 15 yrs and NIHSS score 14 +/- 8) and 20 controls (56 +/- 16 yrs) participated. VC intensity was impaired in patients (PCFR 287 +/- 171 versus 497 +/- 122 L.min(-1)) as was VC Pga (98.5 +/- 61.6 versus 208.5 +/- 61.3 cmH(2)O; p<0.001 for both). RC PCFR was reduced in patients (204 +/- 111 versus 379 +/- 110 L.min(-1); p<0.001), but RC Pga was not significantly different from that of controls (179.0 +/- 78.0 versus 208.0 +/- 77.4 cmH(2)O; p=0.266). Patients exhibited impaired volitional respiratory muscle tests, but twitch T-10 Pga was normal. VC and RC are both impaired in hemispheric stroke patients, despite preserved expiratory muscle strength. Cough coordination is probably cortically modulated and affected by hemispheric stroke.