title: Acute ischaemic hemispheric stroke is associated with impairment of reflex in addition to voluntary cough.
abstract: 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 (P(ga)) were measured during maximum VC and RC. Participants also underwent volitional and nonvolitional respiratory muscle testing. Nonvolitional expiratory muscle strength was assessed by measuring P(ga) increase after magnetic stimulation over the T₁₀ nerve roots (twitch T₁₀ P(ga)). 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 P(ga) (98.5 ± 61.6 versus 208.5 ± 61.3 cmH₂O; p < 0.001 for both). RC PCFR was reduced in patients (204 ± 111 versus 379 ± 110 L·min⁻¹; p < 0.001), but RC P(ga) was not significantly different from that of controls (179.0 ± 78.0 versus 208.0 ± 77.4 cmH₂O; p = 0.266). Patients exhibited impaired volitional respiratory muscle tests, but twitch T₁₀ P(ga) 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.
authors.affiliation: Division of Asthma, Allergy and Lung Biology, Dept of Respiratory Medicine, King's College London School of Medicine, London, UK. katie.ward@kcl.ac.uk
authors.forename: K
authors.initials: K
authors.lastname: Ward
authors.forename: J
authors.initials: J
authors.lastname: Seymour
authors.forename: J
authors.initials: J
authors.lastname: Steier
authors.forename: C J
authors.initials: CJ
authors.lastname: Jolley
authors.forename: M I
authors.initials: MI
authors.lastname: Polkey
authors.forename: L
authors.initials: L
authors.lastname: Kalra
authors.forename: J
authors.initials: J
authors.lastname: Moxham
mesh_terms: D000368:Aged; D002540:Cerebral Cortex / Q000503:physiopathology; D003371:Cough / Q000503:physiopathology*; D045853:Exhalation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000503:physiopathology; D012018:Reflex; D012132:Respiratory Muscles / Q000503:physiopathology*; D020521:Stroke / Q000503:physiopathology*