Cough reflex attenuation and swallowing dysfunction in sub-acute post-stroke patients: prevalence, risk factors, and clinical outcome.

Abstract

Cough and swallowing impairments in post-stroke patients (PSP) have been associated with increased risk for respiratory complications. To assess the prevalence of alterations in protective cough responses in subacute PSP and its association with oropharyngeal dysphagia (OD), clinical, and neurotopographic stroke factors and clinical outcomes. Three months after stroke, the cough reflex test (CRT) was performed by nebulizing incremental citric acid concentrations (7.8-1000mmolL-1 ) to determine the concentration that elicited two and five coughs; OD was assessed by the volume-viscosity swallow test. Clinical and neurotopographic stroke risk factors and complications (readmissions, respiratory infections, institutionalization, and mortality) were recorded from 3 to 12months post-stroke. We included 225 PSP. Prevalence of impaired CRT was 5.8%, that of OD was 40.4% (20.4% with impaired safety of swallow), and of both impairments was, 1.8%. No specific risk factors associated with impaired CRT were found; however, hemorrhagic, wide circulation infarction (TACI), and brainstem strokes delayed the cough response. OD was associated with age, TACI and poor functional and nutritional status. Outcome of PSPs was unaffected by impaired CRT but OD and impaired safety of swallow increased institutionalization, respiratory infections, and mortality with the poorest outcome for those with both impairments. Prevalence of subacute post-stroke OD and swallow safety impairments was much higher than CRT attenuation, and risk factors strongly differed suggesting that the swallow response receives a stronger cortical control than the cough reflex. OD has a greater impact on PSP clinical outcome than impaired cough, the poorest prognosis being for patients with both airway protective dysfunctions.