Conclusions: We conclude that the capsaicin inhalation test is useful to directly assess cough reflex and sensation around the larynx, while it indirectly reflects central nervous system function.
Objectives: To understand the state of the cough reflex before patients with dysphagia start eating.
Methods: We studied the cough reflex by the capsaicin inhalation test in 21 patients with dysphagia and 12 healthy persons without dysphagia.
Results: The control group showed a cough reflex at a capsaicin concentration of 2.61 μM (0.98-7.80), while patients with mild dysphagia did so at 7.28 μM (1.95-15.6), those with moderate dysphagia at 22.07 μM (15.6-62.5), and those with severe dysphagia at 71.75 μM (31.2-250). Control vs mild p < 0.01, control vs moderate p < 0.01, control vs severe p < 0.01, mild vs moderate p < 0.01, mild vs severe p < 0.01, moderate vs severe p < 0.05. There was a significant correlation between the grade of dysphagia and the threshold capsaicin concentration that provoked a cough reflex (ρ = -0.796, p < 0.001).