Supraglottic and pharyngeal sensory abnormalities in stroke patients with dysphagia

Dysphagia and aspiration are two devastating sequelae of stroke, accounting for nearly 40,000 deaths from aspiration pneumonia each year in the United States. While motor deficits in the larynx and pharynx are thought responsible for dysphagia and aspiration in stroke patients, no prior study has evaluated whether these patients also have sensory deficits. The aim of this study was to evaluate the sensory capacity of the laryngopharynx (LP) in supratentorial or brain stem stroke patients who presented with dysphagia. Fifteen stroke patients (mean age, 66.7 +/- 13.8 [SD] years) were prospectively evaluated by means of our previously described method whereby air pulse stimuli were delivered via a flexible fiberoptic telescope to the mucosa innervated by the superior laryngeal nerve. There were 15 age-matched controls. No LP sensory deficits were found in any of the age-matched controls. In all stroke patients studied, either unilateral (n = 9) or bilateral (n = 6) sensory deficits were identified. Deficits were defined as either a moderate impairment in sensory discrimination thresholds (3.5 to 6.0 mm Hg) or a severe sensory impairment (>6.0 mm Hg). These sensory discrimination thresholds were significantly greater than in age-matched controls (7.05 +/- 0.17 mm Hg for the supratentorial group and 6.05 +/- 1.22 mm Hg for the infratentorial group versus 2.61 +/- 0.69 mm Hg for the controls). Among patients with unilateral deficits, sensory thresholds were moderately to severely elevated in all 9 cases on the affected side compared with the unaffected side (p < .01, Fisher's exact test). Moreover, the sensory thresholds of the unaffected side were not significantly different from those of age-matched controls (2.51 +/- 0.25 mm Hg versus 2.61 +/- 0.69 mm Hg, respectively). All 6 patients with bilateral deficits had severe impairments. The results of an outcome assessment in 13 of 15 patients revealed that 2 out of 5 patients with moderate LP sensory impairment and 5 out of 8 with severe impairment developed aspiration. Our results show for the first time that stroke patients with dysphagia have significant sensory deficits in the LP and that these impairments are likely to contribute to the development of aspiration.