Palatal and pharyngeal reflexes in health and in motor neuron disease.

Abstract

Palatal and pharyngeal sensation and motor responses, and volitional palatal movement, were tested in 171 healthy adults and 43 patients with motor neuron disease. In healthy adults palatal and pharyngeal sensation and volitional palatal elevation were present in all; the palatal and pharyngeal motor responses could not be elicited on first testing in two (1.1%) and seven (4.1%) subjects respectively. Pharyngeal motor responses were more easily elicited in older subjects and palatal responses were more easily elicited in women. Eye watering and retching were the most common accompanying features. In 57 normal subjects tested on five occasions there was considerable variation in the stimulus required to elicit the motor responses within subjects: in none of four subjects (7%) who initially had absent responses were they always absent. Pharyngeal motor responses were more easily elicited in patients with motor neuron disease than in matched normal subjects; within the motor neuron disease group pharyngeal motor responses elicited by tongue depression were associated with the symptom of food or drink "going down the wrong way" > 1/month and a reduction in average volume per swallow (ml) and swallowing capacity (ml/s). Volitional palatal elevation was absent in five patients (11.6%). In six of eight patients with motor neuron disease studied repeatedly (on between two and seven occasions) the palatal and pharyngeal responses were elicited with the same stimulus on each occasion. In healthy adults palatal and pharyngeal sensation and motor responses should be present although considerable variation occurs in the stimulus required. In patients with motor neuron disease features of impaired swallowing are associated with a brisk rather than a depressed pharyngeal response.