New clinical applications of the stapedial reflex.

Stapedial reflex data were obtained from 11 myasthenic, 18 hyperthyroid and six hypothyroid patients. Data were studied with respect to reflex threshold, amplitude and decay. Elevated threshold, decreased amplitude, and high and low frequency reflex decay were observed in myasthenic and hyperthyroid patients. Hypothyroidism merely increases stapedial reflex amplitude but causes no significant threshold or decay changes.