Abstract
Twelve adults with unilateral sensorineural deafness received an electrical stimulation (50, 100, 200, 400 and 1600-Hz squire wave) on the promontory in the deaf ear by transtympanic stimulation. Unilateral subjects were selected so that the sensation elicited by electrical stimulation could be compared to the contralateral acoustic sensation. Three kinds of sensation were elicited in the deaf ear: auditory sensation in 9 out of 12 ears, indescribable sensation-neither auditory nor somatic-in 3 out of 12 ears, and somatic sensation in 7 ears. Reports of an uncomfortable loudness level consisted of two sensations; (1) at the maximum auditory level or (2) somatic sensation level. Furthermore, the pitch discrimination for the pulse frequency was discomfiting to the unilaterally deaf subjects. All reported indescribable sensations were elicited in patients with deafness of unknown origin. Therefore, we suggest that candidacy for cochlear implant and the superior side for implantation is in ears with clearly defined etiology, even if the results of promontory test were equivalent.
