Electrical stimulation of the auditory system results in auditory perception as well as auditory suppression. Historically, this is well documented. The recent application of advances of high technology and microsurgery of the ear have allowed basic science and clinical investigation to have access to electrical stimulation of the auditory system and its response. It is historically of great interest that such investigation in the past always involved attempts for evaluation and treatment for either auditory stimulation and/or auditory suppression. I believe the work of Aran (1981) reawakened recent interest in electrical stimulation of the auditory system for tinnitus suppression as well as auditory stimulation. Briefly, in his investigation of a deaf patient, he observed the following: (a) negative currents were more effective than positive currents for auditory stimulation; (b) positive current pulses reduced (suppressed) the intensity of tinnitus; (c) electrical stimulation in deaf patients by negative currents resulted in some sound perception. (In the congenitally deaf patients, it is difficult to evaluate the sensation produced); (d) the intensity of positive pulses necessary to suppress tinnitus is always higher than that of negative pulses resulting in auditory perception; (e) for positive pulses, the range between the threshold of tinnitus suppression and auditory perception when pulses of intermediate intensity are used, without inducing auditory perception, is wide enough to achieve total tinnitus suppression. (In other words, the current effective for electrical stimulation suppressing tinnitus is at a strength well below that producing auditory sensation); (f) negative electrical pulses can produce two different sounds-tinnitus and an auditory sensation; (g) electrical stimulation via the promontory and/or round window can be used both for auditory stimulation as well as for auditory suppression.
Electro acoustic stimulation of the auditory system: UNICAMP's surgical approach
