Junji Sakakihara

Suppression of tinnitus by cochlear implantation

INTRODUCTION Transcutaneous and transpromontory electrical stimulation has been described for the treatment of tinnitus. Based on these observations, we postulate that cochlear implantation may relieve tinnitus. METHOD Twenty patients who underwent cochlear implantation since 1987 were studied. Preimplantation tinnitus was documented and quantified. The change in tinnitus after implantation was investigated. RESULT Before cochlear implantation, 90% of the patients experienced tinnitus. Electrical stimulation of the promontory resulted in relief of tinnitus in 72% of the patients. After cochlear implantation, tinnitus was abolished in 44% and decreased in 39%, for an overall improvement in 83%. CONCLUSION Cochlear implantation has the added benefit of tinnitus suppression in the majority of patients. The mechanism of this suppression remains uncertain. However, this information may be valuable in structuring subsequent treatment programs for patients with tinnitus.

Tinnitus suppression by electrical stimulation of the cochlear wall and by cochlear implantation.

Some recent studies have reported on tinnitus suppression by electrical stimulation of the cochlear wall and by cochlear implant. In the present study, the degree of tinnitus in cochlear implant candidates was determined and the effects of promontory stimulation and cochlear implantation on tinnitus were investigated

Reliability of the promontory stimulation test for the preoperative evaluation of cochlear implants: a comparison with the round window stimulation test.

The electrical stimulatory threshold of the preoperative promontory stimulation test (PST) was compared with the postoperative threshold of the electrode following cochlear implantation. Postoperative results from warble-tone audiometry, the vowel recognition test, the consonant recognition test, and the speech tracking test, which employed a speech processor, were similarly evaluated. In certain patients who responded insufficiently to the PST, an exploratory tympanotomy under local anesthesia was performed prior to cochlear implantation, and stimulatory threshold was measured with an electrode placed directly on the round window [round window stimulation test (RWST)]. No correlation was found between the PST results and the postoperative performance of the cochlear implant. The RWST was determined to be better than the PST in the evaluation of cochlear implant performance.

Psychophysical Tuning Curves in Two Patients with Sensorineural Hearing Loss.

Psychophysical tuning curves (PTC) were examined in two patients with sensorineural hearing loss characterized by moderate to profound hearing loss at all but one specific frequency.With the probe tone fixed to the frequency with normal threshold, PTC exhibited a sharp tip at the probe tone frequency in each case, indicating that frequency selectivity was preserved at the normal threshold frequency region. On the other hand, with the probe tone fixed to the frequency with an elevated threshold, PTC exhibited a sharp tip not at the probe tone frequency but at the frequency with a normal threshold.The shifts in the tip indicated that frequency selectivity was impaired at the probe tone frequency, and that only the region around the normal threshold responded to the probe tone. Thus, the unusual shape of the audiograms of the two patients was thought to represent off-frequency listening by the intact region at frequencies with normal thresholds.