The effects of
cochlear implant on loudness, annoyance, daily duration, location, and residual inhibition of
tinnitus were evaluated by a closed-ended, quantifiable questionnaire in 33 postlingually deafened patients who had received implants at the University of Michigan, Ann Arbor, between 1986 and 1990. Preoperative
tinnitus was present in 85% of patients. A statistical comparison of preoperative vs postoperative loudness and annoyance indicated a significant reduction in both of these complaints postoperatively. Loudness and annoyance were significantly correlated, both preoperatively and postoperatively. Fifteen patients (54%) with preoperative
tinnitus demonstrated a loudness decrease of 30% or more; 43% demonstrated an annoyance decrease of 30% or more; and 48% demonstrated a decrease of 30% or more in daily
tinnitus duration. Patients who experienced a loudness or annoyance decrease of 30% or more after implantation demonstrated significantly higher preoperative levels of these complaints, suggesting that degree of
tinnitus reduction after implantation may be related to preoperative loudness and annoyance levels. Contralateral
tinnitus suppression was reported by 42% of patients. Residual inhibition ranging from 60 seconds to several hours was reported by 50% of patients, predominantly in the ear with the implant. Age, gender, cause of
hearing loss, duration of
tinnitus,
cochlear implant usage, and time after implantation were not predictive of
tinnitus suppression. Overall, the majority of the patients (74%) thought that their
cochlear implant was helpful in
tinnitus suppression, especially in the ear with the implant. Contralateral residual inhibition and
tinnitus suppression suggest a central mechanism contributing to these phenomena.