gms | German Medical Science

77th Annual Meeting of the German Society of Oto-Rhino-Laryngology, Head and Neck Surgery

German Society of Oto-Rhino-Laryngology, Head and Neck Surgery

24.05. - 28.05.2006, Mannheim

Tinnitus suppression by cochlear implant and its brain imaging

Meeting Abstract

  • corresponding author Takeshi Kubo - University School of Medicine, Dept. ORL, Osaka, Japan
  • Y. Osaki - University School of Medicine, Dept. ORL, Osaka, Japan
  • H. Nishimura - University School of Medicine, Dept. ORL, Osaka, Japan
  • T. Kawashima - University School of Medicine, Dept. ORL, Osaka, Japan

Deutsche Gesellschaft für Hals-Nasen-Ohren-Heilkunde, Kopf- und Hals-Chirurgie. 77. Jahresversammlung der Deutschen Gesellschaft für Hals-Nasen-Ohren-Heilkunde, Kopf- und Hals-Chirurgie e.V.. Mannheim, 24.-28.05.2006. Düsseldorf, Köln: German Medical Science; 2006. Doc06hnod064

The electronic version of this article is the complete one and can be found online at:

Published: April 24, 2006

© 2006 Kubo et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.



Tinnitus is an unpleasant auditory sensation without an external auditory source and can be suppressed by a masking sound. Some patients feel a transient suppression of tinnitus even after the masking sound has stopped. This phenomenon is called residual inhibition of tinnitus. Although the underlying mechanism of residual inhibition is thought to involve the central nervous system, this mechanism has not been examined in a neuroimaging study. Moreover, the cortical mechanism of tinnitus in cochlear implant (CI) users, who are representative of patients with tinnitus, has not been studied. In this study, we used positron emission tomography (PET) to investigate brain activation in three tinnitus patients, who were post-lingually deaf CI users and experienced residual inhibition, and six normal controls. Tinnitus patients were selected from the answers of questionnaires about tinnitus. Regional cerebral blood flow (rCBF) was measured and compared under the following three conditions: with tinnitus (T), during noise-sound stimulation (masking effect) (M), and during the residual inhibition of tinnitus (R). The anterior middle- and superior- temporal gyri (Brodmann areas 21 and 38) were activated mainly on the right side during residual inhibition in the patients. The cerebellum was activated during the tinnitus and masking conditions of the patients, however, it was not activated during residual inhibition. No significant rCBF change was observed in the normal controls. Our findings indicate that the right-dominant activation of the anterior temporal cortex is likely related to residual inhibition and reflects the tonal and non-verbal characteristics of tinnitus. The lack of cerebellar activation during the residual inhibition presumably indicates the interruption of the tinnitus-related auditory signal in the central nervous system. The present findings benefit our understanding of the central mechanism of tinnitus and could be important for the clinical management of tinnitus in patients.