James Kaltenbach, PhD, Professor of Otolaryngology at Wayne State University in Detroit, Mich., had similar comments: This is the first study suggesting that direct electrical stimulation of the auditory cortex may be an effective approach to the suppression of tinnitus. Further study needs to be conducted to verify these promising findings in a larger number of patients.
Explore This IssueMay 2006
History of Electrical Stimulation for Tinnitus
Although electrical stimulation as a potential treatment for tinnitus has been tried with mixed results since the 1800s, the type of stimulation used and the location of delivery has varied. The earliest experiments involved anodal direct current, which suppressed some cases of tinnitus but did not result in useful clinical application, according to Jay T. Rubinstein, MD, PhD, and Richard S. Tyler, PhD, in their chapter Electrical Suppression of Tinnitus, in the textbook Tinnitus (Decker 2004). The authors added that only specific frequencies and intensities of alternating current, such as those used in cochlear implants, are safe for chronic stimulation.
Regarding sites for electrical stimulation, Drs. Rubinstein and Tyler mentioned the external auditory canal, auricle, zygoma, tragus, mastoid, and Eustachian tube orifice.
I think most people have suspected that there is a cortical representation for some forms of tinnitus. It is fairly clear that the auditory cortex plays a role in audition and the perception of auditory signals, Dr. Seidman said. Also, it is tonotopically mapped, meaning there are areas within the auditory cortex that map to a specific frequency…so it made sense.
He added that the auditory cortex may not play a role in everybody’s tinnitus. But we think it probably does because it affects your perception of that tinnitus.
Assessing the Patient’s Response
In the assessment portion of his study, Dr. Seidman used conventional pure tone audiometry and speech recognition testing. In addition, the patients were asked to complete a battery of self-assessment questionnaires including the Tinnitus Handicap Inventory, the Tinnitus Reaction Questionnaire, the Beck Depression Inventory, and the Modified Somatic Perception Questionnaire.
Psychoacoustic measures were taken in a sound-treated booth as a continuous tone was presented below threshold and increased until the patient indicated that the tone was equivalent in loudness to the tinnitus. To obtain minimum masking levels, white noise was delivered and measured, and residual inhibition was calculated. The fMRI study allowed for a general localization of the anatomical landmarks within the Heschl’s gyrus of the auditory cortex and the MEG showed a precise area of cortical activation arising from the auditory and visual inputs. Auditory evoked responses were also recorded.