Treating Tinnitus at the Brain Level

If researchers could identify the types of cells that become hyperactive, they could potentially find ways to reduce the level of cellular activity. This could pave the way for development of effective Tinnitus treatments. Research published recently by Dr Tom Brozoski at Southern Illinois University has already identified one group of cells in the dorsal cochlear nucleus that becomes hyperactive after noise exposure. These cells are called fusiform cells, a group of neurons whose levels of activity are known to affect structures higher up in the auditory system.

Future research by Dr Paul Finlayson in our laboratory will help define other types of cells that become hyperactive after intense sound exposure. Experiments by Or Jinsheng Zhang have already demonstrated that certain drugs can inhibit hyperactivity when they are applied directly to the D. C. N. surface. Tinnitus research by Jos Eggermont at the University of Calgary has also found hyperactivity in higher-level structures of the brain, such as the auditory cortex.

Despite these promising signs, many new experiments lie ahead before a treatment for Tinnitus at the brain level will be possible. Chief among these: we need to continue testing a wider range of drugs to identify other chemicals that will affect activity in the dorsal cochlea nucleus without major side effects.

Drugs need to be identified that reduce the spontaneous activity in the D. C. N. without worsening hearing. It also needs to be determined if reductions of this spontaneous activity occur when the same drugs are given intravenously. We believe this information, which will come largely from animal studies, will continue to unveil the neural underpinnings of Tinnitus, a step necessary to pave the way for the development of treatment alternatives worthy of formal clinical trials.

Dr Kaltenbach, PhD is a professor in the Department  of Otolaryngology at Wayne State University in Detroit, Michigan, and is a member of A. T. A's Scientific Advisory Committee.

Reprinted from American Tinnitus Association "Tinnitus Today", March 2005.