Martin L. Lenhardt - lenhardt@hsc.vcu.edu
Douglas G. Richards
Alan G. Madsen
Program in Biomedical Engineering, Virginia Commonwealth University
Box 980158 MCV
Richmond VA 23298-0168
Abraham Shulman
Barbara A. Goldstein
Robert Guinta
Martha Entenmann Tinnitus Research Center
Brooklyn NY 11203
Popular Version of Paper 2pPP14
Presented Tuesday Afternoon, December 4, 2001
142nd ASA Meeting, Fort Lauderdale, FL
Prevalence of Tinnitus:
It has been estimated that over 36 million people in the United States have
tinnitus, a sense of internal auditory ringing in the absence of external sound.
About 10 million have severe tinnitus that is often very difficult to treat.
The most common clinical non-drug approach is to mask the tinnitus with an external
sound, but masking is effective in a little more than half the cases. The suppression
of tinnitus after the masking is removed is termed residual inhibition. Long-term
residual inhibition is a goal of all masking. Another approach is to recondition
or habituate to the tinnitus, a process that can take a year or more and even
then may not be successful.
Present Study:
In the present study we evaluated a novel approach to tinnitus. Imaging studies
strongly suggest a brain site of tinnitus not just the ear, although many individuals
have some degree of high frequency hearing loss. Possibly related to the hearing
loss is that most tinnitus sufferers experience high pitched (<6 kHz) tinnitus.
Recently evidence has been mounting that the brain reprograms its nerve cells
based on sensory loss or learning. If the brain was changing its response as
a result of some hearing loss, then this could be the tinnitus trigger. We considered
the possibility that the reprogramming could be reversed with high frequency
stimulation. To test this, nine subjects with severely tinnitus was evaluated
with a novel method of bone conduction delivery to stimulate residual high frequency
receptors in the inner ear. High frequency bone conduction transducers were
fabricated to deliver frequencies from 6 to 40 kHz. The aluminum ceramic transducers
were placed on the skin behind the ear. Patterned high frequency stimulation
(>10,000 Hz), derived from music, was recorded on a compact disc and played
back through a custom amplifier at only 6 dB above threshold. Two half-hour
sessions for four weeks were provided at the Martha Entenmann Tinnitus Research
Center in Brooklyn N.Y.
Findings of the present study:
Exit questionnaires revealed satisfaction with tinnitus relief from high frequency
stimulation in all subject completing the study (8 of 9) with residual inhibition
lasting on the order of weeks (mean = 1.5 weeks). Using follow up questionnaires
2-4 months after completing the trial, 6 of 8 subjects rated their tinnitus
as improved. No one indicated a worsening of tinnitus.
Encouraged by the limited but convincing findings that high frequency induced
residual inhibition that lasted substantially longer than that from conventional
masking, more extensive trials are underway to explore the efficacy of high
frequency bone conduction treatment in central tinnitus. If verified in a larger
sample, the rapid reduction in tinnitus with this technique would offer a dramatic
improvement over conventional masking and long-term habituation approaches.