Current Research in Hyperacusis
The current level of research reflects a growing interest in hyperacusis. Early on, research emphasis was placed on tinnitus. There were a number of studies in which hyperacusis was mentioned but usually as a footnote. It wasn't until rather recently that hyperacusis was viewed as a separate clinical entity. Studies have shown that hyperacusis and tinnitus co-exist. That is, many patients with hyperacusis have debilitating tinnitus. However, some persons with normal hearing have severe hyperacucis.
There have been only a few studies outlining management strategies for hyperacusic patients. Current assessment indicates that the Jastreboff model for treating hyperacusis is the most widely accepted among practitioners. It is similar, in purpose, to the Jastreboff approach for treating tinnitus: Tinnitus Retraining Therapy (TRT).
This is not to suggest that other approaches fail to provide benefit to those individuals with hyperacusis, but rather that the Jastreboff method has more data to support its claim. However, no one clinical approach has been sufficiently compelling to gain universal acceptance.
Although there has been an increase in the number of studies regarding hyperacusis, much more needs to done. Current research tends to deal with methods of treatment and outcome measures. More needs to be done to gain an understanding of the neuropsychological mechanism or mechanisms involved. Research is a dynamic process. Current research will serve as a foundation for future studies
In my opinion, future studies will reflect more sophisticated research methods and reaasonable data analysis. Such studies will contribute to our understanding of the complex neural mechanisms responsible for the onset and perpetuation of hyperacusis. Sophisticated instrumentation has already been used to provide objective information about changes in brain activity in patients with specific disorders. For some tinnitus patients, fMRI studies have shown changes in activity within the limbic system. Similar studies can be done for the hyperacusic patient as well. We are just at the threshold of a major breakthrough in the use advanced imaging technology to provide objective evidence to clinical assumptions.
A provocative question: If hyperacusis is defined as reduced tolerance to external sounds and tinnitus is defined an acoustic-like sensation generated internally, does one infer that there are two different mechanisms, or are hyperacusis and tinnitus just unique manifestations of the same disorder?. We don't know. I am confident that this question will be answered within the next few years. As we acquire more objective information about changes in brain function related to a specific disorder, the higher the probability that appropriate medicines, surgery, drugs and therapeutic strategies will be employed to ameliorate the severity of the problem.
In summary, I am optimistic about the future of hyperacusis research. These are exciting and challenging times for the audiologist. There will be new methods developed for the treatment of this perplexing disorder. There will be advances in every phase of patient management. We may never fully understand the intricacies of disorders of the auditory system, but future research will provide the diagnostic tools and therapeutic programs necessary to achieve maximum benefit to those individuals having hyperacusis.