Tinnitus neural map; A positron emission tomography study

Abstract

The neural map of tinnitus involves more than the classical auditory pathways and the limbic system. PET findings in six patients, with severe problem tinnitus, revealed the involvement of the cerebellum, insula and frontal cortices when these patients were imaged before and after high frequency bone conduction therapy. The frontal cortex and cerebellum demonstrated the highest ratios of metabolic change but changes were also noted in the thalamus and the medial temporal lobe system. The PET data supports the view that the frequency specific map of auditory cortex is dynamic and can change with high frequency therapy, presumably due to neural reorganization. The PET data further reflect alterations in multiple areas of brain in all patients to tinnitus and/or high frequency therapy. Encouraging was the observation that patients with the most dramatic change in their global pre/post PETs were also the ones who exhibited the greatest behavioral improvement in regards to tinnitus relief measured by informal report and standard questionnaires. In those patients, post therapy minimal masking levels dropped indicating less acoustic energy was need to mask their problem tinnitus, interpreted as reflecting central changes. Taken as a whole, these data support the value of frequency specific tinnitus therapy.