CNS somatosensory-auditory interactions elicit or modulate tinnitus

Evidence has accumulated linking clinical tinnitus to the somatosensory system. Most clinical tinnitus patients can change the psychoacoustic attributes of their tinnitus with forceful head and neck contractions. The significance of such somatic modulation of tinnitus was assessed by testing non-clinical subjects. Like clinical tinnitus patients, about 80% of non-clinical subjects who had ongoing tinnitus at the time of testing (whether or not they had been previously aware of it) could modulate their tinnitus with head and neck contractions. Almost 60% of those with no tinnitus at the time of testing could elicit a tinnitus-like auditory percept with head and neck contractions. Because similar results were found in the profoundly deaf, we conclude that somatosensory-auditory interactions within the central nervous system account for most, if not all, somatic modulation of tinnitus as well as the development of auditory percepts with somatic testing. Other observations implicate the muscle spindle as initiating the neural activation that ultimately modulates the central auditory pathway, including the dorsal cochlear nucleus. Somatic influences upon auditory perception are not limited to tinnitus subjects but are a fundamental property of the auditory system.