Somatic modulation of tinnitus: a review and some open questions

Tinnitus modulation by movements of the temporomandibular joint, head and neck musculoskeletal structures and the eye, can be found in one to two thirds of tinnitus sufferers; unfortunately this condition is often overlooked by otolaryngologists. Although somatic modulation has been initially hypothesized as a fundamental characteristic of tinnitus, there is increasing evidence of a tight connection with disorders of non-auditory regions. The structure that mostly modulates tinnitus is the temporomandibular joint, which mainly causes an increase in tinnitus loudness, followed by head and neck movements that may result in an increase or decrease of loudness and eye movements (gaze-evoked tinnitus). Besides loudness, somatic movements can also modulate tinnitus pitch and localization. Somatosensory tinnitus is a relatively new nding that leaves several open questions: are there individual predisposing factors to somatic modulation? How strong is the association between the capability to somatically modulate tinnitus and an underlying non-auditory disorder? Changes that occur after somatic maneuvers are only transitory? Why patients that have concomitant hyperacusis also have higher chances of tinnitus modulation? Further basic science and clinical research is required to address these and many other questions about somatosensory tinnitus.