Characteristics of patients with gaze-evoked tinnitus

Objective: The authors describe symptoms and population characteristics in subjects who can modulate the loudness and/or pitch of their tinnitus by ey e movements. Study Design: Data were obtained by questionnaire. Setting: The study was conducted at a university center and a tertiary care center. Patients: Respondents had the self-reported ability to modulate their tinni tus with eye movements. Results: Ninety-one subjects reported having gaze-evoked tinnitus after pos terior fossa surgery involving the eighth nerve. Eighty-seven of them under went removal of a vestibular schwannoma (acoustic neuroma), two had bilater al eighth nerve tumors (one underwent bilateral tumor removal; the other un ilateral tumor removal), one underwent removal of a cholesteatoma, and one underwent removal of a glomus jugulare tumor. Seventeen subjects who had ne ver had posterior fossa surgery reported gaze-evoked tinnitus. Of those wit h vestibular schwannomas, tumor size ranged from small (<2 cm) to large (>4 cm). The gender distribution was 48.3% male and 51.7% female. In 77% of pa tients, the gaze-evoked tinnitus was localized to the surgical ear or side of head; 21.8% had bilateral tinnitus that was louder in the surgical ear o r side of head. In 86 of 87 subjects, loudness of tinnitus changed with eye movement. Eye movement away from the central (eyes centered) position incr eased the loudness of tinnitus in all 86 subjects who responded to this que stion. Seventy-three of 85 (85.9%) patients indicated that pitch changed wi th eye movement, with pitch increasing in 64/72 (88.9%) of them. Eighty-thr ee of 87 (95.4%) patients reported total loss of hearing in the surgical ea r. Seventy of 83 (84.3%) patients reported facial nerve problems immediatel y after surgery, 52 of 87 (60%) reported persistent facial weakness, and 16 of 87 (18.4%) patients reported persistent double vision. In those 17 subj ects with gaze-evoked tinnitus and no posterior fossa surgery, the majority of respondents (14/17, 82.4%) were male. Conclusions: Gaze-evoked tinnitus after cerebellar pontine angle surgery is more common than was previously believed. In addition, posterior fossa sur gery is not a prerequisite for the development of gaze-evoked tinnitus. It is likely that gaze-evoked tinnitus is a manifestation of functional reorga nization. Gaze-evoked tinnitus could result from an unmasking of brain regi ons that respond to multiple stimulus/response modalities, and/or from anom alous cross-modality interactions, perhaps caused by collateral sprouting.