Eye movement abnormalities in somatic tinnitus: fixation, smooth pursuit and optokinetic nystagmus.

OBJECTIVE

Smooth pursuit (SP), optokinetic nystagmus (OKN) and fixation were investigated in five subjects with somatic tinnitus modulated by eye movements, jaw or neck.

METHODS

Eye movements were recorded with the EyeLink II video system.

RESULTS

(1) Fixation was characterized by high frequency and amplitude of saccade intrusions; (2) SP had low gain particularly in the vertical direction, and it was characterized by high frequency of catch-up saccades with high amplitude, including predictive saccades; (3) OKN also had low gain particularly in the vertical direction. Each subject showed abnormality for more than one type of eye movement, and for specific directions.

CONCLUSIONS AND SIGNIFICANCE

The results suggest mild dysfunction of cortical-subcortical and cerebellar structures involved in the control of these eye movements. Particularly deficits for vertical pursuit eye movements and fixation instability in line with cerebellar signs. Further studies of more patients with or without modulated tinnitus are in progress.