ABSTRACT
A unique and intriguing form of subjective tinnitus evoked by eye gaze is reviewed. A new perspective is presented because this condition is sufficiently different from other forms of subjective tinnitus and its manifestation cannot be adequately explained by existing models or conceptual frameworks. Our examination of this topic considers pathophysiologic changes in the central nervous system in the context of deafferentation-induced plasticity. Potential neuroanatomical areas contributing to this effect include a number of distributed and functionally diverse areas in the brainstem and neocortex involved in the auditory control of eye movements. We also consider contemporary psychophysical methods to evaluate the perceptual correlates of this phenomenon and tools for the development of objective tinnitus measurements. Although theoretical and speculative in nature, this article is intended to stimulate interest in, advance knowledge of, and provide a better understanding about this condition.
Subject(s)
Central Nervous System/physiopathology , Cranial Fossa, Posterior/surgery , Eye Movements/physiology , Neuronal Plasticity/physiology , Tinnitus/physiopathology , Brain Stem/physiopathology , Cerebral Cortex/physiopathology , Hearing Loss, Sensorineural/complications , Hearing Loss, Sensorineural/etiology , Hearing Loss, Sensorineural/physiopathology , Humans , Neurons, Afferent/pathology , Tinnitus/etiologyABSTRACT
Auditory perceptual and visual-spatial characteristics of subjective tinnitus evoked by eye gaze were studied in two adult human subjects. This uncommon form of tinnitus occurred approximately 4-6 weeks following neurosurgery for gross total excision of space-occupying lesions of the cerebellopontine angle and hearing was lost in the operated ear. In both cases, the gaze-evoked tinnitus was characterized as being tonal in nature, with pitch and loudness percepts remaining constant as long as the same horizontal or vertical eye directions were maintained. Tinnitus was absent when the eyes were in a neutral head-referenced position with subjects looking straight ahead. The results and implications of ophthalmological, standard and modified visual-field assessment, pure-tone audiometric assessment, spontaneous otoacoustic emission testing and detailed psychophysical assessment of pitch and loudness are discussed.
