Cutaneous-evoked tinnitus - I. Phenomenology, psychophysics and functionalimaging

Complete and acute unilateral deafferentation of the auditory periphery (au ditory and vestibular afferents) can induce changes in the central nervous system that may result in unique forms of tinnitus. These tinnitus percepti ons can be controlled (turned on and off) or modulated (changed in pitch or loudness) by performing certain overt behaviors in other sensory/motor sys tems. Clinical reports from our laboratory and several other independent so urces indicate that static change in eye gaze, from a neutral head-referenc ed position, is one such behavior that can evoke, modulate and/or suppress these phantom auditory events. This report deals with a new clinical entity and a form of tinnitus that can be evoked directly by cutaneous stimulatio n of the upper hand and fingertip regions. In 2 adults, cutaneous-evoked ti nnitus was reported following neurosurgery for space-occupying lesions at t he base of the skull and posterior craniofossa, where hearing and vestibula r functions were lost completely and acutely in one ear (unilateral deaffer entation) and facial nerve paralysis (unilateral deefferentation) was prese nt either immediately following neurosurgery or had occurred as a delayed-o nset event. Herein, we focus on the phenomenology of this discovery, provid e perceptual correlates using contemporary psychophysical methods and docum ent in one individual cutaneous-evoked tinnitus-related neural activity usi ng functional magnetic resonance imaging. In a companion paper, neuroanatom ical and physiological interactions between auditory and somatosensory syst ems, possible mechanistic accounts and relevant functional neuroimaging stu dies are reviewed.