The functional neuroanatomy of tinnitus

TLDR

PET and cerebral blood flow imaging were used to map brain activity in four tinnitus patients who could modulate loudness with voluntary oral facial movements, comparing rest, OFM, and pure‑tone conditions to six controls. Modulation of tinnitus loudness activated the contralateral auditory cortex, while unilateral cochlear stimulation produced bilateral effects, and patients showed broader tone‑evoked activation and abnormal limbic‑auditory connectivity, supporting a retrocochlear origin and cortical plasticity underlying tinnitus, though generalization should be cautious due to the patients’ unique modulation ability.

Abstract

We used PET to map brain regions responding to changes in tinnitus loudness in four patients who could alter tinnitus loudness by performing voluntary oral facial movements (OFMs). Cerebral blood flow was measured in four patients and six controls at rest, during the OFM, and during stimulation with pure tones. OFM-induced loudness changes affected the auditory cortex contralateral to the ear in which tinnitus was perceived, whereas unilateral cochlear stimulation caused bilateral effects, suggesting a retrocochlear origin for their tinnitus. Patients, compared with controls, showed evidence for more widespread activation by the tones and aberrant links between the limbic and auditory systems. These abnormal patterns provide evidence for cortical plasticity that may account for tinnitus and associated symptoms. Although audiologic symptoms and examinations of these patients were typical, the unusual ability to modulate tinnitus loudness with an OFM suggests some caution may be warranted in generalizing these findings.