Inferior colliculus syndrome: Clinical magnetic resonance microscopy anatomic analysis on a 7 T system.

We performed detailed structural analysis of a case of a unilateral lesion of the inferior colliculus using magnetic resonance microscopy on a 7 T system. A 36-year-old right-handed man had an intracerebral hemorrhage circumscribed to the right inferior colliculus. Following recovery from the acute phase, he had only residual left ear tinnitus and left trochlear palsy and no hearing loss. Microscopic imaging analysis on a 7 T magnetic resonance imaging system demonstrated a chronic lesion confined primarily to the right central nucleus of the inferior colliculus. Sound localization was significantly impaired in the contralateral hemispace. The case confirms prior clinical reports of unilateral inferior colliculus dysfunction, the specific anatomic characterization of which was demonstrated in this case by magnetic resonance microscopy. It furthermore supports the notion that central nucleus of the inferior colliculus dysfunction can produce tinnitus and sound localization deficits, without hearing loss.