Surgical Decompression of the Eighth Nerve for Tinnitus.

This article reports two cases of vascular decompression for tinnitus, both of which were successful. The pathophysiology of vascular compression syndromes in general and specifically eighth nerve vascular compression syndromes is reviewed. The anatomy of the anterior inferior cerebellar artery and its relationship to the eighth nerve complex is discussed in detail and the literature of vascular compression syndrome reviewed. Although no unequivocal definitive test procedure is available for preoperative diagnosis of vascular compression syndrome, the presence of the following features makes the diagnosis more likely: I-III interpeak latency abnormalities on auditory brain stem response (ABR), abnormalities of stapedius reflex, unilateral sensorineural hearing loss, ipsilateral electronystagmography (ENG) abnormalities, especially spontaneous nystagmus, and radiographic visualization of a vessel contacting the eighth nerve complex.