Singular neurectomy update. II. Review of 102 cases.

During the past 18 years, 102 singular neurectomies (SN) were performed on 95 patients with chronic cupulolithiasis of the posterior canal sense organ. Bilateral sequential singular neurectomies were performed in 7 patients and unilateral singular neurectomies in 88 patients. Ninety-nine (97%) of the 102 singular neurectomies completely eliminated the positional nystagmus and vertigo produced by the involved (undermost) ear in the Hallpike maneuver. Following three singular neurectomies (3%), there was improvement but incomplete relief from the positional nystagmus. A sensorineural hearing loss caused by the singular neurectomies occurred in four patients (4%). A thorough knowledge of the surgical and histologic anatomy of the round window niche and singular canal, together with the use of local anesthesia to allow monitoring of a vestibular response to singular neurectomy are essential for effectiveness and safety.