Histopathologic consequences of surgical approaches to the singular nerve.

Selective sectioning of the singular nerve has proven successful in the relief of incapacitating benign positional vertigo (BPV), presumably on the histopathologic basis of posterior ampullary cupulolithiasis. Although the surgical techniques of transmeatal and the recently introduced retrosigmoid IAC approach have been well described, little has been written about the singular nerve's anatomical relationships determined histologically for each surgical approach. The anatomical relationships of the singular nerve in both the transmeatal and retrosigmoid IAC approaches are discussed. Histologic evidence presented suggests that other mechanisms may also be ultimately responsible for improvement in the symptoms of BPV following transmeatal surgery. Moreover, the high incidence of injury to the endolymphatic duct during retrosigmoid surgery raises questions about the exact role of the endolymphatic duct and sac in inner ear homeostasis.