To identify measurable anatomical factors that may guide the surgical approach for posterior fossa selective vestibular neurectomy (SVN) and predict identification of the vestibulocochlear cleavage (VCC) plane.Study Design
Dissection of fixed cadaveric heads through retrolabyrinthine and retrosigmoid-internal auditory canal (RSG-IAC) approaches with measurement of landmarks.Setting
Cadaveric dissection model.Main Outcome Measures
Area of the Trautmann triangle (TT) and the distance from the posterior semicircular canal to the anterior border of the sigmoid along the posterior Donaldson line (pDL). VCC planes from each approach were calculated and compared.Results
Overall mean pDL was 8.53 mm (range: 5-11.5 mm); mean TT area was 124 mm2 (range: 95-237 mm2). The VCC was identified in 63% of ears through the retrolabyrinthine (RVN) approach alone, whereas 37% of ears required the RSG-IAC approach. In ears requiring IAC dissection, the VCC was found within 1 to 2 mm distal to the porus. The pDL (p < 0.05) and area of TT (p < 0.05) were significantly larger in the RVN group compared with the RSG-IAC group.Conclusion
Ears amenable to the RVN approach had a greater pDL and TT area. These anatomical measurements may have a role in surgical planning and the choice of approach for SVN.