Peroperative monitoring of the facial nerve in surgery for acoustic neuroma

: This paper reports our experience about intraoperative facial nerve monitoring carried out in 97 patients operated on by a retrosigmoid approach. Intra-operative facial nerve monitoring was performed using a pneumatic sensor which transforms into acoustic signals contractions of facial muscles elicited by mechanical, electrical or thermal stimulations of facial nerve. Long term results showed that a normal facial function (grade I) was achieved in 90.5% of patients, 4 patients were grade II, 2 patients grade III, a total paralysis (grades V and VI) was persistent in 3 patients. Our experience with facial nerve monitoring suggests a modification of the strategy of dissection based upon a preservation of the arachnoid veil and a medial to lateral direction of dissection.