73. Acoustic neuroma surgery: Long term follow-up between facial nerve IOM monitored and non-monitored patients

Intraoperative monitoring (IOM) has become the most reliable means to preserve facial nerve function during acoustic neuroma surgery. Since IOM has gradually entered in the operative rooms a proportion of patients did not receive facial nerve IOM. Purpose: to compare faciaI nerve score deficit in monitored versus non-monitored patients. 66 patients (38 non-monitored and 28 monitored) have been evaluated at least two years after operation. The facial nerve compound muscle action potential was recorded by means of surface electrodes; the negative amplitude/area and peak-to-peak amplitude of each sides measured and scored. The mean amplitude/area of the unaffected (1.56 mV/7.30 mV 2 and 1.48 mV/6.69 mV 2 ) and affected sides (0.75 mV/5.12 mV 2 and 0.74 mV/2.56 mV 2 ) and the scores of deficits did not statistically differ. Un-respective of the proportion of the patients with total nerves cut, the results of the study indicated that once the facial nerve was identified and somehow the anatomical continuity preserved, the utility of IOM to improve the quality of facial nerve function was more uncertain because did not affect the neurophysiological outcome, as one might expect instead.