Relationship between intensity of electrical stimulates and prognosis of facial nerve: intrao-perative monitoring of 130 large acoustic neuromas

Objective: The aim of intraoperative monitoring is to preserve facial nerve and other cranial nerves at the basis of total tumors removal. The key elements of facial nerve preservation was analyzed. Methods: We reported 130 cases of large acoustic neuromas with intraoperative multimodality monitoring of facial nerve, acoustic nerve and trigeminal nerve. The 129 patients underwent operation with retrosigmoid approach,1 patient with translabyrinth approach. Results: Constant monopolar voltage stimuli can identify the position of facial nerve excisely. The electrical injury to facial nerve is smaller than that of mechanic stimulate. The stimulate intensity is from low to high step by step and the distance to nerve is from remote to vicinity.The ratio of facial nerve preservation is 94.61%. Conclusions: The electrical stimulate can identify the position of facial nerve quickly and precisely. Stimulate at the exit of facial nerve from brainstem can predict the acute and final facial nerve function following acoustic neuroma resection. If the stimulate is 1V（0.1ms）, the facial nereve function is I grade of Housr-Brackman classification at discharge and numbers of H-B grade I patients increased greatly following up in 1 year later.