gms | German Medical Science

63rd Annual Meeting of the German Society of Neurosurgery (DGNC)
Joint Meeting with the Japanese Neurosurgical Society (JNS)

German Society of Neurosurgery (DGNC)

13 - 16 June 2012, Leipzig

Intraoperative continuous monitoring of facial motor evoked potentials in acoustic neuroma surgery

Meeting Abstract

  • H. Tokimura - Department of Neurosurgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
  • S. Sugata - Department of Neurosurgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
  • H. Yamahata - Department of Neurosurgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
  • R. Hanaya - Department of Neurosurgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
  • H. Hirano - Department of Neurosurgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
  • K. Arita - Department of Neurosurgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan

Deutsche Gesellschaft für Neurochirurgie. Japanische Gesellschaft für Neurochirurgie. 63. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit der Japanischen Gesellschaft für Neurochirurgie (JNS). Leipzig, 13.-16.06.2012. Düsseldorf: German Medical Science GMS Publishing House; 2012. DocFR.12.03

DOI: 10.3205/12dgnc268, URN: urn:nbn:de:0183-12dgnc2686

Published: June 4, 2012

© 2012 Tokimura et al.
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Outline

Text

Objective: Preservation of facial nerve function is one of the most important goals to accomplish in acoustic neuroma surgery. Transcranial electrical motor evoked potentials is a useful neurophysiological method to preserve the pyramidal tract without placement of any electrodes in the operative field. In this study, we have applied facial motor evoked potentials (fMEP) for preservation of facial nerve function during acoustic neuroma surgery.

Methods: We investigated 10 patients with surgically treated acoustic neuroma to identify correlations between parameters in this monitoring and postoperative facial nerve function. fMEP was recorded from the orbicularis oculi and orbicularis oris muscles. Transcranial stimulation using MEE-1232 (Nihon Koden) high-voltage electric stimulator was given through 2 spiral electrodes fixed to the scalp with the cathode at the vertex and the anode placed on the facial motor cortex which was identified by navigation system. fMEP was recorded and checked every 10 second throughout the surgery. We also checked the location of the facial nerve by direct electrical stimulation using NIM response (Medtronic).

Results: Our series includes 6 women and 4 men. The average age was 37.3. The average maximum diameter of the tumors was 37.3 mm. Mean tumor resection rate was 95.4%, and eventual postoperative facial nerve function were all normal. In 1 patient with temporary postoperative facial nerve palsy (House-Brackmann grade II), fMEP was deteriorated one-third of control fMEP. In another patient, although threshold of fMEP was elevated, the amplitude of fMEP was the same as control fMEP. In both cases, response of the facial nerves by direct electrical stimulation was normal before dural closure.

Conclusions: Postoperative facial nerve function appears predictable using intraoperative continuous monitoring of fMEPs. This monitoring is useful to increase the tumor excision rate while avoiding severe postoperative facial nerve palsy in acoustic neuroma surgery.