Usefulness of intraoperative monitoring of oculomotor and abducens nerves during surgical treatment of the cavernous sinus meningiomas.

Purpose: We analyzed the usefulness and prognostic value of intraoperative monitoring for identification of the oculomotor (III) and the abducens (VI) nerve in patients with cavernous sinus meningiomas.
Material/methods: 43 patients diagnosed with cavernous sinus meningiomas were divided according to their topography. Function of the nerves was scored on original clinical and neurophysiological scales.
Results: The percentage of nerves identified correctly with the monitoring was significantly higher (91% vs. 53% for nerve III and 70% vs. 23% for nerve VI, p<0.001). The fractions of nerves III and VI identified correctly by means of the monitoring were significantly higher in the case of tumors with intra- and extracavernous location (89% vs. 32%, p<0.01) and intracavernous tumors (80% vs. 20%, p<0.05), respectively. The quality of post-resection recording correlated with functional status of both the nerves determined 9 months after the surgery (R=0.51, p<0.001 for nerve III and R=0.57, p<0.01 for nerve VI). Even a trace or pathological response to the post-resection stimulation was associated with improved functional status (90% vs. 50%, p<0.05 for nerve III and 93% vs. 38%, p<0.01 for nerve VI).
Conclusions: Neurophysiological monitoring of ocular motor nerves enables their intraoperative identification during resections of the cavernous sinus meningiomas. Intraoperative monitoring of nerve III is particularly important in the case of tumors with extra- and intracavernous location, and the monitoring of nerve VI in the case of intracavernous tumors. The outcome of the post-resection monitoring has prognostic value with regard to the clinical status of the nerves on long-term follow-up.
(Copyright © 2014 Medical University of Bialystok. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.)