Article
Eye muscles intraoperative neurophysiological monitoring for the resection of skull base tumors involving the superior orbital fissure and cavernous sinus
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Published: | June 2, 2015 |
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Objective: Tumors of the skull base can frequently involve the superior orbital fissure and the cavernous sinus, hence the oculomotor, trochlear and abducens nerves are at risk during resection. Intraoperative electrophysiological monitornig could be of help in determining the integrity of such nerves during surgery.
Method: Spheno-orbital meningiomas (2), chondrosarcoma, giant trigeminal schwannoma, giant adenoma and ameloblastoma were operated on through orbito-zygomatic approach. Insertion of EMG needles in the superior rectus, lateral rectus and superior oblique muscles by the guidance of the neuronavigation was performed. Then, multichannel recording of the free run activity and evoked activity through bipolar stimulation was systematically done. Resection of the tumors was pursued during continuous monitoring of these nerves.
Results: No morbidity related to the EMG of the muscles was reported. In all the patients EMG responses were recorded after stimulation of the III, IV, VI nerves. The method was useful for understanding the relationships between the tumor and the nerve and to ascertain the integrity of the nerve at the end of the resection.
Conclusions: The intraoperative EMG monitoring of the extrinsic eye muscles seems reliable and effective. More procedures are needed in order to understand the real impact on the extent of resection and the prognostic role about the functional outcome.