Primary application of cavernous sinus cranial nerve neurophysiological monitoring in extended endoscopic transsphenoidal surgery

Abstract

Objective To investigate the effect of neurophysiological monitoring in extended endoscopic transsphenoidal surgery for cavernous sinus and clivus tumors. Methods We monitored the oculomotor nerve, trochlear nerve, trigeminal nerve and abducent nerve in 18 patients with cavernous sinus and clivus tumors by recording the free⁃electromyography (f⁃EMG) and triggered⁃electromyography (t⁃EMG) from August 2019 to December 2020. Two needle electrodes were inserted percutaneous into the levator palpebrae superioris muscle, superior oblique muscle, extraocular rectus muscle and masticatory muscle. To evaluate spontaneous muscle activity and complex muscle action potentials after cranial nerve stimulation. We evaluated the safety of cranial nerves and provided objective information for neurosurgeon. Results All the 18 patients with cavernous sinus and clivus tumors were treated by extended endoscopic transsphenoidal surgery, including 10 pituitary adenomas, 5 chordomas, 2 craniopharyngiomas and one cystic schwannoma. Total resection rate achieved 9/18, subtotal resection rate was 4/18, and partial resection rate was 5/18. There was no postoperative internal carotid artery (ICA) injury and cerebrospinal fluid leakage. A total of 20 oculomotor nerves, 3 trochlear nerves, 27 trigeminal nerves and 26 abducent nerves were recorded. There were one patient with left abducent nerve palsy and one patient with right abducent nerve paresis before surgery. The median follow⁃up time was 8.63 months, postoperative brain nerve injury occurred in 2 patients, the brain nerve injury rate was 2/18, all of which recovered 3 months after surgery. No patients with postoperative impaired trigeminal nerve function. Conclusions Monitoring of oculomotor nerve, trochlear nerve, trigeminal nerve and abducent nerve in extended endoscopic transsphenoidal surgery for cavernous sinus and clivus tumors is a safe and effective method. By monitoring and evaluating intraoperative f ⁃ EMG and t ⁃ EMG, neurosurgeons can adjust surgical procedures and strategies during tumor resection and reduce cranial nerve injuries.

Keywords

• brain neoplasms
• cavernous sinus
• neuroendoscopes
• nose
• sphenoid sinus
• cranial nerves
• neurophysiological monitoring