Value of Free-Run Electromyographic Monitoring of Extraocular Cranial Nerves during Expanded Endonasal Surgery (EES) of the Skull Base

Abstract

Objective To evaluate the value of free-run electromyography (f-EMG) monitoring of extraocular cranial nerves (EOCN) III, IV, and VI during expanded endonasal surgery (EES) of the skull base in reducing iatrogenic cranial nerve (CN) deficits.

Design We retrospectively identified 200 patients out of 990 who had at least one EOCN monitored during EES. We further separated patients into groups according to the specific CN monitored. In each CN group, we classified patients who had significant (SG) f-EMG activity as Group I and those who did not as Group II.

Results A total of 696 EOCNs were monitored. The number of muscles supplied by EOCNs that had SG f-EMG activity was 88, including CN III = 46, CN IV = 21, and CN VI = 21. There were two deficits involving CN VI in patients who had SG f-EMG activity during surgery. There were 14 deficits observed, including CN III = 3, CN IV = 2, and CN VI = 9 in patients who did not have SG f-EMG activity during surgery.

Conclusions f-EMG monitoring of EOCN during EES can be useful in identifying the location of the nerve. It seems to have limited value in predicting postoperative neurological deficits. Future studies to evaluate the EMG of EOCN during EES need to be done with both f-EMG and triggered EMG.

Keywords

electromyography - lower cranial nerves - expanded endonasal surgery

Note

No grants are pertinent to this paper.

• References

• 1 Alberti O, Sure U, Riegel T, Bertalanffy H. Image-guided placement of eye muscle electrodes for intraoperative cranial nerve monitoring. Neurosurgery 2001; 49 (3) 660-663 , discussion 663–664
• 2 Kawaguchi M, Ohnishi H, Sakamoto T , et al. Intraoperative electrophysiologic monitoring of cranial motor nerves in skull base surgery. Surg Neurol 1995; 43 (2) 177-181
• 3 Schlake HP, Goldbrunner R, Milewski C , et al. Technical developments in intra-operative monitoring for the preservation of cranial motor nerves and hearing in skull base surgery. Neurol Res 1999; 21 (1) 11-24
• 4 Schlake HP, Goldbrunner R, Siebert M, Behr R, Roosen K. Intra-Operative electromyographic monitoring of extra-ocular motor nerves (Nn. III, VI) in skull base surgery. Acta Neurochir (Wien) 2001; 143 (3) 251-261
• 5 Sekhar LN, Møller AR. Operative management of tumors involving the cavernous sinus. J Neurosurg 1986; 64 (6) 879-889
• 6 Sekiya T, Hatayama T, Iwabuchi T, Maeda S. Intraoperative recordings of evoked extraocular muscle activities to monitor ocular motor nerve function. Neurosurgery 1993; 32 (2) 227-235 , discussion 235
• 7 Romstöck J, Strauss C, Fahlbusch R. Continuous electromyography monitoring of motor cranial nerves during cerebellopontine angle surgery. J Neurosurg 2000; 93 (4) 586-593
• 8 Isaacson B, Kileny PR, El-Kashlan HK. Prediction of long-term facial nerve outcomes with intraoperative nerve monitoring. Otol Neurotol 2005; 26 (2) 270-273
• 9 Fukaya C, Katayama Y, Kasai M, Kurihara J, Yamamoto T. Intraoperative electro-oculographic Monitoring for Skull Base Surgery. Skull Base Surg 2000; 10 (1) 11-15
• 10 Sekiya T, Hatayama T, Iwabuchi T, Maeda S. A ring electrode to record extraocular muscle activities during skull base surgery. Acta Neurochir (Wien) 1992; 117 (1-2) 66-69
• 11 Kassam A, Carrau RL, Snyderman CH, Gardner P, Mintz A. Evolution of reconstructive techniques following endoscopic expanded endonasal approaches. Neurosurg Focus 2005; 19 (1) E8
• 12 Kassam A, Snyderman CH, Mintz A, Gardner P, Carrau RL. Expanded endonasal approach: the rostrocaudal axis. Part I. Crista galli to the sella turcica. Neurosurg Focus 2005; 19 (1) E3
• 13 Kassam A, Snyderman CH, Mintz A, Gardner P, Carrau RL. Expanded endonasal approach: the rostrocaudal axis. Part II. Posterior clinoids to the foramen magnum. Neurosurg Focus 2005; 19 (1) E4
• 14 Kassam AB, Gardner P, Snyderman C, Mintz A, Carrau R. Expanded endonasal approach: fully endoscopic, completely transnasal approach to the middle third of the clivus, petrous bone, middle cranial fossa, and infratemporal fossa. Neurosurg Focus 2005; 19 (1) E6
• 15 Kassam AB, Snyderman C, Gardner P, Carrau R, Spiro R. The expanded endonasal approach: a fully endoscopic transnasal approach and resection of the odontoid process: technical case report. Neurosurgery 2005; 57 (1, Suppl): E213 , discussion E213
• 16 Gardner PA, Kassam AB, Snyderman CH , et al. Outcomes following endoscopic, expanded endonasal resection of suprasellar craniopharyngiomas: a case series. J Neurosurg 2008; 109 (1) 6-16
• 17 Harner SG, Daube JR, Ebersold MJ. Electrophysiologic monitoring of facial nerve during temporal bone surgery. Laryngoscope 1986; 96 (1) 65-69
• 18 Harner SG, Daube JR, Ebersold MJ, Beatty CW. Improved preservation of facial nerve function with use of electrical monitoring during removal of acoustic neuromas. Mayo Clin Proc 1987; 62 (2) 92-102
• 19 Nelson KR, Vasconez HC. Nerve transection without neurotonic discharges during intraoperative electromyographic monitoring. Muscle Nerve 1995; 18 (2) 236-238
• 20 Harper CM. Intraoperative cranial nerve monitoring. Muscle Nerve 2004; 29 (3) 339-351
• 21 Thirumala PD, Kassasm AB, Habeych M , et al. Somatosensory evoked potential monitoring during endoscopic endonasal approach to skull base surgery: analysis of observed changes. Neurosurgery 2011; 69 (Suppl. 01) 64-76