J Neurol Surg Rep 2013; 74(01): 043-050
DOI: 10.1055/s-0033-1346975
Georg Thieme Verlag KG Stuttgart · New York

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

Parthasarathy D. Thirumala
1   Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
4   Department of Neurology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
,
Santhosh Kumar Mohanraj
1   Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
,
Miguel Habeych
1   Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
,
Kelley Wichman
1   Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
,
Yue-fang Chang
1   Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
,
Paul Gardner
1   Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
,
Carl Snyderman
1   Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
3   Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
,
Donald J. Crammond
1   Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
,
Jeffrey Balzer
1   Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
2   Department of Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
› Author Affiliations
Further Information

Publication History

13 December 2012

05 March 2013

Publication Date:
13 June 2013 (online)

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.

Note

No grants are pertinent to this paper.