Monitoring surgery around the cranial nerves

Jaime R. López, Alan D. Legatt

Research output: Chapter in Book/Report/Conference proceedingChapter

1 Scopus citations


Intraoperative neurophysiologic monitoring (IONM) of cranial nerve (CN) function is an essential component in multimodality monitoring of surgical procedures where CNs are at risk for injury. In most cases, IONM consists of localizing and mapping CNs and their pathways, and monitoring of CN motor function during surgery. However, CN VIII, which has no motor function, and is at risk for injury in many surgical procedures, can be easily and accurately monitored using brainstem auditory evoked potentials. For motor CNs, the literature is clear that function can be safely and adequately performed using basic electromyographic (EMG) techniques, such as recording of continuous EMG activity and electrically evoked compound muscle actions potentials. Newer techniques, such as corticobulbar motor evoked potentials and reflex studies, show good potential for a greater degree of functional assessment but require further study to determine their clinical utility. EMG remains the basic clinical neurophysiologic technique with the greatest clinical research supporting its utility in IONM of motor CN function and should be used as part of a comprehensive multimodality IONM protocol. Understanding the physiologic basis of EMG and the changes associated with altered motor function will allow the practitioner to alter surgical course to prevent injury and improve patient safety.

Original languageEnglish (US)
Title of host publicationHandbook of Clinical Neurology
PublisherElsevier B.V.
Number of pages33
StatePublished - Jan 2022

Publication series

NameHandbook of Clinical Neurology
ISSN (Print)0072-9752
ISSN (Electronic)2212-4152


  • BAEP
  • Cranial nerves
  • Electromyography
  • EMG
  • Extraocular muscles
  • Facial nerve
  • Intraoperative neurophysiologic monitoring
  • Motor function
  • Neurotonic
  • Skull base surgery

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology


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