Intraoperative Neurophysiological Monitoring for Endoscopic Endonasal Approaches to the Skull Base: A Technical Guide

Table 1

Surgical approaches using the endoscopic, endonasal route and recommended IONM modalities based on pathologies commonly encountered via that approach.

Surgical approach	IONM Montage	Common pathology
Transsphenoidal to sella	None	Adenoma, Rathke’s cleft cyst
Transsphenoidal, transplanum, transtuberculum to suprasellar region	EEG, SSEPs, MEPs	Meningioma, craniopharyngioma, giant pituitary adenomas
To orbital apex	EEG, SSEPs, MEPs, EMG (CN III, IV, VI)	Hemangioma, meningioma, neoplasm
Transethmoidal, transcribiform to anterior cranial fossa	EEG, SSEPs, MEPs	Meningioma, esthesioneuroblastoma, meningocele
Transclival/transpetrous to posterior fossa	EEG, SSEPs, MEPs, EMG (CN VI, VII)	Chordoma, chondrosarcoma
Transpterygoid	EEG, SSEPs, MEPs, EMG (CN V)	Meningocele, meningoencephalocele, schwannoma
To cavernous sinus	EEG, SSEPs, MEPs, EMG (CN III, IV, VI)	Adenoma, meningioma
Transcondylar/transjugular	EEG, SSEPs, MEPs, EMG (CN IX, X, XI, XII)	Chordoma, chondrosarcoma