Evidence map›Paper›PMID 40372119›Full record

ArticleOperative neurosurgery (Hagerstown, Md.)2025

Interpretation and Strategy to Resolve Neuromonitoring Changes Associated With Brain Sag.

Mitali Bose, Matthew Toczylowski, Xiaopeng Guo, David D Liu, Thomas Epplin-Zapf, W Bryan Wilent, Wenya Linda Bi

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Article in Operative neurosurgery (Hagerstown, Md.), 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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5 · Who and what money

Authors and funding

7 authors.

Mitali BoseSpecialtyCare Inc., Neuro Services, Brentwood, Tennessee, USA.
Matthew ToczylowskiSpecialtyCare Inc., Neuro Services, Brentwood, Tennessee, USA.
Xiaopeng GuoDepartment of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
David D LiuDepartment of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
Thomas Epplin-ZapfSpecialtyCare Inc., Neuro Services, Brentwood, Tennessee, USA.
W Bryan WilentDepartment of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Wenya Linda BiDepartment of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.ORCID 0000-0002-4635-0247

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

BACKGROUND AND

objectivesIntraoperative neuromonitoring (IONM) aides in safe maximal resection of brain tumors in eloquent areas. During the resection of large or deep-seated tumors, shifts in the peri-resectional parenchyma and cortical surface relative to cranial electrodes, or brain sag, can cause false-positive loss of sensorimotor signals. We describe patterns of electrophysiological changes associated with brain sag and a facile technique to rapidly resolve these changes intraoperatively by saline infusion.

methodsWe reviewed cases operated on by the senior author and identified cases where brain sag was noted intraoperatively. Preoperative and postoperative imaging, operative details, and IONM electrophysiological traces were analyzed to surmise generalizable patterns.

resultsWe observe stepwise decreases in somatosensory-evoked potentials and transcranial motor-evoked potentials that occur with removal of a large intraparenchymal mass or after significant loss of cerebrospinal fluid. The pattern of upper extremity or lower extremity signal change depends on the location of the lesion and the positioning of the head, depending on which regions of the motor or somatosensory cortices are most affected by brain sag. Recovery of the somatosensory-evoked potentials and transcranial motor-evoked potentials during saline infusion into the resection cavity or ventricle, which reconstitutes the cortical topography, suggests that the IONM signal change was artifactual, rather than reflecting true physiological injury. We present 6 illustrative cases that highlight distinct patterns of electrophysiological change associated with brain sag and the extent of signal restoration.

conclusionBrain sag is commonly encountered during the resection of large or deep-seated tumors. Improved understanding of the spatiotemporal electrophysiological signatures of brain sag and application of the saline infusion technique to reverse false-positive drops in neuromonitoring signals improves the utility of IONM and enhances safe resection.

Indexed as

BrainBrain NeoplasmsIntraoperative Neurophysiological MonitoringNeurosurgical ProceduresAdultAgedEvoked Potentials, MotorEvoked Potentials, SomatosensoryFemaleHumansMaleMiddle AgedRetrospective StudiesBrain sagBrain shiftIntraoperative neuromonitoringMotor-evoked potentialsNeurophysiologySomatosensory-evoked potentials

Identifiers

PMID40372119
PMCPMC12068778

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.