Evidence map›Paper›PMID 39641813›Full record

ArticleActa neurochirurgica2024

Does persistent crossover (ipsilateral) motor evoked potential (MEP) responses represent a technical failure for intracranial motor tract monitoring? A case example and practical solution.

Marshall F Wilkinson, Kristine Pederson, Philip Kawalec, Joseph Silvaggio, M Suheel Abdul-Salaam

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In one paragraph

Article in Acta neurochirurgica, 2024. 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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4 · The record

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5 · Who and what money

Authors and funding

5 authors.

Marshall F WilkinsonSection of Neurosurgery Health Sciences Centre, GB 1 - 820 Sherbrook Street, Winnipeg, MB, R3A 1R9, Canada. mwilkinson@hsc.mb.ca.
Kristine PedersonSection of Neurosurgery Health Sciences Centre, GB 1 - 820 Sherbrook Street, Winnipeg, MB, R3A 1R9, Canada.
Philip KawalecSection of Neurosurgery Health Sciences Centre, GB 1 - 820 Sherbrook Street, Winnipeg, MB, R3A 1R9, Canada.
Joseph SilvaggioSection of Neurosurgery Health Sciences Centre, GB 1 - 820 Sherbrook Street, Winnipeg, MB, R3A 1R9, Canada.
M Suheel Abdul-SalaamSection of Neurosurgery Health Sciences Centre, GB 1 - 820 Sherbrook Street, Winnipeg, MB, R3A 1R9, Canada.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

purposeAttention to motor evoked potential (MEP) stimulation intensity is necessary to avoid false negative MEP results during intracranial procedures. Observing ipsilateral (crossover) MEP responses has been hypothesized to indicate inappropriately strong stimulation intensity. We describe a case where persistent crossover MEP responses falsely suggested that stimulus intensity was too high and describe an alternative method to guide the selection of MEP stimulation intensity.

methodsA patient undergoing a suboccipital craniotomy for tumor resection had bilateral transcranial electrical MEP monitoring under total intravenous anesthesia. MEP results were obtained from left and right hand using C4-Cz and C3-Cz stimulation montages respectively. Selection of an appropriately superficial stimulus intensity was guided using MEP onset latencies.

resultsMEP acquisition proceeded normally for contralateral left hand (C4-Cz montage). However, using the C3-Cz montage, persistent crossover responses were noted at stimulation intensities as low as threshold for contralateral right hand MEP (94 V/166 mA). Appropriate MEP stimulus intensity for subsequent monitoring (approximately 96 V/172 mA) was determined utilizing onset latency measurements from contralateral hand MEP responses. The stimulus intensity chosen was predicated on onset latency being ≥ 2 ms longer than latency at maximal stimulus level (shortest latency). A stimulus intensity-latency plot was generated offline to illustrate this important relationship for intracranial MEP use. MEP acquisition proceeded without incident and gross total resection was achieved without postoperative motor deficits.

conclusionDespite crossover appearance contralateral hand MEP were quantitatively validated for intraoperative application using onset latency guidance.

Indexed as

CraniotomyEvoked Potentials, MotorBrain NeoplasmsHumansIntraoperative Neurophysiological MonitoringMonitoring, IntraoperativeTranscranial Direct Current StimulationCrossoverMotor evoked potentialsNeurophysiological monitoringOnset latency

Identifiers

PMID39641813

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