Transcranial motor evoked potential changes induced by provocative testing during embolization of cerebral...

Cerebral motor evoked potential (MEP) monitoring during arteriovenous malformation (AVM) embolization is not well studied (Söderman et al. 2003). Alterations of cerebral blood flow (CBF) during cerebral embolization could cause ischemia/infarction to the cerebral cortex. Permanent loss of MEPs is correlated with a permanent motor deficit. We report a case of a patient undergoing AVM embolization during which transcranial electrical motor evoked potentials (TCeMEP) reliably predicted changes to CBF induced by selective methohexital testing. Our finding demonstrated that MEPs are a useful means of intraoperative monitoring of motor pathway integrity and predicting changes. The loss of MEP predicted and prevented severe postoperative motor deficits. Intraoperative neuromonitoring with SSEP, TCeMEP and continuous EEG revealed no changes until the posterior cerebral artery (PCA), but not the anterior cerebral artery (ACA), was injected. TCeMEP may be superior to somatosensory evoked potential (SSEP) and EEG monitoring in predicting motor impairment during AVM surgery.