The incidence of unacceptable movement with motor evoked potentials during craniotomy for aneurysm clipping.


OBJECTIVE: To review the experience at a single institution with motor evoked potential (MEP) monitoring during intracranial aneurysm surgery to determine the incidence of unacceptable movement. METHODS: Neurophysiology event logs and anesthetic records from 220 craniotomies for aneurysm clipping were reviewed for unacceptable patient movement or reason for cessation of MEPs. Muscle relaxants were not given after intubation. Transcranial MEPs were recorded from bilateral abductor hallucis and abductor pollicis muscles. MEP stimulus intensity was increased up to 500 V until evoked potential responses were detectable. RESULTS: Out of 220 patients, 7 (3.2%) exhibited unacceptable movement with MEP stimulation-2 had nociception-induced movement and 5 had excessive field movement. In all but one case, MEP monitoring could be resumed, yielding a 99.5% monitoring rate. CONCLUSIONS: With the anesthetic and monitoring regimen, the authors were able to record MEPs of the upper and lower extremities in all patients and found only 3.2% demonstrated unacceptable movement. With a suitable anesthetic technique, MEP monitoring in the upper and lower extremities appears to be feasible in most patients and should not be withheld because of concern for movement during neurovascular surgery.





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Publication Info

Hemmer, Laura B, Carine Zeeni, John F Bebawy, Bernard R Bendok, Mathew A Cotton, Neil B Shah, Dhanesh K Gupta, Antoun Koht, et al. (2014). The incidence of unacceptable movement with motor evoked potentials during craniotomy for aneurysm clipping. World Neurosurg, 81(1). pp. 99–104. 10.1016/j.wneu.2012.05.034 Retrieved from

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Dhanesh Kumar Gupta

Professor of Anesthesiology

The overall theme of my research is the application of clinical pharmacology tools to the individualization of the care of high-risk surgical patients, especially those undergoing neurosurgical procedures.  Current research focuses on creating pharmacokinetic-pharmacodynamic models to allow simulation of dose-concentration-effect relationships that will result in reduced toxicity while maximizing efficacy of intravenous opioids and hypnotics. The perioperative period is a time when patients are exposed to a multitude of drugs from a different classes, some of which may attenuate while others may augment the deleterious cascade of events that starts in the operating room and result in worse neuro-oncologic, neurovascular, or pain outcomes, even after the perioperative medication has been discontinued.  Analytical techniques for perioperative “big data” have not been combined with the clinical pharmacology toolbox to create dose-response models that can help optimize perioperative care. Through collaboration with pharmacometricians and informaticians, care paths can be developed in an iterative fashion to expose the innards of the perioperative black box.

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