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  • Risk Factors and Consequences of Intraoperative Seizures Associated with Direct Cortical Stimulation During Awake Craniotomy

    Final Number:

    Zachary A Abecassis BS; Amit Ayer MD; Nikhil Murthy MD; Jessica W Templer MD; Matthew Christopher Tate MD PhD;

    Study Design:

    Subject Category:

    Meeting: Congress of Neurological Surgeons 2018 Annual Meeting

    Introduction: Intraoperative direct electrical stimulation is a crucial adjunct in neurosurgical oncology, allowing maximal tumor resection while preserving neurologic function. There is limited data describing the incidence, risk factors, and clinical consequences of intraoperative seizures and after-discharges (ADs) in patients undergoing craniotomies.

    Methods: A retrospective chart review was conducted comprised of adult patients undergoing awake craniotomy with direct cortical stimulation using a positive mapping strategy from 2013 – 2017 (n=229). Rates of intraoperative seizures and ADs were recorded based on intraoperative neurological monitoring reports, with seizures and ADs verified by a dedicated epileptologist. Univariate analysis was performed to assess significance of preoperative risk factors (tumor grade, location, genetic factors, history of prior resection).

    Results: 16% of patients experienced intraoperative seizures and 18% experienced ADs. 4% experienced both seizures and ADs. Patients with tumors in the parietal lobe (OR=2.06, p<0.05) and MGMT methylation (OR=3.0, p=0.02) had increased risk of intraoperative seizures, while most preoperative risk factors (tumor grade, length of surgery, non-parietal location) did not statistically increase risk of seizures. There was no relationship between current amplitude and presence of either intraoperative seizures (p=0.1044) or ADs (p=0.9908). Additionally, ADs were not predictive of intraoperative seizures (OR=1.742, p=0.1948). Neither intraoperative seizures (OR=1.543, p=0.3297) nor ADs (OR=0.5065, p=0.2172) were predictive of postoperative seizures. Finally, presence of intraoperative seizures (p=0.146) did not result in an increase in length of stay.

    Conclusions: Intraoperative seizures and ADs are relatively common but do not significantly alter surgical plan nor impact postoperative neurologic function or seizure rates. These results suggest that intraoperative seizures and ADs can be safely managed in the setting of functional mapping during awake craniotomies with minimal harm.

    Patient Care: Cortical stimulation is a crucial adjunct to ensure maximal resection while preserving functionality, especially within eloquent cortex. Understanding the effects of both after discharges (ADs) and intraoperative seizures, both presumably provoked by stimulation, would advance clinical management and knowledge of potential ramifications. This may increase confidence in mapping in the presence of intraoperative ADs and electrographic stimulation-induced seizures, and enable the factors that may precipitate these events.

    Learning Objectives: Outline factors associated with observed intraoperative seizures and after-discharges during awake craniotomy procedures. Describe the frequency of intraoperative seizures and after discharges. Discuss the effects of intraoperative seizures and after discharges on postoperative outcomes.


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