Methohexital (Brevital) effect on electrocorticogram may be misleading

Area of Science:

• Neurosurgery
• Epileptology
• Neurophysiology

Background:

• Intractable complex partial seizures often necessitate surgical intervention like temporal lobectomy.
• Intraoperative electrocorticography (ECOG) is used to map seizure foci.
• Methohexital (MTH) is an anesthetic agent sometimes used during epilepsy surgery.

Purpose of the Study:

• To investigate the effect of intravenous methohexital (MTH) on intraoperative electrocorticogram (ECOG) during temporal lobectomies.
• To assess the significance of MTH-induced spike changes, particularly new spike foci, in predicting surgical outcomes for intractable complex partial seizures.

Main Methods:

• ECOG recordings were analyzed in 63 patients undergoing temporal lobectomy under general anesthesia.
• The impact of intravenous methohexital (MTH) on preresection and postresection ECOG was evaluated.
• Surgical outcomes were correlated with the presence of MTH-activated 'residual spikes'.

Main Results:

• Methohexital (MTH) increased spike frequency (78%), cortical spiking area (30%), and induced new spike foci (43%) in the preresection ECOG.
• Similar, though less pronounced, changes were observed in the postresection ECOG.
• Nine patients with residual MTH-activated spikes had no postoperative seizures, while two did, indicating a weak correlation with surgical success.

Conclusions:

• Methohexital (MTH) significantly alters intraoperative ECOG findings, potentially creating false-positive indicators of seizure activity.
• Caution is advised when interpreting MTH-induced spike foci during epilepsy surgery, as they may not accurately predict seizure recurrence.
• Further research with larger patient cohorts is recommended to understand the implications of MTH-induced false activations.