Dexmedetomidine anesthesia enhances spike generation during intra-operative electrocorticography: A promising adjunct for epilepsy surgery

Background: Anesthetic-induced suppression of cortical electrical activity is a major concern during epilepsy surgery. Dexmedetomidine (Dex) has been recently evaluated in a few small series for its effect on the electrocorticographic spikes intra-operatively.

Methods: In this prospective study, electrocorticogram (ECoG) was monitored during dexmedetomidine infusion in 34 patients (M:F=23:11, age=29.2 ± 10.9 years; duration of epilepsy=15.3 ± 8.9 years) undergoing anterior temporal lobe resection with amygdalo-hippocampectomy for drug-resistant mesial temporal lobe epilepsy (Right: 18, Left: 16). Anesthesia was induced with thiopental/propofol and maintained with oxygen-N2O-isoflurane. ECoG was recorded for 5 min after the end tidal MAC of N2O and isoflurane were decreased to zero; anesthesia was maintained with O2:Air=50:50, vecuronium and fentanyl. ECoG was recorded using a 4-contact strip electrode for: (a) 5 min prior to dexmedetomidine (PreDEX), (b) 5 min during dexmedetomidine infusion (DEX; 1 μg/kg) and (c) 5 min after stopping dexmedetomidine (PostDEX).

Results: The ECoG spikes were manually counted in all the channels. The mean spike rate in the 2 channels with maximum spikes (MAX CH A and MAX CH B) was normalized to a 3-min duration. RM-ANOVA and post hoc comparison of three phases were used to compare the spike rates. The mean spike rate during Dex phase was higher compared to preDEX (MAX CH B: p=0.007 and MAX CH A: p=0.079) and PostDEX (MAX CH B: p=0.17, MAX CH A: p=0.79) phases. The spike rate increased in 67.6% patients, while 11.8% patients showed ≤ 25% reduction and 20.6% patients showed >25% reduction in spike frequency.

Conclusion: Dexmedetomidine is useful during intra-operative ECoG recording in epilepsy surgery as it enhances or does not alter spike rate in most of the cases, without any major adverse effects.