Abstract
Objectives
Avoiding or minimizing the interference of anesthetic agents with electrocorticography
(ECoG) signals during ECoG-guided epilepsy surgery is vital to the successful resection
of the epileptogenic area. Most agents in routine use have widely variable effects
like suppression, enhancement, or no impact on the ECoG signals. Dexmedetomidine is
reported to have no influence, or minimal depressant effect, on the signals, but studies
evaluating its effect on intraoperative ECoG are limited. This study evaluates the
effect of dexmedetomidine on ECoG signals during ECoG-guided epilepsy surgeries conducted
under either isoflurane-based or propofol-based anesthesia regimens. It also assesses
the safety of dexmedetomidine use in these combination forms by determining its impact
on hemodynamic parameters, recovery from anesthesia, and incidence of intraoperative
awareness.
Materials and Methods
Thirty epilepsy patients, randomized into Group-I (dexmedetomidine-isoflurane, n = 15) and Group-P (dexmedetomidine-propofol, n = 15), underwent ECoG-guided epilepsy surgeries. After dural reflection, dexmedetomidine
was administered as a bolus of 1 μg/kg, and ECoG signals were recorded before and
after the bolus via brain surface grids. Dexmedetomidine infusion of 0.5 μg/kg/h was
thereafter continued throughout surgery in both groups. The effect of dexmedetomidine
on ECoG scores, hemodynamic parameters, anesthesia emergence times, and incidence
of intraoperative awareness was evaluated in both groups and compared.
Results
Dexmedetomidine did not cause ECoG suppression when administered with either propofol
or isoflurane anesthesia. However, it caused a significant increase in the ECoG score
in Group-I (baseline: 1.8 ± 0.7; post-dexmedetomidine: 2.1 ± 0.9; p = 0.02), while there was no change in scores in Group-P (baseline: 2.0 ± 0.7; post-dexmedetomidine:
2.10 ± 0.7; p = 0.16). The anesthesia emergence time was within defined normal limits in both groups;
however, in Group-I, it was significantly longer than that in Group-P (p = 0.03). The hemodynamic parameters were not affected by dexmedetomidine, and there
was no incidence of awareness in both groups.
Conclusion
Dexmedetomidine, when used with propofol anesthesia, had no effect on the intraoperative
ECoG signals, hemodynamic parameters, and anesthesia recovery time. Use of dexmedetomidine
with isoflurane anesthesia also did not cause ECoG suppression, but significantly
augmented the ECoG scores, while normal hemodynamic and recovery status were maintained.
There was no incident of intraoperative awareness in either group. As per this study,
the dexmedetomidine-propofol anesthetic regimen appears to be suitable for use in
ECoG-guided epilepsy surgeries. However, the ECoG-enhancing effect observed with dexmedetomidine
when used with isoflurane necessitates further research for validation and to understand
its clinical implications.
Keywords
epilepsy surgery - electrocorticography - dexmedetomidine - isoflurane - propofol
- anesthesia
