The effect of propofol on intraoperative electrocorticography and cortical stimulation during awake craniotomies in children.

Propofol has been proposed as a sedative agent during awake craniotomies. However, there are reports of propofol suppressing spontaneous epileptiform electrocorticography (ECoG) activity during seizure surgery, while others describe propofol-induced epileptiform activity. The purpose of this study was to determine if propofol interferes with ECoG and direct cortical stimulation during awake craniotomies in children. Children scheduled for awake craniotomies for resection of epileptic foci or tumours were studied. An intravenous bolus of 1-2 mg.kg-1 followed by infusion of 100-200 microgram.kg-1.min-1 of propofol was administered to induce unconsciousness. Fentanyl (0.5 microgram.kg-1) was administered incrementally to provide analgesia. After the cortex was exposed, the propofol infusion was stopped and the patient permitted to awaken. Cortical electrodes were applied. ECoG was recorded continuously on a Grass polygraph. Motor, sensory, language, and memory testing were done throughout the procedure. The cortex was stimulated with a hand-held electrode using sequential increases in voltage to map the relevant speech and motor areas. We studied 12 children (aged 11-15 years) with intractable seizures. The raw ECoG did not reveal any prolonged beta-waves associated with propofol effect. Electroencephalogram spikes due to spontaneous activity or cortical stimulation were easily detected. Cognitive, memory and speech testing was also successful. We conclude that propofol did not interfere with intraoperative ECoG during awake craniotomies. Using this technique, we were able to fully assess motor, sensory, cognitive, speech and memory function and simultaneously avoid routine airway manipulation.