gms | German Medical Science

Objective: Intraoperative seizures can be induced by surgical procedure as well as mapping techinques: the aim of the present study is to evaluate risk factors for intraoperative seizures particularly with respect to ECoG features and the type of anaesthesia.

Methods: The occurrence of intraoperative seizures was evaluated in a group of 65 patients with glial tumours, located both in the temporal and extra-temporal regions. ECoG was performed before and during resection and reviewed by two different neurophysiologists independently.

Results: Intraoperative seizures occurred in a sub-group of 19 patients, mainly during awake craniotomy. The majority of lesions (13/19) were localized in the motor or pre-motor areas and the related seizures were characterized by sudden onset with fast rhythms, often undistinguished from stimulation artefacts, florid recruiting epileptiform activity and rapid bilateral diffusion. Seizures arising from temporal lobe or insular region were more difficult to detect, because of a lack of motor signs and unusual ECoG features, dominated by fast activity, recruiting slow waves and global deterioration of basic rhythms.

Conclusions: Seizures during surgery are more likely to occur during awake craniotomy, in patients with a previous history of epilepsy and with interictal highly epileptiform activity in the ECoG. Electrocorticographic monitoring, which is not a routine technique in primary brain tumour surgery, provides useful and real-time information regarding changes in brain electrical activity and patients’ behavioural state during the duration of the operation.