Introduction: Electrocorticography (ECoG) and electrical cortical stimulation (ECS) are often used in tandem during awake craniotomies for mapping the eloquent cortex, which facilitate tumor resection at the functional margins. Intraoperative seizures are of a concern during awake craniotomy, which lead to limitation of the extent of resection and a significant increase in the length of hospitalizations. Due to the manifestation of seizures with brain lesions, epileptiform discharges are of interest. To investigate the frequency of epileptiform discharges we evaluated high-density ECoG (HD-ECoG) during ECS to assess epileptiform abnormalities and post-surgical outcomes.
Methods: A retrospective analysis was done for patients who underwent awake craniotomy using high-density ECoG (HD-ECoG) in combination with ECS between November 2016 and June 2017. A total of 38 patients with primary brain tumor were identified. All patients underwent awake craniotomy with direct cortical stimulation and neuromonitoring. Preoperative risk, complications, tumor characteristics and functional outcome between patients with no intraoperative seizure (nIOS) and patients with intraoperative seizures were assessed.
Results: Thirty-eight patients underwent awake craniotomy with HD-ECoG between November 2016 and June 2017 time period. Patients had a mean of the preoperative Karnofsky Performance Score (KPS) of 82.10, while the mean of postoperative KPS was 84.74 (P = 0.2567). Twenty-four patients underwent awake craniotomy with the utilization of the intraoperative HD-ECoG, 67% of these patients showed improvement after surgery (P = 0.1022). Only 4 patients (10%) (P < 0.0001) had new or worsened seizures and neurological deficits postoperatively.
Conclusions: We describe PFEDs (Periodic Focal Epileptiform Discharges) on HD-ECoG. A seizure-free outcome is most likely achieved with HD-EcoG in compared with Strip monitoring and no monitoring. Close surgical resection was achieved without unexpected morbidity and no mortality. More work uses special sensors may assist in further define the utility of ECoG in patients with and without tumor.
Patient Care: the occurrence PFEDs to expand the electroclinical spectrum of periodic discharges using a clinically-practical, customized, high-density, subdural ECoG grid in brain tumor and seizure patients. Similar to patients with PLEDs a high incidence of seizures prior surgery was present. Identifying focal periodic discharges in the operating room provides a wider spectrum of the periodic discharges in the interictal-ictal continuum. HD-ECoG was superior to scalp EEG and standard ECoG in detecting PFEDs.
Learning Objectives: To determine if HD-grid ECoG electrodes can facilitate the extent of resection during intraoperative ECS during real-time functional brain mapping of eloquent cortex. To establish if ECoG composed of a 64-channel high-density grid can reveal a higher yield in detecting the epileptiform local field potentials.