Predicting surgical outcomes for patients with complicated refractory seizures.

Objectives: To predict and optimize surgical outcomes of patients with refractory seizures using a combination of PET-CT imaging, scalp EEG (SEEG) and intracranial EEG (IEEG) lead tracing.

Methods: Patients, who underwent PET-CT brain imaging and scalp and intracranial EEG localization of seizure focus followed by surgical resection between Jan, 2014 and October, 2016 were included. All PET-CT scans were interpreted by an experienced reader with no knowledge of the clinical or SEEG and IEEG results. An area of hypometabolism on PET-CT scan was identified as the possible site of seizure focus. The identified possible site of seizure focus with PET-CT was correlated with the suggested site using SEEG and subsequently IEEG. Correlation of agreements between PET-CT findings with SEEG and IEEG as well as correlation with the surgical outcome as seizure free, improved seizures or no change in seizure activity was performed.

Results: After IRB approval, 36 patients were included, 20 females and 16 males with a mean age of 23.7 years old. All patients had pre-surgical PET-CT scan and SEEG and 28 patients had IEEG. Concordant site of seizure focus was detected in 7 patients (19%) between PET-CT and SEEG and in 9 patients (32%) between PET-CT and IEEG. Discordant sites were demonstrated in 29 patients (81%) between PET and SEEG and in 19 patients between PET and IEEG. The surgeon usually used the SEEG localization for IEEG mapping and decision on site of resection. Thirty three patients had surgical resection of seizure focus, and 3 patients had vagal nerve stimulation (VNS). The surgical outcomes of the patients in the PET/SEEG concordant and discordant groups are summarized in the table below:

Conclusions: Surgical outcome is favorable in all patients with concordant PET and SEEG results. Patients with discordant results have uncertain surgical outcomes with almost equal chance of favorable versus unfavorable surgical outcomes when guided by SEEG alone.