Abstracts

To assess the role of subtraction ictal SPECT coregistered with MRI (SISCOM) in surgical candidates with diffuse or multiple lesions and with non-lesional epilepsy. Data from twenty consecutive patients with post-surgical seizure outcome who had undergone pre-surgical ictal SPECT was re-evaluated. Patients, either with no MRI lesion, or multiple or widespread non-circumscribed lesions were included, i.e. complicated patients in need of extensive surgical work-up. Concordance between electrophysiological data and SISCOM results was evaluated for patients in different outcome categories. In 13 out of 14 patients undergoing intracranial VEEG, guided by SISCOM, seizure onset was recorded from locations indicated by SISCOM.
Eight of 14 lesional patients underwent invasive VEEG. Five of these had an unfavorable outcome despite concordance between invasive VEEG and SPECT.
All six non-lesional patients underwent invasive VEEG, and five patients, including four with unfavorable outcome showed concordance between VEEG and SPECT. In six lesional patients operated without VEEG three showed favorable results, of which two showed concordance between extracranial EEG and SPECT, and three showed unfavorable outcome (all showed concordance). SISCOM is helpful in guiding the implantation of intracranial electrodes, especially in patients with diffuse or widespread lesions and in patients without discernable lesions in MRI, but this is not a guarantee for favorable outcome, which is presumably determined by the nature and extent of the epileptogenic lesion itself.