Abstracts

Rationale: It is now widely accepted that after drug resistance is established, Epilepsy Surgery, if a defined seizure focus is identified and functional impairment minimized, should be entertained. Neurophysiological testing such as Magnetoencephalography (MEG) and Electroencephalography/Video Telemetry (VEEG) may be beneficial but not always conclusive in identifying a specific seizure focus. Subtraction SPECT when co-registered with both modalities (MEG, VEEG) may be extremely helpful in lateralizing and localizing a designated epileptiform target. Radioisotope degradation and stability, rapidity of injection, rapidity of seizure spread, and availability of the scanner are potential impediments to acquiring an adequate study. Time available to inject the isotope for acquisition (9 hours) and the inability to acquire testing during the night are also limitations at our Center. The two isotopes utilized at our center, Neurolite & Ceretec, were compared for efficacy in acquisition of SPECT and their localization of the epileptogenic zone. Ceretec seemed to have less stability due to the color of the dye, which affects visibility, shorter half-life, and required filter prior to pushing the isotope. We theorized that Neurolite would have better localizing value than Ceretec. Methods: The Epilepsy database was retrospectively reviewed for all patients with prior SPECT Scans done between 7-2010 and 1-2015. The numbers of attempted studies versus successful subtraction studies were compared. Sensitivity and specificity of Neurolite vs. Ceretec were compared. Scalp EEG, surgery data, and in cases where MEG was done, the defined ictal onset zones were collected for analysis. IRB for database review was approved by SETON family of Hospitals. Results: 195 studies were attempted and ictal and inter-ictal studies were able to be carried out in 122 (62.56%). 81 of the 122 provided focal onset zones, 41 did not. 31 were Neurolite and 50 were Ceretec. 50 Ceretec studies were done and 38 correlated with EEG findings. Out of the 50 Ceretec studies, 37 went to surgery and 30 of those were concordant with SPECT. 31 Neurolite studies were carried out and 26 correlated with EEG findings. Out of the 31 Neurolite studies, 22 went to surgery and 18 of those were concordant with SPECT. p-values revealed no statistical difference between both isotopes when compared to Neurophysiological findings (P=0.5756) or Surgical outcomes (P=0.3691). Conclusions: There was high concordance between the potential epileptiform foci on SPECT and both Neurophysiology (MEG, EEG) and the surgical site resected. This study, however, revealed no significant difference in radio-isotopes when correlating the data with EEG and Surgery localizations. There was a trend towards Neurolite having better value in localization than Ceretec, but it was not statistically significant. In Pediatric cases of drug resistant epilepsy, Subtraction SPECT still offers significant value in localization. Funding: None