Contribution of ictal-interictal SPECT and SISCOM to preoperative localization of the epileptogenic zone in frontal lobe epilepsy.

Objective: To describe the contributions of conventional single-photon emission computed tomography (SPECT) and subtraction ictal-interictal SPECT coregistered to magnetic resonance imaging (SISCOM) for the preoperative identification of the epileptogenic zone (EZ) in patients with frontal lobe epilepsy (FLE). Materials and methods: In this retrospective study, we reviewed medical records of all patients with refractory FLE who underwent frontal lobectomy at our institution between 2015 and 2020, all of whom had undergone at least one ictal SPECT, one interictal SPECT, one high-resolution magnetic resonance imaging examination, SISCOM, and at least one year of follow-up. Fourteen patients met the inclusion criteria. Results: After a mean follow-up of 32 months (range, 14-60 months), surgical outcomes were classified as good in five patients (35.7%) and poor in nine (64.3%). For localizing the EZ, SISCOM achieved the highest sensitivity (80%), negative predictive value (85%), and overall diagnostic accuracy (71%), whereas ictal SPECT had the highest specificity (70%) and interictal SPECT had the lowest performance overall. Conclusion: In patients with FLE, ictal and interictal SPECT alone do not seem to predict the surgical outcome. However, SISCOM seems to perform better for that purpose.