Abstracts

Rationale: To evaluates the role of FDG PET and ictal SPECT during multimodality evaluation in patient selection and predicting the outcome in patients with refractory epilepsy with focal cortical dysplasia (FCD). Methods: Retrospective analysis of data of 179 patients with FCD who underwent resective epilepsy surgery and had at least 2 years post-surgery follow-up was performed. The PET and SPECT patterns were classifies as localizing, lateralizing and uncertain. ROC curves were plotted to calculate sensitivity of PET and SPECT and combination of presurgical investigations. Logistic regression analysis was performed to predict the outcome Results: The average age at surgery was 17.9± 11.6 (0 – 64)years with 90(50.3%) women. FDGPET showed localized hypometabolism in142 (79.3%). Among the 101 patients where ictal SPECT was done, localized hyper perfusion was noted in 74 (73.3%). Clear cut FCD on MRI was noted in 157(87.7%). In 22 patients with subtle MRI, PET –MRI fusion helped in localizing the lesion in 14 while SPECT was helpful in four more. The commonest type of surgery was corticectomy/lobectomy done in 122 (68.2%) patients, commonest being frontal in 93 (52.0%). Histopathology was suggestive of FCD Type I in 101 (56.4%). At two years follow-up 106 (59.2%) seizure free. No significant difference was found for seizure freedom among the 126 patients with a localizing PET pattern (83.0% vs 74.0%; p=0.188) or a localizing SPECT pattern (39.6% vs 43.8%; p=0.643). Sensitivity for seizure freedom was 98.1% in patients with lesion on MRI or localizing PET pattern and in 99.1% patients with lesion on MRI or localizing SPECT pattern . The predictors of seizure freedom were complete resection (in clear-cut MRI lesions)of the FCD (96.1% vs 63.6%; p < 0.001), those with type II FCD (53.8% vs 31.5%; p=0.004) and temporal lobe resections (28.3% vs 5.5%; p=0.001). Conclusions: Pre-operative non-invasive multi-modality investigations helps achieve seizure outcome equal to that achieved by invasive EEG evaluation and obviates the need for expensive intracranial EEG evaluation in countries with limited resources. Accurate localization of epileptogenic lesion on MRI, PET and ictal SPECT in either one or a combination of modalities improves the sensitivity of multi-modality evaluation in patients with FCD. Funding: None