Abstracts

To evaluate the role of ictal SPECT by visual analysis in presurgical evaluation of pediatric patients with medically intractable epilepsy. The pitfall of delay ictal SPECT radiopharmaceutical injection (SPECT injection) is eliminated by bedside monitoring of the EEG and clinical seizure by an EEG technologist or epileptologist during injection of SPECT radiopharmaceuticals. We retrospectively studied a consecutive series of pediatric patients who underwent presurgical evaluation of intractable epilepsy between February 2004 and April 2005. Twenty-six patients were identified (ages 13 mo- 20 yrs; mean 9.4 yrs; median 8 yrs). The SPECT injection was performed by either an EEG technologist or, rarely, epileptologist who closely monitored the clinical and electrographic seizure at bedside at all times. Visual analysis of SPECT, video-EEG, and MRI in all patients were reviewed by the primary investigator. Seven patients underwent PET scans. Six patients underwent video-subdural EEG monitoring followed by resections of epileptogenic zones. The ictal SPECT injections were performed within 2-46 sec after the clinical seizure onset (mean 13.4 sec; median 10 sec) and 2-49 sec after the electrographic seizure onset (mean 19.1 sec; median 18.5 sec). The causes of seizure were malformations of cortical development (MCDs) in 10/26 (38.5%), tumor in 3 (11.5%), encephalomalacia in 6 (23.1%), tuberous sclerosis in 3 (11.5%) and unknown in 4 (15.4%). The MRI scans were interpreted by radiologists as normal in 3 patients who had MCDs. SPECT revealed focal hyperperfusion in 24/26 patients (92%) and was non-lateralization in 2. Focal hyperperfusion was 9 in temporal (37.5%), 5 in frontal (20.8%), 4 in parietal (16.7%), 4 in occipital (16.7%), and 2 (8.3%) in one hemisphere. In the focal group, complete convergence between ictal SPECT and other diagnostic findings including MRI, ictal, EEG, interictal EEG, and lateralization of clinical seizures was found in 15/24 (62.5%). Convergence of ictal SPECT with 3 of 4 of the above other diagnostic findings was found in 4/24 (16.7%). Of these 2 groups, 6/24 underwent epilepsy surgery and 18/24 will be proceded to epilepsy surgery. At follow up, 4/6 convergent patients (66.7%) were seizure free, 1 had significant improvement and 1 had mild improvement of seizures. Of patients with convergence of less than 3 of 4 of other diagnostic testings (5/24), 3/5 underwent vagus nerve stimulator placement and 2/5 are in the process of presurgical evaluation. Patients in the diffuse group (2/26) were no longer epilepsy surgical candidates. Complete convergent patients showed concordance with PET in 4/7. Visual analysis of ictal SPECT, used in conjunction with MRI, EEG, and lateralization of clinical seizure, is a very useful diagnostic tool in presurgical evaluation of pediatric patients with intractable focal epilepsy when SPECT injection is performed early after ictal onset.