Abstracts

Rationale: Ictal single-photon emission computed tomography (SPECT) could localize the seizure onset zone in patients with focal cortical dysplasia (FCD) and intractable epilepsy. The aim of our study was to analyze whether parameters of injected epileptic seizures (times of the radionuclide administration, durations, types and ictal EEG patterns of seizures) predict ictal SPECT findings in pediatric FCD cases. The study was conducted on a large population of pediatric epilepsy surgery patients with histologically proven FCD. Methods: We visually evaluated 98 ictal SPECT studies in 69 children with FCD who underwent excisional epilepsy surgery at the Miami Children s Hospital. SPECT findings were classified as non-localized , well-localized (confined to a region of one gyrus or two contiguous gyri), lobar and extensive (multilobar or hemispheric) and compared with injection times, types, durations and scalp EEG patterns of injected seizures. Seizures were classified as simple partial , complex partial and secondarily generalized and EEG ictal patterns as localized , widespread (multilobar or hemispheric) and non-lateralized . Relationship among two categorical parameters (types of seizures and EEG patterns) and SPECT findings were evaluated by Pearson Chi-square tests. Parameters measured in seconds (injection times and seizure durations) and their relationship with SPECT findings were calculated by One-way ANOVA and Kruskal-Wallis test. Data were evaluated in three sets: (1) All studies; (2) Studies in previously non-operated patients and (3) Cases that had postsurgical ictal SPECT. Results: There were 67 ictal SPECT studies in previously non-operated patients and 31 postsurgical scans in subjects before reoperation. 27 ictal SPECT scans were nonlocalized, 19 well-localized, 25 lobar and 27 extensive. SPECT findings were not significantly influenced by injection times (p=0.3094), types of injected seizures (p=0.9152) and their scalp EEG patterns (p=0.3258). Seizure duration significantly influenced extent of SPECT findings: Shorter seizures were associated with localized and longer ones with extensive hyperperfusions. This association was proven in all SPECT studies (p=0.0033) and in studies in previously non-operated patients (p=0.0035), but not in postsurgical SPECT scans (p=0.6538). Conclusions: Duration of injected seizures significantly influence ictal SPECT findings and may affect surgical planning in FCD patients. However, we failed to prove this relationship in previously operated patients who had postsurgical ictal SPECT scan. Injection times, types and scalp EEG patterns of injected seizures appeared non-significant in our series. Supported by Grants VZ MZOFNM2005-6504 and Kontakt Programme ME09042