ILAE-defined epilepsy syndromes in children: Correlation with quantitativeMRI

Purpose: The role of quantitative magnetic resonance imaging (MRI) in evalu ation of childhood epilepsy remains poorly defined, with minimal published data. Previous work from our center questioned the specificity of hippocamp al asymmetry (HA) in an outpatient group whose epilepsy was defined by usin g clinical and interictal data only. By using childhood volunteer controls and defining epilepsy syndromes using video-EEG monitoring, we readdressed the utility of HA in differentiating mesial temporal lobe epilepsy (MTLE) f rom other partial and generalized epileptic syndromes in children. Methods: Seventy children were enrolled; entry criteria were age younger th an 18 years with predominant seizure type recorded on video-EEG telemetry w ith volumetric MRI in all cases. Thirty healthy child volunteers had volume tric MRT. Epilepsy syndrome classification was according to ILAE. Results: Control data revealed symmetric hippocampi, mean smaller/larger ra tio of 0.96 (0.95-0.97, 95% CI) with no gender or right/left predominance. Overall 23% of patients had significant HA. Mean hippocampal ratio for MTLE was 0.78 (95% CI, 0.70-0.86), significantly lower than controls and from a ll other epilepsy syndromes. HA was highly specific (85%) to the syndrome o f MTLE. Other potential epileptogenic lesions were found in 27 (39%) patien ts, lowest yield in frontal and mesial temporal syndromes. Dual pathology w as present in 10% of patients. There was no significant association between HA and risk factors. Conclusions: In this study, we found that HA in children with a well-define d epilepsy syndrome is highly sensitive and specific for MTLE. Whether this will correlate with surgical outcome, as in adults, is the subject of ongo ing study.