MRI Hippocampal Volumetry in Temporal,Extratemporal and Idiopathic Generalized Epilepsy

Purpose:To evaluate the hippocampal volumetric changes in temporal,extratemporal and idiopathic generalized epilepsy using MRI volumetry,and to explore the relationship between hippocam- pal sclerosis and epileptic seizure.Materials and Methods:Seventy-four epileptic patients and 30 healthy volunteers were studied by using MRI volumetry of hippocampal formation (HF).Fifty patients with intractable temporal lobe epilepsy(TLE) were verified as hippocampal sclerosis by operation and pathology,6 patients had focal extratemporal lobe epilepsy,and 18 had idiopathic generalized epilepsy. The mean seizure duration among three groups had no significant difference.The mean value of normal hippocampal volume minus two times the standard deviation was set as the normal lower limit to evaluate whether the absolute volume of HF was abnormal or not.The absolute volume was normalized.Results: Among the 50 TLE patients,33 (66%) had significant small HF volume ipsilateral to the operated side. Among them,10 (20%) also had significant small HF volume on the contralateral side.While among the 6 patients with focal extratemporal lobe epilepsy and 18 with idiopathic generalized epilepsy,all the volumes of HF were beyond the normal lower limit.No significant smallness was demonstrated in them. Conclusion:TLE had special pathology substrate which is different from focal extratemporal lobe epilepsy and idiopathic generalized epilepsy.MRI hippocampal volumetry can help to explore the rela- tionship between hippocampal sclerosis and epileptic seizure.