HIPPOCAMPAL SCLEROSIS IN CHILDREN WITH INTRACTABLE TEMPORAL-LOBE EPILEPSY - DETECTION WITH MR-IMAGING

OBJECTIVE. Hippocampal sclerosis is the most common lesion associated with temporal lobe epilepsy. Temporal lobectomy is effective for the c ontrol of medically refractory seizures in these patients. Before the advent of MR imaging, hippocampal sclerosis was rarely diagnosed preop eratively. The purpose of this study was to determine the frequency of hippocampal sclerosis in children with intractable temporal lobe epil epsy and the accuracy and reliability with which hippocampal sclerosis can be diagnosed on the basis of MR findings in children. MATERIALS A ND METHODS. We reviewed the MR images of 53 children (mean age, 10 yea rs) with medically refractory temporal lobe epilepsy. The MR images we re reviewed blindly and independently by two radiologists on two occas ions, and were classified as showing hippocampal sclerosis, other lesi ons, or no abnormality. Hippocampal sclerosis was diagnosed when evide nce of hippocampal atrophy was present or hippocampal signal intensity was abnormal without evidence of a mass lesion. RESULTS. MR images sh owed hippocampal sclerosis in 30 children (57%), other lesions in 10 ( 19%) (tumors in eight, cavernous angioma in one, and ectopic gray matt er in one), and no abnormality in 13 (24%) (intraobserver agreement: k appa = 0.77 and 0.84, interobserver agreement: kappa = 0.76). MR later alization was concordant with ictal EEG in 36 (92%) of 39 children. Hi ppocampal sclerosis was bilateral in one child and associated with ext rahippocampal lesions in nine. Hippocampal sclerosis was detected on M R images of 11 (85%) of 13 children with pathologic confirmation of hi ppocampal sclerosis. Beneficial results were seen in 26 (90%) of 29 ch ildren who had temporal lobectomy. CONCLUSION. Hippocampal sclerosis i s the most common lesion in children with intractable temporal lobe ep ilepsy, and it can be detected reliably and accurately on MR images. W e suspect that hippocampal sclerosis is underdiagnosed in children, po ssibly leading to postponement of surgery in children with refractory seizures.