Abstracts

Rationale: Little information is available regarding children with hippocampal sclerosis (HS). Our goals were to assess the frequency of HS, to identify the corresponding risk factors and to characterize the associated epilepsy in a large pediatric tertiary center with an active epilepsy surgical center Methods: Reports from brain MRI recorded in Miami Children’s Hospital between 1997 and 2004 were reviewed. Patients with the diagnosis of HS were identified and clinical information was obtained from the charts. Results: 158 children with HS were diagnosed by brain MRI over a 8-year period corresponding to 19.7 new patients per year and an incidence of 5.8 patients per 1000 MRIs and per year. Mean age at recording was 9.5±5.2 y with 51% of patients being recorded at less than 10 y. 81 patients (51%) had dual pathology and 35 (22%) had bilateral HS. Positive family history for epilepsy was noted in 21% of patients and febrile convulsions in 32%. Contributing factors included status epilepticus (33%), encephalitis (6%), perinatal anoxia-ischemia (11%), head trauma (4%). None was identified in 40%. 13 patients (8%) had no epileptic seizures and 5 had one (3%). Positive predictive value of HS for epilepsy was 89% but dropped to 61% in absence of hippocampal atrophy. All patients with dual pathology involving the temporal lobes were epileptic. Associated epilepsy was generalized in 16% of patients, temporal (TLE) in 69%, bitemporal in 7%, extra-temporal in 10%, multifocal and hemispheric in 9%. Three patients had callosotomy and 33 patients had cortical excision that was limited to the temporal lobe in 29 patients. Sixty-six percent of the patients treated by curative surgery and 20% of the remaining patients were seizure-free at a mean age at follow-up of 12.6±5.8 y. Conclusions: HS is a rare MRI finding in an unselected pediatric population. Epilepsy is inconstantly associated and localization of the epileptogenic focus is diverse. Patients treated by curative surgery have a better outcome than the patients treated medically.