Abstracts

In infants and young children with congenital or early onset acquired lesions, interictal scalp EEG may show generalized or multiregional abnormalities but ictal EEG concordant with semiology and brain MRI usually clarifies the epileptogenic zone for surgical option. We studied 6 children with catastrophic epilepsy whose ictal scalp EEG was classified as maximum over the unaffect hemisphere contralateral to the brain lesion. Factors leading to paradoxical lateralization of ictal scalp EEG over the unaffected hemisphere were evaluated., Of 209 patients in the pediatric epilepsy surgery database of Cleveland Clinic Foundation, clinical, EEG, brain imaging, surgery and postoperative records of 6 patients, whose EEG was classified as maximum in the unaffected hemisphere were reviewed. Digital records were restored and analyzed independently. [italic]Paradoxical lateralization[/italic] was defined as scalp EEG seizure pattern that developed eiher exclusively or bilaterally but maximally contralateral to the to the side of the lesion., Six patients, 4 females, 3-14 years in age at the time of the pre-surgical evaluation, were identified. Despite the paradoxical lateralization of ictal scalp EEG during recorded seizures, lateralizing signs ([gt] 1 sign in 3 patients) of focal tonic (4 patients), head versive (2 patients), hemiclonic (1 patient) and asymmetric epileptic spasm (1 patient) were noted contralateral (concordant) to the side of lesion. Interictal EEG showed generalized or lateralized and multiregional epileptiform discharges with predominance ([gt] 65%) over the affected hemisphere in 3/6, generalized but maximum over the unaffected hemisphre in 2/6, and generalized with no focal predominance in 1 patient. Brain MRI showed extensive destructive (encephaloclastic) lesions such as stroke in 3 and encephalomalacia (post status epilepticus and infectious) in 3 patients. All patients underwent hemispherectomy and 5/6 patients were seizure free after 5 months to 3 years of follow-up., Extensive congenital or early onset acquired encephaloclastic lesions may produce an ictal scalp EEG pattern that appear maximum over the unaffected hemisphere. Interictal EEG in these patients may also show bilateral and multiregional abnormalities with or without any predominant region of abnormality. These scalp EEG patterns should be recognized and they do not preclude benefit from epilepsy surgery if the neurological deficits, semiology, and imaging implicate the abnormal hemisphere. Early spread to the normal hemisphere, the presence of encephaloclastic lesion modifying scalp EEG patterns, and secondary epileptogenesis may explain these findings., (Supported by CAPES (Brazil).)