Abstracts

Rationale: It is well established that for children with a pre-exising hemiparesis, who are suffering from an intractable focal epilepsy, which is caused by a hemispheric pathology, a so-called hemispherotomy is an appropriate and most of the time very successful surgical treatment. In children with severe epilepsy, who do not have a hemiparesis, but are also suspected to have a hemispheric pathology, the decision to perform a hemispherotormy is extremely difficult, because the price these children would have to pay for a good outcome, would be a spastic hemiparesis. Under these circumstances a subtotal hemispherectomy sparing the primary sensory-motor area (pSMR) could be considered as a surgical option, if reasonable results can be achieved by this procedure. Methods: Retrospective evaluation of the data (neurological status, seizure-semiology, ictal and interictal EEG, imaging data, neuropathology) of 18 patients (11 girls, 7 boys- average age at operation 1 11/12 years, at operation 8 6/12 years) (from a total of 299 patients operated on between 1998 and 2009 at the Epilepsy Center Vogtareuth), who underwent a subtotal hemispherectomy sparing the pSMR - with variable extensions of the areas surrounding the central sensori-motor area. Prior to surgery, only one patient was mentally normal, 4 were moderately, 10 were severely mentally retarded, for 3 there were no test-results available. Etiology: cortical dysplasia type I 11/18, mild malformation of cortical development 2/18, phacomatosis 3/18, polymicrogyria 1/18, porencephalic lesion 1/18. Results: Seizure-outcome (Engel's classificaton): Class Ia 6/18 (33,3%), Class IIb 1/18 (5,6%), Class III a 6/18 (33,3 %), Class IV a/b 3/18 (16,7%). There is a tendency for a better seizure-outcome in patients, who have been operated on more recently in comparison to patients, who were operated on during the earlier years. About one third of the patients (from the earlier series)became hemiparetic by surgery because of infarctions. In the majority of cases improvement in terms of cognition and behaviour was documented; none had a cognitive decline. Conclusions: There is a significant sub-population of children with hemispheric epileptogenic lesions (predominantly in children with diffuce cortical dysplasia type I), who do not present a hemiparesis. Our data show a favourable post-operative seizure-outcome in more than one third of these patiens after a subtotal hemispherotomy sparing the pSMR. Selection-criteria for this surgical procedure(besides the neurological status) include seizure-semiology, ictal and interictal EEG and neuroimaging data - and the parents' understanding of the complexity of the condition.