Abstracts

Rationale: Partial epilepsy of extratemporal lobe origin can be found in patients with intractable seizure disorders and may be surgically remediable. Potential risk factors for extratemporal lobe epilepsy include prolonged childhood febrile seizures, status epilepticus, central nervous system (CNS) infections, head trauma, neoplasms, perinatal vascular insults, cortical dysplasias, and a family history of epilepsy. The rationale for the present study is to investigate the prognostic importance of an identified putative underlying comorbidity in patients with extratemporal lobe epilepsy undergoing surgical treatment. Methods: A retrospective study of 40 consecutive patients who underwent epilepsy surgery at Mayo Clinic, Rochester, MN between 1971 and 1996 was undertaken. The clinical information extracted from the medical record included a history of remote symptomatic neurological disease, family history of epilepsy, magnetic resonance imaging (MRI), video-EEG monitoring, pathology and operative outcome. The seizure outcome was classified by a modified Engel classification: Class I- seizure-free, auras or only medication-withdrawal seizures; Class II- greater than 95% reduction in seizures; Class III- 80-94% reduction in seizures; Class IV- less than 80% reduction in seizure activity. Results: The mean age at surgery was 27 years (range 3-54), and the mean age at seizure onset was 13 (range 1-54). Potential underlying etiologies included febrile seizures (n=4), status epilepticus (n=4), head trauma (n=5), CNS infections (n=5), neoplasms (n=22), family history (n=1), perinatal vascular insults (n=5), and cortical dysplasias (n=6). 1 patient had no identified risk factor. The percentage of patients achieving a Class I outcome by risk factor was as follows: febrile seizures-0%, status epilepticus-25%, family history-0%, head trauma-40%, CNS infections-0%, neoplasms-36%, perinatal vascular insults-20%, and cortical dysplasias-17%. Overall, Class I outcome was achieved in 28% of patients. Conclusions: The present study indicates that extratemporal lobe epilepsy surgery often achieves a lower frequency of Class I outcome when compared to temporal lobe epilepsy surgery. Furthermore, no particular risk factor seems to be predictive of post-surgical outcome. These results may be useful to counsel patients being considered for epilepsy surgery.