Abstracts

Rationale: Partial epilepsy of temporal lobe origin is the most common surgically remediable epileptic syndrome in patients with intractable seizure disorders. Potential risk factors for temporal lobe epilepsy include prolonged childhood febrile seizures, status epilepticus, central nervous system (CNS) infections, head trauma, neoplasms, perinatal vascular insults, mesial temporal sclerosis (MTS), 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 temporal lobe epilepsy undergoing surgical treatment.Methods: A retrospective study was performed of 476 consecutive patients who underwent epilepsy surgery at Mayo Clinic, Rochester, MN between 1971 and 1996. 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. Individuals without any comorbid condition were considered a control group for purposes of this study. 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 32 years (range, 3-69) and the mean age at seizure onset was 12 years (range, 0-55). Potential underlying etiologies included febrile seizures (n=99), status epilepticus (n=53), head trauma (n=56), CNS infection (n=48), neoplasm (n=39), family history (n=38), and perinatal vascular insult (n=26). 208 patients had no identified risk factor. The percentage of patients achieving a Class I outcome was not significantly different (control group vs. risk factor group, p>0.05): control group- 72%; febrile seizures- 72%; status epilepticus- 68%; positive family history- 74%; head trauma- 68%; CNS infection- 67%; neoplasm- 64%; perinatal vascular insult- 46%. Patients with MRI-identified MTS, regardless of risk factor, were more likely to have a Class I outcome (p<0.02).Conclusions: The present study indicates that a history of remote symptomatic neurological disease or a family history of epilepsy, or both, are not of prognostic importance unless the putative etiological factor is associated with the development of MTS. Preoperative MRI is the most important prognostic factor in the evaluation of patients with temporal lobe epilepsy being considered for surgical treatment. The results may be useful to counsel patients being considered for epilepsy surgery. *Current address for Dr. Cohen-Gadol: Indianapolis Neurosurgical Group, 1801 N. Senate Blvd, Ste 535, Indianapolis, IN 46202, USA.