Abstracts

The success and guidelines for surgery in patients with temporal lobe epilespy (TLE) due to a lesional or non-lesional focus have been well documented. However, the effectiveness and indications for surgery in patients with TLE and normal MRIs is unclear. We report our surgical outcome in TLE patients with normal MRI[rsquo]s undergoing anterior temporal lobectomy and propose a treatment paradigm for patients with intractable TLE. From March 1991 [ndash] July 2001, 57 patients with normal MRI scans underwent surgery for intractable TLE. There were 30 males and 27 females between 12 and 53 years (mean 32 [plusmn] 10 years). Prior to surgery, all patients underwent a screening protocol that was developed by a multidisciplinary epilepsy team (Neurosurgery, Neurology, and Neuropsychology) at our institution. This paradigm consisted of MRI scans, surface electroencephalography looking for ictal events (Phase I video/EEG), positron emission tomography (PET) attempting to localized the seizure focus, and subdural or depth electrode monitoring (Phase II EEG) for patients whose seizure focus cannot reliably be identified. All patients went through MRI and Phase I EEG testing. Among patients, 37 proceeded to have PET scan (which localized the seizure focus in 30) and 22 required Phase II testing. Outcomes were classified as seizure free (Grade I), at least 90% reduction of seizures (Grade II), between 50% [ndash] 90% reduction of seizures (Grade III), and failures or less than 50% reduction of seizures (Grade IV). All 57 patients identified through our TLE treatment paradigm underwent an anterior temporal lobectomy and amygdalo-hippocampectomy. 82.5% of patients (n=47) had Grade I outcome. 12.3% patients (n=6) had Grade II outcome. 1.8% of patients (n=1) had Grade III outcome, and 3.5% of patients (n=2) had Grade IV outcome. Mean follow-up period was 118 [plusmn] 30 months. Our findings show that excellent surgical outcome for patients with MRI normal TLE can be achieved. Functional imaging using PET and neurophysiologic monitory via surface and intracranial electrodes can be used to identify optimal surgical candidates.