Abstracts

More and more centers are now exploring techniques to minimize the invasiveness of the evaluation and surgical treatment of medically refractory temporal lobe epilepsy. Video-EEG monitoring, SPECT scanning, PET and MEG has greatly improved this process. At Vanderbilt University Medical Center, selective amygdalo-hippocampectomy (SAH) has been used as a less invasive alternative to a standard temporal lobectomy and involves resection of the amygdala, hippocampus and the para-hippocampal gyrus.
Although a [ge]5 Hz ictal pattern has been associated with ipsilateral mesial temporal lobe seizure, we sought to show that a [lt] 5 Hz ictal onset pattern within 30 seconds of seizure onset in patients with non-lesional mesial temporal lobe epilepsy who undergo SAH resection also have a good outcome. We compared seizure reduction rates following SAH in patients with rhythmic theta and those with non-theta ictal onset patterns. 28/40 patients who underwent SAH between Dec1999 and Oct 2003 at VUMC had complete medical records and were used for analysis. All patients had mesial temporal sclerosis or normal MRI. All patients had a minimum of 3 seizures recorded during EEG monitoring. We classified scalp-sphenoidal ictal EEG patterns into 2 groups: type 1 ictal patterns included a progressive buildup of a regular [ge]5 Hz rhythm in the temporal electrodes within 30 seconds of seizure onset; type 2 ictal patterns had a frequency [lt] 5 Hz until the termination of the seizure. Patients were classified into 3 groups:
Group 1: All seizures were associated with a regular [ge] 5 Hz lateralized rhythmic discharge on scalp EEG.
Group 2: Some, but not all seizures were associated with a regular [ge] 5 Hz lateralized rhythmic discharge.
Group 3: None of the seizures were associated with a regular [ge] 5 Hz lateralized rhythmic discharge. Twenty-one patients were classified into group 1, three patients in group 2 and four patients in group 3. Epilepsy surgery outcomes were classified according to Engel[rsquo]s Classification of Postoperative Outcome (1). Median time at followup for evaluation of seizure control post-operatively was 17.7 months (Range of 1.5-37 months).
In group 1, 17 patients had an Engel[rsquo]s Class I outcome, 3 patients had a Class II outcome and 1 patient had a Class III outcome.
In group 2, 2 patients had an Engel[rsquo]s Class I outcome and 1 patient had a Class IV outcome.
In group 3, 3 patients had an Engel[rsquo]s Class I outcome and 1 patient had a Class II outcome. Patients with ictal pattern of [ge]5Hz, regular, rhythmic lateralized discharges on scalp EEG patterns had excellent seizure control after selective amygdalo-hippocampectomy. However most patients with types II and a mixture of type I and II ictal EEG patterns whose presurgical workup was consistent with a mesial temporal focus also had good seizure control rates post-operatively.