Ictal spiking patterns recorded from temporal depth electrodes predict good outcome after anterior temporal lobectomy

Purpose: Investigators have shown that the presence of ictal spiking (IS) r ecorded from temporal depth electrodes is associated with mesial temporal s clerosis (MTS. We investigated the relation of IS to seizure control and pa thology after anterior temporal lobectomy (ATL). Methods: All patients undergoing intracranial ictal monitoring from a singl e institution since 1989 were identified. Those who did not undergo ATL or had postoperative follow-up of <1 year were excluded. All received at a min imum bilateral temporal depth electrodes. Ictal recordings were reviewed fo r the presence of IS, and the proportion of seizures with IS was determined for each patient. Outcome was determined by using Engel's classification. Surgical specimens were reviewed for pathology. Statistics used were chi(2) , Fisher exact test, and Wilcoxon rank sum. Results: Forty patients with 571 seizures were reviewed. In 292 seizures fr om 32 patients, IS was seen. Outcomes were 24 class I (22 with IS), five cl ass II (four with IS), three class III tone with IS). seven class IV (four with IS), and one lost to follow-up (with IS). Pathologic review revealed 2 5 with MTS, 22 of whom had IS. The presence of IS was associated with class I outcomes (p = 0.04), but not MTS (p = 0.06). Patients with class I outco mes had a significantly greater proportion of seizures with IS (mean, 0.58 +/- 0.3) compared with other outcomes (mean, 0.30 +/- 0.3, p = 0.02). Conclusions: The presence of IS and higher proportion of seizures with IS c orrelated with good seizure outcome after ATL. This information may be used in preoperative counseling.