Abstracts

Rationale: Hippocampal sparing anterior temporal lobectomy (HS-ATL) can be performed to reduce risk of memory impairment in patients with intractable temporal lobe epilepsy (TLE). Whether this actually reduces risk of memory impairment and postoperative functional performance decline is uncertain. Whether seizure outcome differs from patients who have standard ATL is not known. This study was designed to assess efficacy, neuropsychological outcome, and functional outcome of HS-ATL. Methods: We retrospectively analyzed data from patients without mesial temporal sclerosis (MTS) on MRI who had HS-ATL and compared them with patients who also had no evidence of MTS on MRI but had standard ATL. A 1:1 case: control design was used. Kaplan-Meier curves were generated and differences in seizure outcome tested with the Cox-Mantel statistic. Patients had memory and employment status assessed before and after surgery. The California Verbal Learning Test II (CVLTII)) (sum of trials 1–5, delayed free recall) and the Logical Memory subtest of the Wechsler Memory Scale III (WMS-III) (learning and delayed recall of prose passages) were used to investigate changes in verbal episodic learning and memory before and after surgery. T-test was used for parametric variables. This study was approved by the Thomas Jefferson University Institutional Review Board. Results: Twenty adult patients diagnosed with left (n=18) or right (n=2) TLE, without evidence of MTS who had HS-ATL were included. All patients were right handed. Mean follow-up interval was 4.5 years, SD=2.72 years. The two groups were not significantly different regarding presurgical seizure frequency, presence or absence of presurgical tonic-clonic seizures, presence or absence of MRI lesion, age and duration of epilepsy at surgery, and side of surgery (Table 1). No significant difference in long term seizure recurrence rates following surgery was seen between two groups p= ns (Fig 1).Neuropsychological testing result prior and following surgery were available for 13 of the HS-ATL patients. There was no difference between verbal learning and memory scores before and after surgery. Mean CVLTII sum of all trials scores were 49.8 and 47.5 respectively (P= 0.64). CVLTII free recall average Z scores were 0.11 and -0.23 respectively (p=0.55). Significant improvement in prose passage learning was demonstrated following surgery by WMS-III scores (increase from 10.0 to 11.69, p=0.02). There was no change in WMS-III delay recall scores (mean=9.83 before and mean=11.15 after surgery). Before surgery, 9 were employed and 11 were not. After surgery, 9 patients were employed and 11 were not (no difference). Conclusions: Hippocampal sparing anterior temporal lobectomy in patients with no evidence of MTS on MRI is not associated with worse seizure outcome than resecting hippocampus, and appears to preserve verbal memory. Therefore, it is reasonable to recommend hippocampal sparing procedures in patients with dominant temporal neocortical epilepsy when hippocampus appears normal in the MRI. Funding: No funding