Olga Bogdanova, Henry Buchtel, and Daniela Minecan (2006), Memory Outcome after Left and Right Temporal Lobectomy in Patients with Symmetrical and Reversed Wada Memory Asymmetry Scores. American Epilepsy Society Annual Meeting, San Diego, November 30-December 5, 2006

RATIONALE:
The Intracarotid Amytal testing (Wada test) has been used as part of the presurgical evaluation of patients with temporal lobe epilepsy (TLE). The purpose is to confirm language lateralization and identify patients at risk for memory impairment after the resective surgery. The ideal surgical candidate has better memory scores in the hemisphere contralateral to the expected surgery side.
The concern is in cases with reversed Wada memory asymmetry scores. The memory outcome has been previously analyzed for patients with left anterior temporal lobectomies (ATL) and reversed scores. The significance of symmetrical Wada memory scores (irrespective of the side of surgery) and reversed Wada memory asymmetry scores for patients who undergo right ATL has not been previously evaluated.

METHODS:
Patients were selected from those with temporal lobe epilepsy and who underwent complete presurgical evaluation at the University of Michigan Medical Center between 2000 and 2005. We included patients who had symmetrical and reversed Wada memory asymmetry scores and who were seizure free at least at one year follow up after the resective surgery.
A total of 14 patients were identified. Age range was between 9 and 56 years at the time of the Wada test. Six patients were males. All patients underwent neuropsychometric evaluation as part of the presurgical evaluation and at three months after the resective surgery. Seven patients also had another set of neuropsychometric evaluation performed 12 to 13 months after the surgery date. Nine patients had symmetrical Wada memory scores and two of these patients had right temporal lobectomies. The other five patients had reversed Wada memory asymmetry scores. In this group, four patients underwent left temporal lobectomies. We compared 3 month post-operative verbal and pictorial memory change scores.

RESULTS:
None of the patients with symmetrical Wada memory scores (n=9) have shown any significant change in the memory outcome at the post-surgical neuropsychometric evaluation, irrespective of their site of resection. One patient with left temporal lobectomy showed slightly improved pictorial memory.
All patients with reversed Wada memory asymmetry scores (n=5) had a poorer verbal and/or pictorial memory outcome, despite the fact that they were also seizure free. The decline was considered statistically significant in all of them, again irrespective of the site of surgery.

CONCLUSIONS:
Dominant or non-dominant anterior temporal lobectomy (ATL) patients with reversed Wada memory asymmetry scores are at significant risk for post-operative memory deficits, despite complete seizure control. However, symmetrical Wada memory scores do not pose a threat for either the verbal or the pictorial memory scores of the ATL patients. A larger cohort of patients and longer post-operative follow up may be useful to confirm these results.