Wada memory test performance in atients with mesial temporal sclerosis

The Wada test is widely used in the presurgical evaluation of potential temporal lobectomy patients to predict postoperative memory function. Expected asymmetry (EA), defined as Wada memory lateralized to the nonsurgical hemisphere, or a higher score after injection of the surgical hemisphere would be considered favorable in terms of postoperative memory outcome. However, in some cases, nonlateralized memory (NM) results, with no appreciable asymmetry, may occur because of impaired scores after both injections, often leading to denial of surgery. The reason for such nonlateralized Wada memory in patients with intractable temporal lobe epilepsy (TLE) remains unclear. Given that quantitative morphometric magnetic resonance imaging studies in TLE patients have shown bilateral regional atrophy in temporal and extratemporal structures, we hypothesized that the volume loss in contralateral temporal structures could contribute to nonlateralized Wada memory performance. To investigate this, we examined the relationship between the volume changes of temporal structures and Wada memory scores in patients with intractable TLE with mesial temporal sclerosis (MTS) using an ageand gender-matched control group. Memory was considered nonlateralized if the absolute difference in the total correct recall scores between ipsilateral and contralateral injections was <11%. Among 21 patients, Wada memory was lateralized in 15 and nonlateralized in 6 patients, with all the nonlateralized scores being observed in left TLE. The recall scores after ipsilateral injection were significantly lower in patients with an NM profile than an EA profile (23 ± 14% vs. 59 ± 18% correct recall, p ≤ 0.001). However, the recall scores after contralateral injection were low but similar between the two groups (25 ± 17% vs. 25 ± 15% correct recall, p = 0.97). Compared to controls, all the patients showed greater volume loss in the temporal regions. However, patients with a NM profile showed significantly more volume loss than those with a lateralized memory profile in both contralateral and ipsilateral temporal regions (p < 0.05). Left hemispheric Wada memory performance correlated positively with the size of the left mesial and neocortical temporal structures (r = 0.49–0.63, p = 0.005–0.04). Our study suggests that volume loss in the nonsurgical temporal structures is associated with nonlateralized Wada memory results in patients with intractable TLE. © 2015 Elsevier B.V. All rights reserved. ∗ Corresponding author. Tel. : +1 214 648 9197; fax: +1 214 648 6320. E-mail addresses: Kan.ding@utsouthwestern.edu (K. Ding), unhua.gong@nih.gov (Y. Gong), pmodur@gmail.com P.N. Modur), ramon.diaz-arrastia@nih.gov (R. Diaz-Arrastia), ark.agostini@utsouthwestern.edu (M. Agostini), uneet.gupta@utsouthwestern.edu (P. Gupta), oderick.McColl@utsouthwestern.edu (R. McColl), ryan.hays@utsouthwestern.edu R. Hays), Paul.van ness@utsouthwestern.edu (P. Van Ness). ttp://dx.doi. org/10.1016/j.eplepsyres. 2015.11. 018 920-1211/© 2015 Elsevier B.V. All rights reserved. Introduction Verbal memory decline is one of the major concerns associated with surgery for temporal lobe epilepsy (TLE), especially after dominant anterior temporal lobectomy (ATL). Accurate prediction of memory decline prior to ATL is challenging. The Wada test (also known as the intracarotid amobarbital procedure) was originally developed to determine hemispheric language dominance in prospective ATL candidates to prevent significant language disturbances after surgery (Wada and Rasmussen, 2007).