title: Temporal lobe volume predicts Wada memory test performance in patients with mesial temporal sclerosis.
abstract: 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 age- and 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.
authors.affiliation: Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-8508, USA. Electronic address: Kan.ding@utsouthwestern.edu.
authors.forename: Kan
authors.initials: K
authors.lastname: Ding
authors.affiliation: Department of Radiology, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Blvd, Dallas, TX 75390-8508, USA. Electronic address: Yunhua.gong@nih.gov.
authors.forename: Yunhua
authors.initials: Y
authors.lastname: Gong
authors.affiliation: Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-8508, USA. Electronic address: pmodur@gmail.com.
authors.forename: Pradeep N
authors.initials: PN
authors.lastname: Modur
authors.affiliation: Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-8508, USA; Center for Neuroscience and Regenerative Medicine, Uniformed Service University of the Health Sciences, 12725 Twinbrook Parkway, Rockville, MD 20851, USA. Electronic address: ramon.diaz-arrastia@nih.gov.
authors.forename: Ramon
authors.initials: R
authors.lastname: Diaz-Arrastia
authors.affiliation: Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-8508, USA. Electronic address: Mark.agostini@utsouthwestern.edu.
authors.forename: Mark
authors.initials: M
authors.lastname: Agostini
authors.affiliation: Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-8508, USA. Electronic address: puneet.gupta@utsouthwestern.edu.
authors.forename: Puneet
authors.initials: P
authors.lastname: Gupta
authors.affiliation: Department of Radiology, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Blvd, Dallas, TX 75390-8508, USA. Electronic address: Roderick.McColl@utsouthwestern.edu.
authors.forename: Roderick
authors.initials: R
authors.lastname: McColl
authors.affiliation: Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-8508, USA. Electronic address: ryan.hays@utsouthwestern.edu.
authors.forename: Ryan
authors.initials: R
authors.lastname: Hays
authors.affiliation: Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-8508, USA. Electronic address: Paul.van_ness@utsouthwestern.edu.
authors.forename: Paul
authors.initials: P
authors.lastname: Van Ness
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D004833:Epilepsy, Temporal Lobe / Q000473:pathology* / Q000523:psychology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D011939:Mental Recall; D008875:Middle Aged; D009483:Neuropsychological Tests; D009929:Organ Size; D012189:Retrospective Studies; D012598:Sclerosis / Q000473:pathology; D013702:Temporal Lobe / Q000473:pathology*; D055815:Young Adult
keywords: Mesial temporal sclerosis; Regional atrophy; Temporal lobe epilepsy; Wada test