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Sensitivity of Green’s Word Memory Test Genuine Memory Impairment Profile to Temporal Pathology: A Study in Patients With Temporal Lobe Epilepsy a

b

b

Katie E. Eichstaedt , William E. Clifton , Fernando L. Vale , Selim c

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R. Benbadis , Ali M. Bozorg , Nancy T. Rodgers-Neame & Mike R. bce

Schoenberg a

Florida School of Professional Psychology, Argosy University, Tampa, FL, USA b

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Department of Neurosurgery, University of South Florida Morsani College of Medicine, Tampa, FL, USA c

Department of Neurology, University of South Florida Morsani College of Medicine, Tampa, FL USA d

Private Practice, Florida Comprehensive Epilepsy and Seizure Disorders Center, Tampa, FL, USA e

Department of Psychiatry and Behavioral Neurosciences, University of South Florida Morsani College of Medicine, Tampa, FL, USA Published online: 01 Aug 2014.

To cite this article: Katie E. Eichstaedt, William E. Clifton, Fernando L. Vale, Selim R. Benbadis, Ali M. Bozorg, Nancy T. Rodgers-Neame & Mike R. Schoenberg (2014) Sensitivity of Green’s Word Memory Test Genuine Memory Impairment Profile to Temporal Pathology: A Study in Patients With Temporal Lobe Epilepsy, The Clinical Neuropsychologist, 28:6, 941-953, DOI: 10.1080/13854046.2014.942374 To link to this article: http://dx.doi.org/10.1080/13854046.2014.942374

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The Clinical Neuropsychologist, 2014 Vol. 28, No. 6, 941–953, http://dx.doi.org/10.1080/13854046.2014.942374

Sensitivity of Green’s Word Memory Test Genuine Memory Impairment Profile to Temporal Pathology: A Study in Patients With Temporal Lobe Epilepsy Katie E. Eichstaedt1, William E. Clifton2, Fernando L. Vale2, Selim R. Benbadis3, Ali M. Bozorg3, Nancy T. Rodgers-Neame4, and Mike R. Schoenberg2,3,5 Downloaded by [Pennsylvania State University] at 07:32 16 April 2015

1

Florida School of Professional Psychology, Argosy University, Tampa, FL, USA Department of Neurosurgery, University of South Florida Morsani College of Medicine, Tampa, FL, USA 3 Department of Neurology, University of South Florida Morsani College of Medicine, Tampa, FL USA 4 Private Practice, Florida Comprehensive Epilepsy and Seizure Disorders Center, Tampa, FL, USA 5 Department of Psychiatry and Behavioral Neurosciences, University of South Florida Morsani College of Medicine, Tampa, FL, USA 2

Performance validity tests (PVTs) such as Green’s Word Memory Test (WMT) are designed to have face validity as memory tests while individuals with neurologically based memory deficits can score adequately provided there is sufficient task engagement. Some patients with severe memory loss have performed poorly on the WMT, raising questions about false positive errors. This study compared performances of 43 patients with left, right, or bilateral temporal lobe epilepsy on the WMT to a test known to be sensitive to temporal lobe pathology, the Rey Auditory Verbal Learning Test (RAVLT). The right TLE group outperformed the left on the WMT free recall (FR) scores and RAVLT short-delay and long-delay trials (Trials 6 and 7) (p < .05); no other between-group differences occurred (p ≥ .10). Ten participants (20.4%) performed below the cut-off score on at least one WMT effort subtest, but eight (80%) exhibited the genuine memory impairment profile (GMIP). Logistic regression found no WMT subtest contributed to predicting side of seizure with RAVLT scores in the model. Data suggest WMT primary effort subtests are generally insensitive to known temporal lobe pathology, and using the GMIP is valuable to identify individuals with severe memory loss who score below criterion on WMT primary effort subtests. Keywords: Word Memory Test; Epilepsy; Sensitivity; Performance validity test; Malingering.

INTRODUCTION Performance validity assessment is a necessary component of neuropsychological evaluation (Bush et al., 2005; Heilbronner et al., 2009). All performance validity tests (PVTs) have the potential to make a false positive error in assessing the construct of task engagement, which occurs when individuals with severe neurological impairments score below cut-offs of PVTs due to cognitive impairment rather than poor effort. Thus, Address correspondence to: Mike R. Schoenberg, PhD, ABPP; Chief, Neuropsychology Division, Department of Psychiatry and Behavioral Neurosciences, University of South Florida College of Medicine, Tampa, FL, USA. E-mail: [email protected] (Received 26 April 2014; accepted 2 July 2014)

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the specificity of PVTs to actual severe cognitive impairments must be examined among neurological populations known to exhibit severe impairments (e.g., Green, Montijo, & Brockhaus, 2011; Heilbronner et al., 2009; Howe, Anderson, Kaufman, Sachs, & Loring, 2007; Merten, Bossink, & Schmand, 2007; Rienstra, Groot, et al., 2013). In its consensus recommendations for future scientific investigation related to the assessment of effort, the American Academy of Clinical Neuropsychology highlighted the need for research investigating populations at elevated risk of failing PVTs despite giving best effort (Heilbronner et al., 2009). The Word Memory Test (WMT) is a PVT designed to distinguish individuals with suboptimal task engagement using performance patterns on the WMT subtests observed across specific patient populations (Green, Allen, & Astner, 1996; Green, Iverson, & Allen, 1999). Green (2007) purports the WMT to be more sensitive to detecting feigned cognitive impairment and suboptimal effort than the Test of Memory Malingering (TOMM; Tombaugh, 1996), while still being “insensitive to all but the most extreme forms of cognitive impairment” (Green, Lees-Haley, & Allen, 2002, p. 97). In contrast, Greiffenstein, Greve, Bianchini, and Baker (2008) suggested the WMT and TOMM are comparably sensitive to suboptimal effort, and highlighted the need for further examination of both tests’ sensitivity to genuine cognitive impairment. Subsequent findings regarding the WMT’s utility in distinguishing between feigned and genuine cognitive impairment have been mixed; some studies yield favorable data (e.g., Carone, 2014; Carone, Green & Drane, 2013; Flaro, Green, & Robertson, 2007; Green & Flaro, 2003; Greiffenstein et al., 2008; Rienstra, Groot, et al., 2013; Rienstra, Twennaar, & Schmand, 2013), while others raise concerns about the rate of false positives among neurologically impaired patients (e.g., Allen, Bigler, Larsen, GoodrichHunsaker, & Hopkins, 2007; Connor, Foster, & Kirsner, 2004; Greve, Ord, Curtis, Bianchini, & Brennan, 2008; Shores, 2004). Bowden, Shores, and Mathias (2006) noted existing literature documenting the sensitivity and specificity of the WMT in specific patient populations were lacking, and called for further data. Efforts to reduce false positive errors in patients with severe neurologically related cognitive deficits resulted in a method of profile analysis using an abbreviated version of the WMT, the Medical Symptom Validity Test (Howe et al., 2007; Howe & Loring, 2009; Singhal, Green, Ashaye, Shankar, & Gill, 2009). This approach, known as the genuine memory impairment profile (GMIP) or “dementia profile” is an algorithm comparing scores on different subtests and has since been validated with the WMT as a way to better understand score profiles among patients with probable dementia (Green et al., 2011; Rienstra, Groot, et al., 2013). As described by Green et al. (2011), the GMIP is calculated by comparing the means of the easy subtests (Immediate Recognition [IR], Delayed Recognition [DR], and Consistency [CNS]) with those of the hard subtests (Multiple Choice [MC], Paired Associates [PA], and Free Recall [FR]), with differences of less than 30 points signifying suboptimal effort. The GMIP is appropriately used in cases in which any of the primary effort subtests (IR, DR, or CNS) fall below standard cutoffs but above chance performance, and the patient has a known or suspected neurological condition which could cause severe memory impairments (Green, 2005). Several studies have found the WMT to differentiate patient groups with known neurological disease from groups with psychiatric diagnosis and also correlate with structural neuroanatomical abnormalities (e.g., Carone 2014; Carone et al., 2013; Drane

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et al., 2006; Rienstra, Groot, et al., 2013; Rienstra, Twennaar, et al., 2013). Drane and colleagues (2006) found the WMT performance was significantly different between patients with epilepsy and those with psychogenic non-epileptic seizures (PNES) in that the PNES sample tended to score below established cut-offs on the WMT than patients with epilepsy. Further, individuals with PNES who failed the WMT scored worse on neuropsychological tests than patients with PNES who passed the WMT effort subtests without any group differences in medical history of neurological laboratory findings. The WMT GMIP “dementia” profile appears related to cognitive decline and neuropathological changes. Rienstra, Twennaar, et al. (2013) administered the WMT as part of a neuropsychological assessment to 167 elderly patients with cognitive complaints. Individuals exhibiting the GMIP “dementia profile” were more likely to have cognitive deficits at baseline, and have greater decline in cognitive function 2 years later. In a separate study, Rienstra, Groot, et al. (2013) found older adults with memory complaints who scored below cut-offs on the WMT and TOMM did not exhibit the correlation between hippocampal volume and verbal memory test scores observed in a matched case cohort who passed the WMT and TOMM. The lack of association between neuropathology and failing the WMT was interpreted to indicate that some patients with diagnosis of MCI likely do not have neurological disease. Finally, two case studies illustrate that individuals with severe memory loss and known brain damage can perform satisfactorily on the WMT primary effort subtests or exhibit the GMIP profile (Carone et al., 2013; Goodrich-Hunsaker & Hopkins, 2009). Carone and colleagues (2013) reported two patients scoring above criterion on the WMT effort subtests who were status-post left mesial temporal resection for treatment of medication refractory epilepsy with severe memory deficits. Good-Hunsaker and Hopkins (2009) reported three amnestic patients with bilateral hippocampal degeneration who performed above cut-off scores on WMT effort subtests. In contrast, other studies have suggested that WMT performance can be significantly impacted by neurological disease and/or medication effects, and highlight concerns about the potential for “false positive errors” with the WMT (e.g., Allen, Wu & Bigler, 2011; Greve et al., 2008; Loring et al., 2011; Merten et al., 2007). Merten and colleagues (2007) compared various PVT tests, including the WMT, among participants without cognitive impairment and patient groups with severe cognitive dysfunction, and found cognitive impairment interfered with PVT performance. Moreover, WMT performances strongly correlated with neuropsychological measures of declarative memory, but had low correlations with other PVTs. Unfortunately, this study was limited in that not all WMT subtests were used and, as a result, the GMIP analysis for genuine severe memory impairment could not be completed. Functional neuroimaging data have highlighted that brain activity during the WMT task involves multiple brain regions, leading some researchers to question the interpretation of WMT failure reflecting predominately poor task engagement/effort. Allen and colleagues (2007) assessed brain fMRI activity in four healthy participants completing the WMT, and observed WMT task performance involved cortical regions associated with concentration/cognitive effort, memory load, and task difficulty, which raised questions about interpreting poor performance on the WMT as lack of sufficient task engagement. Allen et al.’s (2011) case example reports fMRI data during the WMT for the same individual 1 year preceding and 1 year following a traumatic brain injury (TBI). While WMT performance remained above cutoffs across time, response times were slower, and significantly stronger and more

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widespread frontal and parietal activity was observed after the TBI compared to baseline. Medication effects may also negatively impact WMT performance (e.g., Loring et al., 2011; but see Rohling, 2013). Together, these studies highlight that the relationship among task engagement, cognitive impairment, and WMT performance may be more complex than previously acknowledged. Patients with temporal lobe epilepsy (TLE) are at high risk for developing severe memory impairment, sometimes associated with mesial temporal sclerosis (see Hoppe, Elger, & Helmstaedter, 2007; Lee, 2010; Lin, Mula, & Hermann, 2012; Rudzinski & Meador, 2013). Differences in material specific memory impairments have been well described, with right TLE (RTLE) patients exhibiting fewer severe verbal memory deficits than patients with left TLE (LTLE) or those patients with bilateral TLE (e.g., Lin et al., 2012; Sherman et al., 2011; Stroup et al., 2003). Material-specific verbal memory deficits associated with LTLE present a challenge to neuropsychological assessment for evaluating the presence of adequate task engagement/attention to memory tests, particularly when external incentives are present, such as in the context of disability evaluations. Estimates of the prevalence of probable insufficient task engagement or symptom exaggeration are about 9% of seizure disorder cases (Mittenberg, Patton, Canyock, & Condit, 2002). Drane and colleagues (2006) found about 8% of patients with epilepsy failed the WMT effort subtests, excluding patients who were post-ictal or profoundly impaired (e.g., institutionalized). The accuracy of such estimates is dependent on PVT specificity, and the effects of lateralized neurological disease and medication on PVT measures represent an unsettled area in need of further exploration. In order to appropriately assess task engagement among patients with TLE, measures with appropriate cut-offs for the diagnostic differential must be selected for the clinical characteristics of the patient sample (Boone, 2011), and alternative cutoff scores for the WMT effort subtests may be needed for patients with LTLE. To our knowledge, WMT performances among patients with epilepsy have not been examined by lateralization of seizure onset. The current study evaluates whether performance on the WMT primary effort indices (IR, DR, and CNS) and memory indices (PA, FR) is affected in patients with known mesial temporal dysfunction associated with TLE. WMT indices will be compared to Rey Auditory Verbal Learning Test (RAVLT; Rey, 1941) test scores, which are known to be sensitive to TLE (Loring et al., 2008). Lastly, the GMIP algorithm to decrease false positive errors for patients with dementia will be assessed among WMT primary effort subtest failures within this TLE sample.

METHOD Participants Participants were 49 patients referred for neuropsychological evaluation as part of comprehensive evaluation of the University of South Florida (USF)/Tampa General Hospital (TGH) Comprehensive Epilepsy Center for pre-surgical assessment for treatment of localization-related temporal lobe epilepsy. Data for this retrospective chart review study were obtained from an archival database of demographic and clinical data collected as part of a larger neuropsychological research project approved by the University of South Florida Institutional Review Board (IRB). All participants gave written informed consent. As such, the patients included represent a non-litigating sample being

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Table 1. Demographic and clinical characteristics by hemisphere of seizure onset Demographic and clinical characteristics by hemisphere of seizure onset (n = 43) Left (n = 26) Right (n = 17) Age in years Years of education Gender (male/female) Number of antiepileptic drugs Years of epilepsy duration

37.81 (11.59) 12.73 (2.59) 14/12 2.27 (.96) 15.90 (12.00)

41.94 (15.26) 13.53 (2.62) 9/8 2.31 (1.01) 17.39 (16.14)

P Value .32 .33 .95 .93 .10

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Unless otherwise stated, all values are presented as mean (standard deviation).

evaluated outside the context of disability determination or other context in which secondary gain might motivate poor performance. Although a portion of our sample reported to be receiving disability benefits at the time of evaluation, previous data suggest neuropsychological performances are unrelated to disability incentive in this evaluation setting (e.g., Williamson, Drane, & Stroup, 2007; Williamson et al., 2004; Williamson, Holsman, Chaytor, Miller, & Drane, 2012). Demographic and epilepsy disease characteristics are listed in Table 1. A total of 26 patients had LTLE, 17 had RTLE, and 6 had bilateral TLE. Seizure localization and lateralization were confirmed with video-electroencephalogram (EEG) and consistent seizure semiology interpreted by a neurologist board certified in neurophysiology. Diagnosis of bilateral TLE was made based on long-term video EEG showing bilateral independent epileptiform activity interpreted by board certified neurologists. Inclusion criteria included: at least 18 years of age; fluency in English; diagnosis of localizationrelated pharmacoresistant epilepsy; completed MRI study of brain, completed methohexital intracarotid (Wada) procedure; and evidence of focal seizure onset that could be localized to the temporal, mesial temporal, or frontotemporal area based on video-EEG and having consistent seizure seimiology. Presence of mesial temporal sclerosis was determined by board certified neuroradiologists using high-quality T1 and T2 MRI images, and no patient had mesial temporal sclerosis or other structural abnormality contralateral to side of seizure onset. Based on MRI results, eight patients with LTLE and four patients with RTLE exhibited mesial temporal sclerosis ipsilateral to seizure focus. No patients with bilateral temporal lobe epilepsy had mesial temporal sclerosis. Measures Each participant completed a comprehensive neuropsychological evaluation that included the RAVLT and WMT as part of pre-surgical work-up for TLE. The WMT was always administered prior to the RAVLT by a minimum of 1 hour following recommendations (Green, 2005). Additionally, data from video-EEG, General Electric (GE) 3-Tesla MRI study of brain with and without contrast, and methohexital intracarotid (Wada) procedure were obtained from each patient in order to confirm seizure lateralization and localization, presence or absence of structural lesion, and lateralization of language and memory functioning, respectively. The video-EEG data were collected using standard interictal samples and all recorded episodes, with 10-20 electrode system (see Benbadis et al., 2009, for more detail). The Wada procedure employed the standard

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protocol outlined by Trenerry and Loring (1995), modified by using methohexital in lieu of amobarbital (Buchtel, Passaro, Selwa, Deveikis, & Gomez-Hassan, 2002). Neuropsychological measures analyzed in this study include the WMT and the RAVLT. RAVLT. The RAVLT is an established measure of verbal episodic memory (Strauss, Sherman, & Spreen, 2006) and predicts presence of language-dominant mesial temporal lobe sclerosis (Loring et al., 2008; Sherman et al., 2011). Although verbal paired-associates tasks of memory are more similar in design to the WMT, the RAVLT was chosen as a comparison measure for this study based on its superior ability to distinguishing lateralization of temporal lobe epilepsy (Loring et al., 2008; Sherman et al., 2011). Standardized scores were obtained using age-matched health normative data from Schmidt (1996, Table 7, pp. 15–20) for age ranges of 20–89 in 10-year increments (20–29, 30–39, 40–49, and so on). Primary measures were Trial 6 (total immediate recall) and Trial 7 (total delayed recall) standardized T-Scores. WMT. The WMT is a memory measure and PVT that uses performance patterns from specific patient populations to evaluate task engagement and memory performance (Green et al., 1996, 1999). The computerized version of the WMT was used, and scores were obtained from computer report. The cutoff score for insufficient effort was set at 82.5% or below for each subtest that is established in the manual (Green et al., 1996). For all cases in which one or more WMT primary effort subtests (IR, DR, and CNS) was failed, the GMIP was calculated in which the means of IR, DR, and CNS percentile score were compared to the means of MC, PA and FR percentile scores (Green et al., 2011). Briefly, scores greater than 30 were considered consistent with severe memory impairment and adequate task engagement. Data analysis Evaluation for differences between groups in demographics of age and education was evaluated with ANOVA and chi-square test for sex. Epilepsy disease variables (duration of epilepsy, number of antiepileptic medications) were compared between groups using student T-tests. Between group differences in RAVLT Total, Trial 6 and Trial 7 along with WMT raw scores were compared using ANOVA. Hierarchical logistic regression was used to evaluate the ability of the RAVLT Trial 7 and WMT indices to account for variance of side of localization related temporal lobe epilepsy. The dependent variable in this analysis was hemisphere of seizure onset with 0 = LTLE and 1 = RTLE. Three models were included in analyses: (1) predictor variables included RAVLT trial 7 raw score and percentage scores for each of the WMT subtests: IR, DR, CNS, MC, PA, and FR; (2) only the RAVLT trial 7 raw score; and (3) only the six WMT subtests excluding the RAVLT scores. Alpha level of p < .05 was used.

RESULTS The LTLE group ranged in age from 20 to 63 years, with a mean age of 37.81 years and standard deviation of 11.59 years. The RTLE group ranged in age

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from 17 to 68 years, with a mean of 41.94 years and standard deviation of 15.26 years. The groups did not differ in terms of age, F(1, 41) = 1.02, p = .32, education, F(1, 41) = 0.97, p = .33, gender x2(1) = .003, p = .95, duration of epilepsy diagnosis, F(1, 41) = 2.82, p = .10, or number of antiepileptic medications prescribed, F(1, 41) = .01, p = .93; (see Table 1). Both LTLE and RTLE groups were predominantly Caucasian, at 77% and 76%, respectively. There were two bilingual Spanish/English-speaking participants who were assessed in English. Both patients had RTLE and passed all WMT subtests. There was one participant with RTLE having right-dominant language based on Wada test who passed all WMT subtests. Five participants with LTLE and five with RTLE reported receiving disability benefits at the time of evaluation, and none failed the WMT. RAVLT The LTLE group average verbal immediate and delayed memory scores were significantly worse than the RTLE group, with significant differences on RAVLT Trial 6, F(1, 41) = 4.79, p < .05, ηp2=.11, and Trial 7, F(1, 41) = 8.46, p < .01, ηp2=.17 (see Figure 1). WMT There were no significant differences between groups on the WMT primary effort subtests (IR, DR, and CNS) (p ≥ . 43). Similarly, LTLE and RTLE groups did not differ on the MC, F(1, 41) = 1.87, p = .10, and PA, F(1, 41) = 2.13, p = .15, subtests of the WMT. The RTLE group scored significantly better than the LTLE group on the WMT

Figure 1. Rey Auditory and Verbal Learning Test (RAVLT) raw score means by hemisphere of seizure onset in temporal lobe epilepsy (TLE). Asterisk denotes significant difference between groups; error bars represent standard deviation.

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FR subtest, F(1, 41) = 6.08, p < .05, ηp2=.13 (see Figure 2), considered to be the most difficult subtest (Greene et al., 2002). Hierarchical logistic regression with all predictors entered simultaneously found no WMT test score significantly contributed to predicting side of seizure onset after the RAVLT delayed recall score entered the algorithm (see Table 2). When all WMT test scores were forced into the Logistic regression, the overall classification rate was 76.7%. Because evaluation of predictors only found the RAVLT to be significant, a subsequent logistic regression using only the RAVLT was performed, with an overall classification rate of 72.1% for seizure lateralization (see Table 3). WMT failure and GMIP analysis A total of six patients with LTLE (23.1% of the LTLE group), one patient with RTLE (5.8% of RTLE group), and three participants with bilateral TLE (50% of bilateral TLE group) failed at least one of the effort subtests of the WMT (IM, DR and/or CNS). The GMIP analysis found all six LTLE failures had a difference greater than 30 points; thus, no patient with LTLE “failed” the WMT using the GMIP algorithm. The RTLE failure obtained a GMIP score of 28, which reflects a narrow “failing” WMT performance. Of the three participants with bilateral TLE that scored below cutoff on one or more WMT primary effort subtest, two participants had a GMIP profile consistent with severe memory impairment (passed GMIP). Thus, only one bilateral TLE patient ‘failed’ the WMT.

Figure 2. Green’s Word Memory Test (WMY) trial percentile means by hemisphere of seizure onset in temporal lobe epilepsy (TLE). Asterisk denotes significant difference between groups; error bars represent standard deviation. IR = Immediate Recall; DR = Delayed Recall; CNS = Consistency; MC = Multiple Choice; PA = Paired Associates; FR = Free Recall.

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Table 2. Logistic regression analysis for hemisphere of seizure onset with all outcome measures from Rey Auditory and Verbal Learning Test (RAVLT) and Green’s Word Memory Test (WMT)

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Variable RAVLT 30’ Delay WMT Free Recall WMT Paired Associates WMT Multiple Choice WMT Consistency WMT Delayed Recall WMT Immediate Recall Constant –2 Log likelihood = 46.59 N = 43

B

Standard error

Wald

Significance

Exp(B)

.26 .14 .07 .04 –.03 .05 –.01 .05 .04 .08 –.08 .28 .02 .03 –.44 .00 Nagelkerke R Square = .31 Model x2 = 11.12, p = .13

3.60 2.47 .53 .05 .08 .28 .03 .00

.06 1.29 .12 1.07 .47 .97 .82 .99 .78 1.04 .60 .93 .87 1.02 .95 .64 Overall Percentage = 76.7

Table 3. Logistic regression analysis for hemisphere of seizure onset using Rey Auditory and Verbal Learning Test (RAVLT) 30-Minute Delay Score Variable RAVLT 30’ Delay Constant –2 Log likelihood = 49.91 N = 43

B

Standard error

Wald

Significance

Exp(B)

.24 .09 –2.10 .77 Nagelkerke R Square = .23 Model x2 = 7.81, p = .005

6.44 7.49

.01 1.26 .01 .12 Overall Percentage = 72.1

DISCUSSION Data suggest WMT can be used for patients with LTLE who also exhibit verbal memory impairment without significant risk of false positive findings when GMIP analysis is employed. However, clinicians are advised to take care to avoid interpreting only the primary WMT subtests, as nearly one quarter of patients with TLE scored below cut-off of one or more primary effort WMT subtest. Patients with bilateral TLE appear particularly at risk for “failing” the WMT primary effort subtests, and clinicians should exercise particular restraint in interpreting insufficient task engagement/effort for these individuals. As expected, the study extended prior research confirming the sensitivity of the RAVLT to temporal lobe epilepsy and mesial temporal lobe dysfunction (e.g., Loring et al., 2008; Sherman et al., 2011). While the RAVLT Trial 6 and 7 scores were strong predictors of side of surgery, these data suggest the WMT FR subtest may also perform as a measure of verbal declarative memory involving the mesial temporal lobe structures. While the RAVLT score was superior to the WMT FR subtest in predicting side of seizure, these data support the contention by Green (2005) that the WMT FR performs more like a declarative memory test than a measure of task engagement/effort. Two patients with TLE both scored below cut-offs on the WMT primary effort subtests and did not exhibit the GMIP “dementia” profile (“failing” the WMT). In both of these cases, it was determined by the neuropsychologist (MRS) that the quality of

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the neuropsychological study was poor, and the findings were interpreted with caution. One of the cases was a patient with bilateral TLE with no signs of mesial temporal sclerosis or other structural abnormality on MRI. This patient was a 33-year-old Caucasian female with 16 years of education and a 1-year history of pharmacoresistent epilepsy. PET study of brain read as showing left temporal hypometabolism. Neuropsychological evaluation was completed over the course of 2 days due to the patient fatiguing quickly. Regarding WMT performance, she passed the IR subtest but failed the DR and CNS subtests by 2.5% each, with scores of 80% on both. Her reliable digit span was 7, but she obtained a full scale intellectual quotient (FSIQ) of 91 on the Wechsler Adult Intelligence Scale, Fourth Edition (WAIS-IV; Wechsler, 2008). She obtained raw scores of six and two on Trials 6 and 7, respectively, on the RAVLT. Alternatively, she scored average to low average on composite indices of auditory (verbal) memory, with a Wechsler Memory Scale, Fourth Edition (WMS-IV; Wechsler, 2009) Auditory Memory Index (AMI) = 105 and Auditory Recognition Memory Index (ARMI) = 88. Her visual memory scores were impaired—WMS-IV Visual Memory Index (VMI) = 65; Visual Recognition Memory Index (VRMI) = 72. The other case of WMT failure with GMIP analysis occurred in a 54-year-old Caucasian male with a 35-year history of pharmacoresistant RTLE and 12 years of education. MRI imaging was unremarkable. PET study of brain read as showing left temporal lobe hypometabolism. On the WMT, he passed the IR and DR subtests, but his CNS score fell at the cutoff score. He obtained a normal reliable digit span (RDS = 12) and his WAIS-IV FSIQ was average (96). He scored eight on both RAVLT Trials 6 and 7, and scored low average to average on WMS-IV auditory and visual memory indices (AIM = 88, ARM = 85, and VIM = 95). These findings are suggestive of variable task engagement/effort at times during the neuropsychological assessment, consistent with WMT interpretation. Neither patient was known to be seeking disability benefits. These data add to the debate about the brain–behavior relationships assessed by the WMT primary effort measures and supplemental indices. Our findings indicate most individuals perform above published cutoffs of the WMT primary effort subtests, and highlight the use of the GMIP to avoid interpretation of insufficient effort/task engagement among individuals with known temporal lobe dysfunction. These data support the need to include all WMT indices and GMIP profile to investigate the sensitivity and specificity of the WMT to known neurological dysfunction, and problems when relying simply on the primary WMT effort indices alone (e.g., Merten et al., 2007). Accordingly, accurate interpretation of WMT performance among patients with known or suspected neurological dysfunction should incorporate advanced interpretation of the WMT with the GMIP profile analysis. Further research should examine WMT performance among a postoperative sample of left and right TLE patients following selective hippocampal resection, as well as further elucidate clinical factors that may contribute to WMT failure even with GMIP among individuals with epilepsy. These data also extend previous literature supporting the clinical use of the RAVLT to assess for language dominant temporal lobe dysfunction, as well as support previous research establishing that verbal memory tests, and the RAVLT in particular, can predict side of seizure onset (e.g, Loring et al., 2008; Lin et al., 2012; Stroup et al., 2003; Sherman et al., 2011).

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ACKNOWLEDGMENTS The authors have no conflicts of interest to report, and none has any financial interest with the subject matter discussed in the manuscript.

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Sensitivity of Green's Word Memory Test genuine memory impairment profile to temporal pathology: a study in patients with temporal lobe epilepsy.

Performance validity tests (PVTs) such as Green's Word Memory Test (WMT) are designed to have face validity as memory tests while individuals with neu...
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