Presurgical neuropsychological testing predicts cognitive and seizure outcomes after anterior temporal lobectomy

The association of cognitive phenotypes with postoperative outcomes after epilepsy surgery in patients with temporal lobe epilepsy

INTRODUCTION

The concept of cognitive phenotypes has been developed to categorize the heterogeneity of neuropsychological profiles in patients with temporal lobe epilepsy (TLE). This study examines the utility of cognitive phenotypes derived from clinical criteria in the prediction of postoperative outcomes.

METHODS

Scores from 9 standardized neuropsychological tests were used to sample preoperative performance in 4 core domains (intellectual, memory, language, & executive function) in 445 patients with TLE (206 right: 236 left). Patients were grouped into 3 clinical phenotypes using clinical criteria: 1. intact cognition, 2. isolated memory and/or language impairment, and 3. widespread impairment. Patients who did not meet the criteria for these phenotypes were characterized as having a mixed profile phenotype.

RESULTS

Approximately half of the sample had intact cognitive function, with one-quarter demonstrating isolated impairments in language and memory function. The remainder demonstrated widespread impairment or a mixed pattern of cognitive impairments. The clinically derived cognitive phenotypes were associated with demographic and clinical characteristics. Patients with widespread cognitive impairments had an earlier onset of seizures than those with other cognitive phenotypes. They also reported higher levels of depression. Higher levels of anxiety were reported in those with isolated memory/language impairments. Phenotypes were not associated with postoperative seizure outcome or postoperative declines in verbal memory or language function, but an intact phenotype was associated with a greater risk of decline in visual learning than right-sided surgery.

CONCLUSIONS

Distinct cognitive phenotypes in TLE can be identified using clinical criteria and may reflect neurodevelopmental influences and mood in addition to progression of the disease. Phenotype may be a more powerful predictor of postoperative decline in visual memory than laterality of surgery.

Typical visual unfamiliar face individuation in left and right mesial temporal epilepsy

Patients with chronic mesial temporal lobe epilepsy have difficulties at identifying familiar faces as well as at explicit old/new face recognition tasks. However, the extent to which these difficulties can be attributed to visual individuation of faces, independently of general explicit learning and semantic memory processes, is unknown. We tested 42 mesial temporal lobe epilepsy patients divided into two groups according to the side of epilepsy (left and right) and 42 matched controls on an extensive series of individuation tasks of unfamiliar faces and control visual stimuli, as well as on face detection, famous face recognition and naming, and face and non-face learning. Overall, both patient groups had difficulties at identifying and naming famous faces, and at explicitly learning face and non-face images. However, there was no group difference in accuracy between patients and controls at the two most widely used neuropsychological tests assessing visual individuation of unfamiliar faces (Benton Facial Recognition Test and Cambridge Face Memory Test). While patients with right mesial temporal lobe epilepsy were slowed down at all tasks, this effect was not specific to faces or even high-level stimuli. Importantly, both groups showed the same profile of response as typical participants across various stimulus manipulations, showing no evidence of qualitative processing impairments. Overall, these results point to largely preserved visual face individuation processes in patients with mesial temporal lobe epilepsy, with semantic and episodic memory difficulties being consistent with the localization of the neural structures involved in their epilepsy (anterior temporal cortex and hippocampus). These observations have implications for the prediction of neuropsychological outcomes in the case of surgery and support the validity of intracranial electroencephalographic recordings performed in this population to understand neural mechanisms of human face individuation, notably through intracranial electrophysiological recordings and stimulations.

Neuropsychology Outcomes Following Trephine Epilepsy Surgery: The Inferior Temporal Gyrus Approach for Amygdalohippocampectomy in Medically Refractory Mesial Temporal Lobe Epilepsy

BACKGROUND

Surgery is indicated in cases of mesial temporal lobe epilepsy(MTLE) that are refractory to medical management. The inferior temporal gyrus (ITG) approach provides access to the mesial temporal lobe (MTL) structures with minimal tissue disruption. Reported neuropsychology outcomes following this approach are limited.

OBJECTIVE

To report neuropsychological outcomes using an ITG approach to amygdalohippocampectomy (AH) in patients with medically refractory MTLE based on a prospective design.

METHODS

Fifty-four participants had Engel class I/II outcome following resection of MTL using the ITG approach. All participants had localization-related epilepsy confirmed by long-term surface video-electroencephalography and completed pre/postsurgical evaluations that included magnetic resonance imaging (MRI), Wada test or functional MRI, and neuropsychology assessment.

RESULTS

Clinical semiology/video-electroencephalography indicated that of the 54 patients, 28 (52%) had left MTLE and 26 (48%) had right MTLE. Dominant hemisphere resections were performed on 23 patients (43%), nondominant on 31(57%). Twenty-nine (29) had pathology-confirmed mesial temporal sclerosis (MTS). Group level analyses found declines in verbal memory for patients with language-dominant resections (P < .05). No significant decline in neuropsychological measures occurred for patients with MTS. Participants without MTS who underwent a language-dominant lobe resection exhibited a significant decline in verbal and visual memory (P < .05). Nondominant resection participants did not exhibit significant change in neuropsychology scores (P > .05).

CONCLUSION

Neuropsychology outcomes of an ITG approach for selective mesial temporal resection are comparable to other selective AH techniques showing minimal adverse cognitive effects. These data lend support to the ITG approach for selective AH as an option for MTLE.

The effect of recurrent seizures on cognitive, behavioral, and quality-of-life outcomes after 12 months of monotherapy in adults with newly diagnosed or previously untreated partial epilepsy

PURPOSE

The purpose of this study was to determine whether seizure recurrence has a negative impact on cognition, psychological function, and health-related quality of life (HRQoL) over a 12-month period of monotherapy in adults with newly diagnosed or previously untreated partial epilepsy.

METHODS

Seizure freedom (SF) was defined as no seizure recurrence during the 40-week maintenance period of medication. Neuropsychological tests, the Symptom Checklist-90 (SCL-90), and the Quality of Life in Epilepsy-31 (QOLIE-31) were administered at baseline and after 48 weeks of carbamazepine or lamotrigine monotherapy. Seventy-three patients successfully continued treatment until the 48-week follow-up time point. Fifty patients (68.5%) had SF, and the remaining 23 were not seizure-free (NSF). A seizure outcome group-by-time interaction was analyzed using a linear mixed model.

RESULTS

A group-by-time interaction was identified for the total QOLIE-31 score (p<0.05) and score on two QOLIE-31 subscales (social function: p<0.001 and seizure worry: p<0.001), with a significant improvement over time only present in the SF group (all p<0.001). There was no significant group-by-time interaction for most cognitive function tests, with the exception of the serial clustering score (p<0.01) and number of recognition hits on the California Verbal Learning Test (p<0.05). Serial clustering did not differ between the SF and NSF groups at baseline, but was significantly more used in the NSF group than in the SF group at 48 weeks (p<0.01). There was no significant group-by-time interaction for any dimension of the SCL-90.

CONCLUSION

Recurrent seizures had a significant effect on HRQoL, a subtle effect on cognitive performance, and no effect on psychological symptoms over one year in newly diagnosed or previously untreated adults with partial epilepsy.

Predictors of surgical outcome in medically-resistant temporal lobe epilepsy with bilateral features on pre-operative evaluation

OBJECTIVE

This study identifies potential prognostic factors for favorable anterior mesial temporal lobe (AMTL) resection outcomes in patients with medically refractory temporal lobe epilepsy (TLE) with bilateral features on pre-operative examination.

METHODS

Thirty-one patients demonstrated bilateral features defined as: bilateral independent temporal or bitemporal ictal onsets on surface or intracranial EEG, or bitemporal interictal epileptiform abnormalities on surface EEG with bilateral radiographic mesial temporal sclerosis. Surgical outcomes were classified according to reduction in seizure frequency: I (100% reduction), II (≥75% reduction), III (50-74% reduction), IV (<50% reduction).

RESULTS

Of 31 patients, 14 (45%) improved to class I and 9 (29%) had a class II outcome at an average of 4 years after surgery. Eight (26%) patients did not exhibit good surgical outcome (class III, class IV). We found that neuropsychological and Wada memory scores were significantly correlated (p<0.05) with surgical outcome, and logistic regression found neuropsychological evaluation significantly predicted better surgical outcome (p<0.05).

CONCLUSIONS

When bilateral features are present on pre-operative evaluation, neuropsychological and Wada test results can provide unique data to better identify those patients more likely to achieve substantial seizure reduction.

Functional MRI, resting state fMRI, and DTI for predicting verbal fluency outcome following resective surgery for temporal lobe epilepsy

OBJECTIVE

Predicting cognitive function following resective surgery remains an important clinical goal. Each MRI neuroimaging technique can potentially provide unique and distinct insight into changes that occur in the structural or functional organization of "at-risk" cognitive functions. The authors tested for the singular and combined power of 3 imaging techniques (functional MRI [fMRI], resting state fMRI, diffusion tensor imaging) to predict cognitive outcome following left (dominant) anterior temporal lobectomy for intractable epilepsy. METHODS; The authors calculated the degree of deviation from normal, determined the rate of change in this measure across the pre- and postsurgical imaging sessions, and then compared these measures for their ability to predict verbal fluency changes following surgery.

RESULTS

The data show that the 3 neuroimaging techniques, in a combined model, can reliably predict cognitive outcome following anterior temporal lobectomy for medically intractable temporal lobe epilepsy.

CONCLUSIONS

These findings suggest that these 3 imaging modalities can be used effectively, in an additive fashion, to predict functional reorganization and cognitive outcome following anterior temporal lobectomy.

Clinical utility of the Wechsler Memory Scale--Fourth Edition (WMS-IV) in predicting laterality of temporal lobe epilepsy among surgical candidates

This study evaluated the accuracy of the Wechsler Memory Scale--Fourth Edition (WMS-IV) in identifying functional cognitive deficits associated with seizure laterality in localization-related temporal lobe epilepsy (TLE) relative to a previously established measure, the Rey Auditory Verbal Learning Test (RAVLT). Emerging WMS-IV studies have highlighted psychometric improvements that may enhance its ability to identify lateralized memory deficits. Data from 57 patients with video-EEG-confirmed unilateral TLE who were administered the WMS-IV and RAVLT as part of a comprehensive presurgical neuropsychological evaluation for temporal resection were retrospectively reviewed. We examined the predictive accuracy of the WMS-IV not only in terms of verbal versus visual composite scores but also using individual subtests. A series of hierarchal logistic regression models were developed, including the RAVLT, WMS-IV delayed subtests (Logical Memory, Verbal Paired Associates, Designs, Visual Reproduction), and a WMS-IV verbal-visual memory difference score. Analyses showed that the RAVLT significantly predicted laterality with overall classification rates of 69.6% to 70.2%, whereas neither the individual WMS-IV subtests nor the verbal-visual memory difference score accounted for additional significant variance. Similar to previous versions of the WMS, findings cast doubt as to whether the WMS-IV offers significant incremental validity in discriminating seizure laterality in TLE beyond what can be obtained from the RAVLT.

The role of neuropsychology on an epilepsy monitoring unit: a peek behind the "do not disturb" sign

Neuropsychological services are considered an essential component of specialized epilepsy centers. In such a multidisciplinary setting, neuropsychologists interact regularly with other professionals involved in epilepsy patients' care. For these other professionals, this article provides an overview of the background of neuropsychologists, the services they provide, and how their findings contribute to the evaluation of the epilepsy patient. Two case examples are included to illustrate how neuropsychological evaluations are employed in the epilepsy monitoring unit setting.

Topiramate and its effect on fMRI of language in patients with right or left temporal lobe epilepsy

Topiramate (TPM) is well recognized for its negative effects on cognition, language performance and lateralization results on the intracarotid amobarbital procedure (IAP). But, the effects of TPM on functional MRI (fMRI) of language and the fMRI signals are less clear. Functional MRI is increasingly used for presurgical evaluation of epilepsy patients in place of IAP for language lateralization. Thus, the goal of this study was to assess the effects of TPM on fMRI signals. In this study, we included 8 patients with right temporal lobe epilepsy (RTLE) and 8 with left temporal lobe epilepsy (LTLE) taking TPM (+TPM). Matched to them for age, handedness and side of seizure onset were 8 patients with RTLE and 8 with LTLE not taking TPM (-TPM). Matched for age and handedness to the patients with TLE were 32 healthy controls. The fMRI paradigm involved semantic decision/tone decision task (in-scanner behavioral data were collected). All epilepsy patients received a standard neuropsychological language battery. One sample t-tests were performed within each group to assess task-specific activations. Functional MRI data random-effects analysis was performed to determine significant group activation differences and to assess the effect of TPM dose on task activation. Direct group comparisons of fMRI, language and demographic data between patients with R/L TLE +TPM vs. -TPM and the analysis of the effects of TPM on blood oxygenation level-dependent (BOLD) signal were performed. Groups were matched for age, handedness and, within the R/L TLE groups, for the age of epilepsy onset/duration and the number of AEDs/TPM dose. The in-scanner language performance of patients was worse when compared to healthy controls - all p<0.044. While all groups showed fMRI activation typical for this task, regression analyses comparing L/R TLE +TPM vs. -TPM showed significant fMRI signal differences between groups (increases in left cingulate gyrus and decreases in left superior temporal gyrus in the patients with LTLE +TPM; increases in the right BA 10 and left visual cortex and decreases in the left BA 47 in +TPM RTLE). Further, TPM dose showed positive relationship with activation in the basal ganglia and negative associations with activation in anterior cingulate and posterior visual cortex. Thus, TPM appears to have a different effect on fMRI language distribution in patients with R/L TLE and a dose-dependent effect on fMRI signals. These findings may, in part, explain the negative effects of TPM on cognition and language performance and support the notion that TPM may affect the results of language fMRI lateralization/localization.

Socioeconomic status, cognition, and hippocampal sclerosis

OBJECTIVE

Poorer surgical outcomes in patients with low socioeconomic status have previously been reported, but the mechanisms underlying this pattern are unknown. Lower socioeconomic status may be a proxy marker for the limited economic opportunities associated with compromised cognitive function. The aim of this study was to examine the preoperative neuropsychological characteristics of patients with unilateral hippocampal sclerosis (HS) and their relationship to socioeconomic status.

METHODS

Two hundred ninety-two patients with medically intractable temporal lobe epilepsy and unilateral HS completed tests of memory and intellectual function prior to surgery. One hundred thirty-one had right HS (RHS), and 161 had left HS (LHS). The socioeconomic status of each participant was determined via the Index of Multiple Deprivation (IMD) associated with their postcode.

RESULTS

The IMD was not associated with age at the time of assessment, age at onset of epilepsy, or duration of active epilepsy. The RHS and LHS groups did not differ on the IMD. The IMD was negatively correlated with all neuropsychological test scores in the LHS group. In the RHS group, the IMD was not significantly correlated with any of the neuropsychological measures. There were no significant correlations in the RHS group. Regression analyses suggested that IMD score explained 3% of variance in the measures of intellect, but 8% of the variance in verbal learning in the LHS group. The IMD explained 1% or less of the variance in neuropsychological scores in the RHS group. Controlling for overall level of intellectual function, the IMD score explained a small but significant proportion of the variance in verbal learning in the LHS group and visual learning for the RHS group.

CONCLUSIONS

Our findings suggest that patients living in an area with a high IMD enter surgery with greater focal deficits associated with their epilepsy and more widespread cognitive deficits if they have LHS. Further work is needed to establish the direction of the relationship between low socioeconomic status and the neurocognitive sequelae of epilepsy.