Bilateral magnetic resonance imaging-determined hippocampal atrophy and verbal memory before and after temporal lobectomy

Altered memory and affective instability in prisoners assessed for dangerous and severe personality disorder

Background

Previous studies of borderline personality disorder report neuropsychological impairments in several domains, including memory. No studies have compared memory functioning in high-risk prisoners with borderline personality disorder with similar prisoners with other personality disorders.

Aims

To explore mnemonic impairments in prisoners undergoing personality assessment as part of the dangerous and severe personality disorder initiative or detained in a medium secure facility.

Method

We investigated memory function in 18 prisoners with borderline personality disorder and 18 prisoners with other personality disorders.

Results

Prisoners with borderline personality disorder exhibited a pattern of multi-modal impairments in the immediate and delayed recall of verbal and visual information, with some association with affective instability. These deficits were not associated with the severity of personality disturbance.

Conclusions

These data suggest that memory deficits have some specificity in relation to the constituent traits of borderline personality disorder and indicate that neuropsychological assessment may be a source of useful adjunctive information for distinguishing between the cognitive and psychological difficulties of individual prisoners.

Comparison of Cognitive Parameters Between Bilateral and Unilateral Hippocampal Sclerosis

INTRODUCTION

Recent studies showed that hippocampal sclerosis (HS) patients with unilateral involvement had more diffuse cognitive impairment than expected. Therefore, we aimed to compare the cognitive profiles of bilateral HS (BHS) patients with unilateral HS (UHS) patients.

METHODS

Consecutive patients, diagnosed with epilepsy, who fulfilled two major magnetic resonance imaging (MRI) criteria (T1 atrophy and T2-FLAIR hyperintensity) for HS were included. Standard neuro-psychological test (NPT) battery consisted of the Turkish version of 15-word verbal memory processes test, Wechsler memory scale visual reproduction subtest, forward and backward digit span, phonemic and semantic fluency, and Stroop test were applied; and the groups with right HS, left HS, and bilateral HS were compared statistically.

RESULTS

Ninety-one patients, completing the NPT (34 males, 57 females)-16 with BHS, 36 with right HS, and 39 with left HS-were included. Six out of 43 operated patients had BHS. There were no significant differences in education and handedness of the groups. Even though NPT performances of the BHS group were found to be poor compared to UHS subgroups, this was beyond statistical significance. Comparison of BHS with the right HS group showed a significant difference in the learning score of the Verbal Memory Processes Test, but recognition scores were found to be similar in all groups. Compared to the BHS group, both right and left HS groups revealed a significant difference in delayed recall score of the Verbal Memory Processes Test. Although there were no significant differences in the postoperative parameters of the BHS group, UHS subgroups had deficits in many postoperative parameters.

CONCLUSION

Our study revealed that bilateral involvement of the hippocampi was correlated with a poor cognitive performance. Retrieval failure, rather than a total recall problem, in the memory of the patients resembles a more diffuse involvement not only limited to limbic structures.

Neuropsychological outcome after epilepsy surgery in patients with bilateral Ammon's horn sclerosis

Object

The purpose of this study was to retrospectively assess the objective and subjective neuropsychological outcome after epilepsy surgery in patients with bilateral Ammon's horn sclerosis (AHS).

Methods

Memory and executive functions were evaluated at baseline and at follow-up in 11 surgically treated patients and compared with 8 pharmacologically treated patients with temporal lobe epilepsy and bilateral AHS. The median follow-up duration was 16 months in the surgically treated patients and 80.5 months in the pharmacologically treated group. Subjective outcome was evaluated by questionnaires and included mood, quality of life, subjective memory, and activities of daily living.

Results

At the follow-up assessment, 82% of the surgically treated patients as opposed to 0% of the nonsurgery patients were seizure free. In the surgical group, nonverbal memory performance did not change significantly in any patient after surgery, but there was a floor effect in 55% of the surgical patients. Regarding verbal memory, 9% of the surgical patients improved while 73% declined, despite severe impairments already evident at baseline. In the nonsurgery control group, 13% of the patients declined in nonverbal memory (floor effect in 63%) and 25% declined in verbal memory (floor effect in 25%) at follow-up. None of the controls improved at follow-up. Executive functions remained unchanged on an impaired level in both groups. At follow-up, the patient groups did not differ significantly with respect to mood, quality of life, subjective memory, or activities of daily living. However, in most aspects, surgically treated patients reported a slightly better subjective outcome than pharmacologically treated patients and a significantly improved quality of life.

Conclusions

These results suggest that beyond benefits concerning seizure control, surgically treated patients with bilateral AHS, despite already poor baseline performance, are still at risk for severe postoperative decline in memory. In the light of predominantly minor benefits on a subjective level, the findings put the overall outcome of epilepsy surgery in bilateral AHS patients into perspective.

Trans-middle temporal gyrus selective amygdalohippocampectomy for medically intractable mesial temporal lobe epilepsy in adults: seizure response rates, complications, and neuropsychological outcomes

OBJECTIVE

Selective amygdalohippocampectomy (AHC) has evolved to encompass a variety of techniques to resect the mesial temporal lobe. To date, there have been few large-scale evaluations of trans-middle temporal gyrus selective AHC. The authors examine a large series of patients who have undergone the trans-middle temporal gyrus AHC and assess its clinical and neuropsychological impact.

METHODS

A series of 76 adult patients underwent selective AHC via the trans-middle temporal gyrus approach over a 10-year period, 19 of whom underwent pre- and postoperative neuropsychological evaluations.

RESULTS

Favorable seizure response rates were achieved (92% Engel class I or II), with very low surgical morbidity and no mortality. Postoperative neuropsychological assessment revealed a decline in verbal memory for the left AHC group. No postoperative memory decline was identified for the right AHC group, but rather some improvements were noted within this group.

CONCLUSIONS

The trans-middle temporal gyrus selective AHC is a safe and effective choice for management of medically refractory epilepsy in adults.

Right temporal lobe plays a role in verbal memory

OBJECTIVES

Comparison of preoperative and postoperative neurological functions in patients undergoing resection of brain tumors, in combination with data from diffusion tensor imaging (DTI) studies, can provide direct evidence of anatomical localization of brain function. The goal of the present study was to use these techniques to characterize memory function of the right temporal lobe in five patients with right temporal lobe brain tumors.

METHODS

Memory function was tested using the Wechsler Memory Scale-Revised (WMS-R) before and after surgery in five patients with right temporal lobe brain tumors. Preoperative DTI was performed in four of five cases.

RESULTS

In all cases, general and verbal memory, including verbal paired association, significantly improved after surgery (P<0.05). The right inferior longitudinal fasciculus (ILF) was compressed by the tumor in all cases.

CONCLUSION

These results suggest that the right temporal lobe plays a role in verbal memory and that this function may be associated with the right ILF.

Hippocampal volumetry and functional MRI of memory in temporal lobe epilepsy

This study examined the utility of structural and functional MRI at 1.5 and 3T in the presurgical evaluation and prediction of postsurgical cognitive outcome in temporal lobe epilepsy (TLE). Forty-nine patients undergoing presurgical evaluation for temporal lobe (TL) resection and 25 control subjects were studied. Patients completed standard presurgical evaluations, including the intracarotid amobarbital test (IAT) and neuropsychological testing. During functional imaging, subjects performed a complex visual scene-encoding task. High-resolution structural MRI scans were used to quantify hippocampal volumes. Both structural and functional imaging successfully lateralized the seizure focus and correlated with IAT memory lateralization, with improvement for functional imaging at 3T as compared with 1.5 T. Ipsilateral structural and functional MRI data were related to cognitive outcome, and greater functional asymmetry was related to earlier age at onset. These findings support continued investigation of the utility of MRI and fMRI in the presurgical evaluation of TLE.

Epilepsy surgery outcomes in temporal lobe epilepsy with a normal MRI

PURPOSE

To determine the long-term efficacy of anterior temporal lobectomy for medically refractory temporal lobe epilepsy in patients with nonlesional magnetic resonance imaging (MRI).

METHODS

We identified a retrospective cohort of 44 patients with a nonlesional modern "seizure protocol" MRI who underwent anterior temporal lobectomy for treatment of medically refractory partial epilepsy. Postoperative seizure freedom was determined by Kaplan-Meyer survival analysis. Noninvasive preoperative diagnostic factors potentially associated with excellent surgical outcome were examined by univariate analysis in the 40 patients with follow-up of >1 year.

RESULTS

Engel class I outcomes (free of disabling seizures) were observed in 60% (24 of 40) patients. Preoperative factors associated with Engel class I outcome were: (1) absence of contralateral or extratemporal interictal epileptiform discharges, (2) subtraction ictal single photon emission computed tomography (SPECT) Coregistered to MRI (SISCOM) abnormality localized to the resection site, and (3) subtle nonspecific MRI findings in the mesial temporal lobe concordant to the resection.

DISCUSSION

In carefully selected patients with temporal lobe epilepsy and a nonlesional MRI, anterior temporal lobectomy can often render patients free of disabling seizures. This favorable rate of surgical success is likely due to the detection of concordant abnormalities that indicate unilateral temporal lobe epilepsy in patients with nonlesional MRI.

Comparison of implicit memory encoding paradigms for the activation of mediotemporal structures

The medial temporal lobes (MTLs) are essential for both encoding and retrieval processes in declarative memory. In addition, they are a frequent seizure focus for medically refractory epilepsy. One of the major side effects of MTL resection is a decline in memory functions. Most functional imaging paradigms have been developed to find preoperative measures that, to obtain a prognosis of postoperative memory performance, employ explicit memory encoding strategies to elicit MTL activation, and require a great amount of cognitive effort. We applied three different implicit encoding tasks, which require less effort and time, to a group of healthy subjects. We found left-lateralized activation for verbal stimuli, bilateral activation for pictures, and right-lateralized activation for faces. The present study shows that even with an implicit memory-encoding paradigm, a lateralized activation of MTL structures can be achieved. This may lead to paradigms for routine clinical application that require less cognitive effort and time on the part of patients.

Changes in verbal and nonverbal memory following anterior temporal lobe surgery for refractory seizures: effects of sex and laterality

We studied the effects on verbal and nonverbal memory of anterior temporal lobe (ATL) surgery for epilepsy in 91 patients (46 men, 45 women), all of whom had left-hemisphere dominance for speech. Patients were divided into four groups according to sex and laterality of the excision. The memory tasks were administered shortly before surgery, 6 months postoperatively, and at a 2-year follow-up. Test scores were submitted to repeated-measures analyses of variance. We found that men treated with left temporal resection declined significantly in long-delay verbal memory after surgery, whereas no clear pre- to postoperative sex differences were found with respect to other verbal memory scores. Only the results on long-delay verbal memory confirm previous findings, showing a greater vulnerability of verbal memory to left ATL surgery in men than in women. Women with left temporal excisions obtained particularly poor scores on a long-delay nonverbal memory test preoperatively, but improved their performance on this test significantly after surgery. The seemingly gradual improvement during the 2-year follow-up suggests a plastic process.

MR-based in vivo hippocampal volumetrics: 2. Findings in neuropsychiatric disorders

Magnetic resonance imaging (MRI) has opened a new window to the brain. Measuring hippocampal volume with MRI has provided important information about several neuropsychiatric disorders. We reviewed the literature and selected all English-language, human subject, data-driven papers on hippocampal volumetry, yielding a database of 423 records. Smaller hippocampal volumes have been reported in epilepsy, Alzheimer's disease, dementia, mild cognitive impairment, the aged, traumatic brain injury, cardiac arrest, Parkinson's disease, Huntington's disease, Cushing's disease, herpes simplex encephalitis, Turner's syndrome, Down's syndrome, survivors of low birth weight, schizophrenia, major depression, posttraumatic stress disorder, chronic alcoholism, borderline personality disorder, obsessive-compulsive disorder, and antisocial personality disorder. Significantly larger hippocampal volumes have been correlated with autism and children with fragile X syndrome. Preservation of hippocampal volume has been reported in congenital hyperplasia, children with fetal alcohol syndrome, anorexia nervosa, attention-deficit and hyperactivity disorder, bipolar disorder, and panic disorder. Possible mechanisms of hippocampal volume loss in neuropsychiatric disorders are discussed.

Hippocampal volume, memory, and cortisol status in major depressive disorder: effects of treatment

BACKGROUND

Depression has been linked to stress, memory deficits, and hypercortisolemia. However, the relationships between depression, hippocampal structure and function, and cortisol levels are unclear and the effects of antidepressant treatment on the measures are not well studied.

METHODS

Whole hippocampal volume, performance on verbal and visual declarative memory function and cortisol status was evaluated in 38 subjects with major depressive disorder (MDD) and 33 healthy subjects. All measures were repeated in a subgroup (n = 22) of depressed patients after successful selective serotonin reuptake inhibitor (SSRI) treatment.

RESULTS

Hippocampal volume was not significantly different between patients with untreated MMD and healthy subjects, after controlling for whole brain volume, age and gender. However, depressed subjects had significantly greater deficits in delayed memory and percent retention on the verbal portion of the Wechsler Memory Scale-Revised (WMS-R) compared with healthy subjects, without significant differences in visual memory, attention, vigilance, or distractibility. Baseline plasma or urinary free cortisol (UFC) was not related to either hippocampal volume or memory deficits. Successful treatment with antidepressants did not change hippocampal volume but did result in a significant improvement in memory function and a reduction in UFC excretion.

CONCLUSIONS

Medication-free nonelderly depressed outpatients without alcohol dependence or adverse experiences in childhood had normal hippocampal volume. Focal declarative memory deficits in depression supported localized hippocampal dysfunction in depressed patients. Treatment with antidepressants significantly improved memory and depression but did not alter hippocampal volume, suggesting that antidepressants may improve hippocampal function in the absence of detectable structural changes.

Structural versus functional prediction of memory change following anterior temporal lobectomy

Decline in recent memory function is a significant risk for patients undergoing anterior temporal lobectomy. We report a patient with a febrile seizure history, complex partial seizures arising from the left anterior temporal lobe, and MRI evidence suggesting left hippocampal sclerosis, all of which indicate a low likelihood of significant postoperative memory decline. However, high normal verbal memory on neuropsychological testing and bilaterally normal Wada memory scores indicated increased risk for postoperative memory decline. Following left anterior temporal lobectomy, the patient displayed a significant decline in verbal recent memory that affected school performance. Despite the worsening in memory, the patient reported a significant improvement in his self-reported quality-of-life perception, demonstrating that factors other than change in cognitive performance are related to whether a patient considers epilepsy surgery worthwhile. In the present case, behavioral measures were superior to structural measures in predicting cognitive change following surgery.

Minimal model to document psychometric change after standard anterior temporal lobectomy for intractable seizure disorder

Neuropsychological assessment of persons with epilepsy is recommended whenever neurosurgery is considered as an alternative therapy for seizure disorders refractory to ordinary medical management. Although psychological assessment is common in centers specialized in the care of epilepsy patients, standardized protocols are not common. This study addresses the question of the optimal minimal test battery necessary to differentiate groups of right-handed patients with refractory, complex partial seizure disorder who receive either right or left anterior temporal lobectomy or no surgery. No variable differentiated the groups before surgery. Only Logical Memory-Immediate of the Wechsler Memory Scale differentiated the groups following surgery. This finding is consistent with the literature.

Neuropsychiatric and memory issues in epilepsy

Epilepsy is an extremely complex disorder characterized by marked variability in clinical presentation, etiology, diagnostic certainty, and therapeutic options. Neuropsychiatric and cognitive concomitant disorders are equally diverse and complex. Depression and anxiety, for example, may be preexisting conditions, occur only in peri-ictal or ictal states, or persist as constant interictal phenomena; both place additional burden on memory functions, which are further taxed by the effects of recurrent seizures, temporal lobe insult, and antiseizure medications. Such factors present considerable clinical challenges, particularly in outpatient settings. This article provides an overview of major psychiatric features of epilepsy and of issues regarding the nature of memory deficits in this neurologic population. The importance of identifying and treating potentially reversible causes of memory impairment and related forms of cognitive impairment is emphasized.

Effects of repetitive transcranial magnetic stimulation on memory subtypes: a controlled study

Repetitive transcranial magnetic stimulation (rTMS) of human cortex may disrupt or facilitate cortical activity. The aim of the present study was to investigate the consequences of rTMS applied over different cortical areas during various memory tasks, measuring immediate, working and episodic verbal memory. The study was performed in 16 right-handed healthy men. A double-blind, cross-over, within-subject repeated measures design was used. There were five rTMS conditions: baseline without stimulation, high frequency (HF) rTMS over right and left dorsolateral prefrontal cortex (DLPFC) and over right cerebellum, and low frequency (LF) parameters over left DLPFC. Digits forwards and backwards and letter-number sequencing of the Wechsler Adults Intelligence Scale (WAIS) were used to assess immediate and working verbal memory, and logical memory of the Rivermead Behavioural Memory Test was used to assess episodic memory encoding. An analysis of variance (ANOVA) for repeated measures in the scores of each memory task according to rTMS conditions was used. Significantly lower scores in the number of memory units of the episodic memory task were observed when rTMS high frequency parameters were applied over left DLPFC (P=0.009). No significant differences were found in the other memory subtype tasks analysed during the different rTMS conditions. These findings provide evidence for the significant role of the left DLPFC in episodic verbal memory processes.

Inferring Function from Structure: Relationship of Magnetic Resonance Imaging-Detected Hippocampal Abnormality and Memory Function in Epilepsy

Although temporal lobectomy is an effective alternative treatment for many patients with medication-resistant epilepsy, the risk of cognitive morbidity is not inconsequential. The ability to predict cognitive outcome is increasingly dependent on convergent information from multiple sources, including direct (e.g., Wada test) and indirect (e.g., psychometric testing) functional assessments along with magnetic resonance imaging studies that detect structural abnormalities. This brief review summarizes the relationship between imaging and function at baseline and predicting cognitive outcome following temporal lobectomy.

Inferring Function from Structure: Relationship of Magnetic Resonance Imaging-Detected Hippocampal Abnormality and Memory Function in Epilepsy

Although temporal lobectomy is an effective alternative treatment for many patients with medication-resistant epilepsy, the risk of cognitive morbidity is not inconsequential. The ability to predict cognitive outcome is increasingly dependent on convergent information from multiple sources, including direct (e.g., Wada test) and indirect (e.g., psychometric testing) functional assessments along with magnetic resonance imaging studies that detect structural abnormalities. This brief review summarizes the relationship between imaging and function at baseline and predicting cognitive outcome following temporal lobectomy.

The relationship between quantitative T2 relaxometry and memory in nonlesional temporal lobe epilepsy

PURPOSE

We investigated the relationship between preoperative quantitative magnetic resonance imaging (MRI) T2 relaxometry and volumetry of the hippocampi and pre- and postoperative verbal memory in temporal lobectomy patients who had nonlesional temporal lobe epilepsy.

METHODS

Pre- and postoperative memory data based on the Logical Memory (LM) subtest of the Wechsler Memory Scale-Revised (WMS-R) and the 30-min delayed recall trial of the Rey Auditory Verbal Learning Test (AVLT) were obtained from 26 left and 15 right temporal lobectomy patients. Coronal MRI T2 maps were generated for these 41 temporal lobectomy patients as well as 61 control patients. Hippocampal T2 relaxation times and hippocampal volumes, converted to z scores using control group data, were correlated with neuropsychological performance in the patients.

RESULTS

In left temporal lobe-onset patients, high T2 in the left hippocampal body predicted higher LM performance after surgery. Asymmetrically high T2 in the left hippocampal body (i.e., the right-minus-left difference), compared with the right hippocampal body, also predicted higher LM performance after surgery. In right temporal lobe-onset patients, high T2 in the left hippocampal body predicted relatively lower AVLT performance after surgery. Multiple regression analysis in left temporal-onset patients revealed that high T2 in the left hippocampal body together with higher preoperative LM performance predict higher postoperative LM performance.

CONCLUSIONS

Our findings suggest that elevated (i.e., abnormal) hippocampal T2 signal is associated with memory ability (or hippocampal functional capacity) independent of MRI-determined hippocampal atrophy. Therefore, our findings support the use of quantitative T2 relaxometry as an independent predictor of verbal memory outcome in both left and right TLE patients who are candidates for temporal lobectomy.

Prediction of verbal memory loss in individuals after anterior temporal lobectomy

PURPOSE

Decreased memory function represents the area of greatest neuropsychological morbidity after anterior temporal lobectomy (ATL), particularly for left ATL candidates. We wished to identify easily derived demographic and neuropsychological predictors of risk of pre- to postoperative memory decline using only information available preoperatively.

METHODS

We assessed decline in memory as measured by the California Verbal Learning Test (CVLT) by deriving multiple regression equations using the following measures as independent variables: age at onset, chronological age at time of surgery, sex, Full Scale IQ (FSIQ), level of education, and preoperative memory scores. In all, 203 patients (93 males, 110 females), undergoing ATL (107 left, 96 right) with preoperative and 6-month postoperative testing, were examined.

RESULTS

The combination of age, FSIQ, sex, side of surgery and preoperative score was highly predictive (p-values < 0.0001) of postoperative memory scores. Higher postoperative scores were associated with higher preoperative score, younger chronological age, higher FSIQ, female sex, and right side of resection. Reliable change index (RCI) values were used to estimate meaningful decline on the total score across five trials. Logistic regression analysis showed preoperative score and age to be predictors of RCI decline for left-sided resections. Sensitivity of decline (> or =90th centile RCI) prediction was 56%, and specificity was 95%. Validation in 30 patients from a separate population of patients undergoing left ATL produced similar figures.

CONCLUSIONS

The derived regression equations can accurately predict verbal memory decline on a list-learning task in approximately 50% of individual patients undergoing ATL, and false-positive prediction errors are very rare.

Naming decline after left anterior temporal lobectomy correlates with pathological status of resected hippocampus

PURPOSE

To evaluate the determinants of postoperative change in visual confrontation naming ability and the differential sensitivity of two common tests of confrontation naming.

METHODS

In a group of 99 patients undergoing lobectomy of the left, language-dominant anterior temporal lobe, we examined naming ability using two measures: the 60 item Boston Naming Test (BNT), and the Visual Naming (VN) subtest of the Multilingual Aphasia Examination (MAE). ATL entailed resection of lateral temporal lobe followed by microsurgical complete removal of hippocampus. Language mapping was not performed. The status of the resected hippocampus was graded on a scale 0-4 of hippocampal sclerosis (HS). A dichotomous grouping HS- (grades 0 and 1, n = 34) and HS+ (grades 3 and 4, n = 61) was effected. Age at surgery, age of epilepsy onset, sex, extent of lateral temporal resection, Full-Scale IQ (FSIQ), and preoperative naming scores were also examined as potential predictors of pre- versus postoperative naming change.

RESULTS

Preoperative BNT and VN scores were significantly worse for HS+ than for HS- (BNT, p < 0.05; VN, p = 0.001). Postoperatively, BNT and VN scores significantly declined for HS- as compared with HS+ patients (p < 0.001). For individual risk, the 90th centile of reliable change index (RCI) was used. By this criterion, of the total sample, 39% evidenced decline on the BNT and 17% evidenced decline on the VN. Logistic regression analysis with backward elimination showed HS to be the only predictor of decline in BNT and HS and sex to be the only predictors of VN decline. Males were more at risk than females. Age, age at onset, extent of lateral resection, preoperative scores, and FSIQ were not predictors. Using age at onset as a proxy for HS+/HS- we calculated probabilities for naming decline for given onset age.

CONCLUSIONS

Both preoperative and postoperative change in naming ability are associated with the pathological status of the hippocampus. The potential interpretations and implications of these findings are discussed.

Functional plasticity after left anterior temporal lobectomy: reconstitution and compensation of verbal memory functions

PURPOSE

This study investigated the functional plasticity of the brain to reconstitute and compensate for verbal memory functions after epilepsy surgery of left temporocortical and temporomesial structures. We hypothesized that memory outcome would be best when surgery is performed within the period of cerebral plasticity, and that the outcome should be worst when fluid intelligence starts to decrease with physiologic aging. We also raised the question of different plasticity and compensation mechanisms for temporomesial and temporocortical memory functions.

METHODS

We evaluated preoperative and 1-year-postoperative memory data and other verbal functions in 104 patients with epilepsy, who underwent a standard left anterior temporal lobe resection. We used memory measures that had been previously shown to be most selective for mesial and lateral functions, respectively. Determinants of postoperative memory outcome were evaluated by multiple regression analysis. Group statistics were calculated on the basis of the periods that are usually assumed to be significant for plasticity and behavioral compensation. Individual postoperative changes in memory functions were evaluated on the basis of test-retest data obtained in a group of 100 nonsurgical patients with localization-related epilepsies (mean retest interval >12 months).

RESULTS

Only changes in cortically represented learning and data acquisition were related to age, plasticity, and capacities for behavioral compensation. No patient in the youngest group (younger than 15 years), 33% of patients who had surgery between the ages of 15 and 30 years, and 61% of the patients undergoing surgery older than age 30 years had significant deterioration in verbal learning. In contrast, postoperative changes in temporomesial consolidation/retrieval processes were independent of age at the time of surgery, plasticity, and capacities for behavioral compensation.

CONCLUSIONS

Our data indicate different time windows for the reconstitution and compensation of mesial and cortical aspects of memory. Whereas the reconstitution of and compensation for cortical functions appear restricted by decreasing plasticity and physiological aging, mesial functions seem to be reconstituted by contralateral mesial structures over a much longer period. Concerning drug-resistant localization-related epilepsies, our results justify early consideration of surgery, especially when cortical structures are affected.

Anterior temporal lobectomy, hippocampal sclerosis, and memory: recent neuropsychological findings

Anterior temporal lobectomy (ATL) is an effective and increasingly utilized treatment for nonlesional, intractable mesial temporal lobe epilepsy. However, this surgery results in domain-specific neuropsychological morbidity for a subset of patients. Within the past decade, multidisciplinary studies have revealed that left ATL patients without significant sclerosis in the resected hippocampus are most at risk for a substantial postacute decline in the ability to encode new verbal information. These patients are also at risk for a significant decrement in confrontation naming and other retrieval-based language abilities. The memory deficit is not attributable to this disruption of language. A relationship between hippocampal sclerosis (HS) status and memory performance has not been identified consistently in right ATL patients, but investigation of new visuospatial measures continues. The influence of variables other than HS on neuropsychological outcome is also discussed.

Recent advances in epilepsy surgery: temporal lobectomy and multiple subpial transections

THIS ARTICLE REVIEWS four major advances in epilepsy surgery, especially the most frequently performed surgery, temporal lobectomy, as follows: 1) the ability to preoperatively identify (using magnetic resonance imaging) the pathological condition of hippocampal sclerosis (a key component to the syndrome of mesial temporal lobe epilepsy, 2) the ability to identify preoperatively which temporal lobe candidates are at risk for postoperative memory problems, 3) the standardization of temporal lobectomy with respect to how much hippocampus should be resected, 4) a validation of the novel surgical technique of multiple subpial transections. This technique allows surgeons to attack foci within nondispensible cortex and therefore enlarges the applicability of surgical treatment to otherwise inoperable patients and potentially improves outcome.