Implementation of talairach atlas based automated brain segmentation for radiation therapy dosimetry.

Radiotherapy for brain cancer inevitably results in irradiation of uninvolved brain. While it has been demonstrated that irradiation of the brain can result in cognitive deficits, dose-volume relationships are not well established. There is little work correlating a particular cognitive deficit with dose received by the region of the brain responsible for the specific cognitive function. One obstacle to such studies is that identification of brain anatomy is both labor intensive and dependent on the individual performing the segmentation. Automatic segmentation has the potential to be both efficient and consistent. Brains2 is a software package developed by the University of Iowa for MRI volumetric studies. It utilizes MR images, the Talairach atlas, and an artificial neural network (ANN) to segment brain images into substructures in a standardized manner. We have developed a software package, Brains2DICOM, that converts the regions of interest identified by Brains2 into a DICOM radiotherapy structure set. The structure set can be imported into a treatment planning system for dosimetry. We demonstrated the utility of Brains2DICOM using a test case, a 34-year-old man with diffuse astrocytoma treated with three-dimensional conformal radiotherapy. Brains2 successfully applied the Talairach atlas to identify the right and left frontal, parietal, temporal, occipital, subcortical, and cerebellum regions. Brains2 was not successful in applying the ANN to identify small structures, such as the hippocampus and caudate. Further work is necessary to revise the ANN or to develop new methods for identification of small structures in the presence of disease and radiation induced changes. The segmented regions-of-interest were transferred to our commercial treatment planning system using DICOM and dose-volume histograms were constructed. This method will facilitate the acquisition of data necessary for the development of normal tissue complication probability (NTCP) models that assess the probability of cognitive complications secondary to radiotherapy for intracranial and head and neck neoplasms.

Magnetic resonance spectroscopic imaging in temporal lobe epilepsy: neuronal dysfunction or cell loss?

BACKGROUND: Magnetic resonance spectroscopy (MRS) has demonstrated consistent metabolic abnormalities in temporal lobe epilepsy. The reason for decreases in N-acetylated compounds are thought to be related to neuronal hippocampal cell loss as observed in hippocampal sclerosis. However, mounting evidence suggest that the N-acetylated compound decreases may be functional and reversible. OBJECTIVE: To establish whether the metabolic changes measured by MRS correlate to hippocampal cell loss in temporal lobe epilepsy. SUBJECTS AND METHODS: We prospectively performed quantitative hippocampal MR imaging volumetry and MRS imaging in 33 patients with intractable mesial temporal lobe epilepsy who were undergoing surgery. A neuronal-glial ratio of cornu ammonis and fascia dentata was obtained and correlated while validating the pathologic analysis by comparisons with specimens of age-matched autopsy control-case hippocampus (n = 14). RESULTS: The neuronal-glial ratio of the patient group was statistically significantly lower than in the control group for the cornu ammonis region (P<.001). Correlations of hippocampal volumes with cornu ammonis and neuronal-glial ratios revealed a significant interdependence (P<.01). However, correlations of the resected hippocampal creatine-N-acetylated compound ratio with the cornu ammonis or fascia dentata neuronal-glial ratios showed no significant interdependence (P>.8). CONCLUSIONS: Our findings support the concept that the metabolic dysfunction measured by MRS imaging and the hippocampal volume loss detected by MR imaging volumetry do not have the same neuropathologic basis. These findings suggest that the MRS imaging metabolic measures reflect neuronal and glial dysfunction rather than neuronal cell loss as previously assumed.

Assessing financial capacity in patients with Alzheimer disease: A conceptual model and prototype instrument.

OBJECTIVE: To investigate financial capacity in patients with Alzheimer disease (AD) using a new theoretical model and prototype psychometric instrument. DESIGN: Cross-sectional comparisons of older control subjects (n=23) and patients with mild (n=30) and moderate AD (n=20). MAIN OUTCOME MEASURES: Financial capacity was measured using the Financial Capacity Instrument, a prototype psychometric instrument that tests financial capacity using 14 tasks of financial ability comprising 6 clinically relevant domains of financial activity: basic monetary skills, financial conceptual knowledge, cash transactions, checkbook management, bank statement management, and financial judgment. RESULTS: The Financial Capacity Instrument tasks and domains showed adequate to excellent internal, interrater, and test-retest reliabilities. At the task level, patients with mild AD performed equivalently with controls on simple tasks such as counting coins/currency and conducting a 1-item grocery purchase, but significantly below controls on more complex tasks such as using a checkbook/register and understanding and using a bank statement. At the domain level, patients with mild AD performed significantly below controls on all domains except basic monetary skills. Patients with moderate AD performed significantly below controls and patients with mild AD on all tasks and domains. Regarding capacity status outcomes (capable, marginally capable, incapable) on domains, patients with mild AD had high proportions of marginally capable or incapable outcomes (range, 47%-87%), particularly on difficult domains like bank statement management (domain 5) and financial judgment (domain 6), but variability in individual outcomes. Patients with moderate AD had almost exclusively incapable outcomes across the 6 domains (range, 90%-100%). CONCLUSIONS: Financial capacity is already significantly impaired in mild AD. Patients with mild AD demonstrate deficits in more complex financial abilities and impairment in most financial activities. Patients with moderate AD demonstrate severe impairment of all financial abilities and activities. The Financial Capacity Instrument has promise as an instrument for assessing domain-level financial activities and task-specific financial abilities in patients with dementia. Arch Neurol. 2000.

Postictal stability of proton magnetic resonance spectroscopy imaging (1H-MRSI) ratios in temporal lobe epilepsy.

Interictal proton (1H) MRS is increasingly used for seizure lateralization in patients with temporal lobe epilepsy (TLE). Studies reporting postictal 1H-MRS metabolite changes in patients with TLE are few and contradictory. The authors prospectively performed interictal and postictal proton magnetic resonance spectroscopy imaging (1H-MRSI) studies in seven patients with TLE. The authors found no consistent changes in metabolite peak area ratios between studies, suggesting that 1H-MRS ratios remain stable between interictal and postictal state in TLE.

Patient-oriented outcome assessment after temporal lobectomy for refractory epilepsy.

OBJECTIVE: To determine patient-oriented outcome after anterior temporal lobectomy (ATL) for refractory epilepsy. BACKGROUND: Health-related quality of life (HRQOL) is an important component of the assessment of outcome from epilepsy surgery, but prior controlled studies of the effect of surgery on HRQOL are inconclusive. Direct assessment of the effect of surgery on patient concerns of living with epilepsy has not been reported. METHODS: We used reliable and valid instruments to compare HRQOL and patient concerns of 125 patients who had received an ATL more than than one year previously to a clinically similar group of 71 patients who were awaiting ATL. All patients were selected for surgery based on similar criteria. We also used bivariate correlation analysis and multivariate regression modeling to determine the association of traditional outcome variables with HRQOL. RESULTS: Patients who had undergone ATL reported significantly less concern of living with epilepsy in 16 of 20 items of the EFA Concerns Index and better HRQOL in 8 of 11 scales of the Epilepsy Surgery Inventory-55. Regression analysis in the postoperative group demonstrated that mood status, employment, driving, and antiepileptic drug (AED) cessation, but not seizure-free status or IQ, were associated with better HRQOL. CONCLUSIONS: Our findings support a positive affect of ATL on patient concerns and HRQOL in refractory temporal lobe epilepsy, although longitudinal studies are needed to corroborate these results. Mood, employment, driving ability, and AED use are important postoperative predictors of HRQOL.

Cognitive correlates of 1H MRSI-detected hippocampal abnormalities in temporal lobe epilepsy.

OBJECTIVES: To examine associations between 1H magnetic resonance spectroscopic imaging (1H MRSI)-detected hippocampal creatine to N-acetylaspartate (Cr/NAA) ratios and neuropsychological measures sensitive to mesial temporal lobe function. BACKGROUND: The measurement of 1H MRSI-detected hippocampal metabolites has proved effective in determining extent and lateralization of neuronal damage. However, relationships between 1H MRSI-detected hippocampal metabolic abnormalities and specific areas of cognitive functioning have received limited attention compared to other studies using MRI volumetry or cerebral blood flow techniques. METHODS: We analyzed right and left hippocampal Cr/NAA ratios in 46 adult mesial temporal lobe epilepsy patients (32 left, 14 right) by 1H MRSI at high magnetic field (4.1 T). We examined the relationship between the right and left Cr/NAA hippocampal ratios to measures of verbal and visual memory, intelligence, attention, visuoperception, and confrontation naming. RESULTS: Measures of episodic verbal memory (n = 33) and visual confrontation naming (n = 46) were selectively associated with left hippocampal metabolic function (p<0.004), whereas neuronal function of the right hippocampal region was strongly associated with performance on a measure of facial recognition (n = 46; p<0.02). CONCLUSIONS: This study shows that specific areas of cognitive function are related to hippocampal neuronal metabolic abnormalities as detected by spectroscopic imaging. The current study indicates that 1H MRSI offers a complimentary technique to structural imaging studies in the study of mesial temporal lobe epilepsy and may enhance understanding of the role of hippocampal function in complex cognitive systems.

Subjective versus objective memory change after temporal lobe epilepsy surgery.

OBJECTIVE: To examine subjective versus objective memory change after anterior temporal lobectomy (ATL). METHODS: A prospective, controlled study. Controls included 39 unoperated patients with intractable temporal lobe epilepsy (TLE) who were administered a series of cognitive and health-related quality of life measures at baseline and at 12-month follow-up intervals. The surgery sample included 65 patients with intractable, focal TLE who had undergone either a right or left ATL. These patients were tested preoperatively and at 6-month follow-up intervals. Subjective and objective memory change was quantified using a newly developed methodology to control for practice effect and regression to the mean. RESULTS: Measures of subjective and objective memory change were not significantly related in the surgery sample. Prevalence of significant subjective memory decline 1 year after surgery ranged from 3 to 7%, whereas prevalence of significant objective memory decline ranged from 26 to 55%. Postoperative levels of emotional distress significantly predicted self-reported memory decline 1 year after ATL. Postoperative medication side effect and seizure outcome were also related significantly to subjective memory change in patients who had undergone left ATL. CONCLUSIONS: Subjective and objective memory change after temporal lobectomy are not related. Complaints of significant memory decline after ATL are infrequent and may serve as a marker for depression or other mood disorder rather than organically based memory decline.

In vivo hippocampal glucose metabolism in mesial temporal lobe epilepsy.

BACKGROUND: The appearance of decreased 2-[(18)F]fluoro-2-deoxy-D-glucose (FDG) uptake in the mesial temporal region in temporal lobe epilepsy may simply reflect loss of gray matter due to hippocampal atrophy. Increased partial volume effects due to atrophic hippocampi may further increase appearance of hypometabolism. METHODS: The authors used a combination of MRI-PET coregistration, with MRI-based gray matter segmentation, and partial volume correction to improve the examination of hippocampal specific glucose uptake in FDG PET. The goal was to determine 1) if relative mesial temporal hypometabolism is an artifact of gray matter (hippocampal) atrophy, 2) whether hippocampal metabolism correlates with atrophy evaluated on MRI, and 3) if MRI-based partial volume correction influences measurement of hippocampal metabolic-volume relationships, including epilepsy lateralization. RESULTS: Findings showed that ipsilateral hippocampi of mesial temporal lobe epilepsy (MTLE) are relatively hypometabolic per unit of gray matter volume, and that hippocampal metabolism directly correlates with hippocampal volume. Specifically, partial volume corrected hippocampal metabolism correlated strongly (r = 0.613, p < 0.001) with hippocampal volume. Without partial volume correction, a weaker, but still significant, correlation was present (r = 0.482, p < 0.001). Degree of asymmetry was consistently greater and provided higher sensitivity of lateralization with partial volume vs non-partial volume corrected metabolic measurements. CONCLUSIONS: Although, decreased metabolism may occur in the absence of neuronal cell loss, hippocampal atrophy and presumed degree of neuronal cell loss appears to be a primary factor involved in the cause of decreased metabolism in epileptogenic hippocampi. Partial volume correction is recommended for optimal interpretation of hippocampal structure and function relationships.

Bilateral hippocampal atrophy: consequences to verbal memory following temporal lobectomy.

BACKGROUND: Bilateral hippocampal damage is a risk factor for memory decline after anterior temporal lobectomy (ATL). OBJECTIVE: To investigate verbal memory outcome in patients with temporal lobe epilepsy (TLE) with either unilateral or bilateral hippocampal atrophy as measured by MRI. METHODS: The authors selected 60 patients with TLE who had undergone ATL (left = 31, right = 29). They determined normalized MRI hippocampal volumes by cursor tracing 1.5-mm slices from three-dimensional MRI acquisition. Hippocampal volumes were defined as atrophic if the volumes were below 2 SD for control subjects. Bilateral hippocampal atrophy was present in 10 patients with left TLE and 11 patients with right TLE. The authors assessed acquisition, retrieval, and recognition components of verbal memory both before and after ATL. RESULTS: Groups did not differ across age, education, intelligence, age at seizure onset, or seizure duration. Seizure-free rates after ATL were 70% or higher for all groups. Before surgery, patients with left TLE displayed worse verbal acquisition performance compared with patients with right TLE. Patients with left TLE with bilateral hippocampal volume loss displayed the lowest performance across all three memory components. After surgery, both groups of patients with left TLE exhibited worse verbal memory outcome compared with patients with right TLE. Bilateral hippocampal atrophy did not worsen outcome in the patients with right TLE. A higher proportion of patients with left TLE with bilateral hippocampal atrophy experienced memory decline compared with the other TLE groups. CONCLUSION: Bilateral hippocampal atrophy in the presence of left TLE is associated with worse verbal memory before and after ATL compared with patients with unilateral hippocampal volume loss or right TLE with bilateral hippocampal volume loss.

Investigation of executive function change following anterior temporal lobectomy: selective normalization of verbal fluency.

The nociferous cortex hypothesis predicts that electrophysiological normalization to distal extratemporal brain regions following anterior temporal lobectomy (ATL) will result in improvements in executive functioning. The present study examined the effects of seizure laterality and seizure control on executive function change. The authors administered the Wisconsin Card Sorting Test (WCST), Trails B, and the Controlled Oral Word Association Test to 174 temporal lobe epilepsy patients who underwent ATL. No significant changes were found on the WCST or Trails B tests, regardless of surgery side or seizure-free status. However, verbal fluency significantly improved in seizure-free patients. Findings were consistent with the nociferous cortex hypothesis suggesting selective executive function improvement following ATL. These findings are discussed in terms of recent research demonstrating extrahippocampal metabolic normalization following surgery.

Chronic temporal lobe epilepsy: spatial extent and degree of metabolic dysfunction studied with magnetic resonance spectroscopy (MRS).

INTRODUCTION: Proton magnetic resonance spectroscopy ((1)H MRS) has been proposed as a lateralizing method for the presurgical evaluation of patients with medically intractable temporal lobe epilepsy (TLE). Studies have shown correlations between temporal lobe (TL) NAA and seizure frequency, and TL NAA/Cr and the duration of epilepsy in patients with TLE. This latter finding may suggest that progressive neuronal dysfunction may occur in both temporal lobes in patients with TLE, even when the seizures originate in only one temporal lobe. We analyzed our data in an attempt to find a possible correlation between extension of neuronal dysfunction based on NAA measures and duration of epilepsy. METHODS: We studied 45 consecutive patients with the diagnosis of TLE, who were referred for presurgical evaluation. Duration of epilepsy was defined as the interval between the age of seizure onset and the time of the MRS examination. All studies were performed in the inter-ictal state, prior to intracranial monitoring or resection. We performed two-tailed Pearson correlation analysis between ipsilateral NAA/Cr and extension of the abnormality (voxels involved) and the duration of the seizure disorder in years. RESULTS: The average duration of epilepsy in this group was 20 years. No significant correlation was found between duration of epilepsy and mean hippocampal NAA/Cr (r=-.131, p=.390); nor was a correlation found between duration of epilepsy in years or the extent of metabolic lesion (voxels involved) (r=-.264, p=.079). CONCLUSIONS: Hippocampal NAA/Cr does not correlate with duration of epilepsy in TLE. Our findings suggest that cross-sectional group measures of hippocampal neuronal function do not suggest damage progression.

Reproducibility of proton magnetic resonance spectroscopy imaging measurements of normal human hippocampus at 1.5 T: clinical implications.

The authors investigate the reproducibility of metabolite signals measured with proton magnetic resonance spectroscopy (1H-MRS) acquired from the human hippocampus in controls and in a phantom. Two 1H-MRS studies separated by 3 weeks were performed in 8 healthy volunteers and in a phantom. N-acetyl compounds (NA), choline (Ch), and creatine (Cr) peak areas and ratios were measured and compared using percentage variation, and Pearson Correlation Coefficient at the level of every voxel, the level of 1 hippocampus (5 voxels), and the level of 2 hippocampi (10 voxels). Sensitivity for observing clinically significant between-session 1H-MRS changes was evaluated using the reliable change index. Reproducibility measures for metabolite peak areas were only moderately concordant with percentage variation ranging from 14% to 20% for NA, Cho, and Cr. Stability was much improved when NA ratios and sum of multiple voxels were considered. Between-session NA/(Cho + Cr) changes greater than 22%, 12%, and 10% in one given participant can be detected with a 90% confidence interval when considered at the single-voxel level, the level of a single hippocampus, or the level of both hippocampi, respectively. Left-right asymmetry indices showed similar and limited inter-hemispheric asymmetry in repeated examination. This study suggests that 1H-MRS reproducibility performance is adequate for the study and monitoring of human hippocampus function when NA ratios and the sum of multiple voxels are considered. Individual metabolite peaks and single-voxel measurements have low reproducibility at 1.5 T and should be used only with clearly established statistical parameters.

A method for assessing clinically relevant individual cognitive change in older adult populations.

The evaluation of individual cognitive change has relied heavily upon the raw change score, defined simply as the difference between follow-up and baseline scores. However, raw changes scores are susceptible to the confounding effects of both regression-to-the-mean and practice effect. The clinical relevance of raw change scores for the older adult is also obscured by normal, age-related cognitive change. The present study illustrates the use of a standardized regression-based (SRB) methodology to generate an alternative to the raw change score; the SRB change score. SRB change scores provide a standardized alternative to the raw change score, allowing the clinician to evaluate the magnitude of change on one or more variables along a common metric that controls for practice effect, regression-to-the-mean, and normal cognitive decline. Case data illustrate how SRB change scores can identify clinically relevant cognitive change in the individual older adult patient.

Hippocampal 1H-MRSI correlates with severity of depression symptoms in temporal lobe epilepsy.

OBJECTIVE: To investigate the association of an indicator of hippocampal function with severity of depression symptoms in temporal lobe epilepsy. METHODS: We evaluated 31 patients with video/EEG-confirmed temporal lobe epilepsy using creatine/N-acetylaspartate ratio maps derived from a previously validated (1)H magnetic resonance spectroscopic imaging ((1)H-MRSI) technique at 4.1 T. We also assessed depression symptoms, epilepsy-related factors, and self-perceived social and vocational disability. We used conservative nonparametric bivariate procedures to determine the correlation of severity of depression symptoms with imaging and clinical variables. RESULTS: The extent of hippocampal (1)H-MRSI abnormalities correlated with severity of depression (Spearman rho = 0.65, p value < 0.001), but other clinical factors did not. CONCLUSION: The extent of hippocampal dysfunction is associated with depression symptoms in temporal lobe epilepsy and may be a more important factor than seizure frequency or degree of disability.

Empirical methods for assessing meaningful neuropsychological change following epilepsy surgery.

Traditional methods for assessing the neurocognitive effects of epilepsy surgery are confounded by practice effects, test-retest reliability issues, and regression to the mean. This study employs 2 methods for assessing individual change that allow direct comparison of changes across both individuals and test measures. Fifty-one medically intractable epilepsy patients completed a comprehensive neuropsychological battery twice, approximately 8 months apart, prior to any invasive monitoring or surgical intervention. First, a Reliable Change (RC) index score was computed for each test score to take into account the reliability of that measure, and a cutoff score was empirically derived to establish the limits of statistically reliable change. These indices were subsequently adjusted for expected practice effects. The second approach used a regression technique to establish "change norms" along a common metric that models both expected practice effects and regression to the mean. The RC index scores provide the clinician with a statistical means of determining whether a patient's retest performance is "significantly" changed from baseline. The regression norms for change allow the clinician to evaluate the magnitude of a given patient's change on 1 or more variables along a common metric that takes into account the reliability and stability of each test measure. Case data illustrate how these methods provide an empirically grounded means for evaluating neurocognitive outcomes following medical interventions such as epilepsy surgery.

Relationships among hippocampal volumetry, proton magnetic resonance spectroscopy, and verbal memory in temporal lobe epilepsy.

PURPOSE: To examine the relationship between hippocampal volumes, 1H magnetic resonance spectroscopy (MRS)-identified hippocampal metabolic function, and verbal memory in patients with unilateral mesial temporal lobe epilepsy (MTLE). METHODS: Hippocampal volumes, 1H MRS-derived hippocampal creatine to N-acetylaspartate (Cr/NAA), and verbal memory assessment were obtained preoperatively in 22 patients (six right, 16 left) with EEG-defined unilateral MTLE. RESULTS: Left hippocampal volume correlated significantly with left hippocampal Cr/NAA (r=-0.549, p < 0.01), whereas right volume correlated significantly with right Cr/NAA (r=-0.478, p < 0.05). Verbal memory correlated significantly with left hippocampal Cr/NAA (r=-0.594, p < 0.01), but not with left hippocampal volume or right hippocampal measures. CONCLUSIONS: Hippocampal volumes and 1H MRS-derived metabolite ratios are statistically related, but share only a small percentage of variance, suggesting separate but related pathophysiologic processes. Left hippocampal Cr/NAA appears to be more sensitive to verbal memory function than volumes.

Verbal retention lateralizes patients with unilateral temporal lobe epilepsy and bilateral hippocampal atrophy.

PURPOSE: To examine the lateralization utility of preoperative verbal retention in patients with and without bilateral hippocampal atrophy. METHODS: The sample consisted of 74 patients with EEG-defined unilateral temporal lobe epilepsy (TLE) who had also undergone volumetric magnetic resonance imaging (MRI). Verbal retention was operationalized by the Logical Memory percentage retention subtest (LM%) of the Wechsler Memory Scale. Patients were divided into groups with (a) bilaterally normal hippocampal volumes, (b) unilateral atrophy, or (c) bilateral atrophy. Two different thresholds (empirically derived vs. normative) were used to lateralize on the basis of LM%. LM% lateralization was then examined by group using chi2, sensitivity, positive predictive values, and odds ratios. Analyses were also conducted separately in the subset of patients who were seizure free after surgery. RESULTS: Mean LM% performance was significantly lower in patients with left versus right TLE in the subset with bilateral hippocampal atrophy (p = 0.018), but not in patients with a normal MRI (p = 0.918) or unilateral atrophy (p = 0.087). The odds of a correct lateralization by LM% increased from 1.67 in patients with normal MRI to 36.11 in patients with bilateral hippocampal atrophy. The power of a right and left lateralization prediction by LM% was 100% and 75%, respectively, in patients with bilateral hippocampal atrophy. Similar results were obtained when analysis was restricted to patients who were seizure free after surgery. CONCLUSIONS: Preoperative verbal retention as measured by LM% may provide meaningful lateralization information in patients who are difficult to lateralize via MRI.

Correlation of scalp EEG and 1H-MRS metabolic abnormalities in temporal lobe epilepsy.

PURPOSE: To correlate the interictal spike field and region of seizure onset with the distribution of 1H-MRS abnormalities in temporal lobe epilepsy (TLE) and improve our understanding of the clinical significance of 1H-MRS abnormalities. METHODS: Scalp electroencephalogram (EEG) monitoring and proton magnetic resonance spectroscopy (1H-MRS) results were correlated in 31 consecutive patients with TLE. RESULTS: Lateralized 1H-MRS-based hippocampal abnormalities were recorded in 95% of the patients with unilateral interictal spikes, with a high degree of concordance for the lateralization side (90%). In 64% of the patients with normal or bilateral interictal EEG spikes, 1H-MRS provided lateralizing information. Bilateral 1H-MRS abnormalities, with or without lateralization, were 3 times more frequent than bitemporal EEG spikes. Anterior predominance of the 1H-MRS abnormalities was more frequent in patients with anterior temporal EEG spiking (50%), than in patients without this EEG distribution (18%). Similar association was noted between distribution of 1H-MRS abnormalities and region of EEG seizure onset. CONCLUSIONS: Our results show a moderate level of concordance between the distribution of 1H-MRS and EEG abnormalities. 1H-MRS identifies abnormalities contralateral to the predominant seizure focus more often than does EEG and may provide lateralizing information in patients with nonlateralizing interictal EEG.

Contribution of neuropsychological data to the prediction of temporal lobe epilepsy surgery outcome.

PURPOSE: We empirically examined the contribution of neuropsychological data to the prediction of postoperative seizure control relative to base rate information in an existing series of patients undergoing anterior temporal lobectomy (ATL). METHODS: A discriminant function predicting surgery outcome (seizure-free vs. non-seizure-free) was computed separately for samples of patients with left (n = 79) and right (n = 62) temporal lobectomy (LATL, RATL). Predictor variables included 14 measures tapping five neurocognitive domains. The predicted base rates were compared with the actual base rates in the two samples. Finally, overall predictive accuracy was examined in optimal versus suboptimal ATL patients. RESULTS: The base rate of seizure freedom in the LATL group was 74.70%; that in the RATL group was 66.10%. The predictive function for the LATL group achieved a hit rate of 80.00% and a positive predictive power of 92.11%. The function for the RATL group achieved a hit rate of 83.33% and a positive predictive power (PPP) of 89.66%. The overall predictive accuracy for the optimal group was only 55%, but that in the suboptimal group was 72%. CONCLUSIONS: Neuropsychological data used in a multivariate statistical fashion may be able to offer an incremental increase in the prediction of postoperative seizure freedom relative to existing base rates of surgery success in patients with ATL epilepsy. The use of neuropsychological data may be of greatest predictive value in a population of ATL candidates with suboptimal findings with a lower base rate of postoperative seizure freedom, but may actually reduce predictive accuracy in a group of ATL candidates from an optimal population with an already high base rate of surgical success.

Occipitoparietal epilepsy, hippocampal atrophy, and congenital developmental abnormalities.

PURPOSE: Diagnostic uncertainty may arise in patients with occipitoparietal epilepsy when there is neuroimaging evidence of a posterior quadrant lesion and coexistent hippocampal abnormalities ("dual pathology"). It is not known whether hippocampal atrophy (HA) in these patients results from seizure propagation to temporolimbic structures or whether it is part of the pathological process underlying the occipitoparietal epilepsy. Clarification of this issue may have a significant bearing on the management of these patients. METHODS: We studied 20 patients with occipitoparietal epilepsy and neuroimaging or pathologic evidence of a congenital developmental abnormality. Normalized hippocampal volumes were obtained in all patients. The medical records and video-EEG recordings were analyzed to correlate the MRI findings with clinical data, seizure semiology, and EEG findings. RESULTS: HA was found in seven patients (35%). Neuroimaging abnormalities concordant with the side of HA were seen in all cases. There was clinical or EEG evidence of temporal spread in 12 patients. There was no correlation between the presence of HA and temporal lobe spread. The only clinical factor associated with HA in this series was a younger age of seizure onset. CONCLUSIONS: HA in patients with occipitoparietal epilepsy due to congenital developmental abnormalities is most likely to be a marker of a more widespread process related to a common pathogenesis during prenatal or perinatal development. HA in these patients is unlikely to be the result of secondary spread from an extrahippocampal focus. Surgical treatment should be tailored toward the primary epileptogenic zone rather the site of seizure spread.