PubMed Health⌕ Search

Biomedical subjects

G J Chelune

Publications and source records attributed to G J Chelune.

At least 19 recordsLinked to original sources
PubMed2001

WMS-III performance in patients with temporal lobe epilepsy: group differences and individual classification.

The utility of the WMS-III in detecting lateralized impairment was examined in a large sample of patients with temporal lobe epilepsy. Methods of analysis included evaluation of group means on the various indexes and subtest scores, the use of ROC curves, and an examination of Auditory-Visual Index discrepancy scores. In addition, performance on immediate and delayed indexes in the auditory and the visual modality was compared within each group. Of the WMS-III scores, the Auditory-Visual Delayed Index difference score appeared most sensitive to side of temporal dysfunction, although patient classification rates were not within an acceptable range to have clinical utility. The ability to predict laterality based on statistically significant index score differences was particularly weak for those with left temporal dysfunction. The use of unusually large discrepancies led to improved prediction, however, the rarity of such scores in this population limits their usefulness. Although the utility of the WMS-III in detecting laterality may be limited in preoperative cases, the WMS-III may still hold considerable promise as a measure of memory in documenting baseline performance and in detecting those that may be at risk following surgery.

Adult↗
PubMed2000

Comparability of the expanded WMS-III standardization protocol to the published WMS-III among right and left temporal lobectomy patients.

We examined whether differences between the expanded standardization protocol (SP) used to derive norms for the final published version (PB) of the Wechsler Memory Scale - Third Edition (WMS-III; Wechsler, 1997a) would result in differences on the Primary Indexes in a neurologic sample. Specifically, we examined the comparability of the performances of 63 patients with temporal lobectomy (TL) who were administered either the expanded SP protocol (n = 33: 22 left TL and 11 right TL) or the PB battery (n = 30: 11 left TL and 19 right TL). Patients who were administered the SP or PB were comparable in terms of age, sex, education, seizure duration, postsurgical seizure status, and Full Scale IQ. Postoperative intervals were significantly longer for the SP group, although correlational analyses demonstrated no significant relationship between postoperative follow-up interval and WMS-III performance. A series of t tests revealed no significant differences on any of the eight Primary Index scores between patients taking the two versions of the WMS-III for either left or right TL groups. Furthermore, repeated measures analyses of variance failed to show significant differences on modality-specific memory scores between the SP and PB for the left and right TL groups. The current study indicates that temporal lobectomy patients obtained comparable scores on the two versions of the WMS-III.

Adult↗
PubMed2000

Temporal lobectomy in children: cognitive outcome.

OBJECT: The authors sought to determine the impact of early temporal lobectomy (in patients younger than age 17 years) on intellectual functioning. The efficacy of temporal lobectomy for treating seizures is well established and the procedure is becoming more acceptable as a treatment for children whose seizures are intractable. However, cognitive outcomes of temporal lobectomy in children and adolescents are largely unreported. The present study takes advantage of a unique multicenter collaboration to examine retrospectively intellectual functioning in a large sample of children who underwent temporal lobectomy. METHODS: Intellectual functioning was assessed before and after temporal lobectomy for treatment of medication-resistant seizures in 82 patients at eight centers of epilepsy surgery. All children underwent standard presurgical examinations, including electroencephalography-video monitoring, magnetic resonance (MR) imaging, and neuropsychological testing, at their respective centers. Forty-three children underwent left temporal lobectomy and 39 underwent right temporal lobectomy. For the entire sample, there were no significant declines in intelligence quotient (IQ) following surgery. Children who underwent left temporal lobectomy demonstrated no significant loss in verbal intellectual functioning and improved significantly in nonverbal intellectual functioning. Children who underwent right temporal lobectomy did not demonstrate significant changes in intellectual functioning. Although group scores showed no change in overall IQ values, an analysis of individual changes revealed that approximately 10% of the sample experienced a significant decline and 9% experienced significant improvement in verbal functioning. Significant improvement in nonverbal cognitive function was observed in 16% of the sample and only 2% of the sample showed significant declines. Risk factors for significant decline included older patient age at the time of surgery and the presence of a structural lesion other than mesial temporal sclerosis on MR imaging. CONCLUSIONS: The present study provides preliminary data for establishing the risk of cognitive morbidity posed by temporal lobectomy performed during childhood. With respect to global intellectual functioning, a slight improvement was significantly more likely to occur than a decline. However, there were several patients in whom significant declines did occur. It will be necessary to study further the factors associated with such declines. In addition, further study of more specific cognitive functions, particularly memory, is needed.

Adolescent↗
PubMed1999

Effects of anomalous language representation on neuropsychological performance in temporal lobe epilepsy.

OBJECTIVE: To examine the effects of anomalous language representation (i.e., mixed- and right-cerebral dominant) on neuropsychological performance. BACKGROUND: Right cerebral language dominance resulting from early cerebral injury is associated with relatively preserved language function with decreased visuospatial ability. However, previous reports of this phenomenon have examined patients with relatively large cerebral injuries (e.g., infantile hemiplegia) or limited sample sizes. METHODS: A total of 561 patients with complex partial seizures of left temporal lobe origin were studied. Patients were classified into left (n = 455), bilateral (n = 58), and right (n = 48) language dominant groups based on Wada testing. RESULTS: Right language dominant patients performed more poorly on multiple tests of visuospatial function, including Performance IQ (PIQ), than did left language patients. No significant group differences were detected for measures of language or general verbal function. The effects of bilateral language on PIQ differed according to handedness. Lowered PIQ was present in the bilateral nondextral group but not for bilateral dextral patients, and this pattern was observed with other visuospatial measures. CONCLUSIONS: In patients with relatively small lesions restricted to the left mesial temporal lobe, a shift in language dominance to the right hemisphere is associated with decreased visuospatial functions but preserved verbal abilities. Nondextral patients with bilateral language representation also displayed decreased visuospatial performance, although dextral patients with bilateral language did not.

Adult↗
PubMed1999

Visual confrontation naming following left anterior temporal lobectomy: a comparison of surgical approaches.

Change in visual confrontation naming was examined following left (speech dominant) anterior temporal lobectomy (ATL) as a function of surgical technique and patient characteristics. Two hundred seventeen patients with intractable left temporal lobe epilepsy were selected according to standard criteria across 8 centers, and combined into 4 surgical approaches to ATL: (a) tailored resections with intraoperative mapping of eloquent cortex, (b) tailored resections with extraoperative mapping, (c) standard resections with sparing of superior temporal gyrus, and (d) standard resections including excision of superior temporal gyrus. Changes in visual confrontation naming were examined with an index of reliable change derived from an independent sample of 90 nonsurgical patients with complex partial seizures. Results showed significant decline in visual confrontation naming following left ATL, regardless of surgical technique. Across surgical approaches, the risk for decline in visual confrontation naming was associated with a later age of seizure onset and more extensive resection of lateral temporal neocortex.

Adult↗
PubMed1998

Does presurgical IQ predict seizure outcome after temporal lobectomy? Evidence from the Bozeman Epilepsy Consortium.

PURPOSE: Considerable debate exists concerning whether the presence of low preoperative IQ should be a contraindication for focal resective epilepsy surgery. METHODS: We examined the relationship between baseline IQ scores and seizure outcome in 1,034 temporal lobectomy cases from eight epilepsy surgery centers participating in the Bozeman Epilepsy Consortium. RESULTS: Those patients who continued to have seizures following surgery had statistically lower preoperative IQ scores than those who were seizure-free (p < 0.009), but only by 2.3 points. This small but statistically significant relationship was fairly robust; it was observed across seven of the eight centers, and indicates that the findings can be generalized. Among patients with IQ scores of < or = 75, 32.8% continued to have seizures following surgery, whereas 23.8% and 16.9% were not seizure-free when IQ scores were between 76 and 109 and > or = 110, respectively. Relative risk analyses revealed no significant increase in risk among patients with low IQ scores who had no structural lesions other than mesial temporal sclerosis. However, patients with IQ scores of < or = 75 had nearly a fourfold (390%) increase in risk for continued seizures as compared with those with higher IQ scores if structural lesions were present. CONCLUSIONS: While our results suggest that preoperative IQ scores alone are not good predictors of seizure outcome and should not be used to exclude patients as potential surgical candidates. IQ scores can be useful for counseling patients and their families concerning the relative risks of surgery.

Comorbidity↗
PubMed1997

Individual patient prediction of seizure lateralization in temporal lobe epilepsy: a comparison between neuropsychological memory measures and the Intracarotid Amobarbital Procedure.

Neuropsychological assessment has been extensively used in the presurgical evaluation of temporal lobe epilepsy (TLE) patients to assist in determining lateralization of seizure onset. Very few studies have examined the accuracy with which commonly used neuropsychological instruments provide this information in the individual patient. In 81 patients (49 right-, 32 left-TLE) without space-occupying lesions in whom correct seizure lateralization was inferred on the basis of postsurgical seizure-free status, we compared the frequency with which discrepancies between the Wechsler Memory Scale-Revised (WMS-R; Wechsler, 1987) Verbal and Visual Memory Indices, Warrington Recognition Memory Test (WRMT; Warrington, 1984) Words and Faces scaled scores, and Intracarotid Amobarbital Procedure (IAP) hemispheric memory scores correctly predicted seizure lateralization in the individual patient. Using both clinical analysis and discriminant function analyses (DFA), the IAP was found to be a clearly superior predictor of seizure laterality to the neuropsychological measures, whether used individually or in combination with one another. Using clinical analysis the WRMT was found to be a superior predictor to the WMS-R, which frequently gave false lateralizing information. Using all 3 measures in combination with one another, 87.1% of patients were correctly lateralized using DFA. Correctly lateralized patients were older and had longer durations of seizure disorder.

Adolescent↗
PubMed1997

Differential rates of age of seizure onset between sexes and between hemispheres?

In a descriptive analysis of 158 patients with temporal lobe epilepsy, Taylor (1969) reported that the age of first seizure varied systematically as a function of laterality and sex. We conducted inferential analyses of Taylor's original data which (1) provided support for his proposal of disproportionate left hemisphere vulnerability to seizure onset in early life, but (2) failed to provide evidence of sex differences in age of onset of unilateral seizures. Examination of these effects in a larger sample of 844 patients drawn from the Bozeman Epilepsy Consortium provided some additional support for findings from the inferential analysis. Specifically, the left hemisphere appeared more vulnerable to seizure onset in childhood, this increased vulnerability extending to about age 5 years. Age of onset of seizures was not different when males and females were compared. Thus, reanalysis of Taylor's original data as well as examination of data from a larger, more contemporary sample suggest that seizure onset varies as a function of laterality, but not sex.

Adult↗
PubMed1997

The use of figural reproduction tests as measures of nonverbal memory in epilepsy surgery candidates.

The construct of nonverbal memory, as assessed by figural reproduction tests, has recently been questioned by a number of investigators. The purpose of this study was to reexamine this construct and its relationship to right temporal lobe dysfunction. Figural reproduction test scores were examined in 757 epilepsy surgery candidates obtained from 8 epilepsy centers participating in the Bozeman Epilepsy Consortium. All participants exhibited unequivocal evidence of left (LTL) or right (RTL) temporal lobe epilepsy observed in ictal and interictal EEG recordings. All subjects also had IQ scores exceeding 70, right-hand preference, and left hemisphere language dominance confirmed by intracarotid sodium amytal testing. Comparisons of LTL and RTL groups showed no significant differences in scores on the Visual Reproduction subtests from the Wechsler Memory Scale (WMS) or Wechsler Memory Scale-Revised (WMS-R) or on the copy and delayed recall conditions of the Rey-Osterrieth Complex Figure Test (ROCFT). Significant differences were observed among centers on WMS and ROCFT scores, which are likely to be a result of variations in administration and/or scoring procedures. The lack of significant differences between LTL and RTL groups in this large sample raise questions about the nature of nonverbal memory and its relationship to right temporal lobe dysfunction.

Adult↗
PubMed1996

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.

Adult↗
PubMed1996

Discriminability of the Wisconsin Card Sorting Test using the standardization sample.

The four neurological patient groups and the normals from the Wisconsin Card Sorting Test (WCST) standardization sample were used to examine the discriminability of the WCST's indices. Results reveal consistent differentiation of normals from the patient groups on all WCST variables, with classification rates averaging 71% accuracy. However, patient groups with frontal, diffuse, and nonfrontal lesions were not consistently discriminable from each other. The results suggest that the WCST is most usefully conceptualized as a measure of executive abilities that involves the frontal lobes, but should not be considered solely as a marker of isolated frontal lobe pathology.

Adult↗
PubMed1995

Objective criteria for reporting language dominance by intracarotid amobarbital procedure.

We propose a standardized method for reporting language lateralization by intracarotid amobarbital procedure (IAP). We retrospectively reviewed 165 IAPs, and classified language lateralization as left, right, or bilateral by three different methods, all based on the duration of speech arrest following each injection: absolute duration, side-to-side difference, and a "laterality index" defined as (L-R/L+R). Cutoff values were obtained by studying a pure subgroup of left hemisphere dominant right-handed subjects. In 142 patients (86%), the classification remained unchanged among all three methods: left in 112 (79%), right in 19 (13%), and bilateral in 11 (8%). In the other 23 patients (14%), language classification varied among the three criteria used. The change of category was never between left and right, and always involved bilateral language. Thus, this index may be helpful in standardizing and comparing IAP results from different series.

Adolescent↗
PubMed1995

Intracarotid amobarbital procedure as a predictor of material-specific memory change after anterior temporal lobectomy.

Memory testing during the intracarotid amobarbital procedure (IAP) is used extensively to identify temporal lobe surgery candidates "at risk" for developing severe postoperative anterograde amnesia. However, the utility of the IAP in predicting commonly observed material-specific memory deficits has not been thoroughly investigated. We examined the utility of contralateral IAP memory testing, as an index of the functional capacity of the surgical temporal lobe, to predict postoperative material-specific memory changes on the Wechsler Memory Scale-Revised (WMS-R) in patients with left hemisphere speech dominance undergoing left (n = 32) and right (n = 31) temporal lobectomy (TL). Left TL patients who "passed" contralateral IAP memory testing (> or = 68% recognition of memory items) had significantly greater verbal memory decrements than those who "failed" the IAP, presumably as a result of removal of functional tissue. A similar relationship between contralateral IAP performance and visual memory performance was not observed among right TL patients. Thus, the functional adequacy of the tissue to be resected appears to be inversely related to postoperative verbal memory decrement, at least among left TL patients. This relationship is consistent with results of recent studies demonstrating an inverse relationship between verbal memory decrements after left TL and preoperative neuropsychological verbal memory performance, magnetic resonance imaging (MRI) hippocampal volumes, and degree of mesiotemporal sclerosis (MTS).

Adolescent↗
PubMed1995

Hippocampal adequacy versus functional reserve: predicting memory functions following temporal lobectomy.

While decrements in memory following temporal lobectomy for intractable epilepsy remain a major neurocognitive complication of surgical intervention, it has been difficult to identify patients who are most at risk for developing decrements in their memory functions following surgery. Two different models of hippocampal functioning have been posited to account for postsurgical memory losses: hippocampal reserve versus functional adequacy. This article briefly examines the basis of the traditional model of hippocampal reserve, which suggests that it is the reserve or capacity of the contralateral hippocampus to support memory after surgery that determines whether changes in memory function will be observed. A more in-depth review of emerging data from studies of function (baseline neuropsychological testing and intracarotid amytal procedure) and structure (histologic cell densities and MRI volumetrics) supporting a functional adequacy model of hippocampal functioning is then presented. Data from these latter studies provide strong convergent support for the view that the risk for memory decrements following mesial temporal lobe epilepsy surgery is inversely related to the functional adequacy of the tissue to be resected. Data reviewed here have broad implications for the field of neuropsychology. Not only do the data reported in this article challenge some of the basic tenets of our understanding of the role of the hippocampus in memory functioning, but they illustrate the importance of ongoing research, critical reevaluation of basic concepts, and the importance of self-scrutiny in light of new technologies.

Journal Article↗
PubMed1993

Comprehension deficits elicited by electrical stimulation of Broca's area.

We report on three patients with intractable focal seizures arising from the language-dominant left hemisphere. In the work-up prior to surgical treatment, arrays of subdural electrodes were placed over the left temporal lobe and adjacent supra-Sylvian region. Electrical stimulation of the inferior frontal cortex language region ('Broca's area') produced marked interference with language output functions including speech arrest, slowing of oral reading, paraphasia and anomia. At some cortical language sites in this region cortical stimulation also produced language comprehension deficits, particularly in response to more complex auditory verbal instructions and visual semantic material. The severe impairment of comprehension verbal information was in clear contrast with ability to process non-verbal material, which was not affected.

Adolescent↗
PubMed1993

Detection of changes in material-specific memory following temporal lobectomy using the Wechsler Memory Scale-Revised.

To determine the utility of the Wechsler Memory Scale-Revised (WMS-R) in measuring material-specific memory changes, within-subject comparisons of the Verbal-Visual Memory Index discrepancy and discrepancy scores using short-term and delayed Logical Memory and Visual Reproduction subtests from the WMS-R were studied prior to and following temporal lobectomy among 30 patients with left temporal lobectomy, 30 with right temporal lobectomy, and 50 epileptic, non-surgical controls. The groups were matched on age, sex, handedness, age at seizure onset, duration of epilepsy, and presurgical Verbal and Performance IQ; the right temporal group had a higher mean educational level (p <.05). All surgical patients were left hemisphere dominant for speech; those who had persistent postoperative seizures were excluded from study. On retesting, left temporal lobectomy was associated with a marked change in short-term and delayed memory discrepancy scores primarily due to a drop in verbal memory. Right temporal lobectomy was not associated with a drop in visual memory, suggesting that the WMS-R appears to reflect decrements in material-specific memory following left but not right temporal lobectomy. The nonsurgical controls showed increases in both short-term and delayed memory discrepancy scores due to increases in short-term and delayed verbal memory. Relative to these controls, the absence of comparable increases in verbal memory among the right temporal patients suggests that right temporal lobectomy may be associated with risk to verbal memory.

Journal Article↗
PubMed1991

Prediction of cognitive change as a function of preoperative ability status among temporal lobectomy patients seen at 6-month follow-up.

The relationship between preoperative ability levels and postoperative changes in cognitive function was examined among 23 left (LTL) and 19 right (RTL) temporal lobectomy patients using a battery of memory, language, and visuospatial tasks administered approximately 3 months before surgery and at 6 months follow-up. Higher preoperative performances on the memory and language measures were associated with larger decrements in postsurgical scores among the LTL patients. The RTL group showed no consistent relationship between preoperative ability levels and subsequent postsurgical cognitive changes. Based on the present data, we constructed base-rate tables for the Wechsler Memory Scale-Revised indicating the likelihood of measurable gains or losses in memory as a function of presurgical ability level for patients undergoing LTL. While tentative, these data provide a useful and practical guide for counseling prospective epilepsy patients of the attendant cognitive risks of LTL.

Analysis of Variance↗