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Biomedical subjects

E D Bigler

Publications and source records attributed to E D Bigler.

At least 19 recordsLinked to original sources
PubMed1992

Degenerative changes in traumatic brain injury: post-injury magnetic resonance identified ventricular expansion compared to pre-injury levels.

Magnetic resonance (MR) scans obtained 42 days and 10 months post-injury were compared to scans obtained in similar planes three months prior to injury. In comparison to pre-injury scans, post-injury MR scan analysis demonstrated significant ventricular volume increase which is considered a measure of the degree of diffuse axonal injury. Most important, the trauma induced degenerative effects appeared to be quite complete by 42 days post-injury as there was little further degeneration that occurred between the 6 week and 10 month post-injury scans. This study demonstrates that in humans the majority of gross trauma-induced degenerative changes are complete by 6 weeks post-trauma.

Adult↗
PubMed1992

The neurobiology and neuropsychology of adult learning disorders.

The area of adult learning disabilities is reviewed from a neurobiological and neuropsychological perspective. The seminal contributions of Galaburda's neuroanatomic studies, Duffy's neurophysiologic findings, and recent magnetic resonance imaging studies have illustrated various possible pathophysiologic bases in dyslexia and are reviewed along with other neurobehavioral disorders that may coexist with learning disorders. Neuropsychological assessment methods in evaluating learning disabilities are reviewed and test results in a case of traumatically induced dyslexia are compared to those obtained in three adults with residual developmental dyslexia. The problems associated with treatment of adult learning disorders are discussed in the context of brain plasticity and recovery of function from the perspective of a brain-injury model. Lastly, the basis common to neurologic factors subserving learning disability and emotional dysfunction is explored.

Adult↗
PubMed1991

Short- and long-term psychological status following stroke. Short form MMPI results.

Indices of self-reported depression and psychological adjustment after stroke were evaluated using a short form of the MMPI. Patients with poststroke periods of 2 to 6 and 7 to 24 months were selected, and indices of general intellectual functioning and lesion size/location were obtained. Despite similar levels of intellectual functioning and lesion parameters, the longer duration group showed significantly higher depression scores and significant (T greater than 70) elevations on several other clinical scales of the MMPI. In contrast, the mean overall profile of the short-duration group was roughly within normal limits. These findings have implications for the clinical assessment and treatment of stroke patients and long-term psychological adjustment after stroke.

Adaptation, Psychological↗
PubMed1990

Basic relations among lesion laterality, lesion volume and neuropsychological performance.

Although it is widely accepted that lesion size is an important determinant of severity of deficit, difficulties in the quantification of lesion size and the absence of a theoretical model of how lesion volume combines with lesion locus to produce deficits have inhibited the development of methodological and statistical procedures for studying naturally occurring lesions in humans. We propose such a unified model and apply it to the analysis of neuropsychological performance in a sample of patients with naturally occurring unilateral lesions. The analysis suggests that a statistical interaction between lesion size and laterality may be an important determinant of neuropsychological deficit.

Adult↗
PubMed1990

Neuropsychology and malingering: comment on Faust, Hart, and Guilmette (1988)

Faust, Hart, and Guilmette (1988) recently reported on the inability of neuropsychologists to detect malingering in children who were asked to "fake bad" on a battery of neuropsychological measures. Because of methodological issues, implications of their research are not generalizable to the actual clinical setting. Limitations of the questionnaire format in detecting factitious results are discussed along with the inherent bias of such a research design to overinterpret pathology. The competency of the clinical neuropsychologist judges and their selection process are questioned. Last, some guidelines are offered for future research dealing with the issue of detection of malingering in neuropsychological practice.

Child↗
PubMed1990

Quantitative assessment of covariation between neuropsychological function and location of naturally occurring lesions in humans.

Studies of localization of brain function in humans depend on analysis of covariation between the location of naturally occurring lesions and measures of neuropsychological ability. Such an analysis presents two problems: how to represent numerically the infinite variety of lesion locations, sizes, and shapes; and how to assess covariation between the location measure and performance. We present a mathematical model of lesion location and its relationship with performance. To demonstrate its utility, the model is applied to a sample of 53 patients with naturally occurring brain lesions who were administered a standard battery of neuropsychological tests. Importance functions derived for the neuropsychological measures generally conform to expectations. Sensory and motor abilities were localized correctly within the contralateral hemispheres, and language functions were localized in the left frontal region. Lesion location accounts for substantially more variation in performance than does lesion volume, with location accounting for more than 50% for some left-hemisphere functions.

Brain↗
PubMed1990

Attention deficit disorder and the mediating effect of age on academic and behavioral variables.

Seventy-nine children, independently diagnosed as having attention deficit disorder (ADD) with or without hyperactivity and ranging in age from 6 years, 0 months, to 12 years, 11 months, were administered the Wechsler Intelligence Scale for Children-Revised (WISC-R), the Wide Range Achievement Test (WRAT), and the Child Behavior Checklist (CBC). Multiple regression analyses indicated a significant multiple correlation between age and achievement variables (R = 0.42, p = 0.003) and age and behavioral (CBC) variables (R = 0.55, p = 0.01). Post hoc analyses indicated that much of this variance was accounted for by a significant negative association between age and Full Scale IQ-WRAT Arithmetic difference scores, and significant positive correlations between age and scores on the Social Withdrawal and Uncommunicative scales from the CBC. A nonparametric chi-square analysis indicated that older children with ADD are significantly more likely (p = 0.037) than younger ADD children to have a discrepancy of 15 or more points between IQ and math achievement scores. Results suggest that older ADD children are more likely than younger ADD children to experience academic and socioemotional difficulties.

Achievement↗
PubMed1990

The relationship between continuous performance tasks and neuropsychological tests in children with attention-deficit hyperactivity disorder.

We examined the relationship between measures of sustained attention and impulsivity, as obtained by computerized continuous performance tasks of the Gordon Diagnostic System and a battery of intellectual, achievement, and neuropsychological tests. Subjects were 119 boys (between the ages of 6 yr., 0 mo. and 12 yr., 11 mo.), diagnosed with Attention-deficit Hyperactivity Disorder, using DSM-III or DSM-III--R criteria. Only two measures, the number of correct responses for Vigilance and Distractibility tasks, correlated consistently with other measures (e.g., intellectual measures, the WRAT--R Arithmetic subtest, Beery Test of Visual and Motor Integration, and various sensory-motor variables from the Halstead-Reitan Neuropsychological Battery). The results suggest a unique contribution of continuous performance tasks in the measurement of attention, in a population of children with ADHD, which is not assessed by more traditional tests.

Attention↗
PubMed1989

Rey-Auditory Verbal Learning and Rey-Osterrieth Complex Figure Design performance in Alzheimer's disease and closed head injury.

Performance on the Rey-Auditory Verbal Learning (R-AVL) and Rey-Osterrieth Complex Figure Design (R-O CFD) tests was examined in patients (N = 94) with dementia of the Alzheimer's type (DAT) and closed head injury (CHI). On the R-AVL, DAT patients demonstrated considerably greater impairment than CHI patients, along with a flat learning/retention curve that showed negligible improvement with repeated trials, recency effects only, and an excessive number of word intrusions (confabulation) on the recognition trial. CHI patients demonstrated both a recency and primacy effect along with improvement over repeated trials (positive slope learning curve). Both groups demonstrated impairment R-O CFD recall; the DAT group again displayed substantially greater copying and recall deficits. Clinical guidelines are given for the use of the R-AVL and R-O CFD for these two patient populations.

Adult↗
PubMed1989

Handedness and language among the mentally retarded: implications for the model of pathological left-handedness and gender differences in hemispheric specialization.

The relationship between handedness and language was examined among 238 mentally retarded subjects representing the four DSM III classification ranges of mental retardation. Language ability was found to be significantly related to handedness, with an increased prevalence of left-handedness among those individuals with language deficits. In addition, both expressive and receptive language ability interacted with gender, with the main effects of each language variable being stronger for females than males. Although no main effects were found for severity of retardation, a significant interaction was found between severity and gender. Results support the model of pathological left-handedness and are discussed within the context of this theory, as well as with regard to gender differences in cerebral lateralization of language and cognitive functioning.

Adolescent↗
PubMed1988

The mediating effect of age on the relationship between Child Behavior Checklist hyperactivity scores and neuropsychological test performance.

The relationship between hyperactivity and neuropsychological test performance at different age levels was examined. It was found that for young children (6 to 8 years of age, n = 90), there was no significant association between hyperactivity/attentional problems (as measured by the Hyperactivity scale of the Child Behavior Checklist) and performance on neuropsychological tasks thought to contain an attentional component (WISC-R Coding, Arithmetic, and Digit Span; WRAT Arithmetic; and the Benton Visual Retention Test). However, for older children (9 to 12 years of age, n = 92), there were significant and large negative correlations between CBC Hyperactivity scores and Coding, WRAT Arithmetic, and Benton VRT scores. Multiple regression analyses supported the above results (for Coding and WRAT Arithmetic), indicating that hyperactivity/inattention has a particularly deleterious effect on test performance (relative to same-age peers) as age increases.

Age Factors↗
PubMed1988

Ventriculomegaly in schizophrenia: is the choice of controls important?

The issue of adequate controls for the study of ventriculomegaly in schizophrenia has been explored initially by Andreasen et al. (1982), who proposed that healthy volunteers, a group with presumably smaller ventricles than medical controls, be considered the optimal comparison group in this area of research. Recently, Smith and Iacono (1986) suggested that group differences may appear to be greater when controls who are patients are used, as a result of the systematic exclusion of medical patients with large though normal ventricles. We conducted a meta-analysis of 37 studies of lateral ventriculomegaly in schizophrenia to clarify this issue. The results indicate that the average effect size in studies with healthy controls does not differ significantly from that obtained in studies employing medical, neurological, or psychiatric (nonpsychotic) controls. Thus, any group without gross neurological damage or severe psychopathology may be used for establishing ventriculomegaly in schizophrenia.

Cerebral Ventricles↗
PubMed1988

Short-form MMPI findings in patients with predominantly lateralized cerebral dysfunction. Neuropsychological and computerized axial tomography-derived parameters.

Short-form MMPI profiles of cerebrovascular accident and head injury patients with evidence of predominantly lateralized (N = 94) or diffuse (N = 59) cerebral damage were examined in conjunction with quantified computed axial tomographic and neuropsychological data. Results indicated that all groups tended to produce similar overall MMPI profiles, with primary elevations on Scales 8 (Sc) and 2 (D). Across the sample as a whole, patients with left hemisphere damage displayed somewhat more frequent Scale 2 elevations, although this finding was influenced by etiology effects. Left frontal lesion size among patients with left hemisphere damage was negatively associated with Scale 2 scores, and right posterior lesion size was positively associated with Scale 2 scores among patients with right hemisphere damage. Longer lesion durations generally were associated with increased MMPI scores. Results underscore the complex and multidimensional nature of the interrelationships between affective processes and localized cerebral damage.

Adolescent↗