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Biomedical subjects

Erin D Bigler

Publications and source records attributed to Erin D Bigler.

At least 19 recordsLinked to original sources
PubMed2007

Quantitative temporal lobe differences: autism distinguished from controls using classification and regression tree analysis.

The temporal lobe is thought to be abnormal in autism, yet standard volumetric analyses are often unrevealing when age, sex, IQ, and head size are controlled. Quantification of temporal lobe structures were obtained in male subjects with autism and controls, where subjects with head circumference (HC) defined macrocephaly were excluded, so that volume differences were not just related to the higher prevalence of macrocephaly in autism. Various statistical methods were applied to the analysis including a classification and regression tree (CART) method, a non-parametric technique that helps define patterns of relationships that may be meaningful in distinguishing temporal lobe differences between subjects with autism and age and IQ matched controls. Subjects with autism were also compared to a separate control group with reading disorder (RD), with the prediction that the temporal lobe morphometric analysis of the reading disorder controls would be more similar to that of the autism group. The CART method yielded a high specificity in classifying autism subjects from controls based on the relationship between the volume of the left fusiform gyrus (LFG) gray and white matter, the right temporal stem (RTS) and the right inferior temporal gyrus gray matter (RITG-GM). Reading disordered individuals were more similar to subjects with autism. Simple size differences did not distinguish the groups. These findings demonstrate different relationships within temporal lobe structures that distinguish subjects with autism from controls. Results are discussed in terms of pathological connectivity within the temporal lobe as it relates to autism.

Adolescent↗
PubMed2006

A motion to exclude and the 'fixed' versus 'flexible' battery in 'forensic' neuropsychology: challenges to the practice of clinical neuropsychology.

Two recent publications in Archives of Clinical Neuropsychology (ACN) have been used by defense attorneys as the centerpiece for an argument that only a 'fixed' battery approach, exemplified by the Halstead-Reitan battery (HRB), satisfies the Daubert criteria for admissibility; and therefore, the HRB represents the only method of forensic neuropsychological assessment that should be admitted into evidence. Since this case has important implications for the practice of clinical neuropsychology in the United States, this 'Motion to Exclude' and its rationale are presented, which demonstrates how the legal profession uses neuropsychological literature. The critical issues of this argument for clinical neuropsychological practice are reviewed.

Criminal Law↗
PubMed2006

Head circumference and height in autism: a study by the Collaborative Program of Excellence in Autism.

Data from 10 sites of the NICHD/NIDCD Collaborative Programs of Excellence in Autism were combined to study the distribution of head circumference and relationship to demographic and clinical variables. Three hundred thirty-eight probands with autism-spectrum disorder (ASD) including 208 probands with autism were studied along with 147 parents, 149 siblings, and typically developing controls. ASDs were diagnosed, and head circumference and clinical variables measured in a standardized manner across all sites. All subjects with autism met ADI-R, ADOS-G, DSM-IV, and ICD-10 criteria. The results show the distribution of standardized head circumference in autism is normal in shape, and the mean, variance, and rate of macrocephaly but not microcephaly are increased. Head circumference tends to be large relative to height in autism. No site, gender, age, SES, verbal, or non-verbal IQ effects were present in the autism sample. In addition to autism itself, standardized height and average parental head circumference were the most important factors predicting head circumference in individuals with autism. Mean standardized head circumference and rates of macrocephaly were similar in probands with autism and their parents. Increased head circumference was associated with a higher (more severe) ADI-R social algorithm score. Macrocephaly is associated with delayed onset of language. Although mean head circumference and rates of macrocephaly are increased in autism, a high degree of variability is present, underscoring the complex clinical heterogeneity of the disorder. The wide distribution of head circumference in autism has major implications for genetic, neuroimaging, and other neurobiological research.

Adolescent↗
PubMed2006

Diffusion tensor imaging of the corpus callosum in Autism.

The corpus callosum is the largest commissural white matter pathway that connects the hemispheres of the human brain. In this study, diffusion tensor imaging (DTI) was performed on subject groups with high-functioning autism and controls matched for age, handedness, IQ, and head size. DTI and volumetric measurements of the total corpus callosum and subregions (genu, body and splenium) were made and compared between groups. The results showed that there were significant differences in volume, fractional anisotropy, mean diffusivity, and radial diffusivity between groups. These group differences appeared to be driven by a subgroup of the autism group that had small corpus callosum volumes, high mean diffusivity, low anisotropy, and increased radial diffusivity. This subgroup had significantly lower performance IQ measures than either the other individuals with autism or the control subjects. Measurements of radial diffusivity also appeared to be correlated with processing speed measured during the performance IQ tests. The subgroup of autism subjects with high mean diffusivity and low fractional anisotropy appeared to cluster with the highest radial diffusivities and slowest processing speeds. These results suggest that the microstructure of the corpus callosum is affected in autism, which may be related to nonverbal cognitive performance.

Adolescent↗
PubMed2006

Post-traumatic amnesia predicts long-term cerebral atrophy in traumatic brain injury.

PRIMARY OBJECTIVE: To examine post-traumatic amnesia (PTA) and its relation to long-term cerebral atrophy in persons with traumatic brain injury (TBI) using objective indicators of PTA duration and Quantitative Magnetic Resonance Imaging (QMRI). It was hypothesized that longer PTA would predict later generalized atrophy (increased ventricle-to-brain ratio (VBR)). As a guide in assessing patients with TBI, this study determined the probability of developing chronic cerebral atrophy based on PTA duration. RESEARCH DESIGN: Probability model using 60 adult patients with mild-to-severe TBI. MAIN OUTCOMES AND RESULTS: A logistic regression model with a cut-off determined by normative QMRI data confirmed that longer PTA duration predicts increased VBR. A probability model demonstrated a 6% increase in the odds of developing later atrophy on neuroimaging with each additional day of PTA. CONCLUSIONS: PTA has previously proven to be a good indicator of later cognitive recovery and functional outcome and also predicts long-term parenchymal change.

Adolescent↗
PubMed2006

Diffusion tensor imaging in the corpus callosum in children after moderate to severe traumatic brain injury.

Diffusion tensor imaging (DTI) is a recent imaging technique that assesses the microstructure of the cerebral white matter (WM) based on anisotropic diffusion (i.e., water molecules move faster in parallel to nerve fibers than perpendicular to them). Fractional anisotropy (FA), which ranges from 0 to 1.0, increases with myelination of WM tracts and is sensitive to diffuse axonal injury (DAI) in adults with traumatic brain injury (TBI). However, previous DTI studies of pediatric TBI were case reports without detailed outcome measures. Using mean FA derived from DTI fiber tractography, we compared DTI findings of the corpus callosum for 16 children who were at least 1 year (mean 3.1 years) post-severe TBI and individually matched, uninjured children. Interexaminer and intraexaminer reliability in measuring FA was satisfactory. FA was significantly lower in the patients for the genu, body, and splenium of the corpus callosum. Higher FA was related to increased cognitive processing speed and faster interference resolution on an inhibition task. In the TBI patients, higher FA was related to better functional outcome as measured by the dichotomized Glasgow Outcome Scale (GOS). FA also increased as a function of the area of specific regions of the corpus callosum such as the genu and splenium, and FA in the splenium was reduced with greater volume of lesions in this region. DTI may be useful in identifying biomarkers related to DAI and outcome of TBI in children.

Adolescent↗
PubMed2006

Day-of-injury computerized tomography, rehabilitation status, and development of cerebral atrophy in persons with traumatic brain injury.

OBJECTIVE: To compare day-of-injury (DOI) computerized tomography (CT) findings with acute injury severity markers, disability at acute hospital admission and discharge from inpatient rehabilitation, injury severity markers, and degree of postacute cerebral atrophy on magnetic resonance imaging (MRI). DESIGN: Retrospective chart review of 240 consecutive traumatic brain injury (TBI) admissions (mean age 31.7 +/- 15.8 yrs) with moderate-to-severe initial brain injury. All DOI CT abnormalities were qualitatively rated. Disability was assessed using the Disability Rating Scale (DRS) and the FIM measure. In a representative subset, cerebral atrophy was determined by the ventricle-to-brain ratio (VBR) method and quantified from MRI scans 25 or more days postinjury. RESULTS: CT classification resulted in nonsignificant differences in DRS and FIM ratings at the time of discharge from the rehabilitation unit, except in brainstem injury subjects who had significantly higher DRS and lower FIM scores at rehabilitation discharge. At 25 or more days postinjury, presence of any DOI CT abnormality was associated with larger VBR. Increased VBR, as an index of cerebral atrophy, was associated with worse rehabilitation discharge DRS and FIM ratings. CONCLUSIONS: Other than brainstem injury, DOI CT findings relate poorly to rehabilitation outcome. Presence of DOI CT abnormalities were associated with the development of cerebral atrophy, which was associated with poorer rehabilitation discharge DRS and FIM scores.

Activities of Daily Living↗
PubMed2006

Prevalence of white matter hyperintensities in a young healthy population.

BACKGROUND AND PURPOSE: White matter hyperintensities (WMHs) are bright objects observed in the white matter on brain magnetic resonance (MR) imaging. WMHs are often reported as "normal" findings but may represent pathological changes. The prevalence of WMHs appears to increase with increasing age although both the typical timing and clinical significance of their appearance among medically and neurologically healthy persons remains unclear. We assessed the prevalence of WMHs in a cohort of younger healthy subjects. METHODS: Our study comprised 243 healthy subjects ages 16-65 years from our prospective normative MR imaging database. MR scans were rated for presence of periventricular and centrum semiovale WMHs using a four-point visual semi-quantitative scale. RESULTS: WMHs occurred in 5.3% (13 of 243) of subjects. All WMHs were small (rating of 0.5) except one subject age 65 years who had large WMHs (ratings of 2). The median age for subjects with no WMHs was 34.5 years compared to 57.0 years for subjects with WMHs. There were no gender differences (P= .76). Older age correlated with presence of WMHs (r = 0.24; P= .01). Age greater than 55 years had a 10-fold increase in the prevalence of WMHs compared to age < or =55 years (odds ratio = 10.01; 95% confidence interval = 3.1-32.3; P < .001). CONCLUSION: WMHs were uncommon in a younger healthy population screened for comorbid diseases, but increased 10-fold in subjects over 55 years of age. When present, the WMHs are generally small (rating of 0.5). While large WMHs appear to be associated with cognitive deterioration, the optimum threshold for identification, clinical significance, and prognostic value of smaller white matter changes requires further research.

Adolescent↗
PubMed2006

Vulnerability of the anterior commissure in moderate to severe pediatric traumatic brain injury.

In relation to the adult brain, the immature brain might be more vulnerable to damage during and following traumatic brain injury, particularly in white-matter tracts. Given well-established evidence of corpus callosum atrophy, we hypothesized that anterior commissure volume (using quantitative magnetic resonance imaging [MRI]) in this structure would be decreased in children with moderate to severe traumatic brain injury relative to typically developing children. Second, given the purported role of the anterior commissure in interhemispheric axon conveyance between temporal lobes, we hypothesized that temporal lobe white matter, temporal lesion volume, and injury severity (Glasgow Coma Scale score) would be predictive of decreased anterior commissure cross-sectional volume in patients with traumatic brain injury. Finally, we wished to establish the relationship between the anterior commissure and the temporal stem, a major white-matter tract into the temporal lobes, using diffusion tensor imaging fiber-tracking maps for each patient. We also hypothesized that children with traumatic brain injury would exhibit decreased fractional anisotropy in relation to typically developing children in a fiber system including the anterior commissure and the temporal lobes. Decreased anterior commissure cross-sectional volume was observed in patients with traumatic brain injury, and, as predicted, anterior commissure and temporal white-matter volumes were positively related to each other and to higher Glasgow Coma Scale scores. Lesion volume was not independently predictive of anterior commissure volume in the overall model. Diffusion tensor imaging fractional anisotropy values differed between the groups for the temporal stem-anterior commissure system, with the traumatic brain injury group exhibiting decreased fractional anisotropy. The anterior commissure, like the corpus callosum, appears to be highly vulnerable to white-matter degenerative changes resulting from mechanisms such as the direct impact of trauma, progressive axonal injury as tissue in other brain regions atrophies, or myelin degeneration. This is the first systematic examination of anterior commissure atrophy following traumatic brain injury using in vivo quantitative MRI and diffusion tensor imaging fiber tracking in pediatric subjects.

Adolescent↗
PubMed2005

Measuring medical complexity during inpatient rehabilitation after traumatic brain injury.

OBJECTIVE: To compare the performance of 3 severity of illness (SOI) indices--the Comprehensive Severity Index (CSI), All Patient Refined Diagnosis Related Groups Severity of Illness, case-mix group (CMG)--and 5 well-known neurologic parameters, as measures of medical complexity. DESIGN: Retrospective chart review. SETTING: Inpatient rehabilitation center within a level I trauma center. PARTICIPANTS: Consecutive traumatic brain injury (TBI) admissions (N=212). INTERVENTION: Acute inpatient TBI rehabilitation. CSI and neurologic parameters were scored by chart extraction. SOI was based on diagnosis codes by using 3M PC Grouper software, version 15. MAIN OUTCOME MEASURES: Adjusted R 2 was used to predict rehabilitation charges as a proxy of medical complexity. RESULTS: The highest adjusted R 2 values for single variables predicting charges were: CMG .349, CSI .293, duration of posttraumatic amnesia .260. Adjusted R 2 values for the CMG combined with the CSI, 5 neurologic parameters, and SOI to predict charges were .446, .431, and .365, respectively. CONCLUSIONS: The CMG was the best single predictor of rehabilitation charges for TBI. Predictive ability was better when the CMG was combined with the CSI or a combination of the 5 neurologic parameters. A severity index based on objective clinical findings rather than diagnostic codes may have distinct advantages for rehabilitation outcome studies and reimbursement methodology.

Adolescent↗
PubMed2005

Anoxic versus traumatic brain injury: amount of tissue loss, not etiology, alters cognitive and emotional function.

Research in neuropsychology suggests that the etiology of a neurologic injury determines the neuropathological and neuropsychological changes. This study compared neuropsychological outcome in subjects who had traumatic brain injury (TBI) with subjects who had anoxic brain injury (ABI), who were matched for age, gender, and ventricle-to-brain ratio. There were no group differences for morphologic or neuropsychological measures. Both groups exhibited impaired memory, attention, and executive function, as well as slowed mental processing speed. Intelligence correlated with whole brain volume, and measures of memory correlated with hippocampal atrophy. There was no unique contribution of hippocampal atrophy on neuropsychological outcome between the groups. In the absence of localized lesions, the amount of neural tissue loss, rather than etiology, may be the critical factor in neuropsychological outcome.

Adult↗
PubMed2005

Memory and learning in children with 22q11.2 deletion syndrome: evidence for ventral and dorsal stream disruption?

This study examined memory functioning in children and adolescents with 22q11.2 Deletion Syndrome (DS; velocardiofacial syndrome). An overall verbal better than nonverbal memory pattern was evident on the Test of Memory and Learning (TOMAL), with children with 22q11.2 DS performing significantly below their siblings and children with low average IQ but similar to children with autism on facial memory. Children with 22q11 DS also performed significantly below their siblings on tests of verbal working memory. Children with autism performed significantly poorer than the siblings of children with 22q11.2 DS only on their recall of stories. Delayed recall was significantly poorer in children with 22q11.2 DS and children with autism, compared to sibling controls. Although there were no significant group differences on tests of multiple trial verbal or visual learning, a relative weakness was noted with multiple trial visual learning in children with 22q11.2 DS and their siblings, suggesting that an alternative or interactive factor other than the deletion may account for the relatively better verbal compared to nonverbal memory abilities. Deficits in facial memory in children with both 22q11.2 DS and autism suggest disruptions in ventral temporal pathways such as between fusiform gyrus and parahippocampal/hippocampal regions whereas deficits in verbal working memory in children with 22q11.2 DS implicates dorsolateral prefrontal regions, both intimating aberrant white matter pathways.

Adolescent↗
PubMed2005

Neurobehavioral sequelae of child sexual abuse.

This study examined intellectual and memory functioning in a sample of sexually abused children compared to demographically and age-matched controls. The severity of abuse and other pertinent factors were also examined in relation to cognitive performance. Elevated levels of psychopathology were present in the abused children, as well as diminished performance on tasks influenced by attention/concentration. However, after controlling for differences in IQ and socioeconomic status (SES), significant differences in memory function were not found. Results are discussed in the context of stress effects on cognition and the potential resiliency of cognitive function in children undergoing treatment for sexual abuse.

Achievement↗
PubMed2005

Frontal and temporal morphometric findings on MRI in children after moderate to severe traumatic brain injury.

In vivo MRI volumetric analysis enables investigators to evaluate the extent of tissue loss following traumatic brain injury (TBI). However, volumetric studies of pediatric TBI are sparse, and there have been no volumetric studies to date in children examining specific subregions of the prefrontal and temporal lobes. In this study, MRI volumetry was used to evaluate brain volume differences in the whole brain, and prefrontal, temporal, and posterior regions of children following moderate to severe TBI as compared to uninjured children of similar age and demographic characteristics. The TBI group had significantly reduced whole brain, and prefrontal and temporal regional tissue volumes as well as increased cerebrospinal fluid (CSF). Confidence interval testing further revealed group differences on gray matter (GM) and white matter (WM) in the superior medial and ventromedial prefrontal regions, WM in the lateral frontal region, and GM, WM, and CSF in the temporal region. Whole brain volume and total brain GM were reduced, and total ventricular volume, total CSF volume, and ventricle-to-brain ratio (VBR) were increased in the TBI group. Additional analyses comparing volumetric data from typically developing children and subgroups of TBI patients with and without regional focal lesions suggested that GM loss in the frontal areas was primarily attributable to focal injury, while WM loss in the frontal and temporal lobes was related to both diffuse and focal injury. Finally, volumetric measures of preserved frontotemporal tissue were related to functional recovery as measured by the Glasgow Outcome Scale (adapted for children) with greater tissue preservation predicting better recovery.

Adolescent↗
PubMed2005

Macrocephaly, corpus callosum morphology, and autism.

Although the cause of autism is undetermined, a general consensus has been that some type of early aberrant neural development underlies the disorder. Given the increased prevalence of macrocephaly in autism, one theory of abnormal neural development implicates early brain growth resulting in larger brain and head size in autism. Surface area measurements of the midsagittal section of the corpus callosum can be used as an index of neural development and white-matter integrity because the corpus callosum is the major white-matter structure that interconnects the two cerebral hemispheres. The purpose of this study was to obtain corpus callosum surface area, shape, and contour in a sample of non-mentally retarded autistic subjects with macrocephaly (n = 12) and compare them with those of matched (n = 8), typically developing control subjects with benign macrocephaly. No significant differences were found in surface area, shape, or contour between groups, nor did corpus callosum surface area relate to measures of IQ or picture vocabulary. These findings suggest no unique difference in overall regional corpus callosum surface area in autism with macrocephaly.

Adolescent↗
PubMed2004

Neuropsychological and information processing deficits following mild traumatic brain injury.

Neuroradiological and neuropathological investigations have found evidence of diffuse brain damage in the frontal and temporal lobes, corpus callosum, and fornices in patients who have sustained a mild traumatic brain injury (TBI). However, neuropsychological assessments of these patients do not typically target many of the subtle information processing deficits that may arise from diffuse damage involving the frontotemporal regions of the brain as well as white matter pathology, including the corpus callosum. Consequently, we have a limited understanding of the deficits that may be attributable to temporary or permanent disruptions to these functional pathways. This study assessed a group of mild TBI patients (N = 40) and a matched control group (N = 40) on a number of standard neuropsychological tests of selective and sustained attention, verbal and non-verbal fluency, and verbal memory. In addition, reaction time (RT) tasks, requiring both the inter- and intra-hemispheric processing of visual and tactile information, were used to assess the functional integrity of the tracts that are likely to be affected by diffuse damage. In the 1st month after sustaining their injury, the mild TBI group demonstrated deficits in attention, non-verbal fluency, and verbal memory. They also demonstrated slower visual and tactile RTs, with the visual RTs of mild TBI patients being more affected by increased task difficulty and the need to transfer information across the corpus callosum, than did their matched controls.

Adolescent↗
PubMed2004

Cerebral volume loss, cognitive deficit and neuropsychological performance: comparative measures of brain atrophy: I. Dementia.

There are several magnetic resonance (MR) imaging methods to measure brain volume and cerebral atrophy; however, the best measure for examining potential relationships between such measures and neuropsychological performance has not been established. Relationships between seven measures of MR derived brain volume or indices of atrophy and neuropsychological performance in the elderly subjects of the population-based Cache County, Utah Study of Aging and Memory (n = 195) were evaluated. The seven MR measures included uncorrected total brain volume (TBV), TBV corrected by total intracranial volume (TICV), TBV corrected by the ratio of the individuals TICV by group TICV (TBVC), a ventricle-to-brain ratio (VBR), total ventricular volume (TVV), TVV corrected by TICV, and a measure of parenchymal volume loss. The cases from the Cache County Study were comprised of elderly individuals classified into one of four subject groups based on a consensus diagnostic process, independent of quantitative MR imaging findings. The groups included subjects with Alzheimer's disease (AD, n = 85), no dementia but mild/ambiguous (M/A) deficits (n = 30), a group of subjects with non-AD dementia or neuropsychiatric disorder including vascular dementia (n = 60), and control subjects (n = 20). Neuropsychological performance was based on the Mini-Mental Status Exam (MMSE) and an expanded neuropsychological test battery (consortium to establish a registry for Alzheimer's disease (CERAD). The results demonstrated that the various quantitative MR measures were highly interrelated and no single measure was statistically superior. However, TBVC, TBV/TICV and VBR consistently exhibited the more robust relationships with neuropsychological performance. These results suggest that a single corrected brain volume measure or index is sufficient in studies examining global MR indicators of cerebral atrophy in relation to cognitive function and recommends use of either TBVC, TBV/TICV, or VBR.

Aged↗