Objective: To quantify the effects of traumatic brain injury on integrity of thalamocortical projection fibers and to evaluate whether damage to these fibers accounts for impairments in executive function in chronic traumatic brain injury.Methods: High-resolution (voxel size: 0.78 mm ϫ 0.78 mm ϫ 3 mm 3 ) diffusion tensor MRI of the thalamus was conducted on 24 patients with a history of single, closed-head traumatic brain injury (TBI) (12 each of mild TBI and moderate to severe TBI) and 12 age-and education-matched controls. Detailed neuropsychological testing with an emphasis on executive function was also conducted. Fractional anisotropy was extracted from 12 regions of interest in cortical and corpus callosum structures and 7 subcortical regions of interest (anterior, ventral anterior, ventral lateral, dorsomedial, ventral posterior lateral, ventral posterior medial, and pulvinar thalamic nuclei). Results:Relative to controls, patients with a history of brain injury showed reductions in fractional anisotropy in both the anterior and posterior corona radiata, forceps major, the body of the corpus callosum, and fibers identified from seed voxels in the anterior and ventral anterior thalamic nuclei. Fractional anisotropy from cortico-cortico and corpus callosum regions of interest did not account for significant variance in neuropsychological function. However, fractional anisotropy from the thalamic seed voxels did account for variance in executive function, attention, and memory. Conclusions:The data provide preliminary evidence that traumatic brain injury and resulting diffuse axonal injury results in damage to the thalamic projection fibers and is of clinical relevance to cognition. Neurology ® 2010;74:558 -564 GLOSSARY ACR ϭ anterior corona radiata; AN ϭ anterior thalamic nucleus; bCC ϭ body of the corpus callosum; CST ϭ cortical-spinal tract; DAI ϭ diffuse axonal injury; DM ϭ dorsomedial nucleus; DTI ϭ diffusion tensor imaging; FA ϭ fractional anisotropy; fMaj ϭ forceps major; fMin ϭ forceps minor; FOV ϭ field of view; FSE ϭ fast spin echo; gCC ϭ genu of the corpus callosum; IC ϭ internal capsule; IFOF ϭ inferior frontal occipital fasciculus; LOC ϭ loss of consciousness; miTBI ϭ mild TBI; msTBI ϭ moderate to severe TBI; NEX ϭ number of excitations; PCR ϭ posterior corona radiata; PTA ϭ posttraumatic amnesia; PU ϭ pulvinar; ROI ϭ region of interest; sCC ϭ splenium of the corpus callosum; SLF ϭ superior longitudinal fasciculus; SS ϭ sagittal stratum; TBI ϭ traumatic brain injury; TE ϭ echo time; TR ϭ repetition time; VA ϭ ventral anterior thalamic nucleus; VL ϭ ventral lateral thalamic nucleus; VPL ϭ ventral posterior lateral nucleus; VPM ϭ ventral posterior medial nucleus. Traumatic brain injury (TBI) is a serious public health problem with a high incidence 1-3 which can result in structural damage to the cerebrum including contusions, edema, and diffuse axonal injury (DAI).4 DAI has been demonstrated in all stages and severities [5][6][7] and is often the only significant pathology in milder injury...

Summary:Purpose: To assess the presence, extent, and clinical correlates of quantitative MR volumetric abnormalities in ipsilateral and contralateral hippocampus, and temporal and extratemporal lobe regions in unilateral temporal lobe epilepsy (TLE).Methods: In total, 34 subjects with unilateral left (n = 15) or right (n = 19) TLE were compared with 65 healthy controls. Regions of interest included the ipsilateral and contralateral hippocampus as well as temporal, frontal, parietal, and occipital lobe gray and white matter. Clinical markers of neurodevelopmental insult (initial precipitating insult, early age of recurrent seizures) and chronicity of epilepsy (epilepsy duration, estimated number of lifetime generalized seizures) were related to magnetic resonance (MR) volume abnormalities.Results: Quantitative MR abnormalities extend beyond the ipsilateral hippocampus and temporal lobe with extratemporal (frontal and parietal lobe) reductions in cerebral white matter, especially ipsilateral but also contralateral to the side of seizure onset. Volumetric abnormalities in ipsilateral hippocampus and bilateral cerebral white matter are associated with factors related to both the onset and the chronicity of the patients' epilepsy.Conclusions: These cross-sectional findings support the view that volumetric abnormalities in chronic TLE are associated with a combination of neurodevelopmental and progressive effects, characterized by a prominent disruption in ipsilateral hippocampus and neural connectivity (i.e., white matter volume loss) that extends beyond the temporal lobe, affecting both ipsilateral and contralateral hemispheres.

There is considerable interest in the assessment of executive function (EF) in pediatric clinical populations but only a few well-standardized measures exist. We examined EF in 53 children aged 8 to 18 years with recent onset epilepsy (31 males, 22 females) and 50 control children (23 males, 27 females) using the Behavior Rating Inventory of Executive Function (BRIEF) and the Delis-Kaplan Executive Function System (D-KEFS). Thirty children had localization-related epilepsy and 23 had idiopathic generalized epilepsy; average duration of 10 months (SD 4y 1mo) and onset age of 11 years 6 months (SD 3y 6mo). The study sample was characterized by good seizure control, with 40 participants taking one antiepileptic drug (AED), one taking two AEDs, and 12 not treated pharmacologically. Children with epilepsy showed greater executive difficulties on both measures than children in the control group. The BRIEF and D-KEFS were significantly correlated, and an 'at-risk' group identified from the BRIEF was more significantly impaired on the D-KEFS than a 'low risk' group. The BRIEF was also a better predictor of performance on the D-KEFS than the Child Behavior Checklist. These findings indicate that children with recent onset epilepsy show significant difficulties in EF, and demonstrate the utility of parent ratings (BRIEF) in the assessment of EF.Cognitive impairment is common in childhood epilepsy and considerable attention has been devoted to identify related seizure characteristics.

Following mild traumatic brain injury (TBI), a percentage of individuals report chronic memory and attention difficulties. Traditional neuropsychological assessments often fail to find evidence for such complaints. We hypothesized that mild TBI patients may, in fact, experience subtle cognitive deficits that reflect diminished initial acquisition that can be explained by changes in cerebral white matter microstructure. In the data presented here, a sample of nonlitigating and gainfully employed mild TBI patients demonstrated statistically significant differences from age and education matched control participants in performance on the first trial of a verbal learning task. Performance on this trial was associated with reduced fractional anisotropy in the uncinate fasciculus and the superior longitudinal fasciculus providing an anatomical correlate for the cognitive findings. Mild TBI patients were not impaired relative to control participants on total learning or memory composite variables. Performance on the first learning trial was not related to any psychological variables including mood. We concluded that patients with mild TBI demonstrate diminished verbal learning that is not often interpreted in standard neuropsychological assessment.