Differential SPECT Activation Patterns Associated with PASAT Performance May Indicate Frontocerebellar Functional Dissociation in Chronic Mild Traumatic Brain Injury

Department of Radiology, University of Washington School of Medicine, Seattle, Washington 98195, USA.
Journal of Nuclear Medicine (Impact Factor: 6.16). 07/2009; 50(7):1054-61. DOI: 10.2967/jnumed.108.060368
Source: PubMed


Patients with mild traumatic brain injury (TBI) often complain of cognitive fatigue during the chronic recovery phase. The Paced Auditory Serial Addition Test (PASAT) is a complex psychologic measure that may demonstrate subtle deficiencies in higher cognitive functions. The purpose of this study was to investigate the brain activation of regional cerebral blood flow (rCBF) with PASAT in patients with mild TBI to explore mechanisms for the cognitive fatigue.
Two groups consisting of 15 patients with mild TBI and 15 healthy control subjects underwent (99m)Tc-ethylene cysteine dimer SPECT at rest and during PASAT on a separate day. Cortical rCBF was extracted using a 3-dimensional stereotactic surface projection and statistically analyzed to identify areas of activation, which were compared with PASAT performance scores.
Image analysis demonstrated a difference in the pattern of activation between patients with mild TBI and healthy control subjects. Healthy control subjects activated the superior temporal cortex (Brodmann area [BA] 22) bilaterally, the precentral gyrus (BA 9) on the left, and the precentral gyrus (BA 6) and cerebellum bilaterally. Patients with mild TBI demonstrated a larger area of supratentorial activation (BAs 9, 10, 13, and 46) but a smaller area of activation in the cerebellum, indicating frontocerebellar dissociation.
Patients with mild TBI and cognitive fatigue demonstrated a different pattern of activation during PASAT. Frontocerebellar dissociation may explain cognitive impairment and cognitive fatigue in the chronic recovery phase of mild traumatic brain injury.

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Available from: Naoya Hattori, Oct 04, 2015
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    • "In the present study, we examine the impact of focal cerebellar lesions on task-related activations in the cerebral cortex. A priori, one might expect the cerebellar pathology to produce either hypo-or hyperactivations relative to controls; respectively suggesting either a failure to recruit cerebral network nodes (Baillieux et al., 2010; Mariën, De Smet, Paquier, & Verhoeven, 2010) or compensatory re-organization of function (Hattori et al., 2009; Nudo, 2013; Thiel et al., 2001). Importantly, we hypothesized that the spatial overlap between the cerebellar pathology in the patients and activation patterns in our previous fMRI study would predict the specific experimental conditions revealing significant group differences in cortical activation. "
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    ABSTRACT: Functional neuroimaging studies consistently report language-related cerebellar activations, but evidence from the clinical literature is less conclusive. Here, we attempt to bridge this gap by testing the effect of focal cerebellar lesions on cerebral activations in a reading task previously shown to involve distinct cerebellar regions. Patients (N=10) had lesions primarily affecting medial cerebellum, overlapping cerebellar regions activated during the presentation of random word sequences, but distinct from activations related to semantic prediction generation and prediction error processing. In line with this pattern of activation-lesion overlap, patients did not differ from matched healthy controls (N=10) in predictability-related activations. However, whereas controls showed increased activation in bilateral auditory cortex and parietal operculum when silently reading familiar words relative to viewing letter strings, this effect was absent in the patients. Our results highlight the need for careful lesion mapping and suggest possible roles for the cerebellum in visual-to-auditory mapping and/or inner speech. Copyright © 2015 Elsevier Inc. All rights reserved.
    Brain and Language 09/2015; DOI:10.1016/j.bandl.2015.08.004 · 3.22 Impact Factor
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    • "Since mTBI involves a diffuse structural and/or physiologic/metabolic derangement [46], [47], [48], patients with mTBI have more frequent and more extensive areas of brain damage than can be seen by anatomical imaging (conventional CT and MRI scans). The preferred brain imaging methods are thus functional/metabolic (SPECT, PET, CT perfusion, and functional MRI). "
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    ABSTRACT: Traumatic brain injury (TBI) is the leading cause of death and disability in the US. Approximately 70-90% of the TBI cases are classified as mild, and up to 25% of them will not recover and suffer chronic neurocognitive impairments. The main pathology in these cases involves diffuse brain injuries, which are hard to detect by anatomical imaging yet noticeable in metabolic imaging. The current study tested the effectiveness of Hyperbaric Oxygen Therapy (HBOT) in improving brain function and quality of life in mTBI patients suffering chronic neurocognitive impairments. The trial population included 56 mTBI patients 1-5 years after injury with prolonged post-concussion syndrome (PCS). The HBOT effect was evaluated by means of prospective, randomized, crossover controlled trial: the patients were randomly assigned to treated or crossover groups. Patients in the treated group were evaluated at baseline and following 40 HBOT sessions; patients in the crossover group were evaluated three times: at baseline, following a 2-month control period of no treatment, and following subsequent 2-months of 40 HBOT sessions. The HBOT protocol included 40 treatment sessions (5 days/week), 60 minutes each, with 100% oxygen at 1.5 ATA. "Mindstreams" was used for cognitive evaluations, quality of life (QOL) was evaluated by the EQ-5D, and changes in brain activity were assessed by SPECT imaging. Significant improvements were demonstrated in cognitive function and QOL in both groups following HBOT but no significant improvement was observed following the control period. SPECT imaging revealed elevated brain activity in good agreement with the cognitive improvements. HBOT can induce neuroplasticity leading to repair of chronically impaired brain functions and improved quality of life in mTBI patients with prolonged PCS at late chronic stage. NCT00715052.
    PLoS ONE 11/2013; 8(11):e79995. DOI:10.1371/journal.pone.0079995 · 3.23 Impact Factor
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    • "). For example, Hattori et al. (2009) "
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    ABSTRACT: Neuroimaging in mild traumatic brain injury (mTBI) is reviewed. While computed tomography remains the acute standard for neuroimaging of mTBI, it is only sensitive to gross abnormalities and is typically performed as a measure to rule out more serious and life-threatening injury. Magnetic resonance imaging (MRI), especially at field strength of 3.0T, is the follow-up neuroimaging standard for assessing potential underlying structural injury to the brain. Several MRI sequences are particularly sensitive to subtle hemorrhagic lesions and signal abnormalities in white matter, sensitive enough to detect pathology when present in mTBI. Clinical correlation of neuropsychological outcome with neuroimaging findings is discussed along with the future potential for functional neuroimaging in evaluating the mTBI patient. KeywordsMild traumatic brain injury (mTBI)-Neuroimaging-Neuropsychological outcome-White matter-Magnetic resonance imaging (MRI)-Computed tomography (CT)-Functional neuroimaging
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