Journal of neurotrauma
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Journal of neurotrauma · May 2011
High intracranial pressure effects on cerebral cortical microvascular flow in rats.
To manage patients with high intracranial pressure (ICP), clinicians need to know the critical cerebral perfusion pressure (CPP) required to maintain cerebral blood flow (CBF). Historically, the critical CPP obtained by decreasing mean arterial pressure (MAP) to lower CPP was 60 mm Hg, which fell to 30 mm Hg when CPP was reduced by increasing ICP. We examined whether this decrease in critical CPP was due to a pathological shift from capillary (CAP) to high-velocity microvessel flow or thoroughfare channel (TFC) shunt flow. ⋯ Decreasing CPP by MAP decreased TFC shunt flow with a smaller rise in NADH and no edema. Doppler flux decreased less with increasing ICP than decreasing MAP. The decrease seen in the critical CPP with increased ICP is likely due to a redistribution of microvascular flow from capillary to microvascular shunt flow or TFC shunt flow, resulting in a pathologically elevated CBF associated with tissue hypoxia and brain edema, characteristic of non-nutritive shunt flow.
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Journal of neurotrauma · May 2011
Prognostic value of magnetic resonance imaging in moderate and severe head injury: a prospective study of early MRI findings and one-year outcome.
The clinical benefit of early magnetic resonance imaging (MRI) in severe and moderate head injury is unclear. We sought to explore the prognostic value of the depth of lesions depicted with early MRI, and also to describe the prevalence and impact of traumatic brainstem lesions. In a cohort of 159 consecutive patients with moderate to severe head injury (age 5-65 years and surviving the acute phase) admitted to a regional level 1 trauma center, 106 (67%) were examined with MRI within 4 weeks post-injury. ⋯ Limitations of the current study include lack of blinded outcome evaluations and insufficient statistical power to assess the added prognostic value of MRI when combined with clinical information. We conclude that in patients with severe head injury surviving the acute phase, depth of lesion on the MRI was associated with outcome, and in particular, bilateral brainstem injury was strongly associated with poor outcomes. In moderate head injury, surprisingly, there was no association between MRI findings and outcome when using the GOSE score as outcome measure.
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Journal of neurotrauma · May 2011
Rasch measurement analysis of the Mayo-Portland Adaptability Inventory (MPAI-4) in a community-based rehabilitation sample.
The precise measurement of patient outcomes depends upon clearly articulated constructs and refined clinical assessment instruments that work equally well for all subgroups within a population. This is a challenging task in those with acquired brain injury (ABI) because of the marked heterogeneity of the disorder and subsequent outcomes. Although essential, the iterative process of instrument refinement is often neglected. ⋯ Results indicated that the MPAI-4 is a valid, reliable measure of outcome following traumatic ABI, which measures a broad but unitary core construct of outcome after ABI. Further, the MPAI-4 is composed of items that are unbiased toward selected subgroups except where differences could be expected [e.g., more chronic traumatic brain injury (TBI) patients are better able to negotiate demands of transportation than more acute TBI patients]. We address the trade-offs between strict unidimensionality and clinical applicability in measuring outcome, and illustrate the advantages and disadvantages of applying single-parameter measurement models to broad constructs.