Articles: brain-injuries.
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Previous studies have shown that traumatic brain injury (TBI) significantly reduces cerebral blood flow determined in vivo and reduces vascular reactivity in the pial circulation measured with cranial window preparations. We have now tested the hypothesis that TBI induces these changes by impairing intrinsic contractile activity of cerebral arteries. Anesthetized rats underwent moderate (2.2 atm) and severe (3.0 atm) midline fluid percussion TBI or sham injury following which posterior cerebral or middle cerebral arteries were isolated and isometric force generation was measured. ⋯ Acetylcholine induced an endothelium-dependent relaxation of posterior and middle cerebral arteries; the magnitude of the response was unaffected by moderate TBI. To determine whether prolonged in situ exposure of vessels to the traumatized cerebral milieu could reveal an alteration in intrinsic contractility, posterior cerebral arteries were isolated 30 min after TBI; again, no differences in the tension or relaxation responses were observed. It is concluded that midline fluid percussion TBI did not affect contraction or relaxation of proximal middle or posterior cerebral arteries in rats.
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Various surgical procedures in neurosurgery end with cranial vault defects. It is generally believed that the reason for repair of the skull defect is cosmetic or protective. ⋯ In the sinking scalp flap syndrome the deterioration has been thought to be related to the concavity of the skin flap and underlying brain tissue secondary to atmospheric pressure and also to the in-and-out displacement of the brain through the skull defect. Five cases of symptomatic patients after craniectomy are reported, of which all had a neurologic deterioration that was improved by cranioplasty.
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Cranioplasty is among the oldest surgical procedures. Trauma, infections, tumors and compression caused by brain edema are some of the reasons for the removal of bone. ⋯ However, there are many theories suggesting that an underlying physiological alteration may occur which may require the correction of the bone defect; many patients improve after surgery. We discuss the physiopathological basis of the "syndrome of the trephined" and try to achieve a better understanding of the present status of cranioplasty and its possible therapeutic role.
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Intensive care medicine · Mar 1997
How reliable is the predictive value of SEP (somatosensory evoked potentials) patterns in severe brain damage with special regard to the bilateral loss of cortical responses?
In patients sustaining severe brain damage (SBD), prediction of later outcome is often very difficult, in particular under conditions of therapeutic management like relaxation and intravenous phenobarbital. Somatosensory evoked potentials (SEP) correlated best with later prognosis and expected neurological deficit. In detail, the primary bilateral loss of cortical responses (BLCR) is regarded to be a reliable marker for poor prognosis. The goal of the following prospective study was to reassess the prognostic value of early serial median nerve SEP recording in severe brain damage in comparison to other neurophysiological, clinical, and neuroradiological parameters and, additionally, to test the hypothesis, that the BLCR-pattern is always associated with a poor prognosis and is never reversible. ⋯ SEP allow an early reliable assessment of both poor and good prognosis in SBD, in particular when applied serially. BLCR does not always imply a fatal diagnosis, as a circumscribed contusional lesion rarely may lead to selective reversible blockage of ascending somatosensory pathways in the brainstem. In contradiction to this lesional etiology, a hypoxia-induced BLCR pattern seems to correlate strictly with a poor prognosis, reflecting a different pathogenesis with diffuse destruction of cortex and thalamocortical pathways.
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Journal of neurosurgery · Mar 1997
Monitoring of autoregulation using laser Doppler flowmetry in patients with head injury.
The authors studied 31 comatose head-injured patients to assess the clinical usefulness of laser Doppler flowmetry (LDF) in continuous autoregulation monitoring. The LDF probes were placed on the surface of the cerebral cortex. Data on LDF, intracranial pressure (ICP), and arterial blood pressure (ABP) were recorded and continuously entered into a computer. ⋯ In 11 patients who had persistent loss of autoregulation, nine died and two were severely disabled. In five cases the LDF probe lost contact with the cerebral cortex and no useful information was obtained. Real-time measurement of autoregulation using LDF and CPP monitors was achieved and the findings were related to outcome in these patients.