Acta neurochirurgica. Supplement
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Acta Neurochir. Suppl. · Jan 2016
Plateau Waves of Intracranial Pressure and Partial Pressure of Cerebral Oxygen.
This study investigates 55 intracranial pressure (ICP) plateau waves recorded in 20 patients after severe traumatic brain injury (TBI) with a focus on a moving correlation coefficient between mean arterial pressure (ABP) and ICP, called PRx, which serves as a marker of cerebrovascular reactivity, and a moving correlation coefficient between ABP and cerebral partial pressure of oxygen (pbtO2), called ORx, which serves as a marker for cerebral oxygen reactivity. ICP and ICPamplitude increased significantly during the plateau waves, whereas CPP and pbtO2 decreased significantly. ABP, ABP amplitude, and heart rate remained unchanged. ⋯ Our data show profound cerebral vasoparalysis on top of the wave and, to a lesser extent, impairment of cerebral oxygen reactivity. The different behavior of the indices may be due to the different latencies of the cerebral blood flow and oxygen level control mechanisms. While cerebrovascular reactivity is a rapidly reacting mechanism, cerebral oxygen reactivity is slower.
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Acta Neurochir. Suppl. · Jan 2016
Dynamic Cerebrovascular and Intracranial Pressure Reactivity Assessment of Impaired Cerebrovascular Autoregulation in Intracranial Hypertension.
We previously suggested that the discrepancy between a critical cerebral perfusion pressure (CPP) of 30 mmHg, obtained by increasing intracranial pressure (ICP), and 60 mmHg, obtained by decreasing arterial pressure, was due to pathological microvascular shunting at high ICP [1], and that the determination of the critical CPP by the static cerebral blood flow (CBF) autoregulation curve is not valid with intracranial hypertension. Here, we demonstrated that induced dynamic ICP reactivity (iPRx), and cerebrovascular reactivity (CVRx) tests accurately identify the critical CPP in the hypertensive rat brain, which differs from that obtained by the static autoregulation curve. ⋯ At each CPP, a transient 10-mmHg increase in arterial pressure was induced by bolus intravenous dopamine. iPRx and iCVRx were calculated as ΔICP/Δ mean arterial pressure (MAP) and as ΔCBF/ΔMAP, respectively. The critical CPP at high ICP, obtained by iPRx and iCVRx, is 50 mmHg, where compromised capillary flow, transition of blood flow to nonnutritive microvascular shunts, tissue hypoxia, and brain-blood barrier leakage begin to occur, which is higher than the 30 mmHg determined by static autoregulation.
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Acta Neurochir. Suppl. · Jan 2016
Acute Hyperglycemia Is Associated with Immediate Brain Swelling and Hemorrhagic Transformation After Middle Cerebral Artery Occlusion in Rats.
Hemorrhagic transformation occurs in as many as 48 % of stroke patients and is a major contributor to post-insult morbidity and mortality. Experimental models of hemorrhagic transformation are utilized for understanding the mechanisms behind its development, as well as for investigating potential therapeutics for prevention and reduction of bleeding. Thoroughly studying animal models of hemorrhagic transformation is critically important for testing novel treatments. ⋯ Animals were sacrificed at 0.25, 1, 3, or 24 h after reperfusion for measurement of infarct volume, brain swelling, and hemoglobin volume. Within 15 min of reperfusion, the infarct volume was significantly larger than in sham animals and did not increase in size over the 24 h. However, both brain swelling and hemorrhagic transformation, which began immediately after reperfusion, increase over 24 h after reperfusion.
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Acta Neurochir. Suppl. · Jan 2016
The Upper Limit of Cerebral Blood Flow Autoregulation Is Decreased with Elevations in Intracranial Pressure.
The upper limit of cerebrovascular pressure autoregulation (ULA) is inadequately characterized. We sought to delineate the ULA in a neonatal swine model. ⋯ Neonatal piglets without intracranial pathological conditions tolerated acute hypertension, with minimal perturbation of cerebral blood flow. Piglets with acutely elevated intracranial pressure, with or without trauma, demonstrated loss of autoregulation when subjected to arterial hypertension.
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Acta Neurochir. Suppl. · Jan 2015
Multicenter StudyCharacteristics of patients without neuropsychological deficits following aneurysmal subarachnoid haemorrhage.
Previous studies have shown that the incidence of neuropsychological deficits (NPD) after aneurysmal subarachnoid haemorrhage (aSAH) is high despite excellent outcome evaluated by traditional neurological grading scales. The aim of this study was to elucidate the clinical characteristics in patients presenting with aSAH who had a good clinical outcome without NPD. ⋯ Patients without NPD after aSAH are likely to present with mild admission scores, develop neither chronic hydrocephalus nor DCI. In this series the aneurysm occlusion modality did not influence the cognitive outcome.