Acta neurochirurgica. Supplement
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Acta Neurochir. Suppl. · Jan 2005
ReviewPhenomenological aspects of consciousness--its disturbance in acute and chronic stages.
The meaning of a disturbance of consciousness is completely different in an acute as opposed to a chronic stage. In the acute stage, the grade of arousal is the most essential component in order to assess the changes of the level of intracranial pressure in neurosurgical emergency room. ⋯ We propose the difference in conception between consciousness and mind; that is, consciousness consists of psycho-sensory afferent system, mind of psycho-motor efferent and afferent system, and memory and language as liaison officers between them. This proposal would play a role to understand mental change in the natural aging processes, when memory and cognition are deteriorating gradually, but is still in evolution in the field of culture.
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Acta Neurochir. Suppl. · Jan 2005
Clinical TrialMRI study of cerebral blood flow and CSF flow dynamics in an upright posture: the effect of posture on the intracranial compliance and pressure.
Postural related changes in cerebral hemodynamics and hydrodynamics were studied using Magnetic Resonance Imaging (MRI) measurements of cerebral blood flow and cerebrospinal fluid (CSF) flow dynamics. Ten healthy volunteers (mean age 29 +/- 7) were studied in supine and upright (sitting) postures. A Cine phase-contrast MRI technique was used to image the pulsatile blood flow to the brain, the venous outflow through the internal jugular, epidural, and vertebral veins, and the bi-directional CSF flow between the cranium and the spinal canal. ⋯ A considerable smaller amount of CSF flow between the cranium and the spinal canal (58%), a much larger intracranial compliance (a 2.8-fold increase), and a corresponding decrease in the MRI-derived ICP were also measured in the sitting position. These changes suggest that the increased cerebrovascular and intracranial compliances in the upright posture are primarily due to reduced amounts of blood and CSF residing in their respective intracranial compartments in the upright position. This work demonstrates the ability to quantify neurophysiologic parameters associated with regulation of cerebral hemodynamics and hydrodynamics from dynamic MR imaging of blood and CSF flows.
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Acta Neurochir. Suppl. · Jan 2005
Clinical TrialRe-defining the ischemic threshold for jugular venous oxygen saturation--a microdialysis study in patients with severe head injury.
Neurological change is more likely to occur when jugular venous oxygen saturation (SjvO2) is less than 50%. However, the value indicating cellular damage has not been clearly defined. We determined the critical SjvO2 value below which intracerebral extracellular metabolic abnormalities occurred in 25 patients with severe head injury. ⋯ Analysis of variance showed that there were rapid increases in glutamate, glycerol and lactate when SjvO2 dropped below 40, 43 and 45% respectively. Extracellular glucose decreased when SjvO2 dropped below 42%. Our findings suggested that the ischemic threshold for SjvO2 in patients with severe head injury is 45%, below which secondary brain damage occurred.
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Acta Neurochir. Suppl. · Jan 2005
Cranial and spinal dural arteriovenous malformations and fistulas: an update.
Awareness of a potential arteriovenous fistula is critical for diagnosis of cranial as well as spinal fistulas. The natural history of cranial and spinal dural arteriovenous fistulas has been clarified during the last decade and interdisciplinary therapies have experienced a substantial development recently. The classification of Cognard & Merland is now the most widely accepted one for cranial dural AVF. ⋯ The risk associated with surgical or endovascular treatment of benign fistulas is higher than the risk of eliminating fistulas that have already led to cortical venous reflux. Transvenous endovascular occlusion or surgical disconnection of draining veins is the treatment of first choice for cranial and spinal dAVF with venous flow reversal. Benign cranial dural arteriovenous fistulas are a developing indication for radiosurgery.
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The optimal therapy of sustained increase in intracranial pressure (ICP) is still controversial. The "Lund concept" is based on the physiological volume regulation of the intracranial compartments. In addition to its other functions the blood-brain barrier (BBB) is the most important regulator of brain volume. ⋯ Reduction of cerebral blood volume. The efficacy of the treatment protocol has been evaluated in experimental and clinical studies regarding the physiological and biochemical (utilizing intracerebral microdialysis) effects. The clinical experiences have been favourable.