Neurological research
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Neurological research · Jun 1997
Multiparametric continuous monitoring of brain metabolism and substrate delivery in neurosurgical patients.
Brain function and tissue integrity are highly dependent on continuous oxygen supply and clearance of CO2. Aerobic metabolism is the major energy source to normal brain, however, during hypoxia and ischemia, lactate accumulation may sometimes be seen, indicating anaerobic glycolysis after severe head injury. Current monitoring techniques often fail to detect such events which can affect substrate delivery to the injured brain. ⋯ Brain pH was inversely related to brain CO2 for all patients. Brain glucose and lactate in patients with poor outcome were 639 microM l-1 +/- 330, and 1642 microM l-1 +/- 788, whereas patients with good outcome had brain glucose levels of 808 microM l-1 +/- 321 and lactate levels of 1001 microM l-1 +/- 417. Extended neuromonitoring using a combined sensor for brain oxygen, CO2, pH and temperature measurements, as well as a microdialysis probe for glucose and lactate analysis may optimize the management of comatose neurosurgical patients in the future, by allowing a fuller understanding of dynamic factors affecting brain metabolism.
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Neurological research · Jun 1997
Brain tissue pO2-monitoring in comatose patients: implications for therapy.
Monitoring of brain tissue partial pressure of O2 (ti-pO2) is a promising new technique that allows early detection of impending cerebral ischemia in brain-injured patients. The purpose of this study was to investigate the effects of standard therapeutic interventions used in the treatment of intracranial hypertension in comatose patients on cerebral oxygenation. In the neurosurgical intensive care unit ti-pO2, arterial blood pressure, intracranial pressure (ICP), cerebral perfusion pressure (CPP) and jugular bulb oxygen saturation (SjvO2) were prospectively studied (0.1 Hz acquisition rate) in 23 comatose patients (21 with severe traumatic brain injury, 2 with intracerebral hematoma) during various treatment modalities: elevation of CPP with dopamine (n = 35), lowering of the head (n = 22), induced arterial hypocapnia (n = 13), mannitol infusion (n = 16), and decompressive craniotomy (n = 1). ⋯ Based on the present data, our understanding of many interventions previously believed to improve brain oxygenation might have to be re-evaluated. A CPP > 60 mmHg emerges as the most important factor determining sufficient brain tissue pO2. Any intervention used to further elevate CPP does not improve ti-pO2, to the contrary, hyperventilation even bears the risk of inducing brain ischemia.
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Neurological research · Jun 1997
Dynamic changes of cerebral oxygenation measured by brain tissue oxygen pressure and near infrared spectroscopy.
The aim of this study was to find out whether a correlation exists between changes in brain tissue oxygen pressure (ti-pO2) and hemoglobin oxygenation (HbO2) measured by near-infrared spectroscopy. We studied 10 patients with severe head injury. A ti-pO2 monitoring device was introduced in the frontal white matter as soon as possible after administration. ⋯ In 3 patients the correlation was poor. The reason for poor correlation might be poor signal quality of the NIRS sensor or inhomogenous distribution of ischemic areas in the whole brain. We conclude that under the condition of a stable NIRS signal and a diffuse brain lesion, changes of ti-pO2 are well reflected by NIRS.
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Neurological research · Dec 1996
An electrical network model of intracranial arteriovenous malformations: analysis of variations in hemodynamic and biophysical parameters.
The propensity of intracranial arteriovenous malformations (AVMs) to hemorrhage is correlated significantly with their hemodynamic features. Biomathematical models offer a theoretical approach to analyse complex AVM hemodynamics, which otherwise are difficult to quantify, particularly within or in close proximity to the nidus. Our purpose was to investigate a newly developed biomathematical AVM model based on electrical network analysis in which morphological, biophysical, and hemodynamic characteristics of intracranial AVMs were replicated accurately. ⋯ The described novel biomathematical model characterizes the transnidal and intranidal hemodynamics of an intracranial AVM more accurately than previously possible. A wide range of hemodynamic and biophysical parameters can be implemented in this AVM model to result in simulation of human AVMs with differing characteristics (e.g. low-flow and high-flow AVMs). This experimental model should serve as a useful research tool for further theoretical investigations of a variety of intracranial AVMs and their hemodynamic sequelae.
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Neurological research · Oct 1996
The venous system of the lateral sellar compartment (cavernous sinus): an histological and embryological study.
The microanatomy of the lateral sellar or parasellar venous system (so-called cavernous sinus) is poorly understood and is still passionately debated. The exact nature of this venous structure is not yet clear whether it is a plexus or a sinus. In order to understand the anatomy of this area better, an embryological and adult microanatomical study was performed. ⋯ They differ from true veins. As other dural sinuses, it may contain different types of channels: from simple venous canal to complex venous plexus. The opinions of different authors are reviewed in the introduction and discussed with the results.