Neurological research
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Neurological research · Jan 1998
Near-infrared reflected spectroscopy and electroencephalography during carotid endarterectomy--in search of a new shunt criterion.
The aim of this clinical study was to evaluate cerebral oximetry with near-infrared reflected spectroscopy (NIRS) as a monitoring system during carotid endarterectomy. The cross-clamping changes of cerebrovascular hemoglobin oxygen saturation (cereb. O2 satn.) were compared with data from a processed EEG analysis. ⋯ Higher cut-off values resulted in a gradual increase of the specificity at the expense of a significant decrease of the sensitivity. In conclusion, improved validation and calibration techniques are necessary before this technique may be used for relevant assessment of cerebral oxygenation during carotid surgery. In particular, in order to define a new shunt criterion, the focal aspect of this new technique is probably one of the limitations.
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Monitoring of regional cerebral oxygen saturation (r. cereb. O2 satn.) was carried out continuously in 12 healthy subjects (mean age 35.2 +/- 4.4 years; range 26-41 years; 4 women, 8 men), prior to, during and following acupuncture. Measurements were obtained with the INVOS 3100 cerebral oximeter (Somanetics Corp., Troy, USA). ⋯ An increase in the cerebral oxygen saturation could be registered with the help of microelectrodes in the cortex. This is parallel evidence to the present results with near infrared spectroscopy and transcranial Doppler sonography. Quantifiable changes in the physiological effects of acupuncture may contribute to improved acceptance of this unconventional complementary medical procedure.
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Neurological research · Jan 1998
Cerebral blood flow and tissue oxygenation monitoring during aneurysm surgery.
Regional cerebral blood flow may be compromised during aneurysm surgery. This may occur during vessel occlusion by temporary clips or result from malposition of the definitive aneurysm clip. Post-operative cerebral vasospasm may also compromise cerebral blood flow and is an important cause of morbidity. ⋯ Initial tissue oxygen levels were low but improved in all cases as the intracranial pressure was reduced. This effect was independent of the cerebral perfusion pressure. Laser Doppler flow provided an indicator of compromised brain function and tissue oxygenation an indicator of established ischemia.
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Neurological research · Jan 1998
Hypothermia influences time course of intracranial pressure, brain temperature, EEG and microcirculation during ischemia-reperfusion.
Time-related effects of hypothermia on intracranial pressure (ICP), brain (Tbr) and rectal temperature (Tc), cortical (LDF) and subcortical microcirculation (ti-pO2) were assessed following a unilateral balloon induced epidural focal mass lesion in rats. Results of injured but normothermia animals (Group A, n = 6) were compared with hypothermia animals (Group B, n = 6). Parameters were recorded during balloon expansion (BE) to an ICP of 60 mmHg followed by a period of sustained inflation (SI) of 30+/-2 min. ⋯ After reperfusion the secondary increase of ICP was reduced (p < 0.006) and CPP was improved by 20% in Group B. EEG restored quicker in Group B than Group A (106+/-11 min vs. 188+/-25 min). Intra-ischemic hypothermia improved cerebral microcirculation, prevented a secondary increase of ICP and improved restoration of EEG after ischemia-reperfusion.
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Neurological research · Jan 1998
Expression of inducible nitric oxide synthase in rats following subarachnoid hemorrhage.
The possible expression of the inducible isoform of nitric oxide synthase (iNOS) was examined in a rat model of subarachnoid hemorrhage (SAH). Subarachnoid hemorrhage was induced by the injection of autologous blood into the cisterna magna using stereotactic technique under general anesthesia. The rats were then killed at specific time intervals between 4 hours to 7 days after SAH. ⋯ This immunoreactivity persisted faintly on Day 2, but had completely disappeared on Day 7. A vascular diameter study disclosed a vasoconstrictive change in the middle cerebral artery after SAH. Taken together, these results are thus considered to confirm the expression of iNOS in the infiltrated inflammatory cells after the insult of SAH, which may therefore play an introductory role in the development of the pathological series of events after SAH, including vasospasm.