Journal of neurosurgical anesthesiology
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J Neurosurg Anesthesiol · Jul 1996
Case ReportsUnilateral blindness due to patient positioning during cervical syringomyelia surgery: unilateral blindness after prone position.
During spinal surgery using a horseshoe headrest with the patient in the prone position, the possibility of central retinal artery occlusion (CRAO) increases, and its cause can be attributed primarily to excessive extraocular pressure, a very rare complication. This report describes a case of CRAO, occurring in an adult, after cervical syringomyelia surgery in which a horseshoe headrest was used.
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J Neurosurg Anesthesiol · Jul 1996
Case ReportsContinuous postoperative lCBF monitoring in aneurysmal SAH patients using a combined ICP-laser Doppler fiberoptic probe.
Cerebral vasospasm remains the principal cause of morbidity and mortality following successful clipping of intracranial aneurysms. Current management often requires subjective judgments concerning presumed abnormalities of cerebral blood flow. In this study, a combined intracranial pressure (ICP)-laser Doppler flowmetry (LDF) fiberoptic probe that permits continuous monitoring of local cerebral blood flow (lCBF) was used in the postoperative management of 20 aneurysm patients. ⋯ The combined probe also provided the ability to obtain precise and detailed information concerning the presence or absence of cerebral autoregulation and CO2 vascular reactivity, and allowed calculation of the cerebral vascular resistance. Continuous monitoring of lCBF in this manner complemented by transcranial Doppler and angiographic data permitted early detection of cerebral ischemia, helped to differentiate cerebral ischemia from edema and hyperemia, was useful in titrating blood pressure and fluid management, provided direct feedback about the effectiveness of instituted therapies, and determined early on when medical management was of no avail and that interventional neuroradiology was indicated. Evidence is presented that the presence of angiographic vasospasm and increased velocities on TCD do not always correlate with ischemia in the microcirculation and that direct measurements of lCBF are often at variance with calculations of cerebral perfusion pressure (CPP).
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Near-infrared spectroscopy is a technique used to monitor cerebral oxygenation. To validate the method, we measured regional oxygen saturation (rSo2) in the brains of 18 dead subjects (mean age, 74.4 +/- 14.6 years) 19.8 +/- 18.2 h (range, 1-73) after cessation of systemic circulation, and in 15 healthy probands (mean age, 34.2 +/- 8.7 years) with an INVOS 3100 cerebral oximeter. The mean (+/-SD) rSo2 in the dead subjects was 51.0 +/- 26.8% [range, 6-88%; left, 48.4 +/- 28.0% (n = 21); right, 54.4 +/- 25.7% (n = 16)]. ⋯ After removal of the brain at autopsy in five of the dead subjects, the rSo2 was 73.4 +/- 13.3% (15 measurements). Six of 18 of the dead subjects had values above the lowest values found in the healthy adults (> or = 60%). These findings raise concerns about the validity of cerebral rSo2 data in adults obtained by the INVOS 3100 system.
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J Neurosurg Anesthesiol · Jul 1996
Case ReportsConventional multimodality monitoring and failure to detect ischemic cerebral blood flow.
We report a case of cerebral infarction following traumatic brain injury associated with low cerebral blood flow, but not detected by measurements of jugular venous oxygen saturation, cerebral lactate production, cerebral perfusion pressure, transcranial Doppler ultrasound, or measures of systemic hemodynamics.
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Isotonic fluids have been thoroughly studied and for the vast majority of neurosurgical patients are both safe and effective. Conversely, HS may have some transient beneficial effects on cerebral physiology in animal models of brain injury. ⋯ Until the risk-benefit ratio of HS is better defined in humans, physicians should exercise caution and adhere to the Hippocratic oath. However, if this risk-benefit ratio is defined, HS may hold promise for the clinical conditions cited herein as well as other novel uses (cardiopulmonary bypass, spinal trauma [55,56]).