Acta neurochirurgica. Supplement
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Acta Neurochir. Suppl. · Jan 1998
Incidence of intracranial hypertension after severe head injury: a prospective study using the Traumatic Coma Data Bank classification.
Intracranial hypertension (ICH) is a frequent finding in patients with a severe head injury. High intracranial pressure (ICP) has been associated with certain computerized tomography (CT) abnormalities. The classification proposed by Marshall et al. based on CT scan findings, uses the status of the mesencephalic cisterns, the degree of midline shift, and the presence or absence of focal lesions to categorize the patients into different prognostic groups. Our aim in this study was to analyze the ICP evolution pattern in the different groups of lesions of this classification. ⋯ 3 patients had a normal CT scan, and none of them presented intracranial hypertension. In diffuse injury type II, the ICP evolution may be quite different. Patients with bilateral brain swelling (Diffuse Injury III) have a high risk of increased ICP (63.2%). Although in our study the frequency of Diffuse Injury IV was low, all patients in this category had a refractory ICP. In the category of evacuated mass lesions, two thirds of the patients presented an intracranial hypertension. In one third, ICP was refractory to treatment. 85% of patients with a non-evacuated mass lesion showed an increased ICP.
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Acta Neurochir. Suppl. · Jan 1998
The relationship of pulsatile cerebrospinal fluid flow to cerebral blood flow and intracranial pressure: a new theoretical model.
An electrical-equivalent circuit model of the cerebrovascular system is proposed, components of which directly relate to cerebrospinal fluid (CSF) compartment compliance and the determination of intracranial pressure (ICP). The model is based on three premises: 1) Under normal, physiologic conditions, the conversion of pulsatile arterial to nonpulsatile venous flow occurs primarily as a result of arterial compliance. Nonpulsatile venous flow is advantageous because less energy is required to maintain constant flow through the venous system, which comprises 75-80% of total blood volume. 2) Dynamic CSF movement across the foramen magnum is the primary facilitator by which intracranial arterial expansion occurs. ⋯ An interference of transcranial CSF movement results in a decrease in cerebral blood flow (CBF) due to inertial effects impeding pulsatile venous flow. Feedback regulation in response to this decreased CBF leads to arteriolar vasodilatation (decreased resistance), thereby lowering the pressure difference between internal carotid and capillary pressures. Assuming no changes in the BBB potential, ICP increases linearly as capillary pressure increases.
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Acta Neurochir. Suppl. · Jan 1998
Morphological and hemodynamic evaluations by means of transcranial power Doppler imaging in patients with severe head injury.
The following conditions of 17 patients with severe head injury (ages 9-76; mean 37:12 focal and 5 diffuse injuries) were evaluated during acute phase (1-14 days after injury, mean 5) by transcranial power Doppler imaging (PDI), a new color Doppler ultrasound technique: a) morphological changes via temporal window, b) hemodynamic changes in major intracranial/cervical arteries based on measured angle-corrected time-averaged mean (TAM)/ peak velocities and vessel diameter (Va), and calculated pulsatility indices (PI), vessel area (Va), and flow volume (Vf = TAM x Va). a) 1) Major trunks of intracranial vessels and circle of Willis and pathological changes in frontal/temporal lobes and midbrain were finely visualized. 2) Contusional hemorrhage and cerebral contusion demonstrated irregular hyper- and hypo-echoic lesions, respectively. 3) Delayed epidural hematoma showed a hyper-echoic band. b) 1) Decreased velocities, significant PI increase, and Va increase tendency were observed in intracranial arteries. 2) Increased velocities with Vf increase but no Va decrease indicated hyperemia rather than vasospasm. 3) Va in the intracranial vessels, however, tended to increase PDI appears useful in evaluating real-time and simultaneous morphological and hemodynamic information in pathogenesis and neurointensive care of patients with severe head injury.
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Acta Neurochir. Suppl. · Jan 1998
Moderate hypothermia and brain temperature in patients with severe middle cerebral artery infarction.
Elevated temperature is known to facilitate neuronal injury after ischemia. After head injury a gradient between temperature and body temperature of up to 3 degrees C higher in the brain has been reported. Hypothermia may limit some of the deleterious metabolic consequences of such increased temperature. ⋯ After MCA stroke, human intracerebral temperature is higher than central body-core temperature. Mild hypothermia in the treatment of severe cerebral ischemia using cooling blankets is safe and does not lead to severe side effects. Mild hypothermia can help to control critically elevated ICP values in severe space-occupying stroke and may improve clinical outcome in these patients.
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Acta Neurochir. Suppl. · Jan 1998
Continuous intracranial multimodality monitoring comparing local cerebral blood flow, cerebral perfusion pressure, and microvascular resistance.
Maintaining cerebral perfusion pressure (CPP) above 70 mmHg is currently a mainstay of neurosurgical critical care. Shalmon, et al. recently showed poor correlation between CPP and regional cerebral blood flow (CBF) [1]. To study the relationship between CPP and CBF, at a microvascular level, we retrospectively analyzed multimodality digital data from 12 neurosurgical critical care patients in whom a combined intracranial pressure (ICP)--laser Doppler flowmetry (LDF) probe (Camino, San Diego) had been placed. ⋯ Autoregulation was impaired or absent in all monitored patients. We conclude that with disrupted autoregulation, CPP above 70 mmHg does not necessarily insure adequate levels of cerebral perfusion. Restoration and maintenance of adequate cerebral perfusion should be performed under the guidance of direct CBF monitoring.