To determine the degree of MCA vasospasm necessary to exceed the ischaemic threshold of blood flow reduction to less than 1/3 normal flow, we developed a computer model of blood flow in the middle cerebral artery distribution. When solved for a 3 mm trunk diameter, it showed a normal flow ...

Cocaine causes serious neurologic and neuropsychiatric complications. Cocaine-induced seizures are common and appear to be due to the local anaesthetic actions of this compound. Cocaine induced stroke has varied mechanisms. With ischemic stroke there is severe vasospasm induced by rises in brain catecholamines. These changes can persist for many weeks ...

The present study examines the possibility that lesions induced by intrastriatal injections of endothelin-1 (ET-1, 0.43 nmol/0.5 microliter) are ischemic in nature due to a vasoconstriction of the cerebral microvessels. In time course and dose-response experiments with ET-1 and in comparisons with ET-3, the volume of the lesions has been ...

PURPOSE: We examined the xenon/CT method of measuring cerebral blood flow in assessing the location, pattern of onset, and severity of delayed cerebral ischemia. PATIENTS AND METHODS: Fourteen patients with delayed neurologic deficits due to ischemia were selected from a group of 66 patients with subarachnoid hemorrhage. All blood flow ...

Simultaneous cerebral blood flow (CBF) and glucose metabolism (CMRglu) studies with a double isotope autoradiographic technique were applied to squirrel monkeys submitted to a unilateral pre- or postganglionic trigeminal lesion. The CBF values were not affected following a pre- or postganglionic lesion per se. In contrast, there was a global ...

Injections of blood into the interpeduncular fossa and cisterna magna in the squirrel monkey produce an angiographically demonstrable, biphasic cerebral vasospasm with a maximal acute spasm at ten minutes and a maximal late spasm at six days after the subarachnoid haemorrhage (SAH). Selective lesioning of the A2 nucleus in the ...

Nimodipine is a calcium antagonist which improves learning and memory in brain-lesioned or aged animals (LeVere & Sandin, 1989; Schuurman & Traber, 1989). It also accelerates the recovery of experimentally damaged sciatic nerves (van der Zee et al., 1987) and reduces age-associated gait abnormalities in aging rats (Schuurman et al., ...

The relationships of intracranial pressure (ICP), systemic blood pressure (SBP) and cerebral blood flow (CBF) during experimental subarachnoid haemorrhage were investigated in cats. Continuous monitoring of regional cerebral blood flow (rCBF) was done by a thermal diffusion method using a Peltier stack. During haemorrhage ICP rose within 5.4 +/- 0.97 ...

Fibrinopeptide A (FPA) levels which have been shown to be a quantitative index of thrombin generation, were measured in blood and cerebrospinal fluid (CSF) samples from patients following subarachnoid haemorrhage (SAH) and from a control population. The levels found in samples obtained in patients following SAH are compared with those ...

A subarachnoid haemorrhage (SAH) in the squirrel monkey was produced by injection of blood via a permanently implanted catheter connected to the cisterna magna and a cannula stereotactically inserted into the interpeduncular cistern. Repeated angiographic examinations of the vertebro-basilar and right internal carotid arteries revealed a biphasic vasospasm with a ...

Prostaglandin E2, thromboxane B2, and 6-oxo-prostaglandin F1 alpha were assayed in blood and cerebrospinal fluid samples from patients after subarachnoid hemorrhage (SAH) and from a control population. The levels found in samples obtained from patients after SAH were compared with those found in controls and were also correlated with a ...

The effect of total obstruction of blood flow on traumatically induced vasospasm was studied in the central arteries of rabbits' ears. All side branches were ligated along a 7 cm segment of the artery. Obstruction of blood flow was achieved by ligation of the central artery distal to this segment. ...

Blood flow velocity in the basal intracranial arteries can be reliably recorded using transcranial Doppler (TCD) ultrasonography. The utility of Doppler ultrasound in detecting stenosis of arteries has therefore been extended to include the intracranial basal arteries. This has been useful in detecting intracranial stenosis from a variety of causes ...

The present study evaluates the interdependence of clinical stage, cerebral vasospasm, intracranial pressure (ICP), and transcranial Doppler ultrasonographic parameters. The mean flow velocity of blood in the middle cerebral artery and the index of cerebral circulatory resistance as a measure of the peripheral vascular flow resistance were determined in 76 ...

The central effects of endothelin-1 (Et-1, 10-30 pmol in 2.5 microliters injected intracisternally) have been investigated in the conscious rat. With 10 and 20 pmol Et-1, no significant change in blood pressure was observed. With 30 pmol Et-1, mean arterial blood pressure rose by 40 +/- 10 mm Hg with ...

This study was performed to examine changes in local cerebral blood flow during hypotensive anaesthesia with either prostaglandin E1 (PGE1) or trimethaphan (TMP). Local cerebral blood flow (LCBF), mean blood pressure (MBP), heart rate (HR), and hourly urine output (UO) were studied in 51 patients undergoing cerebral aneurysm surgery with ...

A primate model was used to determine whether oxyhemoglobin (OxyHb), methemoglobin (MetHb), or bilirubin is likely to be responsible for cerebral vasospasm following subarachnoid hemorrhage (SAH). Forty cynomolgus monkeys were randomly assigned to one of five groups. On Day 0, each animal underwent angiography followed by right craniectomy and placement ...

Previous studies of cerebral oxygen metabolism and extraction in patients with subarachnoid hemorrhage (SAH) have yielded conflicting results. We used positron emission tomography (PET) to measure the regional cerebral metabolic rate for oxygen (rCMRO2), oxygen extraction fraction (rOEF), and cerebral blood flow (rCBF) 16 times in 11 patients with aneurysmal ...

We evaluated N-isopropyl-p-[123I]iodoamphetamine (123I-IMP) single photon emission computed tomography (SPECT) as a method for identifying normal pressure hydrocephalic (NPH) patients eligible for shunting procedures. 123I-IMP SPECT scans were taken before and after cerebrospinal fluid (CSF) taps in NPH cases. Post-subarachnoid hemorrhagic (SAH) patients showed apparent frontal blood flow reduction but ...

The spasmolytic and antispasmodic effects of Xylocaine in different concentrations were studied. Twenty-five Wistar rats were divided into five groups according to the concentrations of Xylocaine used (2 percent, 4 percent, 10 percent, 20 percent, and 40 percent). The diameters of rat femoral arteries were measured with vernier calipers under ...

Impairment of cerebral autoregulation and development of hyponatraemia are both implicated in the pathogenesis of delayed cerebral ischaemia and infarction following subarachnoid haemorrhage (SAH) but the pathophysiology and interactions involved are not fully understood. We have studied the effects of hyponatraemia and SAH on the cerebral vasomotor responses of the ...

The neurosurgical application was evaluated of a flow-directed oximetry thermodilution catheter for measurement of oxygen saturation in the jugular vein, which reflects cerebral blood flow (CBF). The catheter allows estimation of changes in CBF during carotid endarterectomy and therapeutically induced hypertension in the management of delayed vasospasm after subarachnoid hemorrhage.

Multiple injections of autologous blood were made around the basilar artery of rabbits through a silicone catheter placed into the prepontine cistern. The total blood injected was 3 ml/kg in aliquots of 0.5 to 0.8 ml over a 4-hour period. Control angiograms were obtained 7 days before this procedure. Groups ...

Cerebral vasospasm occurs, following subarachnoid haemorrhage, in the majority of patients and is accompanied by cerebral ischaemia in 30%. The objectives of this article are to review (1) the effects of subarachnoid haemorrhage and vasospasm on cerebral blood flow (CBF); (2) the effects of induced hypotension and hypocapnia on CBF ...

The dura-arachnoid junction is examined in normal animals and in animals subjected to subdural infusion of blood immediately prior to death, simulating acute subdural hemorrhages. The Norwegian landrace pig is used as the experimental animal. Horseradish peroxidase (HRP) has been added to the injected blood to serve as a macromolecular ...

Recent interest in the regulatory functions of large cerebral arteries has led to many studies addressing the specific reactivity of these vessels. Current data originate mainly from in vitro experiments, as in vivo studies of larger intracranial cerebral arteries have been cumbersome so far due to the lack of a ...

The amount of effused blood following a subarachnoid haemorrhage (SAH) was estimated in 48 patients by cerebral computerized tomographic scanning. The cerebral oxygen consumption (CMRO2) was calculated as arteriovenous difference for oxygen multiplied by mean cerebral blood flow measured by the 133-Xe inhalation technique. A significant negative correlation was observed ...

1. Central nervous system (CNS) side effects are observed during treatment with all nonsteroidal anti-inflammatory drugs (NSAIDs) but their effects are more common during treatment with indomethacin. 2. The aim of the study was to elucidate the mechanism of the CNS related side effects of indomethacin. Two groups were obtained, ...

While the in vitro reactivity of cerebral conducting vessels following subarachnoid hemorrhage has been extensively studied, in vivo cerebrovascular CO2 reactivity has not been systematically investigated. We tested the hypothesis that, in the canine model of subarachnoid hemorrhage, the rise in cerebral blood flow normally seen with hypercapnia is blunted ...

Angiographic studies on anesthetized dogs and Japanese monkeys showed that oxyhemoglobin (HbO2) injected into the cisterna magna produced a constriction of the basilar artery; the maximal constriction was attained 2-4 h later. Intracisternal injections of autologous blood, prostaglandin (PG) E2 and PGF2 alpha also constricted the artery to a similar ...

Human cerebral vessels were found to contain calcitonin gene-related peptide (CGRP)-like immunoreactivity (-LI) which in the reversed phase HPLC co-eluted with authentic human alpha-CGRP. The level was significantly lower in arteries removed from patients who had died from a subarachnoid haemorrhage (SAH) as compared to patients who died of a ...

In the present work the main relationships among cerebral blood volume (CBV), cerebrospinal fluid (CSF) dynamics, cerebral blood flow (CBF) and cerebrovascular reactivity following subarachnoid hemorrhage are critically examined and discussed. It is hypothesized that, following the rupture of an aneurysm, antagonistic mechanism which regulate CBF (through a vasodilatation of ...

Experimental cerebral vasospasm was produced in a "two-hemorrhage" canine model and examined by immunohistochemistry for leukotriene C4 (LTC4). The immunostain for LTC4 showed a strong positivity in intima and adventitia and a scattered reaction in media of normal basilar artery. The immunoreactivity after subarachnoid hemorrhage (SAH) was little changed in ...

We studied the impairment of autoregulation of cerebral blood flow (CBF) and its effect on the electrical activity of the brain during the development of chronic cerebral vasospasm after subarachnoid hemorrhage, using a vasospasm model in primates. Fourteen animals were divided into two groups: a clot group (8) and a ...

Ninety-six patients with aneurysmal subarachnoid haemorrhage underwent serial measurement of regional cerebral blood flow throughout the period of their treatment over the period of 5 years (1983 to 1988). A portable bedside xenon cerebral blood flow machine was used in this study and the initial slope index (ISI) values showed ...

This study demonstrates that intravenous epinephrine causes arterial vasospasm, but not venous constriction, in the microcirculation of the rat cremaster muscle. This effect can be blocked by a smooth muscle relaxant such as papaverine or an alpha receptor antagonist such as phentolamine. Circulating vasospastic agents such as epinephrine are important ...

We examined the effects of the recently developed calcium antagonist HA1077 on cerebral haemodynamics during the chronic stage of the two-haemorrhage canine model system of vasospasm. Regional cerebral blood flow (rCBF), regional cerebral blood velocity and regional cerebral blood volume in the canine parietal cortex were measured by Laser-doppler flowmeter. ...

The effect of phenobarbital on cerebral blood flow velocity (CBFV) was studied in 12 clinically stable preterm neonates to evaluate possible mechanisms underlying its protective effect on intracranial hemorrhage. Phenobarbital at loading doses of 20 mg/kg, or placebo (saline) were given intravenously. The study was a cross-over study, each infant ...

A new technique to continuously monitor cortical blood flow and intracranial pressure in postoperative patients is described. A thermal diffusion flow probe with a pressure port is left in contact with the cortex at craniotomy. Postoperative intracranial pressure--cortical blood flow can be monitored and acute changes or trends are readily ...

The amount and distribution of blood in the cerebrospinal fluid following subarachnoid hemorrhage can be monitored with CT. An investigation of 110 patients was performed retrospectively in 100 patients with a total of 132 CT examinations, and prospectively in 10 patients with 40 CT examinations. During the days following the ...

A spasm index, defined as transcranial Doppler detected flow velocity in the middle cerebral artery divided by regional cortical cerebral blood flow (CBF), was used on 24 patients with subarachnoid haemorrhage (SAH). The aim was to estimate degree and time course of vasospasm, even in cases with great day-to-day variation ...

The authors describe a method for Doppler ultrasound recording of flow velocity in the basilar artery of normal rabbits and rabbits with experimental subarachnoid hemorrhage (SAH). With this transcranial Doppler (TCD) model, clinical assumptions regarding flow velocity/cerebral blood flow (CBF) relationships, autoregulatory responses, and Doppler spectral waveform analysis can be ...

The cerebrovascular response to CO2 was evaluated by measuring relative changes in blood flow velocity within the middle cerebral artery by transcranial Doppler ultrasonography during normo-, hypo-, and hypercapnia. In seven patients without subarachnoid hemorrhage (five with unruptured arteriovenous malformations and two with aneurysms), the CO2 vasoreactivity was tested on ...

The role of blood components in cerebral vasospasm was evaluated using an in vivo canine model. An intracisternal injection of 5 ml of washed red blood cells (RBCs) and platelet-rich plasma (PRP) resulted in acute vasospasm of the basilar artery as seen by angiography. This was comparable with the degree ...

The relation between angiographically determined cerebral vasospasm following a subarachnoid hemorrhage and regional cerebral blood flow (CBF) was studied in 63 investigations of 45 patients. The CBF was measured using the intra-arterial 133-Xe clearance technique within one hour of angiography. A positive correlation between regional CBF and diameter of major ...

According to several studies, the amount of subarachnoid blood on the initial computed tomogram of patients with aneurysmal subarachnoid hemorrhage has predictive value with respect to infarction and outcome. Of several methods for assessing the amount of subarachnoid blood, none has been subjected to a study of interobserver agreement. We ...

We studied disruption of the blood-brain barrier after experimental subarachnoid hemorrhage induced by an injection of 4 ml autologous arterial blood into the cisterna magna of rabbits. The animals were killed at 40 minutes, 6 hours, 1 day, 2 days, 4 days, or 6 days after subarachnoid hemorrhage. We assessed ...

Cisternal blood injection in the rat induces a biphasic angiographic vasospasm, with a maximal acute spasm at 10 minutes and a maximal late spasm at 2 days after the subarachnoid hemorrhage (SAH). Depletion of substance P-containing sensory nerves to the cerebral arteries with capsaicin prior to SAH prevents the development ...

The short-term (less than or equal to 72-hour) cerebral vascular reaction to subarachnoid injectates of various specific blood components was determined by angiography in a canine model of cerebral vasospasm. Cell-free subarachnoid clots of autologous plasma in the basal cistern were found to produce no significant reaction of the basilar ...

A critical review of the clinical data supports the conclusion that nimodipine decreases the severity of neurologic deficits and improves outcome after subarachnoid hemorrhage. The mechanisms by which mortality and morbidity are reduced are still controversial. First, the frequency of vasospasm is not altered (Figs. 5 and 6). Second, the ...