Intracerebral arteriovenous malformations: intraoperative color Doppler flow imaging

Color Doppler flow ultrasound (US) was used to locate and image intracerebral arteriovenous malformations (AVMs). US was deemed useful in eight of 12 patients who underwent AVM resection. Blood flow in the eight lesions was clearly evident, and major feeding arteries and draining veins, such as the superior sagittal sinus, were identified. Color Doppler flow imaging was used to differentiate adjacent hematoma from AVM in three patients, locate a small (6-mm) AVM deep in the brain in two patients, detect a deep major feeding artery in one patient, detect a residual unresected AVM in one patient, and confirm complete resection in all eight patients.

Intraoperative color-flow Doppler imaging of AVM's and aneurysms

The use of intraoperative color-flow Doppler sonography to image cerebral and spinal arteriovenous malformations (AVM's) and a giant aneurysm is reported in 10 patients. The technique is a useful adjunct in localizing vascular lesions, identifying feeding or draining vessels, and confirming intraoperative surgical excision of AVM's or ligation of giant aneurysms. Imaging of lesions deeper than 4 to 5 cm is, however, limited with the equipment design now commercially available.

Multiple thoracic disc herniations. Case report

A patient with herniated thoracic discs in tandem is reported. The previous literature is reviewed. Difficulties with the preoperative diagnosis and the surgical approach to these lesions are discussed.

Increased leukotriene C4 and vasogenic edema surrounding brain tumors in humans

Leukotrienes are pharmacologically active compounds that promote vascular permeability. In this study we sought to determine whether tissue leukotriene-like immunoreactivity was increased in intracranial tumors associated with peritumoral edema. In 20 patients undergoing craniotomy tissue specimens were immediately frozen after removal and tissue leukotriene C4 levels were determined by radioimmunoassay. An index of peritumoral edema was estimated from preoperative contrast-enhanced computed tomographic scans. There was a significant correlation between brain edema and tissue leukotriene levels (p less than 0.003). Metastatic tumors (n = 8) had the highest leukotriene C4 level at 13.8 +/- 8.5 pg/mg tissue (mean +/- SE) and the highest index of edema 5.7 +/- 1.8. The mean leukotriene C4 level in the gliomas (n = 5) was 6.2 +/- 2.3 pg/mg tissue and the edema index was 2.1 +/- 0.6. There was no edema and no neoplasm in the temporal lobes removed for seizure (n = 2), and their level of leukotriene C4 was 0.4 +/- 0.1 pg/mg tissue. The formation of leukotriene C4 is stimulated by intracranial tumors. Leukotrienes increase blood-brain barrier permeability and may be important in the formation of vasogenic edema surrounding tumors.

Magnetic resonance imaging in the evaluation of low attenuation lesions on computed tomography

Computed tomography has proven invaluable in the assessment of intracranial mass lesions. Low attenuation lesions can, however, present diagnostic difficulties. We report three cases where magnetic resonance imaging was beneficial in clarifying solid versus cystic intracranial lesions.

Preoperative evaluation and surgical management of the Arnold-Chiari II malformation

The authors report their recent experience with 14 meningomyelocele patients with the Arnold-Chiari II malformation. Three major types of fourth ventricle anomalies seen in the Arnold-Chiari II malformation are defined, based on preoperative magnetic resonance imaging and intraoperative ultrasound studies. The Type A deformity is defined as no cystic dilatation of the fourth ventricle. In the Type B anomaly, there is intracranial dilatation of the fourth ventricle. The Type C deformity involves intraspinal dilatation of the fourth ventricle, either dorsal to the cord or within the substance of the cord. The Type A deformity was most common in infants, and in two cases progression from a Type A to Type B deformity was documented. Recognition of the type of Arnold-Chiari II malformation aids in designing an operative approach more specific to that structural abnormality. Intraoperative ultrasound is a valuable adjunct in localization of the underlying anomalies and permits safe decompression of the fourth ventricle. The authors' indications for surgery now include failure to thrive due to either early respiratory and swallowing dysfunction, progressive spasticity, or upper-extremity weakness. Nine patients significantly improved following surgery and three patients with a progressively deteriorating course were stabilized by surgery. Decompression of the fourth ventricle by fenestration and internal shunting appears to be well tolerated, even in young infants, and is recommended in the treatment of the Arnold-Chiari II deformity.

Effect of parenteral nutrition on cold-induced vasogenic edema in cats

The effect of standard parenteral nutritional formulas on cold-induced vasogenic edema formation in cats was examined and compared to the effects of 5% dextrose, 0.9% saline, and 40.5% mannitol. The amount of vasogenic edema formed during a 3-hour period of fluid infusion following cold injury was quantified by a computerized graphics tablet determination of the volume of Evans blue-dyed white matter. Specific gravity measurements were taken as a measure of white matter water content. Serum osmolality, urine output, arterial blood gases, hematocrit, body temperature, and systolic blood pressure were measured periodically throughout the infusion period. Parenteral nutritional formulas and a 40.5% mannitol solution produced greater changes in serum osmolality than did 5% dextrose or 0.9% saline. Greater changes in serum osmolality were associated with larger calculated volumes of edema in the injured hemisphere and lower water contents in the uninjured hemisphere. The data indicate that hyperosmolar solutions may potentiate vasogenic edema formation when the blood-brain barrier is open.

Leukotrienes increase blood-brain barrier permeability following intraparenchymal injections in rats

To examine whether leukotrienes could increase blood-brain barrier permeability, rats were anesthetized and injected intravenously with Evans blue. Ten microliters of vehicle, of leukotrienes B4, C4, or E4, or of arachidonic acid was injected over 1 hour directly into the brain parenchyma. The percentage of the total surface area of Evans blue extravasation in a coronal section of brain centered on the injection site was then determined as an estimate of blood-brain barrier permeability. Leukotrienes B4, C4, and E4, and arachidonic acid all increased blood-brain barrier permeability, but this effect was lost when the total dose was reduced to 20 ng. Increased blood-brain barrier permeability induced by arachidonic acid could be prevented by pretreatment with the lipoxygenase inhibitor BW755C, but not with indomethacin. Leukotrienes may play a role in the development of increased blood-brain barrier permeability after cerebral injury.

Effect of intravenous eicosapentaenoic acid on cerebral blood flow, edema and brain prostaglandins in ischemic gerbils

Eicosapentaenoic acid is converted by cyclo-oxygenase to the prostacyclin, PGI3. Consequently eicosapentaenoic acid might protect the brain from the impairment in cerebral blood flow that follows temporary cerebral arterial occlusion. We studied the effect of 90% pure eicosapentaenoic acid, given intravenously, on cerebral blood flow, brain water and prostaglandins after ischemia in gerbils. Ischemia was produced by bilateral carotid occlusion for 15 min followed by reperfusion for 2 h. In experimental gerbils, 0.833 mg or 0.167 mg of eicosapentaenoic acid (Na salt) was given intravenously followed by a continuous infusion of 1 mg h-1. Control gerbils were given 0.167 mg of linoleic acid (Na salt) intravenously followed by a continuous infusion of 1 mg h-1 or a saline infusion. Regional cerebral blood flow was measured by the hydrogen clearance method and brain water by the specific gravity technique. Brain diene prostaglandins were measured by radioimmunoassay. In control gerbils cerebral blood flow decreased significantly during reperfusion and remained depressed after 2 h of reperfusion. In eicosapentaenoic acid treated gerbils blood flow decreased initially but after 2 h of reperfusion blood flow was significantly higher than in control gerbils. Brain edema and brain diene prostaglandins were not significantly different between control and experimental groups. Our study indicates that eicosapentaenoic acid, given intravenously, improves cerebral blood flow after ischemia and reperfusion. We speculate that this effect may be due to the formation of the prostacyclin, PGI3.

Giant arteriovenous malformation of the vein of Galen in an adult

A case of a large vein of Galen malformation in a 29-year-old man is presented. A two-staged surgical procedure, first with ligation of the feeding vessels, and followed later by thrombectomy, allowed successful surgical treatment of this lesion.

Sodium 5-(3'-pyridinylmethyl)benzofuran-2-carboxylate (U-63557A) potentiates protective effect of intravenous eicosapentaenoic acid on impaired CBF in ischemic gerbils

Eicosapentaenoic acid (EPA) has been reported to improve postischemic cerebral blood flow (CBF). The present study was designed to determine whether sodium 5-(3'-pyridinylmethyl)benzofuran-2-carboxylate (U-63557A), a selective thromboxane synthetase inhibitor, could potentiate the effects of EPA on CBF in ischemic gerbils. Ischemia was produced by bilateral carotid artery occlusion for 15 minutes followed by reperfusion for 2 hours. Immediately after ischemia, gerbils were given either an intravenous bolus of 0.167 mg of EPA followed by a continuous infusion of EPA at 1 mg/hr, or U-63557A (10 mg/kg intraperitoneally), or U-63557A and EPA, or a saline infusion. Regional CBF was measured by the hydrogen clearance method, and brain water by the specific gravity technique. Brain prostaglandins were measured by radioimmunoassay. Preischemic CBF's ranged from 27.4 to 29.5 ml/100 gm/min for the four animal groups. After ischemia and 2 hours of reperfusion, CBF in the saline-infused gerbils was significantly decreased to 19.2 ml/100 gm/min. Gerbils treated with either EPA or U-63557A alone had a CBF of 23.7 and 21.6 ml/100 gm/min, respectively. Postischemic CBF in animals treated with both U-63557A and EPA was 30.0 ml/100 gm/min, significantly higher than in saline-infused gerbils. Brain levels of 6-keto prostaglandin (PG)F1 alpha (the metabolite of PGI2) were significantly higher in gerbils treated with U-63557A and EPA compared to gerbils given EPA alone. This study indicates that U-63557A potentiates the effects of EPA on postischemic CBF. This is probably due to the ability of U-63557A to increase prostacyclin formation in the vessel wall.

Cerebral abscess: loss of computed tomographic enhancement with steroids. Case report

A case of cerebral abscess with decreased computed tomography enhancement and clinical improvement after steroid therapy alone is reported. When the steroids were discontinued, the computed tomography enhancement increased and the patient's clinical condition deteriorated. The abscess subsequently ruptured with the development of ventriculitis. The infection was not eradicated with penicillin or chloramphenicol, but was effectively treated with metronidazole.

Eicosapentaenoic acid: effect on brain prostaglandins, cerebral blood flow and edema in ischemic gerbils

Eicosapentaenoic acid prevents platelet aggregation and inhibits arachidonate conversion into thromboxane A2 and prostaglandins. Consequently eicosapentaenoic acid might protect the brain from the ischemia that follows cerebral arterial occlusion. We studied the effect of eicosapentaenoic acid on cerebral ischemia in anesthetized gerbils. Ischemia was produced by bilateral carotid occlusion for 10 min, followed by reperfusion for 60 min, in gerbils fed either a standard diet (control) or a diet supplemented with menhaden fish oil for 2 months. The menhaden fish oil contained 17 mole % eicosapentaenoic acid. Regional cerebral blood flow was measured by the hydrogen clearance method and brain water by the specific gravity technique. In control animals cerebral blood flow was decreased 30 and 60 min after reperfusion (p less than .001) and brain water was increased (p less than .001). In the experimental group cerebral blood flow did not fall during reperfusion and edema did not appear. Brain prostaglandins and thromboxane were measured by radioimmunoassay. PGF2 alpha, PGE2, 6-keto PGF1 alpha and TXB2 increased after severe ischemia and reperfusion. The synthesis of brain diene prostaglandins was not altered by eicosapentaenoic acid. Our study indicates that eicosapentaenoic acid prevented post-ischemic cerebral edema and hypoperfusion, without affecting the levels of brain diene prostaglandin and thromboxane.

Alteration of pharmacokinetic parameters for pentobarbital by ischemic stroke and reversion to normal by dexamethasone treatment

The values of the pharmacokinetic parameters for pentobarbital were determined in 18 cats, 12 of which were subjected to acute ischemic stroke by ligation of the left middle cerebral artery (LMCA). All 18 ats received 50 mg/kg sodium pentobarbital during operation. The following three experimental groups were formed: control (sham-operated); ischemic stroke plus administration of 4 mg/kg dexamethasone; and ischemic stroke without dexamethasone administration. Ischemic stroke significantly prolonged the plasma half-life of pentobarbital, but concurrent administration of dexamethasone prevented this effect. Ischemic stroke significantly reduced the plasma clearance of pentobarbital, but dexamethasone prevented this reduction. Ischemic stroke significantly increased the area under the plasma pentobarbital concentration-time curve, but dexamethasone prevented this increase. Ischemic stroke significantly reduced the volume of distribution, but dexamethasone did not prevent this reduction. The alterations of the value of these pharmacokinetic parameters for pentobarbital by ischemic stroke and reversion to normal by dexamethasone treatment are discussed in the light of certain known circulatory changes which occur secondary to ischemic stroke and dexamethasone treatment.

The protective effects of dietary fish oil on focal cerebral infarction

The protective effect of the (n-3) fatty acids in menhaden fish oil on acute cerebral ischemia was investigated in cats. Cerebral ischemia was produced by ligation of the left middle cerebral artery of cats fed either a basal diet of feline cat chow or the basal diet supplemented with 8% of the calories as menhaden oil for 18-24 days. Fatty acids esters of 20:5 (n-3) were increased and the 18:2 (n-6) decreased in the heart and liver of cats fed supplemental fish oil, but the brain lipid showed no effect of the diet. We found that the neurological deficit and the volume of brain infarction in the group treated with fish oil was less than that of the control group. The present findings suggest that moderate dietary supplements of fish oil may be beneficial in the prophylactic treatment of ischemic cerebral vascular disease.

Delayed pentobarbital therapy of acute focal cerebral ischemia

The efficacy of pentobarbital in the delayed treatment of acute cerebral ischemia was investigated in cats. Cerebral ischemia was produced by left middle cerebral artery (LMCA) ligation. Ten cats received 50 mg/kg of pentobarbital prior to ligation; a second group of 10 cats received the same dose of pentobarbital 2 hrs after ligation, and the control group of 7 cats received no pentobarbital. Brains were removed after spontaneous or induced death and the volume infarction was determined histologically. It was found that the volume of brain infarction in the group receiving pentobarbital 2 hrs after ligation was significantly less than that of the control group, which received no pentobarbital; but the volume of infarction in the former group was significantly greater than that found in the experimental group, which received pentobarbital prior to ligation. However, the mortality after LMCA ligation was higher in the 2 experimental groups, which received pentobarbital therapy, than in the control group, which did not receive pentobarbital. An hypothesis was advanced, which speculated that secondary adrenal insufficiency and altered cardiovascular function accounted for the increased mortality after pentobarbital treatment of patients with ischemic stroke.

Pharmacokinetics of peniobarbital in the cat and comparisons with the rabbit and man

In eight experiments involving four cats, doses of 12.5 to 50 mg of sodium pentobarbital per kg of body weight were administered intravenously and pentobarbital plasma concentrations (from arterial blood) were measured as a function of time. Pharmacokinetic linearity was evidenced by a mean plasma clearance (C1p) of 1.81 ml/(kg x min), with a coefficient of variation of 16.6%, and a range of 1.51 to 2.36 for all experiments, and, a linear relationship between total area under the curve (AUC) and mg/kg dose in cat "4 given doses of 12.5, 25 and 50 mg/kg. However, the apparent elimination half-life, (t1/2)beta' averaged 4.87 hr, with a coefficient of variation of 40.7%, and range of 1.80 to 7.52 in all experiments, and, in cat "4 the half-life was the same, namely 7.5 hr following the two higher doses, but lower, namely 4.7 hr, after the lowest dose. There was also evidence of kinetic nonlinearity in the intial fall-off portions of some of the curves. Results are compared with literature data for both rabbits anamen. The order of plasma clearances in units of ml/(kg x min) were: rabbit greater than cat greater than man. For neither the rabbit nor the cat were there any significant correlations between calculated pharmacokinetic parameters and mg/kg doses using data from all animals studied; this also suggests kinetic linearity.