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Biomedical subjects

J M Zabramski

Publications and source records attributed to J M Zabramski.

At least 55 records · Page 3Linked to original sources
PubMed1994

A comparison of intra-arterial and intravenous tissue-type plasminogen activator on autologous arterial emboli in the cerebral circulation of rabbits.

BACKGROUND AND PURPOSE: The efficacy of thrombolytic therapy for treatment of embolic stroke has been a subject of both experimental and clinical examination. The aim of this study was to compare the efficacy, in regard to reduction of volume of ischemic brain, of two different modes of administration (ie, intra-arterial and intravenous) of tissue-type plasminogen activator (TPA) given 30 minutes after experimental embolic stroke in rabbits. METHODS: A randomized, blinded, controlled experimental trial was undertaken. Embolic stroke was simulated in rabbits by injecting fragments of autologous arterial thrombus into one internal carotid artery. Thirty minutes after embolization, the rabbits were blindly treated with 2 mg/kg intra-arterial TPA, 2 mg/kg intravenous TPA, or saline (all n = 10). Six hours after embolization the rabbits were killed. The brains were perfused with triphenyltetrazolium chloride and cut into 0.5-cm-thick coronal sections, and the areas of ischemia were measured. RESULTS: Administration of TPA resulted in a significant reduction in the volume of ischemic cerebral injury (P < .0001): control animals sustained ischemic injury to 20.1 +/- 4.6% (mean +/- SD) of total brain compared with 4.6 +/- 4.1% for animals treated with intra-arterial TPA and 3.4 +/- 2.6% for those treated with intravenous TPA. The difference between intra-arterial and intravenous TPA treatment was not significant (P = .786). CONCLUSIONS: In this rabbit model of embolic stroke, administration of TPA within 30 minutes resulted in a dramatic reduction in the amount of ischemic injury, with equal efficacy for the two modes of administration. These results favor the treatment of acute embolic stroke with intravenous TPA, given the rapidity with which intravenous therapy can be established in the clinical setting.

Analysis of Variance↗
PubMed1994

The natural history of familial cavernous malformations: results of an ongoing study.

Cavernous malformations are congenital abnormalities of the cerebral vessels that affect 0.5% to 0.7% of the population. They occur in two forms: a sporadic form characterized by isolated lesions, and a familial form characterized by multiple lesions with an autosomal dominant mode of inheritance. The management of patients with cavernous malformations, particularly those with the familial form of the disease, remains a challenge because little is known regarding the natural history. The authors report the results of an ongoing study in which six families afflicted by familial cavernous malformations have been prospectively followed with serial interviews, physical examinations, and magnetic resonance (MR) imaging at 6- to 12-month intervals. A total of 59 members of these six families were screened for protocol enrollment; 31 (53%) had MR evidence of familial cavernous malformations. Nineteen (61%) of these 31 patients were symptomatic, with seizures in 12 (39%), recurrent headaches in 16 (52%), focal sensory/motor deficits in three (10%), and visual field deficits in two (6%). Twenty-one of these 31 patients underwent at least two serial clinical and MR imaging examinations. A total of 128 individual cavernous malformations (mean 6.5 +/- 3.8 lesions/patient) were identified and followed radiographically. During a mean follow-up period of 2.2 years (range 1 to 5.5 years), serial MR images demonstrated 17 new lesions in six (29%) of the 21 patients; 13 lesions (10%) showed changes in signal characteristics, and five lesions (3.9%) changed significantly in size. The incidence of symptomatic hemorrhage was 1.1% per lesion per year. The results of this study demonstrate that the familial form of cavernous malformations is a dynamic disease; serial MR images revealed changes in the number, size, and imaging characteristics of lesions consistent with acute or resolving hemorrhage. It is believed that the de novo development of new lesions in this disease has not been previously reported. These findings suggest that patients with familial cavernous malformations require careful follow-up monitoring, and that significant changes in neurological symptoms warrant repeat MR imaging. Surgery should be considered only for lesions that produce repetitive or progressive symptoms. Prophylactic resection of asymptomatic lesions does not appear to be indicated.

Adolescent↗
PubMed1994

Hemodynamics of subarachnoid hemorrhage arrest.

Subarachnoid hemorrhage (SAH) causes a spectrum of clinical syndromes from mild discomfort to rapid brain death. The reason for these heterogeneous consequences is poorly understood. A canine autologous shunt model of SAH was used to study this problem. The duration and volume of hemorrhage into the suprasellar cistern at each animal's mean arterial blood pressure were measured at variable hemorrhage flow rates. At high rates of bleeding in seven dogs (18.7 +/- 2.2 ml/min, mean +/- standard deviation), hemorrhage duration was significantly less (191 +/- 116 seconds, p < 0.03) and hemorrhage volume was significantly greater (15.1 +/- 7.0 ml, p < 0.05) than at low flow rates. At low flow rates of bleeding in nine dogs (4.4 +/- 2.2 ml/min), hemorrhage duration was 394 +/- 202 seconds and volume was 10.9 +/- 6.5 ml. Cerebral perfusion pressure (CPP) decreased at all hemorrhage rates but never to 0 mm Hg (perfusion arrest). No correlation between a decrease in CPP and SAH volume or duration was identified. The initial flow rate of SAH had a positive linear correlation with the volume of hemorrhage (23 dogs, r = 0.64, p < 0.01). The data suggest that initial SAH flow rate, and not CPP, has a primary influence on hemorrhage arrest. This finding may influence the clinical rationale for acute management of SAH-induced brain injury.

Animals↗
PubMed1994

Efficacy of endovascular treatment of meningiomas: evaluation with matched samples.

PURPOSE: To evaluate the clinical efficacy, cost-effectiveness, and safety of presurgical devascularization of meningiomas. METHODS: Matched samples of embolized and nonembolized groups of meningiomas were compared. The study variables for clinical efficacy were estimated blood loss, number of transfusions, surgical resection time, and length of hospitalization. The cost-effectiveness was evaluated by adjusting all hospital costs to 1991 dollar amounts, and adding additional embolization costs and fees to the hospital cost totals for the embolized group. A qualitative comparison of complications was made. RESULTS: All dependent variables evaluating the clinical efficacy of the procedure (estimate blood loss, 533 cc versus 836 cc; number of transfusions, 0.39 units versus 1.56 units; surgical resection time, 305.8 minutes versus 337.5 minutes; and length of hospitalization, 10.6 days versus 15.0 days) displayed trends of higher means in the nonembolized group; however, only the estimated blood loss and number of transfusions variables were significant. The cost-effectiveness of the procedure was not statistically significant. The mean cost was $29,605 for the embolized group and $38,449 for the nonembolized group. There were three major and nine minor complications in the nonembolized group and zero major and six minor complications in the embolized group. There were four additional minor complications caused by the embolization procedure. CONCLUSION: Endovascular devascularization of meningiomas is beneficial for large meningiomas because it diminishes the necessity of intraoperative transfusions and decreases blood loss. The additional day of hospitalization, emolization costs, and costs of complications do not conversely increase treatment costs. There were no major complications or adverse long-term effects caused by the embolization procedure.

Blood Loss, Surgical↗
PubMed1993

Self-inflicted orbital and intracranial injury with a retained foreign body, associated with psychotic depression: case report and review.

Reports of intracranial self-mutilation by psychotic individuals are associated with severe mental disorders, criminality, or both. We describe a psychotically depressed male who drove a ballpoint pen through his right medial canthus and into his intracranial compartment. The patient developed a cavernous sinus syndrome and a traumatic dissection of the cavernous portion of the carotid artery. The pen was removed intraoperatively. Postoperatively, the patient was placed on a course of broad-spectrum antibiotics, antidepressants, and antipsychotic medications, and he has received long-term psychiatric follow-up. The literature related to these unusual cases is reviewed, and relevant surgical, medical, and psychiatric aspects of treatment are discussed.

Adult↗
PubMed1993

Ventricular CSF shunt infections associated with Corynebacterium jeikeium: report of three cases and review.

Ventricular CSF shunt infections due to Corynebacterium jeikeium are rare. Such infections may become manifest weeks to months after surgery. They are difficult to eradicate and often recur. We report three cases of C. jeikeium ventricular CSF shunt infections, all of which occurred in patients who received long-term prophylactic therapy with antibiotics and had protracted hospitalizations. Two patients had multiple recurrences, and all patients required shunt revision. Additional therapy with intrathecal vancomycin for 6-10 days after surgery was effective for this unusual cause of ventricular CSF shunt infection. On the basis of our experience and a review of six previously published case reports, we recommend CSF sterilization with intravenous and intrathecal vancomycin, followed by replacement of shunt hardware.

Adult↗
PubMed1993

Intracranial pressure reduction by a central alpha-2 adrenoreceptor agonist after subarachnoid hemorrhage.

Pharmacological manipulation of cerebral venous blood volume is a theoretical approach to reduce elevated intracranial pressure (ICP). Microapplication of alpha-2 adrenoreceptor agonists has been shown to constrict pial veins selectively. This report explores the physiological effects of the intravenous alpha-2 agonist xylazine in a canine model of raised ICP after subarachnoid hemorrhage (mean arterial pressure, heart rate, and ICP were measured and compared in five groups: normal saline [n = 4], xylazine [0.05-1.00 mg/kg] [n = 28], tolazoline [a semiselective alpha-2 antagonist, 5 mg/kg] [n = 6], tolazoline [5 mg/kg] plus xylazine [1.0 mg/kg] [n = 7], and phenylephrine [0.008 mg/kg], a selective alpha-1 agonist [n = 3]). Treatment with xylazine produced a significant (P < 0.01), transient, dose-dependent reduction in ICP that was blocked by pretreatment with tolazoline. Treatment with tolazoline alone produced significant (P < 0.01) increases in ICP and mean arterial pressure. Treatment with phenylephrine produced significant (P < 0.01) increases in mean arterial pressure but had no affect on ICP. These results raise the possibility of using an alpha-2 adrenoreceptor agonist for the treatment of elevated ICP after brain injury.

Animals↗
PubMed1993

False aneurysm associated with rupture of an arteriovenous malformation--implications for treatment: case report.

The morphological features associated with cerebral arteriovenous malformations have been under increasing scrutiny since the advent of high-definition and superselective angiography; certain features may be associated with an increased risk of rupture. In the systemic circulation, the presence of a false aneurysm after the rupture of a vessel has been described; however, no similar phenomenon has been reported in the cerebral circulation. In this case report, we describe a false aneurysm in a young man who had an arteriovenous malformation that hemorrhaged in the posterior fossa. Computed tomography and magnetic resonance imaging revealed a posterior fossa hematoma in the lower brain stem and cerebellum. Angiography indicated that the arteriovenous malformation was fed primarily by the left posterior inferior cerebellar artery. The mass effect of the hematoma was visible as a hypodense region. In the middle of the hematoma, on the distal portion of the posterior inferior cerebellar artery, was a dilatation, measuring 4 x 5 mm, with a stagnation of the contrast medium that was pathologically consistent with a false aneurysm. The patient with a false aneurysm, such as the man we describe, runs a significant risk of hemorrhage at the time of resection of the arteriovenous malformation, with additional implications for endovascular treatment. The volume of embolic injections of the involved vessel should be limited to avoid raising the intra-arterial pressure, and the choice of embolic material must be tailored individually. Recognizing the presence of false aneurysm is important in the choice and timing of therapy.

Adult↗
PubMed1993

Improved transdural exposure and temporary occlusion of the petrous internal carotid artery for cavernous sinus surgery. Technical note.

Safe surgery for vascular and neoplastic lesions involving the cavernous sinus requires adequate proximal control of the cavernous internal carotid artery (ICA). Classically, control of the cavernous ICA has necessitated dissection and isolation of the cervical vessels. The authors describe an alternative method for obtaining vascular control via transdural exposure of the petrous ICA and the use of the Fogarty balloon embolectomy catheter inserted extra-arterially into the carotid canal to provide temporary occlusion. This method is particularly well suited for proximal ICA occlusion during short-segment petrous-to-paraclinoid ICA bypass procedures as it eliminates the need for a temporary proximal ICA aneurysm clip and increases the available working space for completion of the anastomosis.

Carotid Artery, Internal↗
PubMed1992

Iatrogenic arteriovenous fistula presenting as a recurrent subdural hematoma. Case report.

An unusual case of an iatrogenic dural arteriovenous fistula is reported. The patient presented with a history of progressive generalized headache over a period of 3 to 4 weeks. Computerized tomography demonstrated a chronic subdural hematoma that was successfully evacuated by burr-hole drainage. The patient's postoperative course was complicated by recurrent acute subdural hematomas at the drainage site. Coagulation studies were unremarkable. Selective external carotid angiography demonstrated a small dural arteriovenous fistula adjacent to the burr hole used for the initial operative procedure. Extension of the bone flap and coagulation of the fistula resulted in a good outcome. In the patient with recurrent acute subdural hematoma, the possibility of a vascular malformation must be considered. Selective internal and external carotid angiography is key to the correct diagnosis.

Arteriovenous Fistula↗
PubMed1992

Thromboendarterectomy of the symptomatic occluded internal carotid artery.

A retrospective review of 42 patients (mean age 61.4 years) with surgically managed symptomatic internal carotid artery occlusion is reported. A standardized surgical protocol aimed at restoration of flow in the vessel was used. Presenting symptoms included hemispheric transient ischemic attacks in 68% of patients, new fixed neurological deficits in 28%, amaurosis fugax in 28%, and stroke-in-evolution in 9%. Twenty-four arteries were successfully reopened. A proximal remnant angioplasty (stumpectomy) was performed alone in nine patients or in combination with an external carotid endarterectomy in nine. In four patients with persisting symptoms who failed to achieve primary restoration of flow, a superficial temporal-to-middle cerebral artery bypass procedure was performed. The permanent surgical morbidity rate was 2% and the surgical mortality rate was 0%. Transient postoperative deficits were present in three patients (7%). Follow-up review at a mean of 40 months was obtained in 39 patients (93%). Following surgical intervention, five patients died of unrelated causes, two had neurological events consistent with a transient cerebral ischemic attack, and two had vertebrobasilar insufficiency. No patient suffered from stroke. Of the 24 successfully reopened vessels, follow-up ultrasound evaluations were obtained in 17 (73%) at a mean of 28 months after surgery. In 15 patients (88%) the vessels were widely patent, one (5.8%) had stenosis greater than 70%, and one (5.8%) showed asymptomatic reocclusion. Reopening occluded internal carotid arteries in selected patients is associated with low surgical morbidity and mortality rates. Further studies are necessary to determine the impact of this surgical therapy on the natural history of this condition.

Algorithms↗
PubMed1992

Relationship of perfusion pressure and size to risk of hemorrhage from arteriovenous malformations.

The relationship between the size of an arteriovenous malformation (AVM) and its propensity to hemorrhage is unclear. Although nidus volume increases geometrically with respect to AVM diameter, hemorrhages are at least as common, in small AVM's compared to large AVM's. The authors prospectively evaluated 92 AVM's for nidus size, hematoma size, and arterial feeding pressure to determine if these variables influence the tendency to hemorrhage. Small AVM's (diameter less than or equal to 3 cm) presented with hemorrhage significantly more often (p less than 0.001) than large AVM's (diameter greater than 6 cm), the incidence being 82% versus 21%. Intraoperative arterial pressures were recorded from the main feeding vessel(s) in 24 of the 92 patients in this series: 10 presented with hemorrhage and 14 presented with other neurological symptoms. In the AVM's that had hemorrhaged, the mean difference between mean arterial blood pressure and the feeding artery pressure was 6.5 mm Hg (range 2 to 15 mm Hg). In the AVM's that did not rupture, this difference was 40 mm Hg (range 17 to 63 mm Hg). Smaller AVM's had significantly higher feeding artery pressures (p less than 0.05) than did larger AVM's, and they were associated with large hemorrhages. It is suggested that differences in arterial feeding pressure may be responsible for the observed relationship between the size of AVM's and the frequency and severity of hemorrhage.

Adolescent↗
PubMed1991

Cardiocirculatory arrest with hypothermia. Experimental study.

Direct surgical attack on intracranial malformations of great complexity may be facilitated by complete cardiocirculatory arrest under hypothermia. To improve the technical aspects of this procedure and to determine the optimum depth of hypothermia, the duration of arrest that can be tolerated, and the role of barbiturate brain protection, we conducted an experimental study on 11 baboons. Arrest lasted for 45 or 90 minutes at a brain temperature of 12 degrees C. The animals were assessed by clinical, neuroradiological and necropsy examination. All 4 animals subjected to 45 minutes arrest made a good clinical recovery while 3 of the 7 subjected to 90 minutes arrest presented thromboembolic complications. Strict heparinization in the last 2 animals solved these problems. The findings of this study may help to make the procedure safer for clinical use.

Animals↗