Revascularization of occluded internal carotid arteries by hypertrophied vasa vasorum: report of four cases.

OBJECTIVE AND IMPORTANCE: The vasa vasorum are involved in the pathophysiological development of carotid artery atherosclerosis, providing vascular support to the thickened intima and plaque. When advanced atherosclerosis causes carotid artery occlusion, the vasa vasorum may serve as a means of revascularization. CLINICAL PRESENTATION: We studied four patients with internal carotid artery occlusion who exhibited revascularization, distal to the occlusion, by small vascular channels that were inconsistent with recanalization through the thrombus. The channels had an angiographic appearance consistent with their being hypertrophied vasa vasorum. Significant collateral circulation was provided by the revascularization. INTERVENTION: All four patients exhibited adequate collateral circulation and were treated with antiplatelet or anticoagulation medication. CONCLUSION: The vasa vasorum have not been previously reported to contribute to the revascularization of occluded arteries. The four cases presented in this report suggest that the vasa vasorum can be a source of collateral circulation after carotid artery occlusion secondary to atherosclerotic disease.

Enoxaparin increases the incidence of postoperative intracranial hemorrhage when initiated preoperatively for deep venous thrombosis prophylaxis in patients with brain tumors.

OBJECTIVE: Prophylactic therapies have demonstrated efficacy in reducing the incidence of deep venous thrombosis (DVT) in neurosurgical patients. Retrospective analysis of patients undergoing neurosurgical procedures at the University of Michigan demonstrated a high incidence (14%) of postoperative DVT among patients with intracranial neoplasms treated with sequential compression device (SCD) prophylaxis alone. Therefore, we investigated the efficacy and safety of the low-molecular weight heparin enoxaparin in preventing DVT in patients with brain tumors. The goal of the study was to compare SCD, enoxaparin, and combined SCD/enoxaparin prophylaxis among patients requiring surgery for treatment of intracranial neoplasms. METHODS: Eligible patients were randomized to SCD, enoxaparin, or combined therapy. Treatment was initiated before the induction of anesthesia and was continued throughout the hospital stay. Patients were screened for DVT, using duplex imaging, on four occasions in the first 1 month after surgery. The incidences of DVT and serious adverse events were compared between groups using analysis of variance and the Dunnet two-sided t test. RESULTS: Sixty-eight patients completed the study. Postoperative DVT occurred in 3 of 22 (13.6%) SCD-treated patients, 1 of 23 (4.3%) enoxaparin-treated patients, and 4 of 23 (17.4%) SCD/enoxaparin-treated patients. Differences were not statistically significant. Postoperative intracranial hemorrhage did not occur in patients in the SCD-treated group, whereas 5 of 46 patients receiving low-molecular weight heparin suffered clinically significant intracranial hemorrhage. The study was terminated because of the increased incidence of adverse events in the enoxaparin-treated groups. CONCLUSION: Enoxaparin therapy initiated at the time of anesthesia induction increases postoperative intracranial hemorrhage.

Correlation of intraluminal thrombosis in brain tumor vessels with postoperative thrombotic complications: a preliminary report.

OBJECT: Thrombotic complications (deep vein thrombosis and/or pulmonary embolization [DVT/PE]) occur in 18 to 50% of patients harboring brain tumors who undergo neurosurgical procedures. Such patients are at risk for DVT/PE because of immobility, paresis, hypovolemia, and lengthy surgery. The present study was undertaken to see whether tumor patients at highest risk for DVT/PE could be identified so that augmentation of prophylactic measures might be used to reduce the incidence of thrombotic complications. METHODS: The authors conducted a retrospective analysis of 488 patients enrolled in their brain tumor registries between 1988 and 1995, identifying 57 patients (12%) with recorded symptomatic DVT, PE, or both postoperatively. In 24 of these 57 cases histological specimens were retrievable for review, allowing an in-depth analysis. Forty-five patients were lost to follow-up review, and the remaining 386 patients had no record of systemic thrombosis. Slides of pathological specimens were retrievable in 50 cases in which there was no DVT/PE. From these 50 cases, 25 were selected at random to represent the control group by a blinded observer. Seventeen (71%) of the 24 brain tumor specimens obtained in patients with DVT/PE stained positively for intraluminal thrombosis (ILT) after hematoxylin and eosin had been applied. The odds ratio associated with the presence of ILT was 17.8, with a confidence interval ranging from 4 to 79.3. No evidence of ILT was found in 22 patients (88%) within the control group (p < 0.0001, Fisher's exact test). Other factors that may predispose patients with brain tumors to DVT/PE-limb paresis, extent of tumor removal, and duration of the surgery-were also analyzed and found not to be statistically significant. Therefore, these factors were not the basis for differences seen between the study and control groups. CONCLUSIONS: These preliminary observations suggest that the presence of ILT within malignant glioma or glioblastoma tumor vessels may represent a marker of tumor-induced hypercoagulability.

Magnetic resonance evaluation of ventrolateral medullary compression in essential hypertension.

OBJECT: The authors designed a blinded prospective study comparing patients with essential hypertension to patients without hypertension in which magnetic resonance (MR) imaging was used to evaluate the role of lateral medullary compression by adjacent vascular structures as a cause of neurogenic hypertension. METHODS: Patients with documented essential hypertension were recruited to undergo thin-slice axial brainstem MR imaging evaluation. Nonhypertensive (control) patients scheduled to undergo MR imaging for other reasons also underwent thin-slice MR imaging to form a basis for comparison. Magnetic resonance images obtained in patients from the hypertensive (30 patients) and the control (45 patients) groups were then compared by four independent reviewers (two neuroradiologists and two neurosurgeons) who were blinded to the patients' diagnosis and hypertensive status. Images were reviewed with regard to left versus right vertebral artery (VA) dominance, compression of the medulla on the left and/or right side, and brainstem rotation. Medullary compression was graded as either vessel contact without associated brainstem deformity or vessel contact with associated brainstem deformity. CONCLUSIONS: There was a tendency toward left VA dominance in the hypertensive group compared with the control group, although a significant difference was shown by only one of the four reviewers. There were no differences in brainstem compression or rotation between the hypertensive and nonhypertensive groups. These results are contrary to those of recently published studies in which MR imaging and/or MR angiography revealed lateral brainstem vascular compression in hypertensive patients but not in nonhypertensive (control) patients. Reasons for this discrepancy are discussed. On the basis of their own experience and that of others, the authors believe that neurogenic hypertension does exist. However, thin-slice MR imaging may not be a reliable method for detecting neurovascularly induced essential hypertension and the prevalence of neurovascular compression as the source of hypertension may be overestimated when using current imaging techniques.

Use of intravenous contrast material in transcranial sonography.

RATIONALE AND OBJECTIVES: The appearance of the intracranial vasculature was compared on power and color Doppler ultrasound (US) scans obtained with and without a microbubble contrast agent. MATERIALS AND METHODS: Nine patients (three men, six women) aged 42-70 years (mean age, 53 years) participated in the study. Seven patients underwent both color Doppler US and power Doppler US before and after intravenous administration of contrast agent, and two underwent only color Doppler US. All patients had previously undergone cerebral angiography. RESULTS: Before contrast material was administered, power Doppler US was more sensitive than color Doppler US in the detection of intracranial vessels (P < .05); neither technique depicted the entire circle of Willis in eight of nine patients. Postcontrast power Doppler US depicted more vascular segments than postcontrast color Doppler US (P < .01) or precontrast power Doppler US (P < .01). Use of intravenous contrast material enabled the entire circle of Willis to be evaluated from a single temporal bone acoustic window with both power Doppler US and color Doppler US in all patients. Contrast-enhanced power Doppler US depicted vessels not shown by enhanced color Doppler US. CONCLUSION: Contrast-enhanced power Doppler US depicted more vessels, better demonstrated specific vascular segments, and provided better vascular definition of the intracranial vasculature than contrast-enhanced color Doppler US or unenhanced power Doppler US.

Vertebral artery dissection related to basilar impression: case report.

A 50-year-old man with myelopathy secondary to basilar impression developed bilateral vertebral artery dissection after undergoing treatment with 8 pounds of cervical traction. The vertebral artery dissection resulted in vertebrobasilar insufficiency and posterior circulation stroke. In this report, the current management philosophies in the treatment of basilar impression are discussed, and the pertinent neurovascular anatomy is illustrated. This report suggests that vertebral artery injury may result from attempted reduction of severe basilar impression. Regardless of the cause of cranial settling, the risk of vertebral artery injury with cervical traction should be considered in patients with severe basilar impression.

Neurogenic hypertension related to basilar impression. Case report.

The authors report the resolution of essential hypertension following transoral odontoidectomy and medullary decompression in a 39-year-old woman with basilar invagination. Current understanding of central regulation of the cardiovascular system is discussed and the pertinent neuroanatomy illustrated. Experimental and clinical evidence supporting the role of neurogenic mechanisms in the pathogenesis of hypertension is reviewed.

A percutaneous epidural screw electrode for intracranial electroencephalogram recordings.

A new epidural electrode for monitoring brain electrical activity is described. The electrode is a tapered screw that is easily inserted percutaneously and removed without general anesthesia. The epidural screw has been used without complications for ictal and interictal electroencephalogram recordings in four patients with medically refractory complex-partial seizure disorders. The epidural screw electrode offers the advantages of easy insertion and removal, patient comfort, artifact-free electroencephalogram recordings, and minimal risk of intracranial infection or hemorrhage.

Attenuated development of ischemic brain edema in vasopressin-deficient rats.

Brain edema formation was investigated in the vasopressin-deficient Brattleboro rat using a middle cerebral artery occlusion model of early ischemic injury. Water and sodium accumulation after 4 h of ischemia were attenuated 36 and 20%, respectively, in the Brattleboro strain as compared to the control Long-Evans strain. This effect was independent of differences in animal size and state of hydration. In addition, measurements of cerebral blood flow indicated that Brattleboro and Long-Evans rats had equal levels of ischemia following middle cerebral artery occlusion. Systemic treatment of Brattleboro rats with vasopressin normalized their serum electrolyte concentrations and osmolarity but did not alter sodium or water accumulation in the ischemic brain. In contrast, intraventricular administration of vasopressin in Brattleboro rats increased edema formation to that seen in control rats. The reduced water and sodium accumulation in Brattleboro rats subjected to middle cerebral artery occlusion may be related to alterations in blood-brain barrier permeability since the blood-to-brain sodium flux was 36% less in the ischemic tissue of the Brattleboro as compared to the Long-Evans strain. These results support the hypothesis that central vasopressin is a regulator of brain volume and electrolyte homeostasis. Furthermore, our findings suggest a role for central vasopressin in the development of ischemic brain edema.

Eosinophilic granuloma of the cervical spine. A case report and review of the literature.

This is a report of a case of eosinophilic granuloma involving the second cervical vertebra in a 33-year-old woman. There have been 32 case reports in the literature describing eosinophilic granuloma presenting as cervical spine disease. Due to its intimate relation to the central nervous system, the opportunity for neurological sequelae and neurosurgical intervention is common in cervical eosinophilic granuloma. In this report a brief history of eosinophilic granuloma is reviewed and case histories from the literature with cervical spine involvement are summarized. The therapeutic options are described and a recommended protocol for management is outlined.