Persistent autoregulatory disturbance after angioplasty for cerebral vasospasm. A case report.

SUMMARY: Hyperdynamic therapy, consisting of hypervolemia, haemodilution, and hypertension, is an established treatment for cerebral vasospasm following subarachnoid haemorrhage. Angioplasty has emerged as an additional, effective treatment for symptomatic vasospasm. Loss of autoregulation, however, can occur despite effective angioplasty, underscoring the need for treatment with hyperdynamic therapy in combination with angioplasty. A 43-year-old woman underwent endovascular coiling of a ruptured left posterior communicating artery aneurysm. The patient went on to develop symptomatic vasospasm and was treated with hyperdynamic therapy and angioplasty. Autoregulation was assessed with xenon CT cerebral blood flow (CBF) measurement. An initial CBF study was obtained when the patient received dopamine and dobutamine infusions to maintain systolic blood pressure at 160 mmHg. The vasopressor drips were then temporarily held for twenty minutes, allowing the patient's systolic blood pressure to drop to 140 mmHg, and a repeat CBF study was obtained. Several days after angioplasty, CBF decreased significantly when the patient was taken off vasopressors, indicating impaired autoregulation. Hyperdynamic therapy was continued, and another CBF study one week later showed a return of autoregulation and normalization of CBF without induced hypertension. Autoregulation is disturbed during vasospasm. Although angioplasty can improve large artery blood flow during vasospasm, hyperdynamic therapy is also needed to maintain cerebral perfusion, particularly in the face of impaired autoregulation. Quantitative CBF measurement permits the maintenance of optimal CBF and monitoring of response to therapy.

Effect of hematocrit on calculation of cerebral blood flow and lambda in xenon CT.

Knowledge of the patient's hematocrit is necessary for calculation of cerebral blood flow (CBF) with xenon CT, and is a potential source of error. This study quantifies the effect of hematocrit on the calculation of CBF and lambda, and determines if the magnitude of the effect is dependent on actual CBF or lambda. The effect of hematocrit was measured empirically using software employing the numerical calculation method. CBF and lambda were found to be inversely related to hematocrit. The percent error produced by an inaccurate hematocrit is greater for lower actual CBF values.

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.

Endovascular therapy of intracranial arteriovenous malformations. Materials and techniques.

Endovascular therapy can be an integral part of the treatment plan for patients with brain AVMs Safe and successful AVM embolization requires familiarity with the devices and techniques used and keen awareness of the potential pitfalls and complications. This article reviews the technical aspects of endovascular therapy of brain AVMs, with reference to specific therapeutic goals.

Local thrombolytic therapy in deep cerebral venous thrombosis.

Thrombosis of the deep cerebral venous system is a rare entity with a very poor prognosis. We report two patients with thrombosis of the internal cerebral veins and vein of Galen who responded to local urokinase. We review all 49 cases of deep cerebral venous thrombosis in the English literature. The mortality rate for patients treated with either IV heparin or local thrombolytics was 13% compared with 48% in untreated patients (p = 0.037). Based on this retrospective review of the literature and our two cases, we support the use of heparin or local thrombolytics in individual cases of deep cerebral venous thrombosis.

Sequential injections of amobarbital sodium and lidocaine for provocative neurologic testing in the external carotid circulation.

PURPOSE: To present the results of a protocol for embolization in the external carotid territory that includes provocative testing with amobarbital sodium and lidocaine. METHODS: Provocative testing with sequential intraarterial injections of amobarbital sodium and lidocaine was done before embolization of 66 vascular pedicles in 26 patients with the following pathologic disorders: 8 meningiomas, 7 paragangliomas, 5 dural arteriovenous fistulas, 3 angiofibromas, 1 endolymphatic sac carcinoma, 1 metastatic renal carcinoma, and 1 Rendu-Osler-Weber syndrome. Findings during provocative testing and any postembolization deficits were recorded. RESULTS: Of the 66 vascular pedicles tested, only 1 showed positive findings on an amobarbital test, in which the patient had transient numbness in the contralateral leg. Results of lidocaine tests were positive, in 7 cases, in which cranial nerve deficits were suspected on the basis of anatomic findings. All deficits resolved within 15 minutes. If results of amobarbital or lidocaine tests were positive, large particles or coils were used for embolization. Otherwise, small particles or liquid agents were used. There were no complications after embolization. CONCLUSIONS: Provocative testing with amobarbital can reveal dangerous anastomoses. Testing with lidocaine can show vascular supply to the cranial nerves. With the use of appropriate protocols, embolization in the external carotid territory can be done with minimal risk.

Use of the extreme lateral approach in the surgical treatment of an intradural ventral cervical spinal cord vascular malformation: technical case report.

Vascular malformations on the ventral aspect of the spinal cord are difficult to access surgically. Recently, selected lesions have been treated with endovascular embolization. However, embolization using currently approved agents may not be permanently effective, and recanalization rates range from 25 to 83% in the literature. Additionally, many of these lesions are not amenable to endovascular treatment because of the inadequate diameter, tortuosity, or lack of collateral flow of the anterior spinal artery from which the feeding arteries arise. Surgical approaches to these lesions have been posterolateral or anterior. The posterolateral approach requires division of the dentate ligaments and occasionally the adjacent nerve root and then rotation of the cord itself to allow visualization of the lesion. The anterior approach involves a multilevel corpectomy requiring subsequent bone grafting and stabilization. Certain lesions are not readily approachable by either method. We describe the use of the extreme lateral approach to successfully access and obliterate a Type IVa perimedullary fistula located adjacent to the midline ventrally at the C1-C2 level in a 72-year-old woman who had suffered a subarachnoid hemorrhage. The extreme lateral approach was originally designed to access neoplasms located ventral to the cord and brain stem; as a result of the posterior displacement of the spinal cord by the neoplasm, intraoperative visualization is improved. No posterior displacement was present with this malformation. Even without such cord displacement, the extreme lateral approach allowed excellent visualization of and access to the arteriovenous fistula, preserved important anatomic structures, and required essentially no rotation or compression of the spinal cord to successfully obliterate the lesion.

Dolichoectasia of the anterior cerebral arteries in an adolescent.

We report a case of bilateral dolichoectasia of the anterior cerebral arteries in a 14-year-old girl as documented by MR imaging and cerebral angiography. Concurrent thickening of the adjacent medial frontal lobes was found, suggesting either a neuronal migrational abnormality or secondary changes attributable to vascular insufficiency.

Congenital arteriovenous fistulas supplied by a single branch of the maxillary artery.

We report four cases (two children, two adults) of congenital arteriovenous fistula supplied by a single large (pterygoid) branch of the second part of the maxillary artery deep to the parotid gland and mandible, with emphasis on the angiographic findings, therapeutic implications, and cause, with a review of the literature. Awareness of a predilection of congenital arteriovenous fistulas for this site, excellent-quality selective angiography, and careful attention to flow patterns help make the correct diagnosis. Endovascular balloon occlusion is the preferred treatment.

[15O]H2O positron emission tomography determination of cerebral blood flow during balloon test occlusion of the internal carotid artery.

PURPOSE: To determine the utility of [15O]H2O positron emission tomography (PET) for the quantitative determination of cerebral blood flow in patients undergoing balloon test occlusion of the internal carotid artery. METHODS: Twenty-two [15O]H2O PET cerebral blood flow studies were completed on 20 patients for whom temporary or permanent occlusion of the internal carotid artery was being considered because of skull base tumor or internal carotid artery aneurysm. In each study, cerebral blood flow was determined during temporary balloon internal carotid artery occlusion, and again after deflation and removal of the balloon from the internal carotid artery. RESULTS: Patients were divided into three groups based on clinical and cerebral blood flow response to balloon test occlusion. Studies were classified as group I when associated with no clinical symptomatology and with a cerebral blood flow decrease of less than 10 mL/100 g per minute (16 of 22 patients); as group II when there was no clinical symptomatology and cerebral blood flow fell to 25 to 35 mL/100 g per minute on the occluded side (5 of 22); and as group III when the patient was clinically unable to tolerate test occlusion and had a cerebral blood flow of less than 20 mL/100 g per minute on the occluded side (1 of 22). Neurologic sequelae developed in none of the eight group I patients later undergoing permanent internal carotid artery occlusion. Cerebral infarction developed subsequently in the one group II patient who underwent internal carotid artery occlusion. CONCLUSION: During internal carotid artery balloon test occlusion, [15O] H2O PET determination of cerebral blood flow allows rapid quantitative determination of cerebral blood flow throughout the entire brain, predicting the adequacy of collateral flow after permanent occlusion. All patients were able to tolerate the [15O]H2O PET cerebral blood flow determination, and there were no complications of the procedure.

A clinical and neuropathologic study of silk suture as an embolic agent for brain arteriovenous malformations.

PURPOSE: To evaluate the safety and efficacy of silk suture as an agent for preoperative embolization of cerebral arteriovenous malformations. METHODS: Clinical and histopathologic results were analyzed in six patients who underwent embolization of cerebral arteriovenous malformations using silk suture in combination with other agents. RESULTS: Three of the patients treated with silk hemorrhaged after embolization, and two of these patients died. Neuropathologic analysis of four patients showed acute perivascular inflammation, sometimes quite severe. CONCLUSIONS: The inflammatory response to silk may explain its effectiveness in producing vascular occlusion. However, a fulminate vasculitis theoretically can predispose to delayed hemorrhage. Other problems with silk include the pressure required to inject the agent and the inability to determine the final site of deposition of the silk. Although other embolic agents may share some of these potential difficulties, we feel that the disadvantages outweigh the advantages of silk as an embolic agent.

MR of slow CSF flow in the spine.

PURPOSE: To evaluate a slow-flow MR sequence in normal CSF flow and in CSF flow disturbance in cases of spinal stenosis. METHOD: The method was tested for flow sensitivity and applied to 67 sites of spinal canal compromise. RESULTS: Phantom studies show that flow can be depicted at a velocity of 0.5-1 mm/sec. On clinical images, stagnant CSF is black, flowing CSF is bright. Typically, in high-grade (90%-100%) stenosis, CSF above and below the site of spinal canal compromise (SCC) is black. With intermediate stenosis (50%-89%), CSF above the SCC remains white but becomes black distal to the SCC. Low-grade stenosis shows only localized flow disturbances. CONCLUSION: This easy-to-use sequence can solidify the MR diagnosis of high-grade stenosis when a distinct flow pattern is recognized. Flow patterns for intermediate and low-grade stenosis are less reliable.

Disk fragment migration.

This report analyzes the most frequently observed migration paths of disk fragments in 47 patients who had extruded or sequestered disks. Observations are based principally on magnetic resonance (MR) images. When disk fragments moved in a superior (42%) or inferior (40%) direction from the donor disk, the displaced disk components were most frequently (94%) dislodged into the right or left half of the anterior epidural space (AES) and rarely straddled the midline. To explain this phenomenon, the authors investigated the anatomy of the AES by dissecting four cadaver specimens and reviewing 300 MR images of the spine. They conclude that the migrating path of a disk fragment is determined by the anatomy of the AES, a fairly well-defined space delimited posteriorly by the posterior longitudinal ligament and by membranes laterally attached to it. It consists of two compartments separated by a sagitally aligned septum. During migration, sequestered disk fragments usually stay in these compartments.