Electrical stimulation of cerebellar fastigial nucleus reduces ischemic infarction elicited by middle cerebral artery occlusion in rat.

Electrical stimulation of the cerebellar fastigial nucleus (FN) globally and profoundly increases cerebral blood flow via a cholinergic mechanism. In cerebral cortex, the vasodilation is unassociated with alterations in cerebral glucose utilization, a condition favoring protection against cerebral ischemia. We sought to determine whether FN stimulation would modify the size of the focal ischemic infarction resulting from occlusion of the middle cerebral artery (MCA). The MCA was occluded in anesthetized rats of the spontaneously hypertensive (SHR) or Sprague-Dawley (SD) strains with or without 1 h of electrical stimulation of the FN. Twenty-four hours later, rats were killed and the volume of the infarction established in thionin-stained sections. in SHRs, FN stimulation reduced by 40% the well-established cortical and partially subcortical infarctions elicited by occlusion of the MCA (from 186 +/- 35.2 to 113 +/- 47.1 mm3, mean +/- SD, n = 15; p less than 0.001). The zone of retrieval was anatomically constant, consisting of a rim of cortex dorsal and ventral to the infarction and medially within the thalamus and striatum corresponding to the penumbral zone described by others. The effect was comparable in rats of the SD strain having smaller infarctions. The effect of FN stimulation appears to be selective for the FN system in that it is not evoked by stimulation of the dentate nucleus and is blocked by systemic administration of atropine (1.0 mg/kg). We conclude that excitation of an intrinsic system in brain represented in the rostral FN has the capacity to reduce substantially an ischemic infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Elevated intracranial venous pressure as a universal mechanism in pseudotumor cerebri of varying etiologies.

Pseudotumor cerebri (PTC), or idiopathic intracranial hypertension, is a syndrome associated with multiple clinical conditions. We hypothesize that most if not all etiologies result in an increase in intracranial venous pressure as a final common pathway. We studied 10 patients with PTC. Five had dural venous outflow obstruction as demonstrated by venography, and the five remaining patients had normal venous anatomy. Pressure measurements, made during venography in eight patients, all showed elevated pressures. Pressure measurements in the superior sagittal sinus ranged from 13 to 24 mm Hg (mean, 16.6 mm HG). Patients with obstruction tended to have a high pressure gradient across the stenotic segment. Five patients with normal dural venous anatomy had elevated right atrial pressures (range, 6 to 22 mm Hg; mean, 11.8 mm Hg), which were transmitted up to the intracranial venous sinuses. Endovascular techniques, including angioplasty and infusion of thrombolytic agents in some cases, improved outlet obstruction from a hemodynamic perspective but were ineffective in consistently and reliably alleviating the clinical manifestations of PTC. Patients in both groups tended to respond well to conventional CSF diversion procedures. Our study suggests that elevated intracranial venous pressure may be a universal mechanism in PTC of different etiologies. This elevated venous pressure leads to elevation in CSF and intracranial pressure by resisting CSF absorption. Although the mechanism leading to venous hypertension in the presence of outflow obstruction is obvious, the etiology of increased intracranial and central systemic venous pressure in PTC remains obscure.

Preliminary results of intracranial angioplasty for vascular stenosis caused by atherosclerosis and vasculitis.

PURPOSE: To evaluate the results of balloon angioplasty of 17 stenoses resulting from intracranial atherosclerosis and vasculitis. METHODS: Seventeen skull-base and intracranial lesions were dilated with a microballoon angioplasty catheter. RESULTS: Initially, 16 of the 17 stenoses showed improvement at angiography. Moderate residual stenosis was found in 2 of 12 atherosclerotic lesions, both in the distal vertebral artery. Angioplasty in 1 of 12 atherosclerotic lesions caused worsening of the stenotic site, also in the distal V4 region of the vertebral artery. All but one of the patients improved clinically. However, all five lesions caused by acute vasculitis progressed to occlusion after initial improvement. CONCLUSION: Intracranial percutaneous transluminal angioplasty is a viable nonsurgical option for the treatment of atherosclerotic vascular insufficiency, but it may not be as successful in treating lesions caused by vasculitis in the acute phase.

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.

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.

The safety and effectiveness of brain arteriovenous malformation embolization using acrylic and particles: the experiences of a single institution.

The purpose of this article is to report on the safety and effectiveness of brain arteriovenous malformation (AVM) embolization for two series of patients, of which one was treated with particulate embolization and the other with acrylic embolization. Sixty-five consecutive patients from embolization logs and patient records from 1988 to 1993 were reviewed. AVMs were routinely treated with particulate embolization early in the review (1988-1991), and after a transition period, the technique was changed to acrylic embolization for the remainder of the study period (1992-1993). All patients were treated with the ultimate goal of complete AVM obliteration. AVMs were embolized and resected, if possible, and if unresectable, they were reduced in size with embolization and radiated. The course of treatment for each patient was reviewed. The effectiveness at the end of treatment was analyzed for the ability to resect the AVM and, if unresectable, the ability to reduce the AVM to radiation size. Additionally, the safety of each embolization technique was evaluated in the context of comprehensive care, in terms of the safety of the procedure itself, the surgical resection after embolization, and the outcome at the end of comprehensive treatment. This article outlines the safety and effectiveness of acrylic and particulate embolization at a single institution. The ability to surgically resect an AVM after embolization and to reduce nidus size with acrylic was at least comparable with that with particulate embolization. Comprehensive complication rates were lower after acrylic embolization and were heavily influenced by a decreased number of surgical complications in the acrylic series. These data support the need to conduct a randomized prospective clinical trial to compare the relative safety and effectiveness of the two methods of embolization.

Endovascular treatment of intracranial dural arteriovenous fistulas with spinal perimedullary venous drainage.

Intracranial dural arteriovenous (AV) fistulas with spinal perimedullary venous drainage are rare lesions that have distinctive clinical, radiological, and therapeutic aspects. Five patients presented with an ascending myelopathy, which extended to involve the brain stem in three cases. Myelography and magnetic resonance imaging showed slightly dilated spinal perimedullary vessels. Spinal angiograms were normal in the arterial phase. Diagnosis was only possible after cerebral angiography, which demonstrated posterior fossa AV fistulas fed by meningeal arteries and draining into spinal perimedullary veins. Endovascular treatment alone resulted in angiographic obliteration of the lesion in three patients. Two patients required surgery in addition to endovascular therapy. One patient died postoperatively, and in one a transient complication of embolization was observed. Improvement after treatment was good in two cases and fair in two. Transverse sinus thrombosis was observed in three cases and was probably the cause of the aberrant venous drainage of the fistula into the spinal perimedullary veins. The pathophysiology is related to spinal cord venous hypertension. These lesions were classified as Type 5 in the Djindjian and Merland classification of dural intracranial AV fistulas. Endovascular therapy is a safe effective method in the treatment of these fistulas and should be tried first.

Combined surgical and endovascular treatment of a giant vertebral artery aneurysm in a child. Case report.

The case is presented of a 5-year-old child who suffered a subarachnoid hemorrhage from a giant left vertebral artery-posterior inferior cerebellar artery (PICA) aneurysm. Initial treatment consisted of surgical occlusion of the parent vertebral artery combined with a PICA-to-PICA bypass. Because of persistent filling of the aneurysm, the left PICA was occluded at its takeoff from the aneurysm. Endovascular coil occlusion of the aneurysm and the distal left vertebral artery enabled complete elimination of the aneurysm. Follow-up magnetic resonance imaging and arteriography performed 6 months postoperatively showed persistent occlusion and elimination of the mass effect. Combined surgical bypass and endovascular occlusion of the parent artery may be a useful adjunct in the management of these aneurysms.

Selective endovascular techniques in the treatment of cerebral mycotic aneurysms. Report of three cases.

The aim of this study was to evaluate the role of endovascular treatment for intracranial mycotic aneurysms. The clinical and angiographic features of three patients with endocarditic vegetation (two with Streptococcus viridans and one with Staphylococcus) were reviewed retrospectively. Patients were selected for this treatment according to the clinical setting and aneurysm location. In two cases, selective catheterization of a distal middle cerebral and posterior cerebral artery branch with a microcatheter followed by superselective amobarbital testing of the parent vessel was preliminary to the occlusion of that vessel with autologous clot or glue. The third patient was treated by selective occlusion of the aneurysm by intra-aneurysmal placement of platinum minicoils. Two patients presented with intracranial hemorrhage and in one the lesion was found on computerized tomography. All three aneurysms had been excluded from the circulation at the 6-month follow-up review. The only complication from the procedure, despite the septic nature and distal localization, was balloon deflation in one patient, who was successfully retreated with coils. Endovascular embolization is indicated in patients who are at risk of hemorrhage and cannot undergo the standard procedure. The superselective amobarbital test allows selection of patients who will tolerate distal vessel occlusion. This endovascular procedure represents a safe and effective treatment for these lesions.

Materials and embolic agents for endovascular treatment.

The refinement in the intravascular techniques has revolved upon the development of new material and a better understanding of neurophysiology. Access has become less of a limitation, and more emphasis is now placed on getting the job done: closing a fistula, obliterating a malformation, or filling an aneurysm. Embolic materials available have greatly changed according to the indication at hand. The focus now is on the specific uses for the agent instead of toxicity or dose-response trials.

Percutaneous embolization with Ethibloc of lymphatic cystic malformations with a review of the experience in 70 patients.

Cystic lymphatic malformations (CLM) are superficial vascular hemodynamically inactive malformations of the lymphatic compartment. We propose a new approach which uses a sclerosing agent as an alternative to surgical resection. In the past nine years we treated 70 patients with CLM. Fifty-five percent were younger than five years of age with a male preponderance and most (80%) of the CLM were located in the maxillofacial region. They usually presented with functional impairment from the mass effect; others had infections, bleeding, or inflammation. The CLM were injected under fluoroscopic control with a sclerosing agent, Ethibloc, which dries up the pockets and reduces the mass. On follow-up the results were good in 62%, unchanged in 5%, and continued progression in 20%. Fifteen percent underwent surgery failures (24%) occurred in mixed forms of cystic and cellular lymphangiomas. Complications were minors. Percutaneous embolization is useful for CLM, with minimal risk, absence of scar, and it avoids surgery. It should be the first line of treatment for these lesions.

Intrathrombus administration of tissue plasminogen activator in acute cerebrovascular occlusion.

Intraarterial thrombolysis for acute cerebrovascular occlusion has achieved recanalization at a 50-90% rate. Clinical outcome has been unpredictable. The authors sought to test the hypothesis that intrathrombus administration of recombinant tissue plasminogen activator (rt-PA) would improve recanalization rate and to assess the possibility that clinical outcome would be predicted by the extent of collateral flow. Seven patients with acute cerebrovascular occlusion (less than six hours in 6, twenty-four hours in 1) were treated with intrathrombus rt-PA at 1 mg/minute. Examinations were scored on a five-point motor scale. Collateral flow was assessed angiographically. Vessels recanalized in 5 patients, 3 of whom had good outcomes. Vessels failed to recanalize in 2 patients, 1 of whom had good outcome. Good collateral flow was evident in all 4 patients with good outcome and in none of those with poor outcome. Intrathrombus administration of rt-PA is technically feasible. Favorable clinical outcome is more likely in the presence of good collateral flow. In the absence of good collateral flow, ultra-early intervention may be necessary.

Interventional neuroradiology.

The challenge of this "decade of the brain" is to perfect the interventional means for detecting and treating vascular malformations. The prognosis for patients with aneurysms is improved with the introduction of the new Guglielmi detachable coils. Parent vessel occlusion is a good alternative for treating dysplastic aneurysms at the circle of Willis after functional testing. Vein of Galen malformations of the mural type are best treated using the arterial route. The venous route is useful for treating choroidal forms when treatment by the arterial approach fails. These advances have resulted in significant improvement in the outlook for children with these conditions. Arteriovenous malformation embolization with either particles or glue has about a 10% permanent complication rate and, when combined with radiosurgery or surgical resection, is successful in curing 74% of patients. Morphologic features within the arteriovenous malformation are statistically useful markers of clinical course (hemorrhage and steal). Carotid cavernous fistulas can now also be treated by microcatheter and coils through the arterial or venous routes. Angioplasty in the neck and intracranially results in improved cortical perfusion. With technologic improvements and better case selection, serious complications can be minimized.

Unusual pattern of a deep developmental venous anomaly on CT and MR studies.

OBJECTIVE: This article focuses on an unusual cross-sectional imaging pattern of a deep developmental venous anomaly (DVA). Since these anomalies are nonpathologic, they must not be interpreted as a disease that requires further costly workup and potentially injurious procedures (cerebral angiography). MATERIALS AND METHODS: Two women aged 19 (Case 1) and 30 (Case 2) years sought medical evaluation for severe headaches. Both patients underwent CT, MRI, and conventional cerebral angiography. Case 1 also underwent MR venography. RESULTS: The diagnosis of an unusual DVA in Case 1 was confirmed only after conventional catheter angiography and a follow-up MR venogram. In Case 2 the diagnosis was inferred based upon the CT, MRI, and conventional angiography results and the marked similarity to Case 1. The presumptive diagnosis in Case 2 would not have been made with confidence without the prior experience of managing Case 1. CONCLUSION: DVAs (venous angiomas) are extreme variations in the pattern of intracranial venous drainage. These two case reports highlight an unusual pattern of this benign entity. Individuals interpreting cross-sectional imaging studies should be cognizant of this pattern.

Endovascular treatment of arteriovenous fistulas arising from branches of the subclavian artery.

PURPOSE: The goal of this study was to evaluate the role of endovascular techniques in the treatment of arteriovenous fistulas (AVFs) in the subclavian region. PATIENTS AND METHODS: Since 1984 six patients with AVFs arising from branches of the subclavian artery have been treated. All AVFs were of iatrogenic origin (five venous punctures and one pacemaker insertion). Two patients had cardiac insufficiency, three had a bruit, and one had upper extremity venous hypertension. Angiographically, four of the AVFs were located on the thyrocervical trunk and two were on the internal mammary artery. RESULTS: All fistulas were treated by means of endovascular occlusion with a detachable balloon, with full resolution of symptoms. One AVF recurred after a balloon deflated prematurely. The patient was treated again and was subsequently cured. No other complications were associated with treatment. CONCLUSION: Endovascular balloon occlusion of AVFs in the subclavian region is a simple, effective, and safe method that eliminates the need for surgery. It should be the method of choice for treatment of these lesions.

Magnetic resonance imaging demonstrates that electric stimulation of cerebellar fastigial nucleus reduces cerebral infarction in rats.

We sought to determine whether high spatial resolution magnetic resonance imaging is useful for noninvasive quantitation of the ischemic infarct produced by occlusion of the middle cerebral artery and for detection of reduced infarct volume elicited by electric stimulation of the cerebellar fastigial nucleus. Male rats of the spontaneously hypertensive strain were anesthetized, the middle cerebral artery was occluded, and the fastigial nucleus was stimulated for 1 hour. Twenty-four hours later, rats were reanesthetized and T1- and T2-weighted images were obtained. Rats were killed and the volume and distribution of the lesion was established by histopathology. Magnetic resonance imaging estimates of the lesion volume were 271 +/- 41.0 mm3 (middle cerebral artery, n = 5) and 148 +/- 8.4 mm3 (middle cerebral artery + fastigial nucleus stimulation, n = 6; 45% reduction, p less than 0.05). Histopathological analysis revealed a lesion of 229.8 +/- 15.4 mm3 involving somatosensory cortex, lateral caudate putamen, and lateral hippocampus. Fastigial nucleus stimulation resulted in a 36% reduction in infarct volume to 146.0 +/- 10.3 mm3. The retrieved zone was largely in the cortex dorsal and ventral to the lesion and mostly posterior to the lesion. The estimates of lesion volume by magnetic resonance imaging and histopathology did not differ and were highly correlated (r = 0.90; p less than 0.001). This study confirms our previous finding that fastigial nucleus stimulation reduces the volume of a focal ischemic infarct and demonstrates that magnetic resonance imaging not only accurately estimates the volume of the lesion but also can detect changes as small as 50-100 mm3.

Endovascular treatment of vertebral arteriovenous fistula.

The clinical and angiographic features of 46 vertebral arteriovenous fistulas (AVFs) seen during a 12-year period (45 patients) were reviewed. Fourteen patients were asymptomatic, with vertebral AVF discovered at routine clinical examination. Specific symptoms at presentation in the other patients were tinnitus (n = 21), vertigo (n = 6), neurologic deficit (n = 3), and pain (n = 2). Of the 46 AVFs, 19 (41%) were caused by trauma and 27 (59%) were spontaneous. The fistula was found at C-1 to C-2 in 21 (46%) cases, at C-2 to C-5 in five (11%), and below C-5 in 20 (44%). Thirty-four patients (35 vertebral AVFs) were treated with the endovascular technique. Embolization was performed with latex balloons filled with contrast medium in most cases. Endovascular therapy resulted in complete occlusion in 32 cases (91%) and partial occlusion in three (9%). The vertebral artery could not be preserved in three patients. Endovascular balloon treatment of vertebral AVFs is effective in occluding the shunt, avoids general anesthesia and surgical intervention, and results in minimal morbidity. Endovascular therapy is the treatment of choice for vertebral AVF.

Balloon occlusion of the internal carotid artery in 40 cases of giant intracavernous aneurysm: technical aspects, cerebral monitoring, and results.

We have studied the results of carotid occlusion in the treatment of giant intracavernous carotid artery (ICA) aneurysms in 40 patients. Clinical, angiographic, Doppler and cerebral blood flow (CBF) criteria for tolerance of occlusion are discussed. The patients had headaches (47.5%), cranial nerve compression (87.5%), decreased visual acuity (20%), ruptured aneurysm (15%) and 5% were asymptomatic. Balloon occlusion tests were performed under light sedation anaesthesia: a successful test required perfect clinical tolerance and adequate angiographic collateral circulation in arterial, parenchymatous, and venous phases. Additional criteria included xenon 133 CBF measurements, and transcranial Doppler sonography of the middle cerebral artery. According to these criteria, 5 patients did not tolerate test occlusion and required an extra-intracranial (EC-IC) bypass. Mean follow-up was 4.7 years. All patients were radiologically cured of their aneurysm, and in 35 the symptoms resolved, although 3 had persistent ocular motor nerve palsies, and in 4 visual defects were unchanged. Complications were 1 permanent and 3 transient neurological deficits. Balloon occlusion of the ICA is an effective, reliable form of treatment for intracavernous giant aneurysm and should replace surgical ligation of the cervical carotid artery. With CBF or Doppler monitoring, the risk of neurological deficit is diminished. EC-IC bypass prior to ICA occlusion is indicated if test occlusion is not tolerated.