Preoperative embolization of brain AVMs with isobutyl-2 cyanoacrylate.

The role of embolization in the management of brain arteriovenous malformations remains controversial. The benefits of embolization alone are not clear and surgical removal may be technically difficult or impossible in many cases. In an attempt to facilitate surgical removal, we performed preoperative embolization in 15 cases using a mixture of isobutyl-2 cyanoacrylate and glacial acetic acid. In one case, a mixture of polyvinyl alcohol particles, microfibrillar collagen, and 30% ethanol was used. In 10 of these cases the surgeon felt that the embolization significantly aided the operative removal by decreasing blood loss, reducing the size of draining veins, and removing portions of the nidus itself. In no patient did the embolization result in an unanticipated significant neurologic deficit. The major role for embolization in the management of brain arteriovenous malformations may be as an aid to surgical removal.

Saccular aneurysms in basilar artery fenestration.

Of 59 cases of vertebrobasilar junction aneurysms diagnosed and treated from January 1977 to April 1986, 21 (35.5%) saccular aneurysms arose in a fenestration of the proximal basilar artery. Defects of the media at the junctures of the fenestrated segments, as well as the possible presence of turbulent flow at the vertebrobasilar junction, may explain the high incidence of vertebrobasilar aneurysms associated with proximal basilar artery fenestration.

A mathematical model for the mechanics of saccular aneurysms.

We constructed and discussed a mathematical model of intracranial saccular aneurysms based on the static mechanics of hollow vessels and were able to focus on three variables that are fundamental to the process of enlargement and rupture of these lesions. They are blood pressure (P), wall strength (sigma), and total wall substance (VT), which, if assigned values of 150 mm Hg, 10 MPa, and 1.0 mm3, lead to model-predicted values of 8 mm for the diameter and 40 micron for the wall thickness for the critical geometry of aneurysmal rupture. These are quantitatively similar to published measurements. The model is based on the assumption of a uniform thin spherical shell for the saccular aneurysm. The interrelationship of the variables, expressed in the equation for critical size at rupture (dc) (i.e., dc = [4 sigma VT/(pi P)]1/3), draws attention to the need for quantitative studies on aneurysmal geometry and on the stereology of the structural fraction of the aneurysmal wall. We concluded that tissue recruitment from around the initial site or hypertrophy of the wall tissue is commonly involved in the aneurysmal process. We identify the paradox of elastic stiffness and stability, which are characteristic of autopsy specimens in the laboratory, in contrast to plastic behavior and irreversible strain, which are essential to the natural process of enlargement of saccular aneurysms.

How old people tolerate intracranial surgery for aneurysm.

The purpose of this paper is to examine how well (or poorly) patients past the age of 60 tolerate intracranial surgery for aneurysms in all locations. The records of 93 consecutive good risk patients (Botterell Grades 1 and 2) have been reviewed. Co-existing chronic medical conditions, e.g., hypertension, were ignored in patient grading. The results indicate that, for treatment of aneurysms on the anterior circulation, older patients tolerate intracranial procedures as well as younger patients. This is not true for operations upon posterior circulation aneurysms. Some possible reasons for this discrepancy are suggested.

Basilar artery dissection: an early postoperative complication of aneurysm clipping. Case report.

Recurrent subarachnoid hemorrhage (SAH) in the early period following successful clipping of a cerebral aneurysm is unusual. The authors report a unique case of distal basilar artery dissection and fatal SAH on the 6th day postoperatively. It is concluded that this complication was related to vascular trauma inflicted by repositioning the aneurysm clips during a seemingly uneventful procedure for a basilar artery tip aneurysm.

Intravenous digital subtraction angiography and duplex ultrasonography in postoperative assessment of carotid endarterectomy.

Seventy-four consecutive patients who had undergone carotid endarterectomy procedures were examined with intravenous digital subtraction angiography (IV-DSA) and duplex ultrasonography (DUS) at intervals ranging from 1 to 14 months postoperatively. Ninety-one percent of the DUS and 74% of the DSA images were of diagnostic quality. The two modalities agreed in the assessment of the endarterectomy appearance in 84% of the arteries, with 85% showing no evidence of significant residual disease. There were no arteries with severe restenosis or complete occlusion. In the 10 vessels in which the two modalities disagreed in disease assessment, the IV-DSA images were often degraded by artifact or vessel overlap leading to underestimation of disease. The authors conclude that DUS is the examination of choice for routine follow-up studies of carotid endarterectomy.

Hunterian proximal arterial occlusion for giant aneurysms of the carotid circulation.

Hunterian proximal artery occlusion was used in the treatment of 160 of 335 patients harboring giant aneurysms of the anterior circulation. One hundred and thirty-three of these aneurysms arose from the internal carotid arteries, 20 from the middle cerebral arteries, and seven from the anterior cerebral arteries. Ninety percent of the patients had satisfactory outcomes. The safety of internal carotid artery occlusion has been greatly enhanced by preoperative flow studies and by test occlusion with an intracarotid balloon to identify those patients who require preliminary extracranial-to-intracranial bypass, which was used in all of the middle cerebral occlusions. The anterior cerebral artery had magnificent leptomeningeal collateral flow that prevented infarction even without cross flow. Obliteration of the aneurysm by thrombosis was complete, or nearly so, in all but four patients whose treatment was completed. Analysis of poor outcome in 16 patients revealed that hemodynamic ischemic infarction was known to occur after only two of the carotid occlusions.

Clinical presentation and management of giant anterior communicating artery region aneurysms.

OBJECT: The authors reviewed their 20-year experience with giant anterior communicating artery aneurysms to correlate aneurysm size with clinical presentation and to analyze treatment methods. METHODS: In 18 patients, visual and cognitive impairment were quantitated and clinical outcome was categorized according to the Rankin scale. Statistical analysis was performed using Fisher's exact test. CONCLUSIONS: At least 3.5 cm of aneurysm mass effect was required to produce dementia in the patient (p = 0.0004). Dementia was usually caused by direct brain compression by the aneurysm rather than by hydrocephalus. Optic apparatus compression occurred with smaller aneurysms (2.7-3.2 cm) when they pointed inferiorly. Aneurysm neck clipping was possible in half of the cases. Special techniques, including temporary clipping, evacuation of intraluminal thrombus, tandem and/or fenestrated clipping, and clip reconstruction were often required. Occlusion of or injury to the anterior cerebral artery (ACA) was the main cause of poor outcome or death. Proximal ACA occlusion, even of dominant A1 segments with small or no contralateral A1 artery, was an effective treatment alternative and was well tolerated as a result of excellent leptomeningeal collateral circulation.

Long-term prognosis and effect of endarterectomy in patients with symptomatic severe carotid stenosis and contralateral carotid stenosis or occlusion: results from NASCET. North American Symptomatic Carotid Endarterectomy Trial (NASCET) Group.

The purpose of this study was to examine how the prognosis of patients who presented with a recent ischemic event referable to a 70% to 99% stenosis of one carotid artery (ipsilateral) was altered by stenosis and occlusion of the contralateral carotid artery. The benefit of performing carotid endarterectomy on the recently symptomatic artery, in the presence of contralateral artery disease, was also examined. A total of 659 patients were grouped into one of three categories according to the extent of stenosis in the contralateral carotid artery: less than 70% (559 patients), 70% to 99% (57 patients), and occlusion (43 patients). Strokes that occurred during the follow-up period were designated as ipsilateral if they arose from the same carotid artery as the symptom for which the patient had been entered into the study. Medically treated patients with an occluded contralateral artery were more than twice as likely to have had an ipsilateral stroke at 2 years than patients with either severe (hazard ratio: 2.36; 95% confidence interval (CI): 1.00-5.62) or mild-to-moderate (hazard ratio: 2.65; 95% CI: 1.43-4.90) contralateral artery stenosis. The perioperative risk of stroke and death was higher in patients with an occluded contralateral artery (4.0% risk) or mild-to-moderate (5.1% risk) contralateral stenosis. Regression analyses indicated that the results were not affected by other risk factors. An occluded contralateral carotid artery significantly increased the risk of stroke associated with a severely stenosed ipsilateral carotid artery. Despite higher perioperative morbidity in the presence of an occluded contralateral artery, the longer-term outlook for patients who had endarterectomy performed on the recently symptomatic, severely stenosed ipsilateral carotid artery was considerably better than for medically treated patients.

Use of detachable balloons for proximal artery occlusion in the treatment of unclippable cerebral aneurysms.

Of 68 patients with unclippable aneurysms treated by proximal artery occlusion with detachable balloons, permanent occlusion was achieved in 65; of these patients, 37 had carotid artery aneurysms below the origin of the ophthalmic artery, 21 had aneurysms arising from the supraclinoid portion of the carotid artery, six had basilar trunk aneurysms, and one had a distal vertebral aneurysm. Examination for treatment selection included assessment of the circle of Willis by compression angiography and xenon blood flow studies, with the ultimate evaluation being test occlusion under systemic heparinization with the balloon temporarily placed in the desired position. Of 67 patients who underwent a formal occlusion test, eight with carotid artery aneurysms did not initially tolerate the occlusion test, and ischemic signs disappeared instantaneously with deflation and removal of the balloon. During test occlusion, two additional patients had ischemic events that proved to be embolic; these reversed immediately upon balloon deflation. Of the 65 patients in whom permanent occlusion was effected by detachable balloon, there were nine instances of delayed cerebral events. One of these was a seizure leading to respiratory arrest and resuscitation 3 days following occlusion in a patient who had presented with seizures. The other eight cases were delayed ischemic events; seven were completely reversed and one patient had residual weakness in one leg (1.5% permanent morbidity). Extracranial-intracranial bypass procedures were performed in 25 of the 65 cases. All aneurysms of the carotid artery below the level of the ophthalmic artery presented angiographic proof of complete thrombosis. Ten of 21 aneurysms arising from the supraclinoid portion of the carotid artery were completely thrombosed by proximal occlusion alone, without additional trapping procedures. Similarly, in three of six basilar trunk aneurysms, proximal occlusion alone initiated complete aneurysm thrombosis without trapping. The conclusion is that proximal balloon occlusion for unclippable cerebral aneurysms is a convenient, safe, and effective way of producing arterial occlusion in these cases.

Effects of profound hypotension on cerebral blood flow during surgery for intracranial aneurysms.

The progression of changes in cerebral blood flow (CBF) and neurological status were measured in 12 patients in whom profound hypotension (mean arterial blood pressure (MABP): 30 to 40 mm Hg) was used during intracranial aneurysm surgery. Nine patients (Group I) showed autoregulation of CBF to an MABP of 40 to 50 mm Hg during surgery. None of these patients had arterial spasm preoperatively. Postoperatively, mild flow disturbances were noted at the site of retraction. Three Group I patients developed arterial spasm postoperatively, but there was no associated neurological deterioration. The remaining three patients (Group II) had impaired autoregulation during surgery, and CBF decreased by 35% to 65% at an MABP of 50 mm Hg. Two of these patients had angiography immediately before surgery, and both showed moderate to severe arterial spasm. Relatively severe flow disturbances were noted postoperatively at the site of retraction, and two patients developed ischemic deficits of late onset. Brain retractor pressure and the degree and duration of hypotension were equivalent in the two patient groups. There was no correlation between intraoperative reductions in CBF (to as low as 20 ml/100 gm/min in the unretracted hemisphere) and immediate postoperative neurological deficits. The use of halothane and mannitol and the relatively short duration of the flow reductions were suggested as factors contributing to the protection from ischemia that was observed. Arterial spasm was found to produce hemodynamic instability and reduced CBF, although neurological status was unaffected in the majority of patients. Patients with impaired autoregulation during surgery were at increased risk of delayed ischemic complications postoperatively, and showed characteristic flow disturbances at all three stages of their clinical course.

Layered structure of saccular aneurysms assessed by collagen birefringence.

Cerebral aneurysms are composed principally of collagen, a birefringent protein which is responsible for withstanding the forces of blood pressure. The known correlation between collagen birefringence and its mechanics provides the basis for using polarizing microscopy to evaluate the strength of collagen, layer by layer across the aneurysmal wall. In order to obtain better quantitative measurements, several birefringent enhancement stains were investigated. We concluded that sirius red F3B, at a concentration of 0.05% in saturated picric acid, is an excellent stain to enable measurement of both birefringence and directional organization on the same tissue sections. Six aneurysms from autopsy, fixed at 120 mmHg, and one surgical specimen were cut at 4 microns to provide sets of tangential sections. The polarizing optics emphasizes the multi-layered structure of the aneurysmal wall with the mean fiber alignments distinguishing one layer from another. Birefringence measurements showed that the outer third of the wall had mainly higher strength collagen, although not as high as nearby artery adventitia. The inner layers of the aneurysms had intermediate values, similar to the artery media and subendothelium. Our results are consistent with a model of aneurysmal enlargement that requires the reorganization of higher strength outer fibers while new collagen is added to the inner layers.

Selectivity of 4-methoxyphenethylamine derivatives as inhibitors of monoamine oxidase.

It has been established that the oxidative deamination of tyramine by monoamine xodase is inhibited by (+/-)-4-methoxy-beta-hydroxyphenethylamine and its N-methylated derivatives. This particular series of compounds does not inhibit the action of monoamine oxidase when tryptamine is used as the substrate. In contrast, 4-methoxyphenethylamine and its N-methylated homologs inhibit the monoamine oxidase-catalyzed deamination of both tyramine and tryptamine.

Effects of 3,4-dimethoxyphenethylamine derivatives on monoamine oxidase.

The cactus alkaloid 3,4-dimethoxyphenethylamine and its naturally occurring N-methylated homologs inhibited the deamination of tyramine and tryptamine by rat brain monoamine oxidase. In contrast, the beta-hydroxylated derivatives of this series failed to inhibit the action of monoamine oxidase on both tyramine and tryptamine.

Monoamine oxidase inhibiting activity of a series of (+/-)-4-methoxy-beta-hydroxyphenethylamines.

The synthesis and selected pharmacological testing of (+/-)-4-methoxy-beta-hydroxyphenethylamine [1-(4-methoxyphenyl)-2-aminoethanol] and its N-methylated derivatives are presented. Members of this series were found to exert partial prevention of reserpine-induced hypothermia in mice and to inhibit monoamine oxidase in Warburg studies. Activity was essentially dose dependent. The secondary amine was the most active member of the series. The tertiary amine was least active, and the primary amine exhibited intermediate activity.

Current status of the prospective, randomized trials of symptomatic carotid bifurcation disease.

Three contemporary trials that are studying patients who have symptomatic carotid disease have proven beyond doubt that CE is extremely beneficial in reducing the risk of future stroke in patients with high-grade stenosis (greater than 70%). The relative risk of major stroke is reduced by at least 80% at 2 years of follow-up. That such a remarkably positive result for surgery was not predicted is a consequence of the unanticipated malignant natural history of TIAs and minor stroke in severe carotid disease. Previous epidemiological studies had underestimated the risk of future stroke by almost threefold. The current studies also highlight the remarkable power of prospective clinical trials to evaluate the effectiveness of a surgical procedure. In the case of NASCET, only 659 patients were required to prove the benefit of CE, whereas, innumerable previous anecdotal cases had failed to provide a convincing answer. However it must be remembered that the benefit from CE is dependent on a low rate of perioperative morbidity and mortality, a strict measure of the degree of stenosis on angiography, recency of ischemic events, and unequivocal carotid symptoms. The ongoing study of patients with moderate degrees of carotid stenosis holds the promise that in the very near future precise guidelines, which have been properly evaluated by careful scientific scrutiny,, will be available to guide surgeons in the proper management of all patients who present with symptomatic carotid disease.

Combined endovascular/neurosurgical therapy of blister-like distal internal carotid aneurysms.

OBJECTIVE: To describe a novel therapeutic strategy for the treatment of "blister-like" aneurysms of the distal internal carotid artery (ICA). Direct surgical treatments of these fragile lesions have been associated with generally poor outcomes. METHODS: Two consecutive patients presenting with acute subarachnoid hemorrhage from "blister-like" aneurysms were treated with preliminary balloon occlusion of the ICA, followed by surgical trapping of the ICA beyond the aneurysm. RESULTS: The treatment resulted in complete thrombosis of both aneurysms with no clinical complications. CONCLUSION: This combined endovascular-neurosurgical approach offers a controlled, safer alternative to primary surgical therapy of "blister-like" aneurysms.

Isolated spinal cord arteritis.

This patient presented as a subacute progressive cervical myelopathy and the differential diagnosis included cervical spondylotic myelopathy and intramedullary mass. Microscopically, vascular lesions plus a patchy myelomalacia indicated a vasculitis. However, there was no suggestion of a generalized vasculitis at autopsy and the only supporting laboratory study was a raised erythrocyte sedimentation rate. It would seem that a vasculitis similar to polyarteritis nodosa or other collagen disease may be confined to the spinal cord.

The location of conduction abnormalities in human entrapment neuropathies.

Direct stimulation of 23 median, 13 ulnar and 2 peroneal nerves at the time of surgical exploration has been used to locate, and characterize the conduction abnormalities in the nerves. The most frequent location of the major conduction abnormalities in the median nerve was in the first 1-2 cm distal to the origin of the carpal tunnel. In the ulnar nerve the important conduction abnormalities were located most frequently in the segments 1 cm proximal and distal to the medial epicondyle. In the peroneal nerve the major conduction abnormalities occurred proximal or distal to the entry point of the common peroneal nerve into the peroneus longus muscle.

Trigeminal neuralgia: a comparison of the results of percutaneous rhizotomy and microvascular decompression.

Seventy-five patients were treated between March 1976 and June 1980 for classical idiopathic tic douloureux. Fifty-five patients underwent percutaneous trigeminal rhizotomy (PTR) and twenty-four had posterior fossa microvascular decompression (MVD) of the trigeminal nerve. Four patients had both procedures. In the PTR group, 4% were immediate failures, 42% had a delayed recurrence of pain, while 54% remained totally pain free with an average follow-up of 30 months. In the MVD group, 12% were immediate failures, 17% had a delayed recurrence of pain, and 71% have remained free of pain with a average follow-up of 28 months. Neither procedure can be regarded as ideal surgical treatment for patients with pain refractory to medical treatment. Percutaneous rhizotomy has an established place because of its safety, particularly in elderly patients. A high rate of recurrent pain is to be expected. Microvascular decompression has appeal in younger patients because of its non-destructive nature but the long term efficacy of the procedure is not known.