Cerebral perfusion defects, dysautoregulation and carotid stenosis

Single Photon Emission Computed Tomography (SPECT), imaging of cerebral blood flow was carried out in ten patients with haemodynamically significant carotid stenosis. Before and after carotid endarterectomy each patient was investigated by 3--dimensional SPECT brain scanning using technetium--hexamethyl propyleneamine oxine (99 mTcHMPAO, ceretec). Brain blood flow was normal before and after operation in 3 patients whose autoregulation was kept intact. Seven patients received acetazolamide to limit cerebral vascular reactivity and in four of these, preoperative perfusion defects were visible. After carotid endarterectomy the ipsilateral perfusion defects were abolished and it is concluded that carotid stenosis can reduce perfusion in the dysautoregulation brain and that carotid reconstruction can restore normal flow.     

Cerebral revascularization for aneurysms and tumors

OBJECTIVE: To discuss the indications, techniques, pitfalls, complication avoidance, and management of cerebral revascularization techniques for the treatment of aneurysms and cranial base tumors. METHODS: The indications for cerebral revascularization procedures included microsurgical occlusion of a parent vessel during the treatment of aneurysms and occlusion of a major vessel during the treatment of basal tumors. The techniques discussed include arterial patch grafting, end-to-end anastomosis, side-to-side anastomosis, arterial interposition grafting, and extracranial-to-intracranial bypass grafting, using radial artery grafts or saphenous vein grafts. RESULTS: During the 15-year period between 1985 and 2000, the senior author performed 24 radial artery grafts, 105 saphenous vein grafts, and 8 other revascularization procedures, among 50 patients with aneurysms and 83 patients with cranial base tumors. The overall patency rate was 95.6%. Twenty-three patients experienced a cerebral infarction; among those patients, 17 (12.5%) exhibited symptoms but the majority demonstrated considerable recovery during the follow-up period. One hundred one patients recovered to an excellent (Glasgow Outcome Scale score of 5) or good (Glasgow Outcome Scale score of 4) condition. Fifteen patients died as a result of recurrence or progression of tumors during the follow-up period. There were five perioperative deaths. For the last 35 patients, the surgical mortality rate was 0%, with all patients returning to an excellent or good condition. CONCLUSION: Although highly specialized, these sophisticated cerebral revascularization techniques should be learned and practiced by all neurosurgeons who wish to microsurgically treat intracranial aneurysms or cranial base tumors.     

Cerebral aneurysms in childhood and adolescence

In this study, 24 aneurysms occurring in 23 patients under the age of 18 years (mean 12 years) are analyzed. The male:female ratio was 2.8:1, and the youngest patient was 3 months old. Mycotic lesions and those associated with other vascular malformations were excluded. Forty-two percent of the aneurysms were located in the posterior circulation, and 54% were giant aneurysms. Presenting symptoms included subarachnoid hemorrhage in 13 and mass effect in 11. Several of these aneurysms were documented to rapidly increase in size over a 3-month to 2-year period of observation. All aneurysms were surgically treated: direct clipping was performed in 14; trapping with bypass in four; trapping alone in four; and direct excision with end-to-end anastomosis in two. The postoperative results were excellent in 21 aneurysms (87%), good in two (8%), and poor in one. The pathogenesis of cerebral aneurysms is reviewed.     

Cerebral aneurysms in identical twins

The hypothesis that genetic factors play a role in the genesis of cerebral aneurysms may be supported by clinical analysis of cerebral aneurysms in identical twins. In addition to reporting the present case, we review the literature on clinical features and genetical considerations in this matter. A forty-two-year-old male presented with subarachnoid hemorrhage (SAH) due to a left MCA aneurysm. At the age of 39, his identical twin brother also had SAH due to a ruptured left MCA aneurysm. This identical twin brother and his father's sisters died of SAH. Venous blood of the patient and his parents was collected to determine apolipoprotein E, angiotensinogen, angiotensin-converting enzyme, and very low density lipoprotein receptor genes. This analysis suggested a strong genetic association of apolipoprotein E epsilon4 with the pathogenesis. Including our cases, 13 cases of cerebral aneurysms in identical twins have been reported. There was a total of 37 aneurysms. Six twins had the same sites of aneurysm. These aneurysms show a tendency to be small in size, and to cause a high frequency of SAH occurring at a similar age. In young adults, cerebral aneurysms in identical twins tend to rupture. A screening diagnosis should be carried out as early as possible on an asymptomatic twin when the other has been discovered to have a ruptured cerebral aneurysm. Preventive treatment and systemic genome-wide linkage study should be conducted.     

Cerebral aneurysms associated with neurofibromatosis

An uncommonly recognized complication of neurofibromatosis (NF) is an angiopathy of the intracranial and extracranial arteries. Most of the previously reported cases have presented as an occlusive process similar to Moyamoya disease. We present our experience over the past 3 years involving three patients with five cerebral aneurysms and associated NF. Four of the aneurysms were intracranial, two being fusiform in nature. Treatment was surgical occlusion and included Selverstone clamping, balloon occlusion, and direct clipping. There appears to be an association between the development of cerebral artery aneurysms and NF, but the pathophysiology of these vascular changes is not fully understood.     

Cerebral aneurysms unrelated to arterial bifurcations

Summary The majority of saccular cerebral aneurysms arise at arterial branchings; those arising elsewhere are rare. Among 557 saccular cerebral aneurysms surgically treated between 1983 and 1994, 29 (5.2%) were unrelated to arterial divisions. These cases were retrospectively analysed. The ages of the subjects ranged from 6 to 80 years (mean 57); 17 (59%) were female, and 12 (41%) male. Twenty-four (83%) presented with subarachnoid haemorrhage. Seventeen (59%) had a history of hypertension, and ten (34%) had multiple cerebral aneurysms. The most common site was the internal carotid artery (45%), followed by the middle cerebral artery (28%), the vertebrobasilar arteries (17%), and the anterior cerebral artery (10%). The aneurysms were classified in relation to arterial curvature into three groups: dorsal curvature (41%), ventral curvature (10%) and non-curvature (49%). During surgery, sclerotic changes were noted in the arterial wall adjacent to the aneurysms in 14 patients (48%). Five cases (17%) had small thin walled (blisterlike) aneurysms, four of which ruptured during surgery resulting in poor clinical outcomes. We suggest that arteriosclerotic changes in the arterial wall, carotid siphon, and/or local haemodynamic forces are important factors in the development of this type of aneurysms. At surgery, one should bear in mind the possibility of sclerotic or blister-like aneurysms which require special attention to deal with them.     

Cerebral vasospasm and intraluminal filling defects

Angiographically demonstrated arterial luminal narrowing after operations for intracranial aneurysms is a well-documented phenomenon. However, the mechanisms responsible for neurological dysfunction in the presence of vasospasm have not been clearly defined. Destructive changes have been demonstrated within the walls of vasospastic vessels. These changes consist of desquamation of endothelium and thrombus formation, necrosis of smooth muscle cells, and repair by connective tissue proliferation. A 50-year-old man with two aneurysms on the right carotid artery postoperatively developed ischemic symptoms and on angiography was shown to have multiple intraluminal filling defects and vasospasm. Ephemeral intraluminal thrombus is postulated as the inciting cause of morbidity in cerebral vasospasm in some cases.     

Cerebral aneurysms: current anaesthetic management and future horizons

Canadian Journal of Anesthesia/Journal canadien d'anesthésie -     

Cerebral vasospasm in patients with unruptured intracranial aneurysms

Summary Intracranial arterial vasospasm is a typical sequela of subarachnoid haemorrhage. The association between symptomatic vasospasm and unruptured aneurysms has been sporadically presented in the literature. The pathogenesis of this unusual entity is unclear. The published cases were collected in this review and analysed with regard to timing, clinical presentation and possible relationship with surgical factors. We also added an illustrative case which was recently observed in our department.     

腹主动脉瘤病理基础与内科治疗

腹主动脉瘤(AAA)多发生于55岁以上的男性,是一种严重的血管外科疾病,一旦发生破裂,死亡率高达50%～80%,是老年人主要致死原因之一.1991年,Parodi等倡用腔内修复术治疗AAA,但学者对其评价尚不一致.近来通过对AAA发病机理的研究,认为有可能采用药物治疗AAA,并取得一些进展,为AAA的内科治疗展现了一个新的前景[1].     

Cerebral vasospasm in elderly patients with ruptured intracranial aneurysms

Cerebral vasospasm in elderly patients who were operated on the acute stage after subarachnoid hemorrhage was studied under strict criteria. The 138 patients were classified into three age groups: 59 years or younger (group A: 73 cases), 60 to 69 years (group B: 37 cases), and 70 years or older (group C: 28 cases). Severity of both the subarachnoid hemorrhages on computed tomography scan and the angiographic vasospasms was graded. The angiographic vasospasms were analyzed at the internal carotid artery, M1 segments of the middle cerebral artery, and A2 segments of the anterior cerebral. In all the relationships among the subarachnoid hemorrhage grades, the Hounsfield numbers, and the operative approaches to the angiographic vasospasm grade, there was a tendency for the angiographic vasospasm grades to be lower with increasing age in both the internal carotid artery and the M1 segment of the middle cerebral artery. This tendency was more apparent in the larger vessels, that is, the internal carotid arteries. Close correlations of the angiographic vasospasm grades to the incidences of symptomatic vasospasm and to low-density area on computed tomography scan were found in both the M1 and A2 territories in the three groups. However, there were no significant differences among the three groups in the incidences of symptomatic vasospasm and low-density area on computed tomography scan. Regarding the surgical outcome, the older the patients, the higher were the mortality rates: 8% in group A, 11% in group B, and 25% in group C.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cerebral protection during surgery for aortic arch aneurysms.

Surgical repair of aneurysms or dissections involving the transverse aortic arch and the distal aortic arch carries a considerable risk of cerebral complications. Currently, deep hypothermic circulatory arrest (DHCA), moderate hypothermic circulatory arrest or DHCA with selective cerebral perfusion (SCP) and DHCA with retrograde cerebral perfusion (RCP) are used as means to protect the central nervous system. DHCA alone is simple, but the safe time of DHCA is limited. RCP is an alternative technique for cerebral protection that can prolong the safe time of DHCA. SCP offers virtually unlimited time in isolating cerebral circulation. With the improvement of cardiopulmonary bypass (CPB) materials and myocardial preservation, DHCA with SCP is our current preference of an adjunct for cerebral protection, although possible increment of mortality and morbidity associated with a prolonged DHCA and CPB remains to be overcome.