Extracranial-intracranial bypass to the proximal posterior cerebral artery and to the proximal middle cerebral artery for multiple occlusive cerebrovascular disease

A 48-year-old man with a multiple occlusive cerebrovascular disease involving both the carotid and the vertebrobasilar systems is reported. Faced with noneffective conservative treatment, a surgical approach was carried out. As the patient had poorly developed posterior communicating arteries, two extracranial-intracranial bypasses were performed for both the carotid and the vertebrobasilar circulations; extracranial-intracranial bypasses with interposed saphenous vein grafts between the left external carotid artery and the proximal segment of the left middle cerebral artery, and between the right external carotid artery and the proximal segment of the right posterior cerebral artery. Advantages, precautions, and techniques of this kind of bypass procedure are discussed.     

Relief of nonhemispheric symptoms in low flow states by anterior circulation revascularization: a physiologic approach

Operative intervention remains controversial for patients with transient nonhemispheric symptoms with occlusive disease of both the anterior and posterior cerebral circulations. In addition to the standard evaluation of these patients, we have used stable xenon-enhanced computed tomographic mapping of cerebral blood flow (Xe/CT CBF). This relatively new and potentially widely available CBF methodology, by measuring approximately 30,000 CBF values within each of three CT levels, provides a readily interpretable means of evaluating extremes of hemodynamic compromise within any or all vascular territories. In the past 30 months, Xe/CT CBF studies in 300 patients with occlusive vascular disease have identified nine patients with global low flow and nonhemispheric symptoms (vertigo, lightheadedness, and/or blurred vision). Blood pressures determined by ocular pneumoplethysmography of Gee were markedly abnormal with reduced ocular/brachial ratios. Each patient had a combination of both segmental carotid and vertebrobasilar occlusive disease. Each patient had a flow-augmenting procedure performed on the anterior circulation in an attempt to improve global flow: carotid endarterectomy (two patients), subclavian-external carotid bypass (one patient), and superficial temporal artery-middle cerebral artery bypass (six patients). In each case disabling transient symptoms were relieved. There were no operative deaths, but one stroke occurred, probably as a result of a brief period of postoperative hypotension. Postoperative Xe/CT CBF studies show a long-term improved global CBF in all patients.     

Regional cerebral blood flow in patients with vertebrobasilar disease

We have investigated the changes in regional cerebral blood flow (rCBF) in patients with occlusive vertebrobasilar disease. Fifty patients who showed severe stenosis or occlusion of the vertebrobasilar artery territory were studied by angiography. Lesions in 13 of these patients were limited to the vertebrobasilar artery (limited VB group), and 37 patients showed combined vertebrobasilar/carotid artery lesions (combined VB-C group). Measurements of rCBF in the group of 50 patients using the intravenous xenon 133 technique showed that there was a significant decrease in the mean rCBF (47.5 ± 1.4 ml/100 gm/min) as compared with 19 age-matched normal subjects (54.9 ± 1.8 ml/100 gm/min). There was also a significant difference in mean rCBF between the combined VB-C group (45.6 ± 1.5 ml/100 gm/min) and a group of 153 patients with limited carotid artery lesions (C group, 49.8 ± 1.0 ml/100 gm/min). However, no significant difference in mean rCBF was found between the limited VB group and normal subjects. There were no differences in rCBF when evaluated according to the presence or absence of angiographic collateral circulation via the posterior communicating artery (Pcom). Good correlation was found between mean rCBF and direction of collateral flow via the Pcom (p < 0.05). The value of hemispheric rCBF of patients with carotid system transient ischemic attacks (TIAs) was significantly lower than that of patients with vertebrobasilar system TIAs (p < 0.02). In cerebral autoregulation tests of 24 patients with occlusive vertebrobasilar disease (7 patients from the limited VB group and 17 patients from the combined VB-C group), 13 of these 24 patients (54%) showed an impairment of autoregulation.     

Regional cerebral blood flow and oxygen metabolism in normal pressure hydrocephalus after subarachnoid hemorrhage

To clarify the pathophysiology of normal pressure hydrocephalus (NPH) after subarachnoid hemorrhage, the authors measured cerebral blood flow (CBF), cerebral oxygen metabolic rates (CMRO2), the cerebral oxygen extraction fraction (OEF), and cerebral blood volume (CBV) in eight normal volunteers, six SAH patients with NPH, and seven patients without NPH by 15O-labeled gas and positron emission tomography (PET). In the NPH group, PET revealed a decrease in CBF in the lower regions of the cerebral cortex and a diffuse decrease in CMRO2. The decrease in CBF in the lower frontal, temporal, and occipital cortices was significantly greater in the NPH than in the non-NPH group. Reduction of CMRO2 was also more extensive in the NPH group, and both CBF and CMRO2 were more markedly decreased in the lower frontal region. OEF was increased in all areas in both of the patient groups, but the increase was not significant in most areas. CBF, CMRO2 and OEF did not significantly differ between the non-NPH group and the normal volunteers. There was no significant difference in CBV among the three groups. These results indicate that NPH involves impairment of cerebral oxygen metabolism in the lower regions of the cerebral cortex, particularly in the lower frontal region.     

Clinical significance of STA-MCA double anastomosis for hemodynamic compromise in post-JET/COSS era

Background

Even after the recent randomized clinical trials JET and COSS, it is still unclear that impaired cerebrovascular reactivity (CVR) to acetazolamide and oxygen extraction fraction (OEF) can identify the candidates for superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis. This prospective study was aimed to evaluate the benefits of STA-MCA “double” anastomosis on long-term outcome in patients with reduced cerebral blood flow (CBF) and CVR (Type 3 ischemia) and elevated OEF attributable to occlusive carotid diseases.

Methods

This study included 49 patients with reduced CBF and CVR on SPECT in the ipsilateral MCA area. Using ¹⁵O-gas PET, OEF was also measured in all patients. STA-MCA double anastomosis was recommended to the patients with Type 3 and elevated OEF. Those with Type 3 but normal OEF were medically treated.

Results

Of 36 patients with Type 3 and elevated OEF, 25 consented to surgery. No perioperative morbidity or mortality were noted. The other 11 patients with Type 3 and elevated OEF were medically treated. Annual incidence of ipsilateral stroke was 0.7 % and 6.5 % in surgically and medically treated patients with Type 3 and elevated OEF, respectively (P?=?0.0188). None of patients with Type 3 but normal OEF developed ipsilateral stroke during follow-up periods. STA-MCA “double” anastomosis significantly decreased OEF.

Conclusions

STA-MCA “double” anastomosis may still have the potential to reduce the risk of recurrent ipsilateral stroke in hemodynamically compromised patients. Further studies would be essential to advance diagnosis, surgical procedures, and perioperative managements to bring out maximal effects of bypass surgery.     

Saphenous vein bypass grafts for giant aneurysms and intracranial occlusive disease

The authors report their experience with the use of saphenous vein bypass grafts for treating advanced occlusive disease in the posterior circulation (77 patients, all of whom had failed medical management and showed severe ischemic symptoms), deteriorating patients with giant aneurysms of the posterior circulation (nine patients), progressive ischemia in the anterior circulation (26 patients, none of whom had a normal examination), and giant aneurysms in the anterior circulation (20 patients, all of whom presented with mass effect or subarachnoid hemorrhage). Graft patency in the first 65 cases treated was 74%. However, after significant technical changes of vein-graft preparation and construction of the proximal anastomosis, patency in the following 67 cases was 94%. Excellent or good results (including relief of deficits existing prior to surgery) were achieved in 71% of patients with advanced occlusive disease in the posterior circulation, 44% of those with giant aneurysms of the posterior circulation, 58% of those with ischemia of the anterior circulation, and 80% of those with giant aneurysms of the anterior circulation. Mean graft blood flow at surgery in the series was 100 ml/min for posterior circulation grafts and 110 ml/min for anterior circulation grafts. Experience to date indicates that this is a useful operation, and is particularly applicable to patients who are neurologically unstable from advanced intracranial occlusive disease in the posterior circulation or with giant aneurysms in the anterior circulation. The risk of hyperfusion breakthrough with intracerebral hematoma restricts the technique in patients with progressing ischemic symptoms in the anterior circulation, and the intolerance of patients with fusiform aneurysms in the posterior circulation to the iatrogenic vertebrobasilar occlusion limits the applicability of this approach to otherwise inoperable lesions in that system.     

Cerebral circulation and metabolism in the acute stage of subarachnoid hemorrhage

OBJECT: The mechanism of reduction of cerebral circulation and metabolism in patients in the acute stage of aneurysmal subarachnoid hemorrhage (SAH) has not yet been fully clarified. The goal of this study was to elucidate this mechanism further. METHODS: The authors estimated cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO2), O2 extraction fraction (OEF), and cerebral blood volume (CBV) preoperatively in eight patients with aneurysmal SAH (one man and seven women, mean age 63.5 years) within 40 hours of onset by using positron emission tomography (PET). The patients' CBF, CMRO2, and CBF/CBV were significantly lower than those in normal control volunteers. However, OEF and CBV did not differ significantly from those in control volunteers. The significant decrease in CBF/CBV, which indicates reduced cerebral perfusion pressure, was believed to be caused by impaired cerebral circulation due to elevated intracranial pressure (ICP) after rupture of the aneurysm. In two of the eight patients, uncoupling between CBF and CMRO2 was shown, strongly suggesting the presence of cerebral ischemia. CONCLUSIONS: The initial reduction in CBF due to elevated ICP, followed by reduction in CMRO, at the time of aneurysm rupture may play a role in the disturbance of CBF and cerebral metabolism in the acute stage of aneurysmal SAH.     

Regional effects of craniotomy on cerebral circulation and metabolism: PET study on the un-ruptured aneurysmal surgery

Regional effects of craniotomy on cerebral circulation and metabolism, such as regional cerebral blood flow (rCBF), regional cerebral oxygen consumption (rCMRO2), regional oxygen extraction fraction (rOEF), and regional cerebral blood volume (rCBV) were examined by a PET (positron emission tomography) study concerning surgery that was performed on unruptured aneurysm patients. Eight patients with intracranial un-ruptured aneurysms were studied pre- and post-operatively by the 15O labelled-gas steady-state method, using HEADTOME-III. All patients underwent aneurysmal surgery performed by the transsylvian approach. There was a significant increase in the mean OEF values taken from the whole-brains of 8 patients, but there was not a significant change in CBF, CMRO2 or CBV. The increase in OEF was caused by decrease of O2 content, which was caused by post-operative decrease in the Hb value. So, this OEF increase was not the direct effect of craniotomy. In 2 patients, the rCBF and rCMRO2, in the fronto-temporal region (where craniotomy was performed) increased post-operatively. This regional effect suggests transient reactive hyperemia following compressive ischemia during the operative procedure, and metabolic demands for recovery of brain function. In 2 other patients, who had relatively low rCBFs during the pre-operative study, rCBF and rCMRO2 in the bi-frontal region had decreased more at the post-operative study. This change appears to have been caused by removal of cerebrospinal fluid and depression of the frontal lobe. From this study, it becomes evident that the regional effect of craniotomy on cerebral circulation and metabolism is not so great, when adequate microsurgical techniques are used.     

Construction of a new posterior communicating artery in a patient with poor posterior fossa circulation: technical case report

OBJECTIVE AND IMPORTANCE: The carotid and the vertebrobasilar circulation were connected, effectively creating a new posterior communicating artery (PComA). The excimer laser-assisted nonocclusive anastomosis technique is a new anastomosis technique whereby formerly untreatable patients may be treated with an intracranial artery-to-intracranial artery bypass procedure. This report is the first one in which an angiographically proved patent internal carotid artery-posterior cerebral artery segment P1 bypass is presented. CLINICAL PRESENTATION: Our patient presented with repeated episodes of vertebrobasilar ischemia because of vertebral artery occlusion and stenosis. INTERVENTION: An internal carotid artery-posterior cerebral artery segment P1 bypass procedure was performed. Because the patient experienced transient ischemia in the left cerebral hemisphere at the end of postoperative angiography procedure, no radiological intervention was performed, and the patient refused to undergo a new radiological intervention at a later stage. TECHNIQUES: Both anastomoses were made using the excimer laser-assisted nonocclusive anastomosis technique. CONCLUSION: Intraoperative flowmetry was performed using an ultrasound flowmeter, which disclosed blood flow of 35 ml/min through the bypass. We hope that this new PComA suffices to protect the patient from infarction in the territory of the vertebrobasilar circulation.     

Superficial temporal and occipital artery bypass pedicles to superior, anterior inferior, and posterior inferior cerebellar arteries for vertebrobasilar insufficiency

Eighty-three patients underwent 85 intracranial to extracranial pedicle bypass anastomosis procedures to the posterior circulation. There were 15 patients with occipital artery (OA) to posterior inferior cerebellar artery (PICA) anastomosis, 20 patients with OA to anterior inferior cerebellar artery (AICA) anastomosis, and 50 patients with superficial temporal artery (STA) to superior cerebellar artery (SCA) anastomosis. All patients had transient ischemic attacks (TIA's) suggestive of vertebrobasilar ischemia. Twenty-seven patients had crescendo TIA's or stroke in evolution and were considered to be clinically unstable. All patients had severe bilateral distal vertebral artery or basilar artery disease. Twenty-two patients had bilateral vertebral artery occlusion and three had basilar artery occlusion. In this series, 69% had complete resolution of symptoms; the mortality rate was 8.4% and the morbidity rate 13.3%. Clinically stable patients did better than unstable patients. The STA-SCA anastomosis was well tolerated and technically less demanding than the OA-PICA or OA-AICA anastomosis procedures. Patients with symptomatic severe bilateral vertebral or basilar artery disease have a grave prognosis and the option of a surgical arterial pedicle revascularization procedure should be offered to them.     

Hemodynamic and metabolic effects of cerebral revascularization

Pre- and postoperative positron emission tomography (PET) was performed in six patients undergoing extracranial to intracranial bypass procedures for the treatment of symptomatic extracranial carotid occlusion. The six patients were all men, aged 52 to 68 years. Their symptoms included transient ischemic attacks (five cases), amaurosis fugax (two cases), and completed stroke with good recovery (one case). Positron emission tomography was performed within 4 weeks prior to surgery and between 3 to 6 months postoperatively, using oxygen-15-labeled CO, O2, and CO2 and fluorine-18-labeled fluorodeoxyglucose. Cerebral blood flow (CBF), cerebral blood volume (CBV), cerebral metabolic rates for oxygen and glucose (CMRO2 and CMRGlu), and the oxygen extraction fraction (OEF) were measured in both hemispheres. Preoperatively, compared to five elderly control subjects, patients had increased CBV, a decreased CBF/CBV ratio, and decreased CMRO2, indicating reduced cerebral perfusion pressure and depressed oxygen metabolism. The CBF was decreased in only one patient who had bilateral carotid occlusions; the OEF, CMRGlu, and CMRO2/CMRGlu and CMRGlu/CBF ratios were not significantly different from control measurements. All bypasses were patent and all patients were asymptomatic following surgery. Postoperative PET revealed decreased CBV and an increased CBF/CBV ratio, indicating improved hemodynamic function and oxygen hypometabolism. This was associated with increased CMRO2 in two patients in whom the postoperative OEF was also increased. The CMRGlu and CMRGlu/CBF ratio were increased in five patients. Changes in CBF and the CMRO2/CMRGlu ratio were variable. One patient with preoperative progressive mental deterioration, documented by serial neuropsychological testing and decreasing CBF and CMRO2, had improved postoperative CBF and CMRO2 concomitant with improved neuropsychological functioning. It is concluded that symptomatic carotid occlusion is associated with altered hemodynamic function and oxygen hypometabolism. Cerebral revascularization results in decreased CBV, indicating improved hemodynamic reserve, but does not consistently improve oxygen metabolism.     

解剖外途径动脉转流术治疗锁骨下动脉闭塞症

为提高锁骨下动脉闭塞症的治疗效果,作者报告了１９８９年～１９９６年采用非经胸解剖外途径治疗２０例锁骨下动脉闭塞症的经验。本组男９例,女１１例。１７例有上肢缺血表现,１１例有脑部缺血症状。１７例行颈动脉－锁骨下／腋动脉转流,３例行腋动脉－腋动脉转流术。除１例大动脉炎因远端流出道差转流血管阻塞疗效不理想外,其余患者患肢及脑缺血表现均明显改善或消除。无手术死亡。作者认为采用解剖外途径治疗锁骨下动脉闭塞症,无需开胸,创伤小,操作简便安全,并发症少,通畅率高,尤其适合于手术耐受性差的患者,值得进一步推广使用。     

Two cases of "steal VBI" with stenosis of the internal carotid artery

Although previous reports have suggested "steal VBI" due to occlusive carotid artery diseases, there have been no reports that clearly define "steal VBI" from the viewpoint of cerebral hemodynamics. The authors presented two cases with "steal VBI" due to severe stenosis of the internal carotid artery. Both patients had well-developed collateral circulation through the ipsilateral posterior communicating artery. Although no occlusive lesion was found in the vertebrobasilar system, blood flow studies revealed impaired hemodynamics in the contralateral occipital lobe, which fact correlated with their neurological deficit, visual field disturbance. Carotid stenting markedly corrected the stenotic lesions, leading to neurological improvement. Follow-up blood studies showed normalization of hemodynamics in the contralateral occipital lobe. The findings strongly suggest that carotid surgery or stenting can improve cerebral hemodynamics in the carotid systems, resolving "steal VBI" due to developed collaterals from the posterior to the anterior circulation.     

Pseudoaneurysm complicating superficial temporal artery-superior cerebellar artery bypass

A 60-year-old man with vertebrobasilar ischemia unrelieved by anticoagulation was found to have a midbasilar stenosis with an inadequate basilar collateral circulation. He underwent a right superficial temporal-superior cerebellar artery bypass. Following this operation he had a subarachnoid hemorrhage and right third nerve palsy that was due to formation of a pseudoaneurysm at the site of the anastomosis. This aneurysm was managed by ligation of the right superficial temporal artery. Subsequently it became necessary to perform a left superficial temporal artery-superior cerebellar artery bypass because of severe posterior circulation ischemic symptoms.     

Embolic lesions from the subclavian artery causing transient vertebrobasilar insufficiency

Thirteen patients with transient vertebrobasilar insufficiency caused by emboli from a proximal subclavian artery lesion were treated over a 5-year period. This group was characterized by the absence of significant carotid disease (12 of 13 patients) and equal arm pressures bilaterally in most patients (8 of 13 patients). An isolated supraclavicular bruit (12 of 13 patients) and a history of ipsilateral digital ischemia (5 of 13 patients) were common. Arch angiography demonstrated proximal subclavian lesions in 12 patients, with obvious ulcerations in 10 cases and thrombus in an old carotid-subclavian bypass graft in one case. Surgery directed at removal or exclusion of the lesion was successful in all cases. Isolated lesions in the subclavian artery can be a source of emboli into the vertebrobasilar circulation. These lesions are effectively treated by exclusion and vascular reconstruction.     

Positron emission tomographic measurement of acute hemodynamic changes in primate middle cerebral artery occlusion.

Specific hemodynamic changes in acute ischemia were investigated using a middle cerebral artery occlusion primate model and positron emission tomography. The cerebral blood flow (CBF), cerebral blood volume, oxygen extraction fraction (OEF), and cerebral metabolic rate for oxygen were measured 1, 3, and 9 hours after occlusion. OEF showed an increase in ischemic areas, and especially where CBF was below 18 ml/100 gm/min 1 hour after occlusion the OEF increased significantly (0.69 +/- 0.20, p < 0.05). Nine hours after occlusion, the OEF values were lower compared to those 1 and 3 hours after occlusion. Areas where CBF ranged from 18 to 31 ml/100 gm/min showed an increase in OEF at all times (p < 0.05). Clearly, OEF changes remarkably in the acute stage.     

Revascularization of vertebro-basilar occlusive disease

Various surgical techniques have been reported for vascular reconstruction in cases of vertebro-basilar occlusive disease, but sufficient study has not been made on the question of which technique should be applied in various pathological conditions. Based on our experience, we have examined the advantages and disadvantages of these techniques. In 34 patients with clinically and angiographically diagnosed vertebro-basilar insufficiency, the reconstructive vascular surgery to the posterior circulation was performed. Preoperatively, 24 had vertebro-basilar TIAs, 2 had RIND, 3 had progressing symptoms and 5 had brain stem infarctions verified by persistent deficits. In the 18 patients with intracranial vertebro-basilar occlusive lesions, the bypass were done to the proximal posterior inferior cerebellar artery in 7 cases, proximal superior cerebellar artery in 9 cases, posterior cerebral artery in one and anterior inferior cerebellar artery in one. In the 16 patients with extracranial occlusive lesions of vertebral artery, endarterectomy or subclavian-vertebral transposition was performed. With the exception of one of the progressing stroke cases, in which the surgery was ultimately too late, there were no cases in which neurological symptoms become aggravated following operation. Patency was 94% (32/34). In light of these findings, the following conclusions concerning the operative indication and the selection of the technique have been drawn. In cases with occlusive lesions of basilar artery, the first choice should be bypass to the proximal superior cerebellar artery. In cases with occlusive lesions of vertebral artery, bypass to the posterior inferior cerebellar or superior cerebellar or anterior inferior cerebellar artery should be performed.(ABSTRACT TRUNCATED AT 250 WORDS)     

Extrathoracic carotid reconstruction: the subclavian-carotid artery bypass.

Although the predominant location of symptomatic carotid artery occlusive disease is the carotid bifurcation, proximal common carotid artery lesions cause similar symptoms. Common carotid artery lesions occur as isolated disease or in tandem with carotid bulb disease. Restoration of carotid artery inflow from subclavian based extraanatomic bypasses should provide adequate reconstruction of these lesions. To evaluate subclavian-carotid artery bypass, a retrospective review of all patients undergoing this procedure from Jan. 1, 1977, to Feb. 20, 1989, was performed. Twenty patients (14 men, 6 women) with a mean age of 60 years were treated. Fifteen patients (75%) were admitted with transient ischemic attacks. Five (25%) had nonfocal symptoms (e.g., dizziness, syncope). Arteriographic evaluation demonstrated severe proximal occlusive disease of the common carotid artery in all cases. Reconstruction bypasses were performed to the carotid bulb (45%), internal carotid artery (30%), and external carotid artery (25%). Four patients underwent endarterectomy of the internal carotid artery in conjunction with subclavian-carotid artery bypass. Bypass conduits included saphenous vein (75%) and prosthetic grafts (25%). Asymptomatic phrenic nerve neuropraxia was identified by postoperative chest radiography in four cases, with no resultant respiratory disease. No perioperative strokes occurred. One postoperative death (5%) resulted from a myocardial infarction. Long-term results were available for 18 patients (90%), with a mean follow-up of 50 months (range, 1 to 122 months). Four patients have died of causes unrelated to carotid vascular disease. Serial duplex scans have documented graft patency in all 18 patients. A single patient returned with focal neurologic symptoms as a result of a posterior circulation infarct.(ABSTRACT TRUNCATED AT 250 WORDS)     

Posterior cerebral circulation revascularization

Posterior circulation revascularization has evolved as a method to treat selected patients with vertebrobasilar ischemia who have inaccessible atherosclerotic occlusive disease and who have failed maximal medical therapy. In addition, complex unclippable aneurysms of the posterior circulation are another indication for revascularization of the vertebrobasilar territory. Careful preoperative evaluation and meticulous attention to detail intraoperatively yield good patient outcomes with minimal morbidity and mortality. This article reviews the vascular anatomy of the posterior circulation and the indications, preoperative evaluation, operative techniques, clinical outcomes, and alternative treatments for patients requiring posterior circulation revascularization procedures.     

Resolving occlusive lesions of the basilar artery

Progression of severe basilar artery stenosis to occlusion is a well-recognized phenomenon, but regression of a severe basilar artery atherothrombotic lesion has not been described previously. In this report, two patients with a symptomatic severe basilar artery occlusive lesion showed substantial angiographic improvement after 3 months of anticoagulation in one case and 4 months after superficial temporal artery to superior cerebellar artery bypass in the other case. The findings in these cases indicate that clinical improvement in similar cases may reflect recanalization of a basilar artery occlusive lesion. The uncertain natural history and potential for regression of symptomatic basilar artery atherothrombosis make us hesitant to recommend posterior circulation revascularization immediately after such lesions are first demonstrated angiographically.