Current perspectives and future directions of the treatment for non acute intracranial artery occlusion / 中国综合临床

Non-acute intracranial artery total occlusion can lead to severe neurological defect and high recurrence rate of stroke.At present, there is no effective treatment recommended by the guidelines.Traditional treatment methods include medical therapy, extracranial-intracranial bypass surgery and minimally invasive endovascular recanalization therapy.In recent years, with the development of microsurgical vascular anastomosis technique and neurosurgical intervention, and the development of interventional materials, the treatment of non-acute intracranial artery total occlusion has become a hot spots.In this paper, the concept of non on-acute intracranial artery total occlusion, medical therapy, extracranial-intracranial bypass surgery and endovascular interventional therapy are reviewed.

An anatomic study of superficial temporal artery to anterior cerebral artery bypass using ipsilateral parietal branch of superficial temporal artery as graft / 中华显微外科杂志

Objective Revascularization of the distal segment of the anterior cerebral artery (ACA) using extracranial donors requires long interposition grafts.A novel bypass procedure which uses the two main branches of the superficial temporal artery (STA) to reach the A3 segment of the anterior cerebral artery with a single skin incision was designed.Methods Ten cadaveric specimens were dissected through a single skin incision to harvest the frontal and parietal branches of the STA from June,2017 to September,2017.An anterior interhemispheric approach provided access to the middle internal frontal artery (MIFA).The parietal STA was used as an interposition graft between the frontal STA and MIFA.Lengths and calibers of the distal branches of STA and MIFA were measured at the anastomotic sites.All data was statistical analysis by t-test.Results The average caliber of MIFA was (1.4±0.2) mm,which matched the caliber of both frontal and parietal branches of STA.The mean distance for an end-to-side bypass from STA to MIFA was (144.5±7.4) mm and the average harvested donor-graft complex length was (203.1±27.9) mm.This bypass construct provided around 140％ donor graft length.Conclusion Using the parietal branch of the STA as an interposition graft enabled a successful tension-free STA-MIFA bypass.The advantages of this technique over existing approaches include sufficient graft length,caliber match and relative technical ease.

Modelo animal experimental para adiestramiento en realización anastomosis extra intraracraneales e intracraneales, con técnicas microquirúrgicas / Experimental animal model for training in performing extra-intracranial and intracranial anastomosis, using microsurgical techniques

Las técnicas de anastomosis extra e intracraneales se han utilizado desde los aٌos 70 para el manejo de diferentes patologيasvasculares, que van desde la enfermedad cerebrovascular hasta la exclusiَn de aneurismas y malformaciones arteriovenosasde la circulaciَn o el manejo de condiciones como la enfermedad de Moya Moya. Si bien se ha cuestionado su aplicaciَnen algunas de estas patologيas hoy en dيa se sabe que constituyen una opciَn terapéutica. Las técnicas descritas requierende un entrenamiento especializado del Neurocirujano en el laboratorio de microcirugيa, entrenamiento que no siempre estلal alcance de todos los residentes. Existen dilemas éticos en cuanto al uso de animales y es poco probable que durante losaٌos de formaciَn el residente tenga la oportunidad de realizar anastomosis vasculares en el quirَfano dada la complejidadde estos procedimientos. En el presente artيculo se describe la técnica quirْrgica y microquirْrgica para la realizaciَn de unbypass extra e intracraneal en un modelo animal (cabeza de cerdo), donde se describe paso por paso el procedimiento ylos utensilios con los que debe contar el estudiante. Se hace una revisiَn de la literatura acerca de la patologيa vascular, lastécnicas de bypass y las particularidades de la anatomيa de estos animales.

Extracranial-intracranial bypass techniques have been used since the 70’s for the handling of different vascular diseases, fromcerebrovascular disease to the exclusion of aneurysms and arteriovenous malformations from the circulation or the managementof conditions such as Moyamoya disease. Although its application has been questioned in some of these diseases weknown now that this technic constitutes a therapeutic option. The described techniques require specialized training of the neurosurgeonin the of microsurgery laboratory, training that is not always available to all residents. There are ethical dilemmasregarding the use of animals and it is unlikely that during the formative years the resident may have the opportunity to performvascular anastomosis in the operating room because of the complexity of these procedures. In this article we describe thesurgical and microsurgical techniques for carrying extra- intracranial bypass in an animal model (pig’s head), and outline stepby step the procedure and utensils which the student must have. It is a review of the literature on vascular disease, bypasstechniques and peculiarities of the anatomy of these animals.

Extracranial­Intracranial Cerebral Revascularization: Indications and Results / Revascularização cerebral extracraniana-intracraniana: indicações e resultados

Objective To present a case-series study of extracranial­intracranial (EC­IC) bypass procedures performed in our service and evaluate indications and results. Method The medical records of 30 patients undergoing 32 EC­IC anastomosis procedures were evaluated. Seventeen patients were male (56.6%). The age ranged from 26 to 85 years (mean: 58.2). The follow-up ranged from 1 to 211 months (mean: 54). We evaluated the indications and complications of the surgical procedures. Results The bypass procedures comprised 28 STA­MCA anastomosis (87,5%) and four posterior circulation anastomosis. The main indications included cervical internal carotid artery occlusion (19 cases), Moyamoya disease (3 cases), giant aneurysms (3 cases), intracranial arterial stenosis (2 cases), and vertebral­basilar insufficiency (3 cases). On follow-up, graft patency was 93.7%, confirmed in half of the cases by arterial digital subtraction angiography, magnetic resonance angiography, and CT angiography. There was no surgical mortality. Three patients had PO complications (9.3%), including one case of ischemia (3.1%). Conclusion The EC­IC bypass is a procedure with low morbidity and mortality. The indication of EC­IC bypass surgery for cerebral atherosclerotic disease should not be generalized. The EC­IC bypass can be indicated for cerebral revascularization in Moyamoya disease, intracranial stenosis, and in the management of complex aneurysms. This procedure can be an alternative in the treatment of vertebral­basilar insufficiency.

Objetivo Apresentar uma série de casos de anastomose extra-intracraniana (EC-IC) avaliando suas indicações e resultados. Método Foram avaliados retrospectivamente os prontuários de 30 pacientes submetidos a 32 procedimentos de anastomose EC-IC. Dezessete pacientes eram do sexo masculino (56,6%) com média de idade de 58,2 anos. O período de seguimento variou de um a 211 meses (média: 54). Foram avaliadas as indicações e complicações dos procedimentos cirúrgicos. Resultados Foram realizadas 28 anastomoses entre a artéria temporal superficial e a cerebral média (87,5%) e quatro anastomoses na circulação posterior. As principais indicações foram oclusão de carótida interna cervical (19 casos), doença de Moyamoya (3 casos), aneurismas gigantes (3 casos), estenose arterial intracraniana (2 casos) e insuficiência vertebrobasilar (3 casos). A patência tardia do bypass confirmada em metade dos casos por angiografia, angiorressonância ou angiotomografia foi de 93,7%. Não houve mortalidade cirúrgica. Um paciente (3,1%) apresentou isquemia no pósoperatório. Outros dois pacientes (6,2%) apresentaram complicações não isquêmicas. Conclusões A revascularização EC-IC é procedimento de baixa morbidade e mortalidade. A indicação do procedimento para oclusão carotídea não pode ser generalizada. O bypass EC-IC pode ser indicado na doença deMoyamoya, nas estenoses intracranianas e no manejo de aneurismas complexos. Pode ser alternativa no tratamento da insuficiência vertebrobasilar.

Arachnoid Membrane Suturing for Prevention of Subdural Fluid Collection in Extracranial-intracranial Bypass Surgery

OBJECTIVE: Water-tight closure of the dura in extracranial-intracranial (EC-IC) bypass is impossible because the superficial temporal artery (STA) must run through the dural defect. Consequently, subdural hygroma and subcutaneous cerebrospinal fluid (CSF) collection frequently occur postoperatively. To reduce these complications, we prospectively performed suturing of the arachnoid membrane after STA-middle cerebral artery (STA-MCA) and evaluated the clinical usefulness. MATERIALS AND METHODS: Between Mar. 2005 and Oct. 2010, extracranial-intracranial arterial bypass (EIAB) with/without encephalo-myo-synangiosis was performed in 88 cases (male : female = 53 : 35). As a control group, 51 patients (57 sides) underwent conventional bypass surgery without closure of the arachnoid membrane. Postoperative computed tomography (CT) scan was performed twice in three days and seven days later, respectively, for evaluation of the presence of subdural fluid collection and other mass lesions. RESULTS: The surgical result was excellent, with no newly developing ischemic event until recent follow-up. The additional time needed for arachnoid suture was five to ten minutes, when three to eight sutures were required. Post-operative subdural fluid collection was not seen on follow-up computed tomography scans in all patients. CONCLUSION: Arachnoid suturing is simple, safe, and effective for prevention of subdural fluid collection in EC-IC bypass surgery, especially the vulnerable ischemic hemisphere.

Giant Intracranial Aneurysm with Blind Sac on Middle Cerebral Artery: Case Report / 대한뇌혈관외과학회지

A case of a giant intracranial aneurysm (GIA) with a blind sac on the left middle cerebral artery (MCA) accompanied by mural thrombosis is described. A 62-year-old male presented with headache and motor dysphasia. Magnetic resonance imaging and digital subtraction angiography revealed a GIA that arose from the proximal MCA. The M2 segment of the MCA was not visualized due to intramural thrombosis. The patient was treated with an extracranial-intracranial arterial bypass and trapping of the aneurysm. Literature relevant to the management of this rare lesion is reviewed and discussed.

Clinical Results of in situ Vascular Reconstruction for the Treatment of Complex Intracranial Aneurysms / 대한뇌혈관외과학회지

CONCLUSION: Vascular reconstruction is an important part of the treatment of complex intracranial aneurysms. We report our clinical experience using vascular reconstruction techniques without an extracranial arterial stump for the treatment of complex intracranial aneurysms. METHODS: We conducted a retrospective review of five patients who underwent in situ bypasses and two patients who underwent direct neck suture secondary to clip reinforcement for the treatment of complex intracranial aneurysms between January 1999 and May 2008. RESULTS: Five of the aneurysms were fusiform and the other two were blood blister-like aneurysms (BBAs). Fusiform aneurysms were located at the anterior cerebral artery (ACA) in two patients and the middle cerebral artery (MCA) in three patients. The aneurysms were treated with end-to-side anastomosis after aneurysm excision in three cases and end-to-end anastomosis after aneurysm excision in two cases. Two cases of BBA on the dorsal intracranial artery (ICA) wall were treated by direct suture secondary to the wrapping-clipping method. Follow-up angiography was performed in five patients and revealed patent bypasses in four patients. Follow-up angiography was not performed in two patients due to their poor postoperative condition, and it revealed delayed occlusion due to granuloma formation in one patient with BBA. The patient outcomes were excellent in five patients and poor in two patients whose clinical condition was Hunt- Hess grade V preoperatively. CONCLUSION: In situ bypass is an effective alternative to extracranial-intracranial bypass for distally located fusiform aneurysms. In addition, arterial suturing followed by the wrapping-clipping method is a useful technique for fragile aneurysms unamenable to direct clip or encircled clip for true ICA trunk aneurysms. Although technically challenging, this technique of vascular reconstruction without extracranial arterial graft should be considered for appropriate candidates.

The Application of Extracranial-Intracranial Vascular Bypass Graft in the Treatment of Intracranial Aneurysms / 国际脑血管病杂志

This article expounds the indication,preoperative ischemic tolerance test,evaluation of collateral circulation,different surgical modes,complications and their prevention in the treatment of intracranial aneurysms during extracranial-intracranial(EC/IC)graft bypass.It is considered that EC/IC bypass graft is an effective therapeutic mode in preventing the occurrence of cerebral ischemia in the treatment of intracranial aneurysms.

Result of Extracranial-Intracranial Bypass Surgery in the Treatment of Complex Intracranial Aneurysms : Outcomes in 15 Cases

OBJECTIVE: The standard treatment strategy of intracranial aneurysms includes either endovascular coiling or microsurgical clipping. In certain situations such as in giant or dissecting aneurysms, bypass surgery followed by proximal occlusion or trapping of parent artery is required. METHODS: The authors assessed the result of extracranial-intracranial (EC-IC) bypass surgery in the treatment of complex intracranial aneurysms in one institute between 2003 and 2007 retrospectively to propose its role as treatment modality. The outcomes of 15 patients with complex aneurysms treated during the last 5 years were reviewed. Six male and 9 female patients, aged 14 to 76 years, presented with symptoms related to hemorrhage in 6 cases, transient ischemic attack (TIA) in 2 unruptured cases, and permanent infarction in one, and compressive symptoms in 3 cases. Aneurysms were mainly in the internal carotid artery (ICA) in 11 cases, middle cerebral artery (MCA) in 2, posterior cerebral artery (PCA) in one and posterior inferior cerebellar artery (PICA) in one case. RESULTS: The types of aneurysms were 8 cases of large to giant size aneurysms, 5 cases of ICA blood blister-like aneurysms, one dissecting aneurysm, and one pseudoaneurysm related to trauma. High-flow bypass surgery was done in 6 cases with radial artery graft (RAG) in five and saphenous vein graft (SVG) in one. Low-flow bypass was done in nine cases using superficial temporal artery (STA) in eight and occipital artery (OA) in one case. Parent artery occlusion was performed with clipping in 9 patients, with coiling in 4, and with balloon plus coil in 1. Direct aneurysm clip was done in one case. The follow up period ranged from 2 to 48 months (mean 15.0 months). There was no mortality case. The long-term clinical outcome measured by Glasgow outcome scale (GOS) showed good or excellent outcome in 13/15. The overall surgery related morbidity was 20% (3/15) including 2 emergency bypass surgeries due to unexpected parent artery occlusion during direct clipping procedure. The short-term postoperative bypass graft patency rates were 100% but the long-term bypass patency rates were 86.7% (13/15). Nonetheless, there was no bypass surgery related morbidity due to occlusion of the graft. CONCLUSION: Revascularization technique is a pivotal armament in managing complex aneurysms and scrupulous prior planning is essential to successful outcomes.

Augmentation of the Patency of an Extracranial-Intracranial Bypass Accompanied by the Occlusion of an Intracranial Stenotic Lesion

We describe a case that showed augmention of the superficial temporal artery (STA) pedicle's patency 15 months after extracranial to intracranial (EC-IC) bypass surgery for a carotid artery occlusion with contralateral intracranial internal carotid artery stenosis. It is rare that meager patency of the STA pedicle in the early postoperative angiogram can be become well augmented with time where most branches of the middle cerebral artery (MCA) are robustly filled with blood from the STA. A 28-year-old woman with a history of a previous left hemispheric stroke presented with slurred speech after several bouts of seizure. Magnetic resonance imaging showed a new infarct on the right hemisphere in addition to an old infarct on the left hemisphere. Carotid angiography revealed stenosis of the right carotid siphon and occlusion of the left carotid artery. The patient underwent EC-IC bypass on the right side. Even though the early postoperative angiogram showed meager filling of MCA with no significant stenotic lesion change, a subsequent angiogram taken 15 months later, demonstrated a widely patent STA pedicle with occlusion of the previous intracranial stenotic lesion. Selected cases with an inaccessible intracranial stenotic lesion can benefit from EC-IC bypass surgery; however, its clear indication should first be established.

A New Understanding of Extracranial-Intracranial Arterial Bypass for Ischemic Cerebrovascular Disease / 国际脑血管病杂志

There has been no consensus on the efficacy of extracranial-intracranial arterial bypass (EIAB) for ischemic cerebrovascular disease. As an important factor in the pathophysiologic mechanisms of ischemic cerebrovascular disease, the changes of cerebral hemodynamics have received attention. The article expounds the clinical significance of EIAB from the point of view of cerebral hemodynamics, particularly presents its preoperative assessment, operative procedures, and efficacy criterion.

Management Options and Prognosis of Carotid Artery Occlusive Disease / 대한뇌혈관외과학회지

OBJECT: The effective management of carotid occlusive disease still remains a challenge to neurosurgeons. The authors analyzed the series of management of carotid occlusive disease in order to determine whether our management strategy affected patient's clinical outcomes. Methods of identifying patients who stand to benefit from this therapy need to be established. METHOD: Clinical findings, management, complications and outcome in 52 patients with high grade carotid stenosis of at least 70% and occlusion were investigated. The patients were treated by percutaneous transluminal angioplasty (PTA) and/or stent (PTAS), Extracranial-Intracranial (EC-IC) bypass surgery, carotid endarterectomy (CEA) according to the neurologic status, medical condition, severerity of stenosis, collateral blood flow. RESULTS: The causes of carotid stenosis were 40 atherosclerosis arteries, 9 spontaneous dissections and 2 traumas, 1 fibomuscular dysplasia (FMD) of 52 patients. 9 patients were treated by PTA alone, and 28 patients by PTAS, 9 patients by EC-IC bypass surgery, 3 patients by PTAS followed by EC-IC bypass surgery, 3 patients by CEA. For the outcome according to management, 26 patients (100% of all bypass surgery only and CEA, 35% of all PTA and PTAS) recovered excellently, 14 patients (35% of all PTA and PTAS) had a good outcome. 2 patients died. CONCLUSION: The results of this study suggest that PTAS should be a useful and effective treatment method for some patients with the severe atherosclerotic stenosis or carotid artery dissection. However, the surgical management must be considered for the high risk, high grade carotid stenosis patients with collateral blood flow, and with or without mild or moderate deficits.

Treatment of a Sequential Giant Fusiform Aneurysm of the Basilar Trunk

We report an exceptional case of a de novo giant fusiform aneurysm of the basilar trunk, which developed shortly after the therapeutic occlusion of the right internal carotid artery for a fusiform carotid aneurysm. It would appear to be appropriate to call this entity a sequential giant fusiform aneurysm. The patient was successfully treated with endovascular occlusion of the giant basilar trunk aneurysm following bypass surgery.

Effectiveness of Bypass Surgery in Treatment and Prevention for Cerebrovascular Occlusive Disease

To study the effect of extracranial-intracranial(EC/IC) bypass on symptomatic patients with hemodynamic cerebral ischemia, we prospectively reviewed 76 patients who underwent EC/IC bypass surgery in patients with occlusive cerebrovascular disease. A series of 76 patients treated in a 7 years period met following criteria. (1) symptomatic internal carotid artery(ICA) or middle cerebral artery(MCA) obstruction or stenosis over 80%. (2) decrease in basal cerebral blood flow(CBF) over 10%. (3) decreased reactivity of CBF in response to acetazolamide. Among these, the types of ischemic episodes were transient ischemic attack(TIA) or reversible ischemic neurological deficit(RIND) in 39, minor stroke in 22, and major stroke in 15. Based on our criteria, superficial temporal artery(STA)-MCA anastomosis was performed in 67 cases and EC-IC bypass grafting using saphenous vein or radial artery in 9. Average follow up period was 26 months(3 months~7 year). Patency of bypass was confirmed by postoperative angiography or magnetic resonence angiography(MRA) in all case except four cases. Of the 72 patients with patiency of bypass, 68 patients(94%) have had an excellent to good outcome with improvement of preoperative neurologic or cognitive dysfunction, 3 patients showed no improvement of preoperative neurologic symptoms and remaining one patient had new developed deficit. All 72 patients with patency of bypass had experienced no further cerebral ischemic events during following period. Postoperative significant improvement of CBF to acetazolamide was showed in 68 cases(94%) of the 72 cases with patency of bypass, while the basal CBF showed significant improved in 31cases. Postoperative permanent neurologic deficit occurred only in one. In view of these finding, the author suggest that EC-IC bypass surgery is a reliable and resonably safe method for establishing new pathways of collateral circulation to the brain and to be considered as an appropriate therapy for improvement of the cerebrovascular reserve capacity in patients with hemodynamic cerebral ischemia, defined using the strict selection criteria employed in this study.

Surgical Treatment of Cerebral Ischemia / 대한뇌혈관외과학회지

Since the proportion of ischemic stroke has been increasing compared to hemorrhagic stroke in our country, only recently the medical community began to systematically emphasize the importance of managing ischemic stroke patients as aggressively as possibly in an attempt to improve outcome and facilitate the development of useful treatment algorithms. It is necessary to estimate initially which vascular territory among large or small artery is compromised for planning treatment strategies in patients with acute ischemic stroke. The author focuses on the efficient assessment and surgical management of patients with acute ischemic stroke by reviewing the operative techniques and perioperative management of carotid endarterectomy and extracranial-intracranial bypass surgery

Hyperperfusion Syndrome after Extracranial-Intracranial Bypass Surgery

OBJECTIVE: Cerebral hyperperfusion syndrome after extracranial-intracranial(EC-IC) bypass is a rare event but it may be disastrous. It can cause vomiting, confusion, seizure and intracerebral hemorrhage. We report 11 cases of hyperperfusion syndrome after EC-IC bypass surgery for recent 5 years in detail. METHODS: Authors performed EC-IC bypass surgery for augmentation of cerebral blood flow in 60 patients for recent 5 years. In 60 patients of EC-IC bypass procedures, we experienced 11 cases of hyperperfusion syndrome. It was observed that hyperfusion induced headache and vomiting in 2 cases, seizure in 1 case, temporary neurologic deficit in 5 cases, and intracerebral hemorrhage in 3 cases. RESULTS: All patients except three cases of intracerebral hemorrhag recovered completely. Five patients with temporary neurologic deficit improved within maxmum of 10days. In three cases of intracerebral hemorrhage, emergency hematoma removal was performed. Two of them, with moyamoya disease, recovered with minor neurologic deficit. The other, with traumatic intracarotid artery injury died. CONCLUSION: Hyperfusion syndromes may be due to relative hyperperfusion of a cerebral hemisphere in which autoregulation had been impaired because of preoperative chronic hypoperfusion. We strongly recommend that revascularization is deferred to 8 weeks till impaired autoregulation is restored, and meticulous blood pressure control should be done in the postoperative course of EC-IC bypass surgery.

Current Indication of Extracranial-Intracranial Bypass Surgery / 대한뇌혈관학회지

Since the negative results of the international extracranical-intracranial bypass surgery (EIBS), this procedure is rarely employed in the treatment of patients with ischemic stroke. However, recent evidence suggests that patients with hemodynamic cerebral ischemia (HCI) are at particular risk for subsequent stroke compared to those with similar occlusive lesion but intact cerebrovascular reserve (CVR). Furthermore, several investigators have suggested that EIBS is effective in preventing recurrent ischemic attacks in patients with HCI due to occlusive disease and insufficient collateral blood supply. In addition, EIBS has been frequently used for the patients with moyamoya disease and for the patients who need therapeutic occlusion or sacrifice of a parent vessel during the treatment of complex intra or extracranial aneurysms or cranial base tumors. Based on a review of literature the rationale and the indication of EIBS will be summaried.

Extracranial-Intracranial Bypass Surgery: Surgical Techniques and Perioperative Management / 대한뇌혈관학회지

Options for extracranial-intracranial bypass surgery of anterior circulation include saphenous vein grafts, occipital to middle cerebral artery (MCA) anastomosis, and most commonly superficial temporal artery (STA) to MCA anastomosis. Although less common, posterior circulation revascularization has been successfully peformed. The operative techniques and perioperative management such as anesthetic techniques and electrophysiologic monitoring are reviewed. Finally the author's surgical experiences of STA-MCA anastomosis in 30 patients with symptomatic internal carotid artery or MCA stenoocclusion are reported.

Improvement of Cerebrovascular Reserve Capacity by Bypass Surgery in Patients with Hemodynamic Cerebral Ischemia

To study the effect of extracranial-intracranial(EC/IC) bypass on symptomatic patients with hemodynamic cerebral ischemia, we prospectively reviewed 14 patients who underwent EC/IC bypass surgery. A series of 14 patients treated in a 2 years period met the following criteria, 1) symptomatic internal carotid artery(ICA) or middle cerebral aetery(MCA) obstruction or stenosis over 80M, 2) decrease in basal cerebral blood flow(CBF) over 10%, 3) hyporeactivity to acetazolimide of CBF Amomg these, the type of ischemic episode was transient ischemic attack(TIA) or reversible ischemic neurological deficit(RIND) in 4, minor stroke in 8, and major stroke in 2. Of these, 10 patients had multiple episode of ischemic attack. CT or MRI were showed infarction of the MCA territory in 3, border zone infarction in 5, basal ganglia infarction in 2 and multiple lacunar infarction in 4. Based on our criteria, superficial temporal artery(STA)-MCA anastomosis was performed in 13 cases and EC-IC bypass grafting using radial artery in one. Average follow up period was 24 months. Postoperative course was uneventful in 12 patients. One patient suffered a postoperative stroke with complete recovery and another suffered operative wound infection. Of the 14 patients 12(85.7 % ) have had an excellent to good outcome with complete resolution or significant improvement of preoperative neurologic symptom, remaining two show no improvement of preoperative neurologic deficit. Bypass patency was confirmed by postoperative angiography in all cases except for one. Postoperative follow up studies of the basal CBF and response to the acetazolamide of the CBF showed significant increased CBF activity to acetazolamide in 12 cases(85. 7%) while the basal CBF was essentially unchanged in all cases except for two. In view of these finding, the authors suggest that EC-IC bypass surgery to be considered as an appropritate therapy for improvement of the cerebrovascular reserve capacity in patients with hemodynamic cerebral ischemia, defined using the strict selection criteria employed in this study.