The gold standard for treating cervical carotid artery stenosis has been carotid endarterectomy (CEA). However, in patients at high risk for surgery, there is no evidence of the risk-benefit ratio of CEA. Carotid stenting (CS) has recently become an alternative treatment in high-risk cases. We discuss our current strategy for cervical carotid artery stenosis, and report our clinical results of CS and some technical contrivances to reduce the procedural risk.
We have treated 106 cases involving 116 severe carotid artery stenoses between June 1998 and December 2000. CS was applied to only high-risk cases, while patients at low-risk for surgery were treated with CEA. Lesions with features contraindicating endovascular procedures (tortuous lesion, severe calcification, unstable soft plaque) were also treated by CEA. As a result, 65 of 116 lesions underwent CS mainly with the use of a self-expanding stent, and 51 lesions were treated with CEA. The technical success rate and peri-procedural risk of stent placement were 98.5% and 4.6%, respectively. Diffusion-weighted MR imaging (DWI), which is a useful modality to detect acute cerebral embolism including asymptomatic lesion, demonstrated procedure-related lesions in 32 of 65 CS treated cases (49.2%). Distal protective balloon (dPB) for prevention of distal embolism during stenting was partially effective to reduce the occurrence of procedure-related ischemic lesions on DWI.
We concluded that CS and CEA should be complementary treatments of cervical carotid artery stenosis. For establishment of CS procedure as an alternative treatment for carotid stenosis, more effective protective devices and more objective information on the safety and efficacy of CS are required.

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To delineate the current standard of endovascular treatment for intracranial dural arteriovenous (AV) fistulas, we retrospectively evaluated the results of endovascular procedures in the last 10 years.
We experienced 98 lesions of intracranial dural AV fistulas in 93 patients from 1991 to 2001. Location of the lesion was the cavernous sinus (CS) in 37 patients, transverse-sigmoid sinus (TSS) in 37, superior sagittal sinus (SSS) in 4, marginal sinus (MS) in 1, tentorium in 3, anterior cranial base (ACB) in 6, craniocervical junction (CCJ) in 7, and other cortical veins in 3. Of these 93 patients, 9 (6 with CS, 2 with TSS, and 1 with CCJ lesions) were treated conservatively, and 10 (6 with ACB, 2 with CCJ, and 2 with tentorial lesions) were treated with surgical intervention. Seventy-five patients (32 males and 43 females with 79 lesions, mean age of 62.6 years) underwent 155 sessions of endovascular treatment. Thirty-one CS lesions were treated with 52 endovascular procedures (13 transarterial embolization (TAE), 37 transvenous embolization (TVE), and 2 surgical transvenous embolization (surgical TVE)). Thirty-five TSS lesions were treated with 82 procedures (45 TAE, 26 TVE, and 11 surgical TVE). The other 13 lesions (4 SSS, 1 MS, 1 tentorium, 4 CCJ, and 3 cortical lesions) were treated with 21 procedures (19 TAE, 1 TVE, 1 surgical TVE).
The outcome and complications of these treatments were retrospectively analyzed and the current standard of endovascular treatment was delineated.
[CS] Angiographic results were complete or subtotal obliteration of the fistula in 30 of 31 patients. Transient minor complications occurred in 3 procedures. Eye symptoms were relieved in all patients but one who experienced the so-called paradoxical worsening after treatment (TAE). Hemiparesis remained in 1 patient, who had presented with an intracerebral hematoma. [TSS] Angiographic results were complete obliteration in 21, subtotal in 8 of 35 patients. Transient and permanent complications occurred in 2 and 1 patients, respectively. Clinical outcome was GR in 28, MD in 3, SD in 1, VS in 1, and D in 2 (acute myocardial infarction and pulmonary embolism after treatment). [other lesions] Angiographic results were complete obliteration in 5, subtotal in 4, and partial in 4 patients. Two permanent complications occurred in TAE of CCJ lesion. Clinical results were GR in 9 patients, MD in 1, SD in 1, and VS in 1. One patient died from hemorrhagic shock caused by retroperitoneal bleeding.
Endovascular procedures were a very efficacious method to treat dural AV fistulas involving the cavernous and transverse-sigmoid sinuses. Transarterial embolization effectively played a supplementary role of reducing the arterial inflow. Transvenous embolization, if available, was a radical treatment for these lesions. Surgical transvenous embolization was an alternative treatment for lesions with no venous access routes. Surgical intervention played a leading part for lesions involving the tentorium and cortical veins at the anterior cranial base and craniocervical junction.

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We performed a retrospective study to estimate the relationship between aneurysmal thrombosis and geometrical characteristics in giant aneurysms. We used aspect ratio (aneurysm depth/neck) and area ratio (ratio of the cross-sectional area of bifurcated arteries) to evaluate the geometrical characteristics. We analyzed 25 cases with giant saccular aneurysms that underwent precise neuroradiological examinations in our institute over a recent 10-year period. Twelve aneurysms developed at the ICA cavernous portion. These aneurysms were classified as non-branching aneurysms and showed a mean aspect ratio of 5.2. Nine aneurysms classified as bifurcation aneurysms developed at the MCA bifurcation (5 cases) and at the basilar bifurcation (4 cases). All of these aneurysms were buried in the brain tissue. The mean aspect ratios were 8.2 and 5.1, respectively, and the mean area ratios were 2.6 and 1.2, respectively. In the non-branching aneurysms, blood flow was shown along the aneurysmal wall, and intra-aneurysmal thrombuses were shown in the center of the aneurysms. In the bifurcation aneurysms, blood flow was demonstrated around the neck, and intra-aneurysmal thrombus was shown in the dome side. The area of thrombus was positively associated with stagnant areas of blood flow. We discuss the mechanism of intraaneurysmal clotting.

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To determine the usefulness of performing ultra-early surgery to treat massive hypertensive intracerebral hemorrhage (ICH), we evaluated 52 patients, aged 49 to 79 years, over a 6-year period. Among them, 35 patients were classified as Group Va, and the remaining 17 cases were grouped as Vb (Kanaya's classification). All patients underwent microsurgical treatment within an average of 4.2 hours after the onset of hemorrhage.
Thirty (Va: 17/35, Vb: 13/17) out of the 52 patients required an emergent tracheal intubation due to respiratory failure when admitted, and a tracheostomy was needed in 13 patients within 1 month after the operation. However, after 6 months, only 3 patients continuously required a tracheostomy. Ventriculostomy was performed in 30 patients (Va: 13/35, Vb: 17/17), and a ventriculo-peritoneal shunt was required in 27 out of the 30 patients (Va: 10/13, Vb: 17/17). Three months after the operation, a Barthel Index above 40 points was found in 27 cases (Va: 16/35, Vb: 11/17), and 50% of patients showing good outcome kept a Barthel Index above 40 at a 6-year follow-up. During the follow-up period, only 3 patients suffered from other medical complications and died within 1 month after the operation.
Our results suggest that decrease of early mortality rate and maintenance of good long-term functional outcomes can be achieved by ultra-early surgery. Ultra-early treatment of respiratory failure and intensive control of the intracranial pressure by a ventriculostomy in the peri-operative period also improve the long-term outcome for patients with massive ICH. Moreover, a meticulous follow-up in the outpatient department is essential.

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We analyzed overall outcome after surgical revascularization in 149 patients with moyamoya disease. Of 61 childhood patients, 58 (95.1%) have not experienced further ischemic episode during follow-up periods. Postoperative angiograms showed well-developed collaterals via STA-MCA anastomosis and indirect synangiosis. Total IQs were significantly lower in childhood patients who had cerebral infarction at onset. Of 40 adult patients with ischemic-type moyamoya disease, 35 (87.5%) have not experienced further episodes of stroke. However, 3 (7.5%) patients had cerebral infarction in the contralateral side or in the vertebrobasilar territory, and 2 (5.0%) suffered intracranial bleeding during follow-up periods. Of 34 adults who underwent bypass surgery for hemorrhagic-type moyamoya disease, 7 (20.6%) developed rebleeding. Statistical analysis revealed that STA-MCA anastomosis combined with indirect synangiosis may significantly reduce the risk for rebleeding. Clinical strategies should be decided for adult patients with asymptomatic moyamoya disease.

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In cerebral aneurysm surgeries, preservation of the perforating arteries is essential. In the case of anterior communicating artery (Acom) aneurysms, confirmation and dissection of the perforating arteries are sometimes difficult due to the complexity of the Acom complex and relatively deep and narrow operative fields. Moreover, necks of the Acom aneurysms are occasionally broad and/or fragile and easy to be torn by dissection procedures. When the dissection of the neck and/or the perforating arteries is difficult because of some of the above-mentioned reasons, we have used dome puncture techniques to reduce tension and volume of the aneurysms under temporary parent artery clipping or tentative dome/neck clipping. In a recent series of 48 consecutive aneurysms of the anterior circulation of the Willis ring, including 11 Acom aneurysms, dome puncture technique was used in 7 aneurysm cases (3 Acom, 3 middle cerebral artery (MCA) and 1 internal carotid artery (ICA) aneurysms). Sizes of these 3 Acom aneurysms were 10 mm, 10 mm and 8 mm each. In contrast to the Acom aneurysms, all MCA/ICA aneurysms were “large” (12 mm or larger) except 1 MCA aneurysm located at the junction of the M1 and the striate artery. Of these 7 cases, there were neither perforator injuries nor neck injuries. We stress the usefulness of dome puncture techniques for safe and reliable neck clipping in the case of “large” or complicated aneurysms. Especially in the case of Acom aneurysm, this technique efficiently prevents injuries of the perforating arteries and the necks, even if the aneurysmal size is relatively small.

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Treatment of cervical carotid stenosis with the contralateral internal carotid artery (ICA) occlusion or severe stenosis has not been established because of its specific cerebral circulation. We sought to clarify the clinical features and best surgical treatment of cervical severe carotid stenosis with contralateral ICA occlusion or severe stenosis.
We studied 8 patients with bilateral severe ICA stenosis (≥70%) and 5 patients with ICA severe stenosis and contralateral ICA occlusion. To evaluate cerebral circulation, regional cerebral blood flow (rCBF) of the middle cerebral arterial territory and stump pressure of the ICA were measured. rCBF was measured before and after CEA. Rates of association of systemic diseases were analyzed. There was no perioperative complication or new stroke in the follow-up time (2-138 months) in this series. In 3 of the 8 patients, rCBFs were bilaterally decreased below 40 ml/100 g/min. rCBF of severe ICA stenosis with contralateral ICA occlusion or severe stenosis was lower than that of unilateral ICA stenosis. In 6 of 9 patients who underwent CEA, rCBF increased over 15% after operation. Stump pressures of the ICA in the patients with severe ICA stenosis associated with contralateral ICA occlusion or severe stenosis were significantly (p<0.05) lower than those of unilateral ICA stenosis. SEP became flat during ICA cross-clamping in 4 patients but recovered after reflow of the ICA. Bilateral ICA occlusive disease had been highly associated with ischemic heart disease compared with unilateral stenosis. In the follow-up period, 4 patients had angina pectoris and 2 patients had coronary artery bypass grafting surgery.
The patients with bilateral severe occlusive disease had low rCBF and low collateral flow. Because of low collateral flow via Willis ring, an internal shunt was necessary to avoid cerebral ischemic complication during ICA cross-clamping. SEP was useful for detecting cerebral ischemia during ICA cross-clamping. Vascular reconstruction increased rCBF, especially in the patients with low rCBF. The treatment of patients with ischemic heart disease is very important but controversial.

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We review our 20-plus years of experience of patients treated with carotid endarterectomy (CEA), or percutaneous transluminal angioplasty and stenting for severe carotid stenosis. Of 246 patients, 221 underwent CEA and 25 underwent stenting. Of 221 patients treated with CEA, 6 who underwent CEA at the subacute period after stroke suffered from perioperative complication (2.7%). Ipsilateral stroke did not occur during the follow-up period (1-21.4 years) after CEA, although 2 patients had asymptomatic restenosis. Of 25 patients treated with stenting, 2 patients experienced transient occlusion of the middle cerebral artery and 1 had permanent occlusion of the retinal artery during procedure. Neither ipsilateral stroke nor restenosis occurred during the follow-up period (1-4 years) after stenting. CEA and endovascular treatment effectively prevented stroke in patients with good perioperative clinical course and without medical risk factors.

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Based on many reported studies on patients with subarachnoid hemorrhage and unruptured cerebral aneurysm, I tried to calculate the incidence rate of cerebral aneurysm rupture. (1) Unruptured cerebral aneurysm exists in about 2% of the total population. (2) The annual occurrence of subarachnoid hemorrhage is 20 cases in a town of 100,000 population. (3) The turnover of patients with unruptured cerebral aneurysm is for the 50-year cycle of patients with cerebral aneurysm in ages from 30 to 80. (4) The size distribution of unruptured and ruptured cerebral aneurysm is already known.
In a town of 100,000 population, the number of unruptured cerebral aneurysm cases and that of subarachnoid hemorrhage cases occurring in 50 years are 2,000 and 1,000, respectively. This finding shows that the rupture rate is 0.67% per year.
The distribution of patients for different sizes of aneurysm can be estimated for a total of 3,000 patients with unruptured and ruptured cerebral aneurysm.
On the other hand, the growth process of cerebral aneurysm from its occurrence may be classified into 4 patterns as the follows. Type I : The aneurysm ruptures within a span of time as short as a few weeks to a few months after formation. Type II : The aneurysm builds up slowly for a few years after formation and ruptures in this process. Type III : The aneurysm keeps growing slowly for a long time without rupture. Type IV : The aneurysm grows to a certain size, within 10 mm in diameter, and remains unchanged thereafter.
Aneurysms larger than 10 mm mostly grow slowly. Among patients in this category, the aneurysm ruptures in 48.9% of 10-14 mm size group, 21.7% of 15-25 mm, and in 9.1% of 25 mm or larger size. Some aneurysms smaller than 10 mm rupture soon after formation (Type I), and the others remain unchanged (Type IV). Particularly, a considerable proportion of 5-9 mm aneurysms rupture soon or immediately after formation, while aneurysms smaller than 5 mm mostly remain unchanged.

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We report a case of embolization of a downward aneurysm in the basilar artery-anterior inferior cerebellar artery bifurcation using Guglielmi detachable coil (GDC).
A 68-year-old man complaining of a sudden headache was admitted. On admission his consciousness was clear and neurological examination showed no abnormalities. Computed tomography demonstrated subarachnoid hemorrhage (SAH). However, cerebral angiography (CAG) revealed no definite vascular lesion. CAG 6 days after onset revealed a downward aneurysm of 2.5 mm in diameter at the left anterior inferior cerebellar artery bifurcation. This aneurysm was embolized using GDC.
We approached this lesion from the ipsilateral vertebral artery with a microcatheter shaped as an acute curve. However, the microcatheter was unstable when we pushed the GDC into the aneurysm. Therefore, caging was not carried out. Finally, we approached from the contralateral vertebral artery with a microcatheter shaped as a less acute curve and were able to pack 2 GDCs 10 (2 mm×1 cm) firmly into the aneurysm. A 6-day follow-up angiogram revealed no definite coil compaction.
Approaching a basilar artery-anterior inferior cerebellar artery downward aneurysm from the contralateral vertebral artery was effective for embolization.

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Intracavernouscarotid aneurysm rarely causes SAH and is not considered to be a life-threatening lesion, although it sometimes causes compression syndrome. Therefore, asymptomatic intracavernouscarotid aneurysm is commonly treated by observation rather than surgery in spite of the recent development of endovascular treatment. We describe a rare case with subdural hematoma caused by rupture of an intracavernouscarotid aneurysm. A 55-year-old woman was brought to our hospital because of sudden headache. CT scan showed a mass of high-density region at the left cavernous sinus with sign of empty sella. She was discharged as no other lesion was observed. A few days later, she was admitted again to our hospital because of sudden headache followed by coma. Her JCS level was 200 and GCS was 4 on arrival. CT scan revealed a subdural hematoma extending from the intrasellar and suprasellar region to the bilateral hemispheric areas. Angiograms showed a left intracavernouscarotid aneurysm 10 mm in diameter. Although embolization of the aneurysm was successfully performed and her JCS level recovered to Level 3 without further rupture of the aneurysm, she died from the complication of sepsis and DIC.

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