No multi-institutional studies on radiosurgery for cerebral arteriovenous malformations (AVMs) have been published. We analyzed the results of >3 years' follow-up in 885 patients with AVMs, who underwent gamma knife (GK) radiosurgery between May/1991 and March/1994 at one of Japan's 11 gamma knife centers. Postradiosurgically, 681 (77%) of the 885 patients were periodically examined by angiography. Complete nidus obliteration was angiographically confirmed in 443 patients (50%), subtotal obliteration in 114 (13%), shrinkage in 99 (11%) and no significant change in the remaining 25 (3%). These rates correspond to 65%, 17%, 15% and 4%, respectively, of the 681 patients who had follow-up angiography. Hemorrhages occurred during the postradiosurgical latency period, ranging from 1 to 48 months, in 41 patients (4.6%). The annual rates were 2.4% during the first postradiosurgical year, 0.9% during the second, 0.8% during the third, and 0.3% during the fourth. Although 14 (34%) of the 41 patients showed full recovery, 13 (32%) died and the other 14 (34%) have persistent deficits. Radiation-related aggravation of clinical symptoms was seen in 24 (2.7%) of the 885 patients between the 5th and 36th post-radiosurgical months. Steroid treatment was required in all 24 patients, 16 of whom recovered completely while the other eight had persistent deficits. The herein-reported overall obliteration rate seems relatively low as compared with those reported previously. However, the annual incidence of (re-) bleeding during the latency period was low as compared with those reported for untreated AVMs.

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Recently 3 major therapeutic modalities have been available for cerebral arteriovenous malformations (AVMs): microsurgical resection, endovascular embolization, and radiosurgery. We have treated patients with AVMs mainly by surgical resection with and without preoperative endovascular embolization. We discuss surgical strategies for cerebral AVMs based on our clinical results. We have treated 57 patients with cerebral AVMs in the last five years. Of these 57, we have resected 44 AVMs, which comprised 30 ruptured (Gr I: 9, II: 8, III: 9, IV: 2, V: 2) and 14 non-ruptured (Gr I: 3, II: 2, III: 7, IV: 2, V: 0) ones, according to following strategies: 1) preoperative embolization of only the feeders that hide behind the nidus at the surgery, 2) microsurgical resection with sharp dissection technique, 3) confirmation using intraoperative angiography, and 4) intra- and post-operative intensive management while maintaining adequate blood pressure. Total resection of the nidus achieved in 41 patients. In the 3 patients in whom a small residual nidus was remained postoperatively, additional radiosurgery and endovascular embolization were performed in 2 and 1 patients, respectively. Intraoperative angiography was very useful for identifying small feeders that appeared at last after the occlusion of main feeders. Thirty-eight patients (86.4%) had no complications. Six patients suffered neurological deterioration due to surgery and/or embolization, but 4 of them returned to their previous social status. Surgical resection has the advantage of immediate disappearance of the lesion. With minute planning and preparation, the majority of the cerebral AVMs could be resectable without major complications.

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We reviewed the management strategies for arteriovenous malformations (AVM) treated in our department to assess the efficacy of a multimodality approach. Seventy-five consecutive patients of intracranial pial AVM treated over the last six years are retrospectively analyzed. Owing to the referral pattern of our hospital, 65% of cases presented with intracerebral hemorrhage (ICH). One-third of AVM located in the basal ganglia and infratentorial region. Seventy-three percent of cases were categorized into Spetzler's Grade I to III and 8% of cases had large AVMs, whose maximum diameters were larger than 6cm.
Multimodality options for the treatment of AVM consisted of preoperative staged embolization, microsurgical staged removal assisted by intraoperative angiography and LINAC radiosurgery. Treatment indication and options were decided depending on patients' age, their presentation, angiographic architecture and the extent of the parenchymal damage. We consider surgical removal the treatment of choice when non-giant, superficial AVM presented ICH. Preoperative embolization and surgical removal were performed on 29 and 43 patients, respectively. LINAC was adopted for 19 patients, and no treatment was indicated for 10 patients, all of whose AVMs were incidentally found. 76% of Glasgow Outcome Scale on discharge obtained from treated cases were good recovery and moderately disabled. Many of the poor outcome cases were due to primary brain damage of initial bleeding. Complications related to treatments were 3 bleeding and 1 ischemic event after embolization and 2 radiation necrosis after LINAC. Total removal or occlusion was obtained two-thirds of all the treated cases and 88% of operated cases. These results indicated that the indication for a multimodality approach should be determined on a case-by-case basis, and total extirpation or occlusion of the AVM with minimum complication can be achieved when an appropriate combination of these treatment options is selected.

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We retrospectively analyzed treatment modalities and outcomes in 51 cases of cerebral arteriovenous malformation Grade IV (Spetzler- Martin's classification) admitted to our institute since 1986. Twenty-five out of 33 cases with hemorrhagic onset received surgical resection with or without preoperative embolization. Total resection was achieved in 21 cases, and small residual nidus was treated by postoperative radiosurgery in 2 out of 4 subtotally resected cases. Six out of 33 hemorrhagic cases received radiosurgery with or without preradiosurgical embolization. Twenty-six out of 33 hemorrhagic cases obtained complete disappearance of nidus. On the other hand, 4 out of 18 non-hemorrhagic cases received surgical total resection, 4 radiosurgery, 6 partial embolization, and 4 observation. Surgical morbidity was 7% and mortality was 0%, and post-treatment hemorrhage was seen in 8 cases (1 after subtotal resection, 2 after radiosurgery, 5 after partial embolization). Surgical resection can be achieved with acceptable morbidity, and complete obliteration of nidus should be accomplished in any treatment modality to avoid post-treatment hemorrhage.

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Recently developed interventional radiologic techniques, such as embolization with platinum coils, may induce change of selection for cerebral aneurysmal therapy. The aim of the present study was to investigate current and future status of the treatment for cerebral aneurysms.
We analyzed 159 cases with cerebral aneurysms by choice of treatment, surgery or interventional coil embolization. One hundred cases were ruptured, and 59 with 63 aneurysms were unruptured during the past 3 years. Fundamentally, the ruptured aneurysms were treated better than H & K grade IV.
For patients who were older than 70 years, had a H & K grade IV, and/or were difficult to clip surgically, interventional coil embolization was selected. Thirteen cases with ruptured aneurysms were treated with embolization after subarachnoid hemorrhage, and one was embolized after failed surgical treatment. In the case of unruptured aneurysms, aneurysms with surgical difficulty, such as posterior circulation aneurysms or internal carotid (C2-3) aneurysms, coil embolization was selected. Among 63 unruptured aneurysms, 9 were treated with coil embolization.
Fourteen percent of ruptured and unruptured aneurysms were treated with coil embolization. The factors by which treatment was decided, such as anesthesia, safety of technique, invasiveness of treatment, patient condition and longstanding effectiveness of each treatment, are important for future choices of treatment of aneurysms.

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We report our 10 years of experience with the use of radial artery bypass grafts to treat large or giant vertebro-basilar artery aneurysms (5 patients, 2 of whom had a ruptured aneurysm and 3 of whom showed deterioration by medical treatment). All were diagnosed as unclippable in preoperative examinations.
Prophylactic vascular reconstruction to the rostral brainstem before treating the aneurysm was required. Radial artery bypass grafts were adopted between intracranial vertebral artery (V4) and proximal basilar artery (V4-RA-BA, n=1), vertebral artery (V3) and distal basilar artery (V3-RA-BA, n=1), vertebral artery (V3) and posterior cerebral artery (V3-RA-PCA, n=2), and proximal superficial temporal artery and posterior cerebral artery (STA-RA-PCA, n=1). Aneurysms were treated by proximal ligation (n=1), excision (n=1), intraoperative coil embolization (n=1) and direct clipping (n=1). In one case in which STA-RA-PCA bypass was performed, intolerance of the proximal basilar artery occlusion was shown by intraoperative SEP monitoring. The aneurysm remained without any treatment.
Excellent or good results were achieved in 2 patients. One patient was unchanged. One patient, in whom the basilar artery was totally occluded although the graft remained patent, worsened. One patient died of acute myocardial infarction.
Our results indicate that the vascular reconstruction to the rostral brainstem, especially the high flow bypass, should be considered whenever proximal basilar artery occlusion is performed in aneurysm patients.

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We evaluated and analyzed the effect of superficial temporal to middle cerebral artery (STA-MCA) bypass for ischemic cerebrovascular diseases (CVDs) on pure motor function using motor activation single photon emission computed tomography (SPECT), and we also compared this effect with the resting cerebral blood flow and reserved capacity.
Motor activation SPECT studies were carried out on 22 cases with STA-MCA bypass performed for symptomatic ischemic CVDs. All motor activation SPECT studies using the finger opposition task on the affected side were performed before bypass, at 1 month, and 3 months after the bypass. Visual inspection was used to determine whether the result of the motor activation SPECT was as negative or positive. The activated region was detected anatomically precisely by superimposing the SPECT images on the MR images. Before we started this study, we performed the same examination on 11 normal control cases. Among the 11 cases, 10 (91%) showed the activated area on the sensorimotor cortex after the finger opposition task.
Before bypass, the resting SPECT studies revealed reduction of cerebral blood flow (CBF) on the affected side in all 22 cases. All 22 cases also showed a disturbed response to acetazolamide (ACZ). Nine cases were positive in the motor activation SPECT study. One month after bypass, the resting CBF increased in 11 cases. Seven showed preoperative positive motor activation. Fifteen cases were positive in the motor activation SPECT. Three months after bypass, 20 cases showed improvement in the resting CBF, and 19 cases were positive in the motor activation SPECT. Among these, 10 cases were negative in the preoperative motor activation SPECT. At one month after surgery, ACZ activation SEPCT was performed in 12 cases. Five showed improvement of the response to ACZ. At 3 months after surgery, 8 of 12 cases treated with ACZ activation SPECT showed improved response to ACZ. In most of the cases, improved response to ACZ could be seen after response to motor activation improved.
STA-MCA bypass is useful not only for resting CBF but also for pure motor function based on motor activation SPECT. We concluded from the preoperative motor activation study that cases with preoperative positive motor activation could attain the effect of bypass earlier than preoperative negative cases. Improvement of the motor activation response could be seen before improvement of the ACZ response in most cases.

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We have introduced a newly devised shunt system for carotid endarterectomy (CEA) in patients who have relatively high cervical lesions. Among 155 patients, 170 CEAs were performed using this shunt system, and mortality and morbidity were 0% and 2.4%, respectively. Bilateral carotid endarterectomy were performed in the 15 patients without complications. Additionally 5 patients showed contralateral carotid occlusion with ipsilateral severe stenosis, two of whom had staged operations; STA-MCA anastomosis was performed for the occluded side and CEA for stenotic lesion. Their outcomes were also good. The effects of angioplasty on carotid stenotic lesion was intraoperatively investigated by inflation of a balloon catheter 3 or 4 times with 2.5-3.5 atmospheric pressure. Only 3 of 12 stenotic lesions were macroscopically dilated with intravascular exudation of atheroma and laceration of the intima.
We have demonstrated CEA can be safely and easily performed with a routine application of our shunt system even in multiple occlusive lesions.

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Moyamoya disease is a unique disease of unknown etiology typically characterized by progressive occlusion of both internal carotid arteries accompanied by an abnormal collateral circulation referred to as moyamoya vessels. To compensate for lack of blood flow in the frontal region, the collateral circulation develops from delicate basal networks and the vertebrobasilar system, and often is demonstrated by angiography, MRI or MRA. To investigate whether nitric oxide (NO) contributes to formation of abnormal collateral circulation in patients with moyamoya disease, we measured concentrations of NO metabolites in cerebrospinal fluid (CSF) obtained during treatment of this disease with bypass surgery.
CSF samples were obtained from the subarachnoid space of the sylvian fissure during combined bypass surgery for moyamoya disease and kept frozen untill NO metabolites, nitrate and nitrite were measured using a Griess method.
Compared with control specimens of CSF obtained from 16 patients with hemifacial spasm (n=8), trigeminal neuralgia (n=2), nonruptured aneurysm (n=5), or tremor (n=1), concentrations of NO metabolites in the CSF of 23 patients with moyamoya disease were significantly higher (18.6+1.1 vs. 11.0+1.0μM). NO metabolite concentrations (21.6+2.3μM) in CSF obtained during initial surgery in 7 resampled patients decreased to 16.9+1.5 μM in CSF obtained during a second, contralateral precedure. Angiographically early moyamoya disease tended to show lower concentrations of NO metabolites than cases of with greater development of moyamoya vessels.
NO concentrations in CSF were chronically elevated in moyamoya disease, probably reflecting development of collateral circulation. Vascular bypass surgery can reduce NO metabolites together with abnormal collateral circulation.

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The treatment of regrowing aneurysms some years after neck clipping is challenging for neurosurgeons, because severe adhesion is inevitable in the operative field, especially around the previous clip. This obstructs the dissection around the aneurysmal neck and also the clipping itself.
Removal of the previous clip without rupture of aneurysms is optimal but remains controversial. In this report, we presented 3 successful cases whose regrowing aneurysms were precisely clipped again by removing the previous spring clips, which were placed 10, 17 and 18 years before respectively. We used the same approach as the previous one to remove the clip. The key point to remove the clips was the sharp dissection of the tough granulomatous tissue surrounding the clip. After that, the clips could be easily loosened and removed by the clip applier without rupture. When the clip was reinforced by coating materials, the meticulous and complete dissection around the clip was necessary to avoid injury of the aneurysmal wall.

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