脳動静脈奇形(AVM)に対しgamma unitによる治療が行われ2年以上を経過した25例のうち, 治療が不満足な結果に終っている8例を報告し, 治療不成功の要因を検討した. 症例の内訳は, 初回照射治療により病巣の完全閉塞が得られず, 再照射を行った2例. 照射後の脳血管撮影では部分閉塞しか確認されていないにもかからわず, その後の検査が患者の不承諾のため行われていない3例. 完全閉塞が確認されたが, 放射線障害を残したものと, 脳血管撮影後に合併症で失ったもの各1例. 残るは,患者の承諾が得られないため, 照射後の脳血管撮影が全く行われていない1例である. 治療が不成功となった要因としては (3例では複数の要因が考えられた), 適応判断に問題があったもの3例, 術中の脳血管撮影で病巣が完全に描出されなかったもの1例, 照射計画に問題があったと考えられたもの3例, および術後のfoilow-upに問題があったもの4例であった. AVMに対するgammaunit治療を成功裡に行うには, 的確な適応判断と正確な治療が肝要なことは既に周知のごとくである. それに加え, 照射後の綿密な追跡を長期にわたり行うことの重要性を強調したい.

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Seventy-three patients with arteriovenous malformation (AVM) were treated with gamma knife. The patient's mean age was 29.9 presenting symptoms included prior hemorrhage in 60 (82%) and seizure in 6 (8%). Neurological dificits were present in 33 patients (45%). Eighty-one percent of AVMs were located in eloquent areas and the mean size was 19.6×19.8×20.2mm. AVM volume of less than 10cm3 was found in 60 patients (82%). The lesions were classified according to the Spetzler grading system: 42 (58%) wer Grade III, 10 (14%) were Grade II, and 11 (15%) were Grade VI. Prior surgery had been performed in 30 patients. Embolization procedures were performed in 7 patients. Conventional external irradiation was done in 4 patients. All patients were irradiated to the entire volume of the AVM nidus. The mean dose delivered to the AVM margin was 19.2 Gy and that delivered to the center was 36.9 Gy. Embolization was very useful in reducing some lesions larger than 3 cm in diameter.

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1991年5月末より9カ月間に24例の動静脈奇形を経験し, うち22例をガンマナイフ手術にて加療した. これらの経験より動静脈奇形の治療方針について検討した. ガンマナイフでの治療はきわめて安全で, 患者は治療翌日より術前と同様の活動が可能であった. しかしながらガンマナイフ手術中および術後7カ月の各1例で,動静脈奇形からの出血があり直達手術により救命されたが, 脳内出血による脳損傷のために後遺症が残存した. 動静脈奇形の理想的治療としては可能な限り早期の完全消失が望ましく, 直達手術や血管内手術は今後も重要な治療法であり, 特に脳内出血を伴う例の早期治療に必要である. 血管内手術の進歩により大きな動静脈奇形に対するアプローチが可能となったが, 機能的領域に存在する場合には血管内手術の危険性はいまだ高い. nidusをいくつかに分画し, 各々を独立した50%等量線にて治療するガンマナイフ手術が今後役立つと考えられる. この方法には選択的血管撮影とMRIが有用であるが, 残存するであろうnidusに対する二期的なガンマナイフ手術が予定される必要がある.

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Eighty brain arteriovenous malformations (AVM's) in 76 cases (age 3-57, average 28) have been treated primarily by embolization using a newly development liquid embolization method (estrogen-alcohol combined with polivinyl acetate polymer). Super selective embolization was performed in 166 sessions. After confirmation of negative provocation test using amytal with or without lidocaine, infusion of estrogen-alcohol was followed by injection of polyvinyl acetate. The former was used to obliterate fine vascular networks inside the nidus by chemical embolization property, and latter was used to occlude the more proximal artery to fistulous connection. After the embolization, 11 lesions (13.8%) disappeared angiographically. The number of nidi that had a diameter large than 3cm was reduced from 45 (56.2%) to 7 (8.7%). As an adjunctive treatment, conventional neurosurgical resection was performed in 9 cases without difficulty. In 9 cases, the residual nidus was irradiated by conventional way (30 Gy in 3 weeks). Follow-up angiography (average 17 months after embolization) was performed in 39 cases. Six nidi embolized completely showed no revascularization. In the remaining 36 cases, 5 lesions were reduced in size (all were irradiated cases), 21 unchanged and 7 enlarged (not by recanalization but by collateralization and/or neovascularization). The mortality rate related to embolization was 1.3% (1 case) and morbidity rate was 23.5%. Annual rebleeding rate in incomplete embolized cases was 3.6%
Recently the gamma knife become available in Japan. Gamma knife surgey achieves complete obliteration of the nidus in about 80% of the cases irrespective of the site of the AVM, with a low complication rate (around 4%). But this favorable result is strictly dependent on the size of the nidus.
Keeping the above mentioned results in mind, our treatment strategy of AVM at present is as follows. Surgical removal might be considered in small cortical lesions. Embolization would be a primary treatment for the lesions larger than 3cm or 10ml, except when the acute surgical removal of hematoma is required in hemorrhagic case. After embolization, the lesion would be surgically removed or treated by gamma knife according to the risk of the tretment modalities. For the hemorrhagic lesions smaller than 3cm, embolization would be considered if the feeders were easily catheterized without significant risk. For the non-hemorrhagic lesions less than 3cm, gamma knife would be the treatment of choice.

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Successful gamma knife radiosurgery depends on the volume of nidus of cerebral arteriovenous malformations (AVMs). Because of lower possibility of obliteration of large AVMs treated by gamma knife radiosurgery, embolization therapies were carried out in 10 cases out of 50 AVMs to reduce the volume of nidus before gamma knife radiosurgery. The strategy is as follows: 1) when the volume of nidus is less than 5ml, gamma knife radiosurgery is selected as the first treatment. 2) when the volume of nidus is from 5 to 10ml, embolization is recommended in selective cases in which the procedure seems to be safely performed. 3) When the volume of nidus is over 10ml, embolization should be tried in all cases. In this strategy, it is essential to evaluate the accurate volume of nidus before gamma knife radiosurgery to decide whether embolization should be carried out or not. Angiography with painless fixation of Leksell frame was thought to be best procedure to meansure the accurate volume of nidus before gamma knife radiosurgery.

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The experiences of the first 144 cases of arteriovenous malformation (AVM) treated with the gamma knife at the University of Tokyo Hospital between June 1990, and May 1992 are described. One year after radiosurgery, complete obliteration was observed in 16 (31.4%), remarkable decrease in 7 (13.7%), and partial obliteration in 24 (47.1%) of 51 patients who underwent angiography. There seems to be a tendency for smaller AVMs to be obliterated earlier. The minimal dose at the periphery required for total obliteration was estimated to be 20Gy. Bleeding after radiosurgery was observed in 5 (3.5%) cases. The bleeding rate was higher for AVMs located close to ventricles. Nine (13.2%) of 68 patients showed neurological deterioration three to twelve months after radiosurgery. A low density area on CT was demonstrated in ten (17.5%) of 57 patients. These outcomes are compatible with previous reports and confirm the efficacy of stereotactic radiosurgery for cerebral arteriovenous malformations.

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In aortitis syndrome, cerebral revascularization is considered for patients showing cerebral or retinal ischemic symptoms. In these patients, all branches from an aortic arch are usually occluded. Cerebral perfusion pressure is choronically so low that the range of cerebral autoregulation is shifted to the left or disappears. In such a condition, surgical revascularization may cause a breakthrough or hyperperfusion syndrome including an intracerebral hematoma. These complications make a poor prognosis.
The authors monitored the lumbar spinal pressure to detect the hyperperfusion or breakthrough during the operation for a patient with aortitis syndrome. Spinal pressure raised markedly just after an opening of the vein graft from the aorta to the common carotid artery, showing the breakthrough phenomenon. The graft was partially occluded, and the systemic blood pressure was lowered. Reopening of the graft only made a mild spinal pressure elevation. Systemic blood pressure was gradually returned to a habitual level postoperatively. Postoperative course was uneventful. Spinal pressure reflects the intracranial pressure well, which is raised by an increase of cerebral blood volume caused by the breakthrough phenomenon. This method is simple and does not need trepanation. It is an useful monitoring technique not only during the revascularization for aortitis patients, but also during carotid endarterectomy.

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Three cases of rare dural arteriovenous shunts (dAVS) involving marginal sinus were presented with special reference to the site of abnormal arteriovenous (AV) shunting and treatment. Patients included two women and one man, ranging in age from 42 to 65 years. Clinical symptoms were bruit, headache with or without chemosis and diplopia. Angiography revealed abnormal AV-shunts situated in the marginal sinus neighboring the junction between the inferior petrosal sinus and jugular bulb. Arterial feeders contributed from the dural branches of external, internal carotid and vertebral arteries. Among them, the neuro-meningeal trunk of the ascending pharyngeal artery served as the main feeder, and dural branches of vertebral artery characteristically supplied the lesion through odontoid arterial arch collaterals in 2 cases. The lesion was drained by the veins either through the jugular bulb or through the inferior petrosal sinus. In all 3 cases, the cavernous sinus was visualized through reversed shunting flow, causing the symptoms mimicking cavernous dAVS. Trans-arterial embolization was performed in one case with clinical improvement. Trans-venous embolization using platinum coils was carried out for the rest of the patients with both angio-anatomical and clinical cure.
These lesions may represent a new clinical entity and could be recognized as marginal sinus dAVS instead of that involving the inferior petrosal sinus. Trans-venous embolization offers most curative means of treatment with fewest complications. Identification of exact AV shunting site and selection of appropriate embolization material are mandatory to achieve effective and safe embolization therapy.

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Between 1981 and 1990, superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis was performed on 43 patients who had steno-occlusion of the internal carotid or middle cerebral artery. All of these patients were followed for an average of 6.5 years (range, 0.5 to 10 years). A follow-up study showed that 7 of these cases had a recurrence of an attack on the contralateral side or in the posterior circulation, but not on the ipsilateral side. Two of them had re-attacks on the contralateral side of EC/IC bypass, and 5 re-attacks took place in the posterior circulation. The symptoms of re-attack ware: 3 cases of TIA (vertigo, nausea), and 4 cases of stroke. The times of re-attacks were: immediately following surgery, 1 case; within 2 weeks following surgery, 1 case; 6 months or more following surgery, 5 cases. Fifteen out of 43 cases had 16 steno-occlusive lesions other than the operative side on preoperative angiography. Six of the 7 re-attack cases had steno-occlusive lesions on the re-attack sides. Positron emission tomography (PET) was performed on 18 cases before and after STA-MCA anastomosis. Five of these cases had re-attacks; 2 were in the form of misery perfusion on the contralateral side prior to surgery, and the re-attacks following surgery occurred on the same side. Another 2 cases who had cerebellar ischemias after postoperative PET study showed increasing of OEF on the cerebellar hemisphere postoperatively compared with the preoperative PET study.
In conclusion, bypass surgery is effective in preventing recurrence of ischemic symptoms on the operated side. But in cases with steno-occlusive lesions on the non-operated side, a follow-up study such as cerebral hemodynamics and metabolism is necessary for predicting the occurrence of the ischemic attack of that area following surgery.

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The clinical features of common carotid artery occlusion and principles of its adequate treatment were assessed by analyzing the disease in 7 cases who underwent reconstructive surgery between 1980 and 1985. The occlusions were unilateral in 4 cases and bilateral in 3 cases, and the causes were arteriosclerosis in 2 cases, arteritis in 1 case and aortitis syndrome in 4 cases. The modes of onset were TIA-RIND in 4 cases and minor stroke in 3 cases. Concerning the hemodynamics, the patency of the internal carotid artery via collateral circulation was observed in 8 blood vessels out of a total of 10 occluded blood vessels, and the external carotid artery was patent in 2 cases in whom occlusion extended to the internal carotid artery. The cases of aortitis syndrome were complicated by multiple large vessel occlusions. Operations were performed according to the hemodynamics. These were 9 grafts (8 vein grafts and 1 artificial blood vessel) and 2 transpositions: subclavian-internal carotid artery bypass in 1 case, subclavian-external carotid artery bypass plus STA-MCA bypass in 2 cases, subclavian-common carotid artery bypass in 2 cases and bilateral aortaecommon carotid artery bypass in 1 case.
Patency of the bypass was obtained in all the cases. A reoperation was required in 1 case as stenosis of the vein graft occurred in 1.7 years. The therapeutic results were 'good recovery'in 4 cases and 'moderately disabled'in 3 cases, and the symptoms resulting in'moderately disabled'were caused by neurological deficits that existed preoperatively. Improvements were attained of the symptoms due to low perfusions such as amaurosis fugax and orthostatic dizziness. Selection of the operative mode for common carotid artery occlusion should be made according to the hemodynamics by collateral circulation and occlusive lesion complicated, and operative indications were found as subclavian-common carotid artery bypass in the cases of patent common carotid artery, subclavian-internal carotid artery bypass in the cases of patent internal carotid artery and subclavian-external carotid artery bypass plus STA-MCA bypass in the case of patent external carotid artery. Multiple graftings should be made by exposing the aortic arch in aortitis syndrome associated with multiple large blood vessel occlusion.

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後大脳動脈末梢部,,とりわけ,P3,portion,以降の動脈瘤はまれで,,動脈瘤全体の0.3%を占めるにすぎない.,手術方法は動脈瘤の部位や大きさによって異なるが,,大別すると,pterional, subtemporal, temporooccipitalおよび occipitalapproach などが報告されている. 最近経験した後大脳動脈末梢部動脈瘤の急性期手術例を報告し,手術アプローチおよび合併する脳室内出血について若干の文献的考察を行った. 症例は突然の頭痛,嘔吐および意識障害で発症した62歳の女性で, CTでシルヴィウス溝や脳底槽のクモ膜下出血の所見のほかに, 左側脳室後角近傍の脳実質内出血に連続し脳室内出血が描出された. 脳血管撮影では左後大脳動脈末梢の parieto-occipitalartery から外上方に突出する, 最大径8mmの嚢状動脈瘤が造影された. 手術は腹臥位で脳室ドレナージ後に左後頭開頭を行った. 後頭極をテントより圧排・挙上して四丘体槽に到達し, 最初に後大脳動脈近位部を確保して脳内血腫を除去したのち, 後大脳動脈を順行性に辿って動脈瘤を確認してクリップした. この occipital supratentorial approach はP3以降の後大脳動脈末梢部動脈瘤に対して十分な視野が得られ有用であった.

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The major cause of complications of intracranial aneurysm surgery can be attributed to difficulties in visualizing the perforators originating from the contralateral side of aneurysm and/or parent arteries. To facilitate microsurgical treatment of intracranial aneurysm the authors applied an optic fiber scope with 45° or 90° angled fiber tip. This method was applied in three patients and demonstrated applicability for visualizing the contralateral perforators.

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