Arteriovenous malformations (AVMs) in the basal ganglia region have been a problem in neurosurgical practice. Because of their location, hemorrhage from deep-seated AVMs may result in severe neurological deficits and mortality. But the surgical management of deep-seated or large AVMs has been complicated and is fraught with considerable risk. We report a successfully excised case of AVM in the medial temporal lobe~basal ganglia.
A 24-year-old man was admitted to our clinic complaining of severe headache and left upper quadrant anopsia after a third subarachnoid hemorrhage. Their plain CT scan on admission demonstrated diffuse subarachnoid hemorrhage, right infratemporal hematoma and clots in the right lateral ventricle. Cerebral angiograms showed an arteriovenous malformation (AVM) in the right medial temporal lobe~basal ganglia. The feeding arteries were the anterior temporal polar artery and the lenticulostriate arteries. The draining vein was the basal vein of Rosenthal. This AVM was classified Grade IV according to Spetzler and Martin's classification systems. 123 I-IMP SPECT demonstrated a low perfusion area in the whole right hemisphere. Enhanced CT scan showed a frontoparietal enhanced lesion within the low perfusion area. From these findings it was assumed that the risk of normal perfusion pressure breakthrough syndrome was very high. Because of these pathophysiological conditions, we decided to do a multi-staged operation.
First operation: Via a pterional transsylvian approach, the feeding arteries were dissected. The anterior temporal polar artery and two main lenticulostriate arteries were clipped. At this point the local cortical blood flow at the precentral gyrus was markedly elevated from 32ml to 74ml/100g/min. 0.3ml of ethyl-cyanoacrylate was injected into the nidus from the distal end of the anterior temporal polar artery.
Second operation: Two weeks after the first operation, microsurgical total excision was performed. First the hematoma cavity was approached through a cortical incision at the insula. The nidus was relatively well demarcated from the cavity and gliotic plane of the temporal lobe and basal ganglia. The AVM was totally removed without temporary occlusion of the anterior choroidal artery nor the many perforating arteries.
After total exision of the AVM, left hemiparesis developed but later recovered to an almost normal level.
In conclusion, the staged approach to deep-seated or large AVM's is proposed as a method to render totally excisable, AVM's that were previously considered inoperable. We show the feasibility of satisfactory microsurgical treatment of these lesions based on a knowledge of microanatomical studies and pathophysiology of AVMs.

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Dural arteriovenous malformations (AVM's) in the anterior fossa are not as rare as heretofore reported.
The authors experienced four cases of dural AVM in the anterior fossa over a period of 10 years: 3 of 4 patients had frontal intracerebral and/or subarachnoid hemorrhagic and one of them developed hemorrhagic attacks twice in a month. The other suffered from headache and chemosis without hemorrhage.
Angiographically, the AVM's were all fed by the anterior ethmoidal artery, either unilaterally or bilaterally; the external carotid system also sent the feeders. The draining veins were all pial with vascular sacs and finally reached the dural venous sinuses through ascending superficial and/or deep venous channels. One had an unruptured aneurysm at the origin of the ophthalmic artery.
All the AVM's were excised with microsurgery. The nidus was located in the dura or between the dura and bone. In one case, ethyl-cyanoacrylate was intraoperatively injected into the nidus from which uncontrollable bleeding developed, and the procedure is quite useful as operative adjuvant. All the patients have returned to their jobs.
Review of the pertinent literature reveals the following clinical characteristics:
1) AVM's are not so very rare,
2) 82% of the cases are male,
3) 89% of the cases have intracranial hemorrhages, a great majority of which are intracerebral and/or subarachnoid,
4) all are fed by the anterior ethmoidal arteries, with 46% incidence of contralateral feeding vessels,
5) the draining venous system includes the pial pathway in 100% of the cases, with association of vascular sacs (96%), which could be attributed to the source of hemorrhage, and
6) excision is the choice of treatment and operative results are good.

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The case histories of two patients with dural arteriovenous malformation (AVM) in the posterior fossa who were treated by transcatheter embolization with Ivalon followed by sinus isolation are reported in this paper.
Case 1: A 44-year-old male was admitted to our hospital complaining of visual disturbance. Neurological examination showed bilateral choked disc, bilateral visual field narrowing, left abducens palsy and right cerebellar signs. Marked elevation in cerebrospinal fluid pressure (500mmHg) was noted when lumber puncture was performed. The selective 6-vessel study revealed a dural AVM in the region of the straight sinus through the bilateral transverse sinuses, which was supplied by many dural and tentorial branches of the external carotid and the internal carotid and vertebral arteries. First, all main feeders from the bilateral external carotid arteries were embolized with Ivalon particles. After embolization was performed again on the recanalized arteries, isolation of the occipital, straight and bilateral transverse sinuses was done with minimum bleeding. Transient visual loss occurred just after the operation, but signs and symptoms based on increase intracranial pressure gradually disappeared.
Case 2: A 48-year-old male was admitted to our hospital because of pulsatory tinnitus and visual disturbance. He had a bilateral choked disc. The 6-vessel study revealed a dural AVM in the region of the left transverse through sigmoid sinus fed mainly by dural and tentorial branches of the left external and internal carotid arteries. Cerebellar cortical branches from the left superior cerebellar and anterior inferior cerebellar arteries also fed the dural AVM. After the first transcatheter embolization with Ivalon particles was performed, pulmonary embolism was unfortunately encountered in this patient, who was treated with heparin and urokinase. After the second embolization of the recanalized feeders, isolation of the straight, left transeverse, left sigmoid, left superior petrosal and occipital sinuses was done. As acute cerebellar swelling occurred during the operative procedure, uncapping of the left cerebellum was done. His visual disturbance disappeared gradually.
Although complete occlusion of the dural AVM was not achieved, transcatheter embolization followed by sinus isolation was effective in the treatment of neurological signs based on increased intracranial hypertension. However, several side effects including acute visual loss (Case 1), pulmonaly embolism and brain swelling (Case 2) were encountered in these cases. Further experience is needed to clarify the effectiveness of this procedure for dural AVM's in the posterior fossa.

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We reported the successful total removal of dural arteriovenous malformations of the posterior fossa and studied the hemodynamic change before and after the operation in three cases. Cerebral angiography showed the early opacification of the transverse sinus, retrograde filling of the cortical vein, and the occlusion of the transverse sinus in the venous phase. Preoperative dynamic computed tomography scan revealed the prolongation of the cerebral circulation time in both hemispheres, which suggested venous congestion. Postoperative dynamic computed tomography scan demonstrated improvement of the cerebral hemodynamics despite total resection of the transverse and sigmoid sinuses. These findings suggest that, when angiography shows either retrograde venous filling or sinus occlusion, total removal can be done safely. Intraoperative serial angiography was also useful in the total removal of the dural arteriovenous malformation.

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Balloon catheter technique is presently being utilized in various intravascular procedures and transluminal angioplasty, but what morphological changes in intracranial vessels take place after balloon inflation and dilatation are still unknown. This study reports on morphological changes in normal canine basilar arteries after transluminal angioplasty (TA) with 1.5 atmospheres of inflation pressure and 30% dilatation.
Histological changes one hour after TA consisted of denudation of endothelial cells, deposition of fibrin, which covered the denuded endothelium, stretching and focal dehiscence of internal elastic lamina, and altered myocytes in the media. These morphological changes were more prominent when the balloon was inflated longer. Seven days after TA, however, the endothelium had been almost completely regenerated, while slight chronic changes still remained in the internal elastic lamina and media. Angiographic and morphometric analysis did not disclose any significant differences.
This report proposes that under some conditions intraarterial inflation and dilatation of the intracranial arteries causes reversible changes, which are mainly noted in endothelium. In addition, a new in vivo experimental model which might be used for physiological or pathophysiological investigations of intracranial arteries is introduced.

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Ten cases of EC-IC bypass with interposed saphenous vein graft were reported. In five cases of prophylactic anastomosis for giant aneurysm, the outcome was good with the exception of one patient with a giant basillar top aneurysm in which ligation of the basilar artery with common carotid to posterior cerebral artery anastomosis was performed. On the other hand, the outcome of five patients with ischemic cerebrovascular disease were mostly poor due to hemorrhagic infarction or general complications. In the follow-up study, recurrent stroke was observed in one patient in where the recipient artery was too small to obtain enough bypass flow. Graft patency was confirmed in all cases after the operation, and was also confirmed in all 6 case at follow-up.
EC-IC bypass with interposed saphenous vein graft seems to be a proper procedure for prophylactic anastomosis which requires high blood flow. It should be pointed out, however, that high flow bypass for a brain with ischemic damage might cause hemorrhagic infarction. Therefore, care should be taken in the selection of candidates for venous bypass graft. Finally, these results suggest that both the size of graft and recipient artery are the key factors to modulate graft flow, therefore, the selection of recipient artery is also an important consideration in this operation.

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This report deales with a case of ultra early embolectomy for an ICA occlusion. A 44-year-old female who suffured sick sinus syndrome had a sudden onset of left hemiparesis. On admission she was drowsy and left hemiparesis was present. An angiogram demonstrated embolic occlusion of the right ICA at the C₁-C₂ portion.
At operation the right MCA was exposed. The embolus appeared to be lodged at the M₁M₂ bifurcation and also extended into the two main branches. The arteriotomy was made at this bifurcation and the embolus was removed. Four and a half hours after onset, blood flow of the MCA was fully restored. After operation, high-dose barbiturate therapy was administered for four days. A final CT scan showed a low density area in the right M₁ perforators' territory, but the patient was discharged with no neurological deficits.
Angiographically, the proximal end of the embolus is seen as a deficit of the dye, but the distal end of the embolus is not revealed, while arteriotomy for embolectomy is a suitable procedure for the distal end of the embolus. However, in most ICA occlusion cases, it is suspected that the distal end of the embolus is lodged at the top of the ICA or at the bifurcation of the MCA territory. Therefore, embolectomy would be accomplished by a transsylvian approach if any ICA occlusion exists.

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In order to check the effect of an EC-IC bypass in patients with ischemic cerebral lesions, we measured the change in regional cerebral blood flow (% r CBF) in 15 patients who under-went EC-IC bypass surgery based on the criteria of the International Cooperative Study. Using N-isoprophyl-p-[¹²³I] iodoamphetamine (¹²³I-IMP) SPECT, the percent of r CBF was calculated as the ratio of ROI A to ROI B on early images of the rest state and STA-compressed state, postoperative-ly. ROI A was positioned in the low perfusion area (anastomosed site) on SPECT and ROI B was in the opposite side (normal cortex).
The following results were obtained: 1) Eleven of the 19 patients (58%) showed a significant in-crease of r CBF. 2) These eleven patients had an EC-IC bypass about 40 days after the ischemic attack. 3) The bypass was more effective on patients with RIND than those with TIA or minor stroke. 4) The operation on patients with watershed infarction was more effective than those with other types of infarction. 5) Bypass operation on patients who did not show a redistribution phenomenon in the low perfusion area on delayed images was not effective.
Based upon these results, we consider that the decision to undertake EC-IC bypass surgery in cases of ischemic cerebral lesions should be based at least on measurement of CBF by SPECT.

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Though vascular dementia was, until recently, understood to be a synonym for multiple infarct demntia, we have found a considerable number of cases of apparent“vascular dementia”caused by a stenotic lesion of the cerebral main trunk and have reported the efficacy of revascularization for those cases. In the past five years we have operated on more than 60 patients with vascular dementia with stenotic cerebrovascular disease. We analysed these cases with a neuropsy chological function test and cerebral blood flow, and reviewed the corelation between the interval from the onset to operation and the effectiveness of operation. Those cases were divided into three sub-groups according to the signs and symptoms at onset: 1) pure dementia; 2) dementia associated with transient ischemic attack (TIA); 3) dementia associated with minor stroke. All cases proved to have obstructive disease in the cerebral main arteries, such as the internal carotid artery or the middle cerebral artery, and some areas of low perfusion were revealed on CBF study. As a neuropsychological test we used a simplified frontal lobe function test (Hamamatsu method), Mini-mental scale (MMS), and Wechsler Adult Intellegence Scale (WAIS). In the pure dementia group, four out of seven patients (57%) improved markedly after operation. The effect was more marked if the operation occurred within 6 months after onset. But CBF did not necessarily increase along with the functional improvement. All 8 cases of the demential plus TIA group were operated on within 6 months after onset and improved markedly. In the dementia plus minor stroke group, cerebrovascular reconstruction was effective in 14 out of 17 cases (82%). In conclusion, we recommend early cerebro-vascular reconstruction within 6 months after onset for the above-mentioned type of vascular dementia.

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In surgery of carotid aneurysms below the bifurcation of the posterior communicating artery (C₂-C₃), dissecting the proximal internal carotid artery and the neck of the aneurysms is difficult. Unroofing of the optic canal and anterior clinoidectomy are well known methods of exposing the proximal side. In this paper, each method is discussed on the basis of our experience. Unroofing is an easy method of gaining a view of the medial aspect of the internal carotid artery (C₂) and is suited for small aneurysms projecting medially; the so called suboptic type. However, this method is insufficient for large and proximal aneurysms where it is neccessary to get a more proximal view and to gain a wider space for applying variable clips. On the other hand, total removal of the anterior clinoid preocess permits visualization of more of the proximal internal carotid artery (C₃ siphon) without entering the cavernous sinus. Furthermore, this technique makes a wide space around the proximal internal carotid artery by detaching a ring of dura. It is a promising technique for various types and sizes of proximal internal carotid artery aneurysms.

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A cerebral Ca²⁺overload blocker-flunarizine hydrochloride-was used with excellent results for prophylaxis of delayed ischemic neurologic deficits (DIND) in severe subarachnoid hemorrhage.
Of 72 patients treated with oral flunarizine, only one developed permanent DIND. A consecutive 37 of these patients, who were in Fisher's group III and were treated with flunarizine from immediately after early surgery, were compared retrospectively with the consecutive 37 Control Group patients-who belong to Fisher's group III and had been treated at our department up to the initiation of the present study. Among the Control Group patients, eight died from DIND and ten developed infarction from DIND, while flunarizine strongly prevented (p<0.001) DIND.
It might be considered that association of severe vasospasm in angiogram was less frequent (18% vs 57%) in the Flunarizine Group (p<0.02).
Serum concentration of flunarizine was considerably lower in the unconscious patients. The reasons for this and the way of improvement are discussed.
There were no side-effects from flunarizine.
From this evidence, the authers concluded that flunarizine significantly inhibits the occurrence of severe neurological deficits due to delayed vasospasm. These highly benefical effects on severe vaso-spasm might be attributable to flunarizine's intense inhibitory action on intracelluar Ca²⁺ overload especially in severe pathological situations.

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The clinical, operative and pathological characteristics of intracranial dissecting aneurysms are presented. A review of the literature suggests that these types of intracranial aneurysms are being recognized with increasing frequency and can be characterized by its symp-tomatology and radiological patterns. For this five years, 31 cases with intracranial dissecting aneurysm were treated in our institute. The mean age and the site of aneurysm are assumed almost the same as that of previous reports, but the incidence of extravascular bleeding is 58% in our series, which may be higher than that of previous reports. Although the cause or mechanism of intracranial dissecting aneurysm has yet to be sufficient clarified and it largely depends upon future multilateral studies, but we would like to emphasize that the diagnosis is most important in this disease. It has been considered that“double lumen”on angiogram is a true diagnostic sign of dissecting aneurysm. Only four cases of 31 showed“double lumen”, but no one showed it in acute stage. 17 cases (55%) showed“string and pearl”sign and 72% of the cases with ruptured dissecting aneurysm revealed it in acute stage. From these results, it seems to be quite all right to consider that“string and pearl”sign should be the true diagnostic sign in acute stage like as“double lumen”in chronic stage. We have obtained some interesting information through detailed examinations about surgical treatment of intracranial dissecting aneurysms. But we will mention it in detail on another occasion. Finally, we will conclude by listing the above-mentioned important points of the investigation about the di-agonosis of intracranial dissecting aneurysms.

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We have given up aggresive treatment of intraventricular casting hematoma with midbrain or brain stem symptoms because of poor result of such treatment. When the cause of the moribund state is mainly the compression of the brain stem by casting hematoma rather than brain stem damage, removal of all casting hematoma should be performed in acute stage, as far as possible. Seven moribund patients with coma, decerebrating posture, negative pupil reflex and central respiratory disturbance (CNH) were operated on to remove these casting hematoma, using a supratentorial and subtetorial approach. The primary focus of bleeding was the thalamus in four patients and the cerebellum in three. Supratentorial removal was by frontal transcortical or transcallosal approach. A two stage operation was performed in two cases and a one stage operation in five. The time from onset to operation was 2~12 hours (1~4 hours after midbrain symptom). The outcome was good in five cases but two patients suffered brain stem death. ABR monitoring was performed in three cases: one pre-post follow-up and two post-operative monitoring. ABR will be valuable in the near future.
The indications for operation are 1). Miner brain damage and massive ventricular hematoma, 2). possibility of decompression within eight hours. 3). the symptom will be better than the level of lower brain stem symptom. 4). no midbrain or brain stem damage on CT.

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Nine cases of surgically treated brain stem cavernous angiomas are reported in this paper, and their clinical and radiological features are reviewed. There were 8 males and 1 female with ages ranging from 9 to 69 years (average 34 years). Four of the cavernous angiomas were located in the dorsal pons, two in the middle cerebellar peduncle, and 1 each in the cerebral peduncle, the hypothalamus and the superior colliculus. All 9 patients came to medial attention because of the sudden onset of neurological abnormalities following brain stem hemorrhage. Six of the 9 patients showed neurological deterioration due to rebleeding at various intervals ranging from 10 days to 2 years. The CT scan disclosed a nonspecific hematoma in the brain stem in all cases. After intravenous injection of iodinated contrast material, negative contrast enhancement was commonly seen. In a few cases, there was faint contrast enhancement of the nodule at the Periphery of the hematoma. Serial CT scans over a protracted period revealed an unchanged hyperdense mass lesion, which was thought to be a most characteristic, and indicative CT feature of the cavernous angioma. On MRI, the combination of a reticulated core of mixed signal intensity with a surrounding rim of decreased signal intensity (hemosiderin rim) suggested the presence of a cavernous angioma. Enhanced MRI, using gadopentate dimeglumine, was thought to be more sensitive than contrast enhanced CT in detecting cavernous angiomas.
All these patients underwent surgery, with good results. Abnormal vascular tissue in the wall of the hematoma cavity was recognized at operation and pathological confirmation was obtained in all cases. These data indicate that brain stem cavernous angiomas can be surgically removed with acceptable morbidity.

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The case histories of five patients with cavernous angiomas are presented in this paper. Two of the lesions were located in the brain stem and three in the spinal cord. Three men and two women experienced episodic brain stem or spinal cord dysfunction, ranging in duration from one month to 17 years. Total removal was performed in four patients and biopsy and evacuation of the hematoma were performed in one. Neurological function improved in two patients, was unchanged in two and worsened in one.
Magnetic resonance imaging (MRI) is invaluable in the diagnosis of cavernous angiomas, particularly in the brain stem and spinal cord. The combination of a reticulated core of mixed signal intensity with a surrounding rim of decreased intensity strongly suggests the diagnosis of a cavernous angioma.
The management of cavernous angiomas in the brain stem and spinal cord is controversial. In recent years an increasing number of successful removals of these lesions has been reported. Surgical treatment is indicated in patients with progressive or episodic neurological dysfunction due to recurrent hemorrhages. In such cases complete removal of the lesion is feasible because a gliotic margin provides an adequate cleavage plane.

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Intracerebral cavernous hemangiomas are relatively easy to remove surgically, but extracerebral cavernous hemangiomas attached to the cavernous sinus are extremely difficult to treat. In this paper, the authors report four cases of extracerebral cavernous hemangioma in the middle fossa that were treated with radiotherapy. The follow-up studies with serial computerized tomography (CT) scans during and after irradiation are described.
In Case 1, radiotherapy after partial removal of the tumor decreased the tumor size on contrast-enhance CT scan, reduced its Hounsfield units on the nonenhanced CT scans, and facilitated later total tumor removal. In Case 2, the tumor responded to irradiation of approximately 30 Gy, showing significant reduction in size and Hounsfield units of the tumor. Subtotal removal was then possible. In Case 3 and Case 4, the tumor responded to irradiation, the patient's symptom improved after delivery of approximately 50 and 40 Gy respectively. The CT scan showed progressive reduction in the size and Hounsfield units of the tumor until the first year after irradiation. No surgical intervention was deemed necessary.
It is concluded that, in case of extracerebral cavernous angioma with massive hemorrhage, radiation of up to 30-50 Gy was a method of choice. Radiation therapy offers an increased probability of total removal of the tumor and the possibility of eliminating surgery.

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In this paper, the authors reported four cases of choroid plexus angioma which were detected by computerized tomography and were excised surgically. These four cases had the following characteristic CT findings. The initial CT scan showed intraventricular hemorrhage with or without intracerebral hematoma in each case. More than two weeks later, when the intraventricular hemorrhage had disappeared completely on the plain CT scan, a small high density area corresponding to the site of the angioma was demonstrated on the contrast enhancement CT scan. An angiomatous stain was also visualized on the angiogram in two of the four cases. In one case, vertebral angiography showed an arteriovenous malformation in the fourth ventricle supplied by the bilateral posterior inferior cerebellar artery, and in the other, right carotid angiography revealed a faint angiomatous stain in the plexal segment of the anterior choroidal artery. Each patient underwent a successful operation on the angioma located in the fourth ventricle, the left trigone, the right trigone and the right trigone of the lateral venticle respectively. The histological diagnosis of the excised specimens was arteriovenous malformation in all four cases.
Twelve reported cases with CT findings of choroid plexus angioma were reviewed, which were verified histologically. Among 16 cases including the four present ones, contrast enhancement CT (CE CT) scan was performed in 11 cases. In eight of the 11 cases (73%), a small highly density area corresponding to the site of the angioma was demonstrated on CE CT scan, while angiography revealed an angiomatous stain in only six of 14 cases (43%).
Our conclusion is as follows. In cases of intraventricular hemorrhage with or without intracerebral hematoma, choroid plexus angioma should be considered as one of the causes of bleeding, even though it is supposed to be uncommon. In such cases, CE CT scan should be performed to detect the lesion of the angioma, especially in the late stage, when the hemorrhage have disappeared completely on a plain CT scan. Surgical removal of the angioma is recommended because of the high incidence of recurrent and fatal hemorrhage.

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Cerebral revascularization using an artificial blood vessel has not been so common. This is due to the fact that conventional artificial blood vessels have been too firm. The purpose of this study is to develop a soft artificial blood vessel suitable for cerebrovascular reconstructive surgery.
This new artificial blood vessel is made of polyurethane and is designed to be porous (porous polyurethane). Thus, multiple small-sized pores exist both in the inner or outer surfaces and in the wall of the porous polyurethane graft.
To test the mechanical properties of this artificial blood vessel, we evaluated stress-strain curves and compliance. In comparison to an expanded polytetrafluoroethylene graft (Goretex^®), which has been one of the most commonly used artificial blood vessels in cardiovascular surgery, the mechanical properties of the porous polyurethane graft more closely resembled those of the common carotid artery in dogs. Thus, this porous polyurethane graft proved to be a compliant new artificial blood vessel.
In the in vivo animal experiments, the porous polyurethane graft (2.3~3.2mm in diameter, 40 50mm in length was transplanted into the common carotid artery of dogs. For the patency of the grafts, the mean size of the pores had to be larger than 5.5μm.
Histological examination, done two months after the transplantation, demonstrated that a monolayer of endothelium-like cells lined the luminal surface of the graft. Neoadventitia made of collagen developed around the external surface of the graft. Foreign body reactions were minimal.
In conclusion, the porous polyurethane graft has improved mechanical properties suitable for reconstructive surgery of the extracranial cerebral arteries. Histological evaluation showed that the graft adapts well to recipient arteries.

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Over the past 9 years, we have experienced 8 cases of intracerebral venous angiomas, which were identified angiographically or histologically. We analyzed their clinical symptoms, neuroradiological findings, clinical courses, and outcomes.
There were 4 males and 4 females whose ages ranged from 19 to 79 years (mean: 49.4 years). Initial clinical symptoms were epilepsy (3 cases), hemiparesis due to intracerebral hemorrhage (1 case), and headache (1 case). Three cases were incidentally found. The angiomas were located in the frontal lobe in 5 cases, in the cerebellum in 2 cases, and in the parietal lobe in 1 case. CT scans without contrast enhancement revealed the sites of venous angiomas as high density areas (nodules) in 6 cases out of 7 examinations. Contrast-enhanced CT scans in 8 cases demonstrated highly enhanced angioma sites 7 cases. Angiography demonstrated typical (characteristic) caput medusae in 7 out of 8 cases. No angioma was angiographically found in one patient who presented intracerebral hemorrhage. MRI scan was done in one case. In T₁WI, the drainer showed a low intensity, and in T₂WI, the nidus was seen as a high intensity area and the drainer showed a low intensity. During this observation period between 4 months and 6 years, one patient out of the 8 died due to senility but the remaining seven were without further epilepsy and stroke attacks. Therefore, the clinical course of intracerebral venous angioma is considered to be benign. Surgical treatment should be considered in patients who present intracerebral hematoma and have typical venous angioma seen with CT and angiography. Otherwise, conservative therapy is the treatment of choice.

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In the classification of cerebral vascular malformations, a mixed or transitional type of malformation has come to be recognized as distinct from the classical assortment, that is, AVM, capillary telangiectasia, cavernous angioma and venous angioma. We recently experienced two cases in which findings of cerebral angiography indicated arteriovenous malformation; however, histological examination of the lesion showed a typical venous angioma. We could not find a report of a similar case in the literature. We consider that these two cases belong to a transitional or mixed type of cerebral vascular malformation composed of arteriovenous malformation and venous angioma.

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The prognosis for patients with dural arteriovenous malformation (DAVM) is thought to be good. However, the prognosis for some patients with venous abnormalities is not so good. Of 25 DAVM patients, in our study 12 (48%) had some venous abnormalities. Based on angiography, they were classified as follows: (1) Obstruction, stenosis or partial deficit of dural sinuses near DAVM. (2) Venous reflux into dural sinuses. (3) Venous reflux into cortical veins. (4) Obstructions of sinuses far from DAVM. The authors devided the DAVMs with venous abnormalities into three groups according to the type of venous abnormality. Group (1): Cases with obstruction or stenosis of dural sinuses near the DAVM and with venous reflux into cortical veins. Group (2): Cases with obstruction or stenosis of dural sinuses but without venous reflux into cortical veins. Group (3): Cases with sinus obstruction far from DAVM. The outcome for patients in group (1) was not good, because of intracerebral bleeding or increase of intracranial pressure. The mechanism of venous abnormalities was not clear. There were no cases of DAVM following dural sinus thrombosis.

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Three cases of multiple dural arteriovenous malformations (dAVM's) were reported in connection with occlusive dural sinus lesions. The first case was diagnosed as dAVM of the right cavernous sinus and it disappeared spontaneously 4 months from the onset of symptoms. After an interval of 4 months, another dAVM newly appeared in the right lateral sinus (transverse and sigmoid sinus) with occlusion of the right sigmoid sinus. With the second patient, multiple dAVM's were demonstrated on angiogram, one in the cavernous sinus and the other in the left lateral sinus. The last case had a dAVM in the posterior fossa. The transverse sinus was occluded several weeks after surgical intervention. The frequency of multi-occurrence and possible mechanisms of sinus occlusion are reviewed and discussed in this paper.

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