In this paper, the case of a large-high flow cerebellar AVM, which was totally removed in a two-stage operation, is reported. The patient, a thirteen-year-old girl complaining of headache, vomiting and unconsciousness, was admitted to our hospital in a coma and suffering from decerebrate rigidity.
Computerized tomography (CT) scans demonstrated a massive hematoma in the vermis and the forth ventricle. Posterior fossa craniectomy and removal of the hematoma were performed immediately. Then a V-P shunt was performed for hydrocephalus. The patient gradually improved. Cerebral angiography showed a large high-flow AVM occupying the whole left cerebellar hemisphere, which was fed by Lt AICA and Lt SCA. Bilat PCA and Rt SCA could not be found. The two-stage operation was designed to protect against normal perfusion pressure breakthrough. Total removal of the AVM was decided on. At first artifical embolization was undertaken, until normal circulation was seen. Then by reopening the previous suboccipital craniectomy the AVM was totally removed. Thus the left cerebellar hemisphere, including the deep cerebellar nuclei, was lost. Postoperative neurological positive findings were slightly Lt limb ataxia and trunchal ataxia, but she can walk alone and now is going to school again.
The surgical indication and operative technique for posterior fossa AVMs are discussed, and the literature on these subjects is reviewed in this paper

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The natural history of intracranial arteriovenous malformations (AVMs) was studied in 143 patients. The main emphasis of the study was hemorrhages. One hundred four of the patients were treated surgically, and 39 were managed nonsurgically. The initial symptom in 68.5% of all patients was hemorrhage. In particular, small and medium-sized AVMs located in the posterior fossa and deep-seated AVMs had a higher risk of hemorrhage.
Follow-up information was obtained from 65 patients, excluding those who underwent acute surgery and died of initial bleeding. The mean follow-up time was 5.6 years. Rebleeding occurred in 60% of 20 patients for whom this was their first hemorrhage, and those cases were followed for an average of 5.3 years.
The rate of rebleeding was 20 a year initially, 3.5 a year after 5 years, and then 1 a year after 10 years. The small-sized AVMs had a higher risk of rebleeding.
On the other hand, patients presenting the symptom of seizure were followed for an average of 5.9 years, and 4 of those patients had a hemorrhage event. Their prognosis was more favorable than patients with only hemorrhage.

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The natural history and operative results of 85 cases of intracranial arteriovenous malformations (AVMs) were studied. Seventeen AVM patients had died due to initial bleeding, but are not included in this study. Of the 85 cases, 62 received surgical care, and 23 were treated conservatively. Of the patients treated surgically, total removal of AVMs was performed on 55 patients, subtotal removal was performed on 3, and proximal ligation was performed on 4. The mean period of follow-up was 6.5 years. The treatment results of the surgical and conservative groups were compared. The possible influence of age, the location and size of the AVM, and the type of onset were analyzed; but these factors were particularly studied in the conservative group to determine the bleeding characteristics of AVMs.
Of the 55 patients where a total resection of AVMs was performed, 2 died due to operative complications-a mortality rate 3.6%; 4 were dependent, and 46 were independent. In none of these 55 patients did the hemorrhage of AVMs occur during the follow-up period. On the other hand, of 23 patients that received conservative treatment, 6 died-a mortality rate of 26%; 3 were dependent, and 14 were independent. In the 7 cases (30.4%) where hemorrhage occurred during the follow-up period, 4 died due to fatal intracerebral hematoma. Where the age of the patients was young, bleeding of the AVMs from the onset, and where there were deep seated AVMs, there tended to be a higher risk of hemorrhage during the follow-up period. The size of the AVM was not significantly related to the risk of hemorrhage, however.
We conclude that the cases mentioned above (having a younger age, and/or with ruptured and deep seated AVMs) should be treated surgically if possible. Even in patients with unruptured AVMs, surgical treatment should be used if the lesions can be resected without causing additional neurological deficits.

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Twenty-nine arteriovenous malformations (AVM) in the motor-sensory and speech regions were followed up from 3 to 20 years. Of these, 17 received surgical care and 12 were treated conservatively.
The long-term follow-up results showed a mortality rate of 17% in the group of patients receiving conservative treatment; the post operative mortality was 6%.
None of the patients operated on had recurrence of bleeding, Whereas 6 of 12 patients treated conservatively had 1~3 bleeding occurrences. The rebleeding rate was more frequent in patients with small AVMs than in those with large AVMs.
Definite improvement in the preoperative neurological defect was observed in 53%(9/17) of operative cases. Eleven patients (65%) returned to normal. Neurological defects improved in only 17%(2/12) of the conservatively treated patients. The neurological defects, of 50%of these patients either deteriorated or remained unchanged. Forty-one percent of the conservatively treated patients returned to normal work.
The operative treatment had no benefit for patients with epilepsy; and there also had been no difference in long-term outcome between conservatively and surgically treated patients with large AVMs.
We have come to the conclusion that surgical treatment is the method of choice in small and medium size AVMs in the speech and motor-sensory regions, especially when they bled. Large AVMs are also operable, but they must be well demarcated.

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The purpose of the present study was two-fold.
The first was to determine the clinical factors having a strong bearing upon the bleeding property of cerebral arteriovenous malformations (AVMs). The case records of 160 AVM patients were reviewed as related to sex, the age at onset, initial symptoms, the location of the AVMs, and the size of the AVMs. A proportional hazard model was employed for statistical analysis. Among these five clinical variables, initial symptoms and the location; i. e. deep-seated or not, were revealed to be statistically significant factors. This study showed that the cumulative risk of later hemorrhage was a critical problem in patients with deep-seated AVMs who had experienced bleeding as an initial episode.
The other aim of the study was to detect, from an analysis of the postoperative course, the indication for surgical treatment in patients with deep-seated AVMs. Follow-up study was carried out in ten cases of surgery for deep-seated AVMs in the past several years. In each case, the AVM was small (less than 2cm) and the intraparenchymal hematoma was present close to the AVM. There was no mortality among these ten cases. As to working capability, nine out of the ten cases could finally return to normal social life. However immediate worsening of neurological symptoms was observed following surgery in eight out of the ten cases. Approximately six months were necessary for them to overcome such deficits.
The present results indicate that there are strong indications for surgery in deep-seated AVMs, if the lesion is small and hematoma is present. The period necessary for recovery from postoperative worsening is generally about six months

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We reported 17 cases of AVMs in the basal ganglia and the thalamus. The results of 8 cases of direct surgery are compared with those of 9 non-surgically treated patients in this report. Five of the non-surgically treated patients are doing well and are free from neurological sequele. Only one patient died of rebleeding. In surgically treated patients, six AVMs were totally removed and two were subtotally removed. In all cases of surgical treatment, initial symptoms were caused by hemorrhage. Aphasia and motor weakness caused by hemorrhage improved gradually. In five of six cases where the AVM was totally removed, postoperative neurological deficits temporary worsened, but improved later. All of these patients were able to take care of themselves. Operative indication for AVMs in the basal ganglia and the thalamus is considered to be limited to the patients who had experienced a bleeding episode. In our series, the patients with small AVMs were more likely to have a large hematoma. On the other hand, patients with large AVMs were less likely to have a large hematoma. The surgical indication for ruptured medium sized AVMs should be based on the prospective of the neurological deficits after surgery but on the social state of each patient.

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Arteriovenous malformations (AVMs) of the basal ganglia represent a special group of malformations because of the difficulties of their resection. For better understanding the surgical indication, the outcome of 28 cases of basal ganglia AVMs were retrospectively analyzed. Out of the 28 cases, 13 patients had their AVMs surgically removed. The other 15 cases were conservatively treated because of the large size of the nidus, the particular location of the nidus, having no history of hemorrhage, etc. In the conservatively treated group, 10 patients had a history of hemorrhage. Of the 10 patients with hemorrhage, 8 cases had rebleeding. Looking at the follow-up results of these 8 patients, 5 died, one was bed-ridden, and only 2 were working. Thus, the prognosis of patients with hemorrhage is poor, if conservatively treated.
In 13 patients who had surgical removal of the AVM, the effects of surgery on motor function were evaluated. Six patients showed hemiparesis before the operation. Of these 6 patients, only one improved after the operation, and 5 remained unchanged. However, the follow-up results showed that 4 are working, one is caring for herself, and one is bed-ridden. Based on these results, it can be said that the life of patients with large intracerebral hematoma can be saved by evacuating the hematoma and removing the AVM. Furthermore, motor weakness can also be improved to some extent by rehabilitation. Regarding the 7 patients with hemorrhage and no paresis, 3 deteriorated after the operation; two of these had renticular AVMs and one had a thalamic AVM. Fortunately, one of these patients is now working, and the other two are caring for themselves. Surgical indication of renticular AVM patients, who have had a history of hemorrhage but no neurological deficits, must be carefully decided.
Speech disturbance occurred after the operation in 5 out of 6 dominant-side AVMs. Except for one case in which the internal capsule was damaged by the operation, post-operative speech disturbance completely disappeared within 1 year. The relationship between the surgical approach and the post-operative visual field defects was also evaluated. Out of 5 cases operated on by the transtemporal approach, 4 showed post-operative visual field defects. Such post-operative visual field defects did not improve to a great extent.
Based on these results, the following conclusions were drawn: 1) Prognosis of the patients with a history of hemorrhage was poor if conservativey treated. Such patients should somehow be treated to prevent the second hemorrhage. 2) Patients with large intracerebral hematoma should be operated on. 3) Certain patients with hemorrhage but without deficits can be safely operated on, if the patient is young, the nidus is small and is located in the caudate nucleus or the thalamus. 4) Postoperative speech disturbance will improve within one year after the operation. 5) Persisting visual field defects were produced in most cases of the transtemporal transventricular approach.

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The treatment of intracranial AVM's is one of the most difficult problems in neurosurgery. Especially large AVM's and AVM's on the eloquent area are the most challenging operation because of the postoperative NPPB or functional damage. Therefore the purpose of this paper is to clarify the treatment of intracranial AVM's. 126 cases of intracranial AVM's were operated on in our university hospital from Jan. 1977 to April 1989, including 101 cases of direct operation and 25 cases of embolization.
(Method) 1) A matching study was done to compare the results of liquid embolization and direct operation in cases of the same location and size. 2) CT, MRI, angiography and SPECT were taken pre- and post-operatively to evaluate NPPB. 3) With AVMs on the motor cortex, surgical excision was performed under MEP monitoring. 4) Preoperative embolization was done in the cases in which feeding arteries were located deep and were difficult to appraoch.
(Results) 1) Liquid embolization was a good indication for dural AVM. Surgical excision was better for cerebral AVM's. 2) Preoperative embolization with IBCA+myodil+tantalum powder was useful for large AVMs with hidden feeding artery.

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The purpose of this AVM study is to investigate the relation between Spetzler's grade and operative result, and examine the application of appropriate surgical treatment, especially for high grade (over grade III) AVMs.
Overall, operations were performed on 60 of 73 cases of AVM. Fifty-three patients (88%) had good prognosis, and 7 (12%) had poor. Patients with poor prognosis had not always been classified high grade, but commonly the AVM was located in the eloquent area.
Therefore, we classified Spetzler's grade more minutely according to a combination of factors. Then we re-examined the relation between the eloquence of the adjacent brain and the prognosis.
As a result, AVMs in the non-eloquent area were found to be closely related to their grade and prognosis, but this was not always found to be true in the eloquent area and, on the contrary, some low grade patients had poor prognosis.
As Spetzler's paper shows, it is important, in cases of AVMs in the eloquent area, to estimate the circulation and metabolism of the adjacent brain. For instance, in excising a small AVM in the eloquent area, if the circulation and metabolism of the surrounding normal brain are preserved, it is important to do least possible operative injury to the surrounding brain. But large AVMs have more or less stolen from the surrounding normal brain, so the eloquence may vary from normal, therefore, operative injury has less influence on the operative result. So appropriate treatment of post operative circulation change has great influence on the operative result.
Spetzler's grade, with preoperative assessment of circulation and metabolism of surrounding brain, may suggest the appropriate management of high grade AVMs, especially in the eloquent area.

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In a retrospective study of 120 patients who underwent surgery for arteriovenous malformations, a statistical analysis of demographic, clinical, and neuroradiological data was undertaken to discover the predictors of operative prognosis. The multivariate statistical method of analysis was used. Ninety-four patients underwent complete resection of the nidus, sixteen partial resection, and ten clipping of feeders. Operative prognosis was evaluated by the Karnofsky Index at discharge and at the last consultation. Target variables were as follows: sex, age, first symptoms, with bleeding or without, nidus side, nidus location, diameter of nidus, eloquency, deep venous drainage, Spetzler and Martin grade, and surgical method.
Nine patients (7.5%) had intractable seizure postoperatively. Postoperative bleeding was noted in five patients, four among them underwent partial resection of the nidus, and three died. Twenty-five patients developed neurological deterioration after operation. Operative mortality rate of the 120 patients treated surgically was 3.3% and operative morbidity rate 20.8%. The diameter of the nidus, the age of the patient, eloquence of the adjacent brain, deep venous drainage, and intracranial hemorrhage affected the outcome.
Evaluation of operative results of AVMs using the multivariate statistical method of analysis is useful for management of AVMs, and the operative indication should be identified with the multiple factors.

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Radiosurgery is one form of therapy utilized in the management of arteriovenous malformations (AVMs).
During the past seven years, we have had 12 patients with AVMs who were subjected to stereotactic radiosurgery. We were able to conduct angiographical follow-up in 11 of these 12 cases.
This angiographical check indicated complete disappearance of the AVM in 5 cases and incomplete disappearance in 6 cases. Thus, an effect of radiosurgery was found in all 11 cases.
We then conducted a follow-up of the 11 cases utilizing CT and MRI. In the 6 cases of incomplete AVM disappearance as indicated by angiography, enhanced CT indicated complete disappearance in 5 cases, and MRI indicated complete disappearance in 3 cases. In other words, the CT and MRI findings were false negative.
Our attempt to find a satisfactory non-invasive method of estimating the effects of radiosurgery revealed the capabilities of MRI, which revealed AVMs as small as 0.13 cm³.

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The management of surgically inaccessible, deep-seated arteriovenous malformations of the brain is one of the most challenging subjects in the field of radiation therapy. It is necessary that high doses be confined to the nidus with accurate patient set-up. So far ten patients with this disease have been treated using the CT-linac online system in the department of Radiology, University of Tokyo. A linear accelerator and a gantry of the CT scanner are installed face to face in the same treatment room and they share a communal couch. For the extremely accurate radiation of this disease, a special set-up method with this system, called internal reference set-up, has been developed. In this technique, CT image should be taken before radiation, then the couch rotates and travels toward the treatment machine. Finally the center of the tumor as determined on the CRT of the CT scanner is automatically placed onto the isocenter of the linear accelerator. Treatment result was quite favorable and this technique proved to be effective particularly for radiation therapy of small arteriovenous malformations of 2 cm or less in diameter. The treatment method, including the fractionation schedule as well as clinical feasibility of this technique, are discussed in this report.

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The result of radiation therapy for arteriovenous malformations (AVM) are analyzed and the indication of radiation therapy are discussed in this paper.
This study was conducted on 8 patients who received radiation therapy at the Yamaguchi University Hospital and DEL SOL Hospital in Buenos Aires from 1973 to 1988. There were three males and five females. The ages ranged from 7 to 67 with the average of 39.9. There were four cerebral AVMs and four dural AVMs. Among the cerebral AVMs, one was located in the right thalamus, two in the left central sulcus and one in the left parietal lobe. Among the dural AVMs, three were spontaneous carotid cavernous fistulas (CCF) and one was a dural-pial AVM of the transverse-sigmoid sinus.
Three cerebral AVMs and three dural AVMs were subjected to conventional radiation of 3000-4000 rads with linear accelerator X ray. One cerebral AVM was subjected to 2750 rads of gamma X ray stereotaxic radiosurgery. The dural-pial AVM was subjected to had conventional radiation combined with embolization.
The radiosurgery obliterated the AVM in the central sulcus. The conventional radiation obliterated two spontaneous CCFs.
From these results, it is concluded that conventional radiation is useful in the treatment of spontaneous CCFs, but is not effective for cerebral AVMs. Stereotaxic radiosurgery is recommended for the treatment of cerebral AVMs.

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Embolization is used as a radical therapy, as well as an adjunctive therapy with surgery for cerebral arteriovenous malformations (AVM). Although several liquid embolic agents, including IBCA, NBCA and others, are available and are reported to be useful for this purpose, these cyanoacrylic agents share common disadvantages. They are strong adhesives and become a hard mass after polymerization. Therefore, a new liquid embolic agent which overcomes these disadvantages, has been considered necessary. EVAL(ethylene-vinyl-alcohol copolymer) is a newly developed liquid embolic agent, which is not an adhesive and takes a soft spongy shape. We used this agent for embolization in 9 cases of AVMs, of which 4 were deep seated and 5 were large AVMs in the dominant hemisphere. A 90% or greater reduction in size was achieved in 3 cases by embolization; and in 2 cases, the size was reduced by more than 50%. In 3 cases, the embolization facilitated the surgical removal of the AVMs.

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New liquid embolization method using estrongen-alcohol and polyvinyl acetate was utilized in brain AVM's. Estrongen dissolved in 25% ethanol (estrogen-alcohol) causes diffuse capillary to arteriole obliteration, while ethanol soluble polymer, polyvinyl acetate containing material (PVac solution) causes larger vessel occlusion without resultant catheter gluing, unwanted tissue reactions. Thirty six cases of surgically inaccessible or difficult AVM's were embolized by the infusion of estrogen-alcohol followed by PVac solution in 73 sessions. Angiographical cure was achieved in 3 cases, more than 90% obliteration in 16 cases without any difficulties related to embolic materials. Successful surgical resection was carried out in 8 cases. Adjunct radiation therapy was used in 9 cases which lead to progressive diminution of nidus. This newly developed method may be more effective and safer than the conventional one to treat the inoperable brain AVM's and to make surgical excision or radiosurgical therapy suitable in surgically difficult AVM's.

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Twelve cases of cerebral arteriovenous malformation (AVM) were managed with intravascular surgery preoperatively, in order to facilitate surgical removal. In 10 of these cases, preoperative balloon occlusion of the feeding arteries was performed by means of detachable balloon catheter. In the rest of the cases, preoperative embolization of the AVM was performed by EVAL through Tracker infusion catheter. There was no complication after preoperative balloon occlusion and one transient aphasia related to preoperative embolization. None of the cases developed normal perfusion pressure breakthrough. Preoperative balloon occlusion was thought to be safe and to decrease the difficulty in surgical resection of the AVM. Preoperative embolization seems to be more effective than balloon occlusion; however, it should be performed carefully without causing complications.

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We report the cases of two patients, each of whom had two separate angiographically demonstrable intracerebral arteriovenous malformations (AVMs). One patient had an intraventricular hemorrhage with AVMs in the basal ganglia and the insula on the left side, and the other had a pontine hemorrhage with AVMs in the pons and the occipital lobe on the right side. The AVMs in the former patient were totally removed without residual neurological deficit. We discuss the diagnostic problems of multiple intracerebral AVMs and stress the need for thorough neuroradiological evaluation so as not to miss an occult AVM. We also stress the necessity of total excision of all the lesions and point out several problems faced in surgery for AVMs.

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The Wyburn-Mason Syndrome is a rare congenital anomaly, consisting of arteriovenous malformations involving the retina and midbrain, and occasionally subcutaneous facial structures. This malformation is also called Bonnet-Dechaume-Blanc syndrome or faciomesodiencephalic angiomatosis. We have experienced 3 cases of Wyburn-Mason syndrome during the past 20 years.
Case 1: A 14-year-old boy suddenly suffered from headache and vomiting. A CT-scan and spinal tap revealed a subarachnoid hemorrhage. A huge AVM was demonstrated in the right basal ganglia, extending to the midbrain. Retinal AVM and facial angioma were found on the right side. He was treated conservatively, and is working now with no deficits. Case 2: A 16-year-old female suffered from headache and left hemiparesis. A huge AVM was demonstrated in the left basal ganglia, extending to the midbrain. Retinal AVM and facial angioma were found in her left side. She was treated with radiotherapy but her neurological deficits gradually became worse. Case 3: A 9-year-old boy suffered from headache, anorexia and lethalgia. A huge AVM was demonstrated in the chiasmatic region, extending to the bilateral hypothalamus, the basal ganglia, and the right orbit. A retinal AVM and a facial angioma with bruit were found. He went into a coma and died 8 days after admission. At autopsy, an AVM was found in the bilateral basal ganglia, extending to the cerebral peduncles and appeared as a spongy mass with small sized vessels. Microscopically, the AVM mainly consisted of dilated and thickened venous channels. The authors have collected previous reports of 43 cases throughout the world, including our 3, and analysed them.

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