A nationwide questionnaire investigated the current therapeutic strategy for asymptomatic cerebral aneurysms in the 1102 neurosurgical institutes in Japan. Replies were received from 445 institutes (40.4%4). The institutes were divided into 3 groups: university, category A and category C hospitals. The mean number of operated cerebral aneurysms in 1997 was 25.1. Only 21% of institutes operated in more than 35 cases. Direct surgery was performed in less than 10 cases in 22.9% of institutes. Asymptomatic cerebral aneurysms accounted for 23% of operated cases, but significantly fewer in category C hospitals.
The mean number of endovascular procedures performed for cerebral aneurysms was 2.7. A few asymptomatic cerebral aneurysms were treated by endovascular surgery (mean number was 0.86). Most Japanese neurosurgeons selected direct surgery for asymptomatic cerebral aneurysms, especially in the anterior circulation. More than half of the institutes selected endovascular surgery or course observation rather than direct surgery for the posterior circulation aneurysms.
About 90% of cases of both symptomatic and asymptomatic cerebral aneurysms are treated by direct surgery in Japan. However, the use of endovascular surgery to treat cerebral aneurysms is apparently increasing.

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To determine the surgical indication of asymptomatic unruptured cerebral aneurysm (AUCA), we reviewed the management of a total of 136 patients with AUCA's (158 aneurysms) that were diagnosed at our hospitals during the past 23 years. Ninety-six patients had incidentally discovered aneurysms and no history of subarachnoid hemorrhage (SAH) (Group A), and 40 patients had a history of SAH from a different aneurysm that had been repaired successfully (Group B). In 103 patients surgically treated (79 in Group A and 24 in Group B), we assessed operative outcome. No patient died and morbidity occurred in 9 patients (8.7%, 8.9% in Group A and 8.3% in Group B, 4.7% in patients with a small AUCA and 29.4% in those with a large AUCA). Statistical analysis revealed that group, patient age and sex, and aneurysmal location had an independent correlation with surgical outcome and that only aneurysmal size approached statistical significance (p=0.004). In 33 surgically untreated patients followed for a median follow-up time of 4.8 years, there were 11 first episodes of hemorrhage from a previously unruptured aneurysm, giving a total rupture incidence of 33.3% (23.5% in Group A and 43.8% in Group B, 28% in patients with a small AUCA and 57% with a large AUCA) and an average annual rupture incidence of 6.9%. The risk of aneurysmal rupture was associated with hypertension. Statistical analysis revealed that the only variable that tended to predict rupture was the size of the aneurysm (p=0.056). There was no difference of rupture incidence between ages from 50's to 70's, except for 80's with no incidence of rupture. We concluded that a small AUCA should be operated on because the risk of rupture exceeded the risk of morbidity, especially in patients of Group B and those with hypertension. If the patient is not over 80 years old, surgery is also indicated for a large AUCA because of its higher rupture rate.

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A multi-center study in 42 hospitals was performed to evaluate the clinical efficacy of routine regional cerebral blood flow (rCBF) measurement studies using brain perfusion SPECT in patients who underwent several SPECT studies in a clinical examination. Seven hundred and nine measurements of rCBF were carried out by a noninvasive Patlak-plot method using Tc-99m ECD in 333 patients. The usefulness of qualitative and quantitative images were analyzed by both the physicians in charge of the patients and image reading committees. Both groups reported that the quantitative method was more useful than the qualitative one in approximately 70% of all the studies. These results suggest that quantitative rCBF measurements using a noninvasive Patlak-plot method play an important role in diagnosis and evaluation of therapeutical effects.

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Expanded polytetrafluoroethylene (ePTFE) has been widely used as a dura substitute since the use of cadaveric dura mater was prohibited because of the possibility of transmission of Creutzfeldt-Jakob disease. This material, however, is often associated with the leakage of cerebrospinal fluid. We have recently developed a method of sealing the suture line with absorbable mesh and fibrin glue. This method, named mesh-and-glue technique, proved to be extremely effective to prevent CSF leakage based on the clinical results and on basic experiments. On the other hand, subdural hygroma after craniotomy, which can be regarded as a CSF collection through the arachnoid tear, has sometimes become a serious complication requiring surgical extirpation. Hence, we have tried to apply the mesh-and-glue technique to seal the arachnoid tear.
In the conventional wound closure, the dissected arachnoid membrane is left alone. After the dura mater is closed water-tightly, normal saline is usually injected to prevent postoperative tension pneumocephalus. It is worth noting that the injected normal saline locates in subdural space, not the subarachnoid space. If the dissected arachnoid membrane adheres incompletely to form a one-way valve, the subarachnoid space will then be enlarged. Thus, the water-tight closure of the arachnoid membrane must be effective to prevent the postoperative subdural hygroma. The mesh-and-glue technique would be a useful tool for this purpose.
In our new closure method, the dissected arachnoid membrane is sealed with the mesh-and-glue technique after the intracranial surgical manuver. Thereafter, the normal saline is injected into subarachnoid space, reestablishing normal tension in the slack brain. Then the dura mater is closed watertightly without injecting the saline into the subdural space. We have applied this closure method in a small number of craniotomies, mainly for non-ruptured middle cerebral or internal carotid aneurysms, and no subdural hygroma was encountered. Of course, several diseases require wide opening of the arachnoid membrane, which make it difficult to close the whole opening of the arachnoid membrane completely. Nevertheless, the mesh-and-glue technique is a useful way of closing the arachnoid membrane, which will decrease the occurrence of postoperative subdural hygromas.

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We evaluate the effect of endovascular treatment at the acute stage with Guglielmi detachable coils on the outcome of the patients with severe SAH from ruptured cerebral aneurysm and on the incidence of symptomatic vasospasm. Twenty-five patients with aneurysmal SAH were treated at the acute stage with Guglielmi detachable coils. The reasons for adopting endovascular treatment in these cases were as follows: poor grade (Hunt & Kosnic grade IV and V), 16 cases; high age, 3 cases; basilar trunk aneurysms, 4 cases; and other reasons, 2 cases.
All the cases of Hunt & Kosnic grade II and III obtained good recovery in Glasgow outcome scale at discharge. The outcome of cases with poor grade (GCS at admission was 9 or less) was good recovery in 5 cases (31%), moderately disabled in 2 (13%), and severely disabled in 9 (56%). The overall outcome was better than that of surgically treated cases in the same condition. The difference in outcome between GDC and surgically treated cases is possibly caused by the difference in the degree of insult to the brain associated with treatment modalities.
The incidence of symptomatic vasospasm was smaller in GDC treated cases (8%) than in surgically treated cases (12%). In the cases treated with GDC and followed by an intratecal administration of urokinase, subarachnoid clots were cleared more rapidly than in those treated surgically with continuous cisternal irrigation. This improved clearance of subarachnoid clots in the GDC group might have acted favorably to prevent delayed vasospasm.
The long-term efficacy of GDC embolization in preventing recurrent aneurysmal bleeding has not yet been determined. However, this method is apparently less invasive to the brain, and suitable for the treatment in severe SAH patients who suffered serious primary brain damage.

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It has been generally accepted that perioperative management is quite difficult with chronically hemodialized patients who suddenly develop subarachnoid hemorrhage (SAH) due to a ruptured aneurysm. Two main problems are present: hemorrhagic tendency caused by platelet hypofunction and excessive brain swelling elicited by disequilibrium syndrome during and after the operation.
We experienced 7 of these cases in our institutes during the past 7 years. Direct surgery was performed in 5 mild and moderate SAH cases and embolization using GDC in 2 severe SAH cases. Postoperative hemodialysis was usually performed intermittently for mild and moderate SAH patients using short-acting anticoagulants following installation of intracranial pressure monitoring. This treatment was well tolerated without any untoward effect. However, we were sometimes obliged to continuously perform hemodialysis. For the patients with a fluctuating intracranial pressure, continuous hemodiafiltration was chosen, and for the patients suffering from impending intracerebral hemorrhage or hematoma, continuous ambulatory peritoneal dialysis was used for several days.
Overall outcome was satisfactory except for 2 surgical cases with a massive intracerebral hematoma and/or large infarction related to the original aneurysmal rupture. Although our experience is small, we strongly feel that GDC embolization is likely to be an effective and promising treatment of choice especially for such severe SAH hemodialized patients.

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We experienced three cases of duplication of the middle cerebral artery among 750 cases by angiography in our institute. One case showed a saccular aneurysm at its origin. The rest were detected during examinations for cerebral infarction. One had an accessory middle cerebral artery in itself. We discuss our clinical findings with some reference to the literature.

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A 62-year-old female was admitted to our hospital with subarachnoid hemorrhage. Cerebral angiography showed a giant saccular aneurysm arising from the inferior wall of the C2-C3 portion of the left carotid artery. We performed radical surgery according to Dolenc's method. The obliteration of the aneurysmal neck was confirmed by inspection and puncture of the aneurysm and Doppler on the aneurysm after neck clipping with two encircled clips and an angled ring clip. The clip was apparently placed adequately over the proximal neck. However, postoperative angiography revealed a slight remnant of the proximal neck of the aneurysm. A second operation was performed, and an encircled clip was added proximal to the previous clips. Intraoperative angiography showed complete obliteration of the aneurysm.
It is not so easy to obliterate the proximal neck of the giant aneurysm at the C2-C3 portion of the internal carotid artery because the optic strut inhibits insertion of the clip and the aneurysmal wall is thick, so it is very important to confirm the complete obliteration of the aneurysm.
Confirmation of complete obliteration of the aneurysmal neck is hard to obtain both visually and by puncture of the aneurysm and Doppler in case thrombotic change occurs at the puncture point of the aneurysm. Therefore, use of the intraoperative angiography is very desirable to confirm the safe and complete neck clipping.

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Ruptured aneurysms of the anterior inferior cerebellar artery (AICA) are rare, occuring in less than 1% of aneurysms of the posterior circulation. The patient we report was a 66-year-old woman who complained of sudden severe headaches. She consulted our hospital 10 days after the first headache. At that time, she had no neurological abnormalities apart from the headaches and a CT scan did not indicate subarachnoid hemorrhage (SAH). However, tests revealed that the cerebrospinal fluid of the patient was xanthochromic so she was diagnosed as SAH. Subsequent cerebral angiography (CAG) did not reveal any ruptured aneurysms. After 14 days, CAG was re-examined and a ruptured saccular aneurysm at the distal portion of the meatal loop of the AICA was detected.
Forty days after onset, neck clipping of the aneurysm via the right lateral suboccipital craniectomy was performed. The clipping was successful and she was discharged without any deficits. This case is consistent with the findings of reported cases in that the patient had no neurological abnormalities of cranial nerves VII VIII and the aneurysm could not be detected on the initial CAG.

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Direct surgical clipping has long been the gold standard for the treatment of cerebral aneurysms. Since the development of endovascular treatment, management of intracranial aneurysms has become controversial. There are several merits and demerits in either mode of treatment. There are many in the literature advocating one or other, or combined treatment. In our study, we have tried to identify indications for either mode of treatment for incidental aneurysms.
Endovascular treatment was introduced in Fujita Health University in 1994. From that time to the end of 1998, we had 566 cases of aneurysms, including 129 incidental aneurysms, which form the material of the present study. Ninety cases were treated by direct surgery. Thirty three cases were treated by endovascular intervention. Six cases were untreated.
In the direct surgical group, all 90 patients with incidental aneurysms had excellent results except for one case impossible to approach, followed by coiling. In the endovascular intervention group, 6 had subarachnoid hemorrhage (SAH), including 1 death as a complication. Pseudoaneurysm developed in 1 case in the parent artery, which was embolized with coil. Coil embolization failed in 5 case-3 were followed by direct surgery, 1 was followed without surgery or intervention and 1 died due to ruptured aneurysm. Coil compaction occurred after 6 months in 2 cases that were reembolized.
An advantage of endovascular treatment is that it does not depend on the site of the aneurysm or its relationship to surrounding vessels or nerves. Its disadvantage is in dealing with aneurysms with a wide neck or aneurysms involving branches or perforators. Therefore we examined the aneurysms in detail with 3D CT angiography, especially with endoscopic views. Adequate narrowing of the neck of the aneurysm is a good indication for endovascular coil embolization. However, if there is a nipple type of a bleb present it may rupture easily. As these aneurysms should be treated early and quickly, surgery is more reliable in such cases.
Indication for direct surgery is incidental aneurysm with bleb or wide neck. Indications for endovascular coil embolization include: a) incidental aneurysm especially of basilar system without bleb with narrow neck and b) cases with other systemic complications.

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We present three cases of cerebellar hemorrhage following aneurysmal surgery for the anterior communicating artery.
Postoperative cerebellar hemorrhage located remotely from the supratentorial site is a rare complication. In a review of the literature, we identified 29 such cases, including 23 cases of aneurysmal surgery. We examined the possible etiologies for cerebellar hemorrhage in these reports. Almost all the reports described CSF overdrainage by epidural suction, causing cerebellar hemorrhage. These cases showed a specific configuration in which the hematoma spread transversely along the cerebellar folia and strictly curvilinearly on CT scan. The location of this hematoma consisting with the position of cerebellar hemispheric bridging veins.
We suggest that the mechanism of this complication is dislocation of the dependent part of the cerebellum, and destruction of the bridging veins on the tentorial surface causing CSF overdrainage.
The strict management of draining is important to prevent this complication.

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