There are two major approaches to a basilar bifurcation aneurysm, the subtemporal approach developed by Drake, and the pterional approach developed by Yasargil. In either approach, however, it is hazardous and difficult to approach a basilar bifurcation aneurysm with a megadolichobasilar anomaly because strong retraction of the brain, nerves and vessels is required.
Two successful cases of a ruptured basilar bifurcation aneurysm with a megadolichobasilar anomaly treated directly through the third ventricle are reported in this paper.
A 62-year-old woman and a 60-year-old woman were admitted with disturbance of consciousness.
Their plain CT scans on admission demonstrated massive and diffuse subarachnoid hemorrhage and clots in the third ventricle.
Their left vertebral angiographies demonstrated basilar bifurcation aneurysms which were considered to be inaccessible by conventional approaches because of their high position. Therefore, we applied the new approach described below.
The operation was performed at an acute stage, using a bifrontal craniotomy. Dissecting interhemispheric fissure, we approached the third ventricle via the lamina terminalis. After evacuating the clot in the third ventricle, the basilar bifurcation aneurysm could be visualized. After opening the floor of the third ventricle at the midline to dissect the neck of the aneurysm and perforating arteries, clipping was performed.
The postoperative courses were uneventful.
The key surgical points and the prospective view in approaching via the lamina terminalis and through the third ventricle for a high position basilar bafurcation aneurysm are discussed in this paper.

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We had 127 patients who had unruptured aneurysms associated with ischemic cerebrovascular diseases in our institute from 1969 to 1986.
In 45 cases, direct surgery was performed on the unruptured aneurysms. Conservative treatment was administered in the other 82 cases. There have been five patients with conservative follow up who subsequently had attacks of subarachnoid hemorrhage, and four patients died due to this hemorrhage. Twenty-nine patients (64%) who underwent surgery recovered uneventfully the after operation; on the other hand, the neurological condition of 16 (36%) patients worsened. Six of these patients had only transient symptoms, but 10 had permanent deficit without improvement.
As far as the problem can be said to reside with the patient, the causes of symptomatic worsening after surgery were thought to be fragility of the ischemic brain and arteriosclerotic change around the aneurysm. On the other hand, the techniques of the operation, such as excessive brain retraction, damage to veins or perforating arteries, and stenosis or occlusion of major vessels may have contributed to the worsening of symptoms. Operative processes which would not be injurious in ordinary cases may have had some harmful effect in these cases. Furthermore, senility or general complications may also be considered as causes of deterioration during the post operative course.
So we concluded that surgery for an unruptured aneurysm associated with cerebral ischemia could be performed only in selected cases where the patient has a risk of future aneurysmal rupture but severe complications and major neurological deficit are unlikely to arise. And when surgery is determined to be necessary more cautious and delicate operative techniques are indispensable.

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A total of 1,435 patients with cerebral infarction or hemorrhage received angiography during the eight years from 1978 through 1985, and 46 (3.2%) of them were demonstrated to have unruptured aneurysms; operation was performed on 27 with a transient morbidity of 22%(6 cases) and a mortality of 3.7%(one case).
Excepting cases without preoperative motor weakness and those with vertebrobasilar insufficiency, 16 cases were entered in the present study in which six cases of deterioration and 10 stable cases were compared to find any factor contributory to the aggravation of symptoms.
The deteriorated and stable groups differed distinctly in the interval between the end of the initial acute stage and the performance of surgery-12 days in the former and 33 days in the latter group. The rate of depression of the blood pressure during operation was 28% in the deteriorated group and 14% in the stable group. These cases seem to justify the performance of surgery more than one month after the clearing of initial acute symptoms. They also alert the surgeon to the danger of intraoperative blood pressure depression.

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The authors analyzed a series of 38 cases of occlusive cerebrovascular disease with unruptured aneurysms. There were 16 patients who underwent direct surgery for unruptured aneurysms and 22 patients who were treated conservatively.
Surgical morbidity occured in three cases. One developed visual loss due to optic nerve injury, and the other two patients had aggravation of ischemic symptoms after operation. Of the latter two patients, one underwent surgery in the acute stage of stroke and the other showed a high density in the ischemic lesion on CT scans even in the chronic stage of ischemia. In each of these three cases, operation for aneurysms was performed with an ipsilateral approach to the ischemic lesion. Of 22 patients who did not undergo surgery, only one patient suffered aneurysmal rupture and three patients over 70 years of age died of other causes during the follow-up period (mean: 2.3 years). The risk of hemorrhage was 2%/year.
When considering surgery for unruptured aneurysms in patients with occlusive cerebrovascular disease, one should compare the risk of aneurysmal rupture against that of surgery. From our results, we have decided several criteria for surgery for unruptured aneurysms with ischemic stroke:1) Age must be under 70 years; 2) General condition must be good; 3) Ischemic symptoms must be minor; 4) More than two months must have passed from the onset of the last ischemic attack. In addition, more caution should be exercised when surgery is performed with an ipsilateral approach to the ischemic lesion.

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We have experienced thirty-four cases with incidental unruptured aneurysms in ischemic cerebrovascular diseases. All of the aneurysms were surgically treated. There were 16 males and 18 females. The mean age was 60. The ischemic symptoms were TIA in six cases, RIND in four, and completed stroke in 21. Unruptured aneurysms were distributed at ICA (15), MCA (11), A corn (6), ACA (5) and BA (1). The mean diameter of the aneurysms was 5.7mm. CT showed low density areas in 24 cases. Atherosclerotic obstructive changes of major cerebral arteries were found in 11 cases. Thirty-four of 38 aneurysms were clipped and four were coated. STA-MCA anastomosis was added at the same stage of aneurysms operation in two cases and carotid endarterectomy was done one month after the obliteration of aneurysms in two cases. Twenty-four of 34 cases had no postoperative symptoms, seven cases showed transient symptoms and two permanent neurological dificits. One patient died due to postoperative bilateral intracerebral hematoma. Surgical complications consisted of six seizures, six subdural effusions, three intracerebral hematomas, two meningitis, one brainstem infarction and a minor epidural hematoma. Status epilepticus occurred in two cases without prophylactic anticonvulsant. Subdural effusions in two cases turned out to be chronic subdural hematomas. One of three intracerebral hematomas was an ipsilateral hematoma and another was a remote hematoma.
In review of our series and other reports, the morbidity and mortality of the direct operations for unruptured aneurysms with ischemic symptoms are relatively high compared to other unruptured aneurysms. Patients who are over 70 years old, have severe atherosclerotic changes of major cerebral arteries, ventriculomegaly or severe brain atrophy, should be considered to be high-risk cases for surgery on unruptured aneurysms. Preoperative prophylactic administration of an anticonvulsant is indispensable.

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The results of surgical treatment were analysed in 33 cases of nonruptured aneurysms associated with ischemic cerebrovascular disease.
Twenty-six cases had a single aneurysm and seven had multiple aneurysms. Of the 33 cases, the aneurysms were located in the MCA in 14 cases, in the IC-PC in seven, in the IC-B in three, in the IC-ophthalmic in three, in the AcomA in eight, in the distal AC in four and in the Basilar-tip in one. Thirty-seven aneurysms were clipped and three were wrapped with muscle between three weeks and 17 years after the onset of ischemic cerebrovascular disease. As for the type of stroke, 22 out of 33 cases had Completed Stroke, two TIA, two RIND and seven vertebrobasilar insufficiency. On CT scan, small, low density areas was seen in 20 cases and large, low density areas in four. On angiogram, the occlusion of the main cerebral trunk was revealed in six cases and the stenosis in 16.
The operative results on discharge were as follows: In 26 cases, the postoperative course was un-eventful, but in four out of 26 cases, a generalised convulsion followed immediately after surgery. In three, the symptoms got transiently worse.
In seven out of 33 cases, the course was unsatisfactory; the symptoms got worse due to postoperative intracerebral hematoma in three cases, the enlargement of the infarcted area in three, and subarachnoid hemorrhage in one.
Based on these results, it was emphasized that the accurate treatment of aneurysms and careful retraction of the ischemic brain are necessary to prevent postoperative intracerebral hematoma and enlargement of the infarcted area.

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A study was conducted to evaluate the postoperative complications associated with incidental asymptomatic aneurysms in 30 patients with 34 cerebral aneurysms who suffered from ischemic or hemorrhagic cerebrovascular diseases. On postoperative CT scan, seven patients were shown to have developed new infarctions and seven patients had new cerebral or cerebellar hemorrhages. Among the patients who developed new infarctions, the problem was directly due to operative procedures in three cases, and in another two cases the problem was thought to be associated with STA-MCA anastomosis which had been simultaneously performed. The other two cases were considered to be due to hemodynamic ischemia during surgery and anesthesia. Three of the patients with infarction almost totally recovered to their preoperative neurological state.
Two of the seven patients with hemorrhage had received preoperative antiplatelet therapy for their original diseases, and one had liver cirrhosis with thrombocytopenia. One received STA-MCA anastomosis as mentioned above and both hemorrhage and infarction developed. Two patients died of late systemic complications.
Aside from infarctions confirmed by CT scan, five patients had postoperative focal neurological deterioration, from which they made an almost total recovery. These cases may have been due to transient ischemia. Nine patients suffered postoperative epileptic seizures. On CT scan, one was shown to have multiple cerebral and cerebellar hemorrhages, two to have infarctions, and one to have both. Five patients had no remarkable signs on CT scan except for slight cerebral edema. Five developed status epilepticus, and one died of diffuse cerebral edema secondary to uncontrollable status epilepticus. The other two patients died of late systemic complications after developing an impaired mental state after seizures. There was no correlation between these complications and the patients' age or length of time between the first onset of cerebrovascular disease and surgery for aneurysms. Of the 30 patients, the surgical morbidity rate was 70%, including transient neurological deficits and epilepsy, and the late mortality rate was 13% (four patients), including systemic complications.
In conclusion, patients who are found to have aneurysms incidentally during a course of ischemic or hemorrhagic cerebrovascular disease have a high risk in direct surgery, and intensive care should be taken during surgery and in the pre- and postoperative period. Preoperative anticonvulsants, evaluation of coagulation capacity, stable blood pressure during surgery and the postoperative period, and no non-essential procedures other than aneurysm surgery, are important considerations for these patients.

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The indication of surgery for unruptured cerebral aneurysms associated with ischemic cerebrovascualr disease is still controversial because of the relative high operative morbidity.
Fifteen patients suffering from this condition were analyzed clinically in this report. Eleven were male and four were female. The ages ranged from 46 to 72 (mean, 60.8). Middle cerebral arteries had nine aneurysms, internal carotid and basilar arteries had two each, anterior communicating and posterior cerebral arteries had one each. The size of the aneurysms varied: nine ranged between 5 and 9mm, two were between 10 and 14mm, three were under 4mm and one was over 15mm.
Eight patients were operated on. The main clinical problems of these eight patients included hemiparesis, sensory disturbance and dysarthria, and these symptoms were mild in all. CT showed only a small low density area in seven patients but one patient with TIA had a large low density area. Angiography revealed stenosis in one and arteriosclerosis in four. The pterional approach was used in all cases, through the same side as the ischemic lesions in six cases and the opposite side in two. The interval between the onset of the ischemic cerebrovascualr disease and aneurysmal operation ranged from twenty-one days to one year, averaging four months. Six patients recovered uneventfully but two suffered from postoperative neurological deficits (one was transient but the other was permanent). Postoperative CT showed new low density areas in each. Both patients were operated on through the same side as the ischemic lesions and in the short interval from the onset of ischemic cerebrovascular disease to aneurysmal surgery. The long-term results were that six reco-vered uneventfully, one had hemiplegia, and one died of pneumonia.
Seven patients didn't received the aneurysmal operation. Six of them, excluding one with TIA, had severe neurological dificits due to the ischemic cerebrovascular disease and showed large low density areas on the CT image. The long-term results were as follows: three patients showed no change in the condition, two worsened due to increased ischemic lesions and two expired due to other causes.
When unruptured cerebral aneurysms are associated with ischemic cerebrovascular disease, the treatment should be determined by the severity of neurological problems caused by the ischemic cerebrovascular disease. We consider that the unruptured cerebral aneurysms should be operated on if the neurological problems are mild, but if not surgery should not be performed.

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We performed the direct procedure on 12 cases of unruptured cerebral aneurysms associated with ischemic cerebrovascular diseases (TIA, two cases; RIND, five cases; completed stroke, five cases). In the postoperative course of all cases of TIA and RIND, no permanent ischemic deficit was observed. However, in two cases of completed stroke with angiographic occlusive lesion, the deterioration of existing ischemic deficits was permanent. In these two cases, the operative approach was on the same side as the deficit. Therefore, a direct procedure for cerebral aneurysms should be performed in cases of TIA and RIND. However, additional considerations may be necessary for cases of completed stroke with angiographic occlusive lesion, when the side of the operative approach would be ipsilateral to the side of the ischemic cerebrovascular disease.

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About five percent of patients who undergo cerebral angiography for the evaluation of ischemic vascular lesions will be found to have an incidental intracranial aneurysm. However, controversy exists about the treatment for this condition. Since 1978, the authors have operated on six patients with symptomatic intracranial aneurysms which were accompanied by ischemic symptoms. All these patients showed minor completed stroke. Cerebral angiograms showed branch occlusion of the middle cerebral artery (MCA) with aneurysms in two cases, stenosis of the internal carotid artery with aneurysms in two, wall irregularity of the MCA with multiple aneurysms in one case and a partially thrombosed ophthalmic aneurysm causing cerebral embolism in the last case. Three patients were treated by aneurysm clipping, and superficial temporal artery to middle cerebral artery bypass was performed at the same time. One patient, (Case 5), underwent clipping of the aneurysm one month after carotid endarterectomy. Another, (Case 6), was treated by clipping of a right side aneurysm one month after the clipping of multiple aneurysms on the left side. Operative results were good in all cases of one stage operations but there were complications in the two stage operations. From our own operative results and from the literature, the authors have discussed treatment for asymptomatic cerebral aneurysm when accompanied by ischemic events and have concluded that the combined therapy of aneurysm clipping and bypass surgery in a one-stage operation may be a useful method for preventing complications.

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Five surgically treated cases of “incidental”aneurysm associated with cerebrovascular disease are presented in this paper. There is still diversity of opinion as to whether or not unruptured aneurysms should be treated surgically. Unruptured intracranial aneurysms fall into the following three categories: 1) symptomatic aneurysms; 2) multiple aneurysms in cases of subarachnoid hemorrhage; 3) so-called “incidental”aneurysms demonstrated during angiographic investigation of a variety of disease process. The last category has proved increasingly common as angiography, DSA, high resolution CT scan, and other innovative techniques have brought unsuspected lesions to medical attention.
During a fifteen month period, cerebral angiography was performed in 104 cases of patients for the following indications: cerebrovascular disease (88 cases), brain tumor (five cases), others (eleven cases). The patients included 71 men and 33 women, with a mean age of 53.3. We found five cases of“incidental”aneurysms.
Preoperatively all five patients had various degrees of neurological dysfunction such as motor dysfunction, aphasia, and dysarthria. Postoperatively three cases improved, but two cases deteriorated. In the latter cases, the parent artery of the “incidental”aneurysm fed both cerebral hemispheres. We suspected that compression of the ischemic brain, spasm of the parent artery caused by surgical procesure, and changes of cerebral circulation during operation and postoperation worsened the patients' prognoses.
In this paper we discuss the treatment of “incidental”aneurysms and the reports in the literature are reviewed.

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Among fifty-two angiographically examined patients with vertebro-basilar disorders, incidental intracranial aneurysms were found in five cases. Except for one patient who seemed unable to tolerate the operation, radical surgery was performed. These four cases were all males, ages ranging from 42-67. The vertebro-basilar disorders were of ischemic origin in three cases and hemorrhage in one case. These incidental aneurysms were located in the internal carotid artery, the middle cerebral artery and the anterior communicating artery. They were multiple in three cases. Intervals between strokes and operations were 51-81 days.
In spite of a successful operation, mild to moderate disturbances of consciousness appeared in three cases. In two cases the problem subsided in a week, but in one case it persisted for two months. Fortunately, the final results in all cases were good. This transient deterioration of consciousness level might probably be ascribed to vertebro-basilar insufficiency which had once subsided but resumed due to the operative affections. Based on the experience with this small number of four cases, three points are suggested to prevent such hazards. 1) Extreme systemic hypotension as well as hypertension should be avoided during the operation. 2) GOF might be the anesthesia of choice in such cases. 3) The operation should be performed at a favorable time more than six months after the ictus.

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In this paper, we reported two cases of carotid ophthalmic aneurysm. Case 1 had the subchiasmal type of this aneurysm and could be operated on successfully through the interhemispheric approach. Case 2, with bilateral carotid ophthalmic aneurysms, was operated on through a bifrontal craniotomy extenging to the left temporal area. The aneurysm on the left side was treated by wrapping and the one on the right was clipped through a combined contralateral pterional and interhemispheric approach. This combined approach seemed to be particularly useful for some aneurysms on this portion. The surgical approach to carotid ophthalmic aneurysms is discussed.

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In this paper we introduce a“high pressure irrigation and suction system”designed for acute stage surgery of ruptured intracranial aneurysms, and the new operative method using this equipment. The mechanism and the structure of this system are omitted here, but in use it can be handled in the same manner as a sucker, and clots in the subarachnoid space can be washed immediately.
Until now“dry field”and“blunt dissection”have been the routine in neurosurgery and general surgery. But a completely dry field raquires“sharp dissection”without any damage to vessels. Recent developements of microscopes and microsurgical instruments seem to bring“sharp dissection”into chronic stage operations. But, in acute stage operations this is not easy because of subarachnoid clots adhering to vessels and the arachnoid trabeculae. Complete“sharp dissection”can be accomplished with this irrigation and suction system, not only in chronic stage operations but also in acute stage operations.

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The possibility of a portable intravenous digital subtraction angiography (IVDSA) is discussed in this paper. First, serial angiograms using Fuji Computed Radiography 201 (FCR) were taken after a bolus injection of Iopamidol 300 through bilateral cubital veins to find the best dose of contrast medium and the best timing when the cerebral venous system could be visualized. The angiograms were taken in fifteen cases in which CT scan had shown no mass effect and four cases in which a mass effect had been seen on CT. It was found that the best way to present the cerebral venous system was to make a bolus injection of 1.5ml/patient's body weight (kg) of contrast medium at a rate of 10ml/second. After the beginning of injection of the contrast medium, the venous system could be visualized on an average from 15.8 to 22.0 seconds in cases without a mass effect and from 15.2 to 21.4 seconds in cases with a mass effect. A portable IVDSA using a portable X-ray apparatus and imaging plates of FCR was performed in four cases without a mass effect and two cases with a mass effect using the best method of injection of contrast medium and the best timing which were deduced as mentioned above. In all cases, the cerebral venous system, involving cortical veins, sinuses and deep venous system, could be visualized as clearly as with conventional angiograms. No complications occured in our experience. We emphasize that this method will be useful in following the clinical course of patients with cerebral venous thrombosis.

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We have already pointed out that some of the patients with negative Balloon Matas test (BMT) have a risk of subclinical ischemia. In this study of eleven cases with giant aneurysms of ICA and five cases with traumatic carotid-cavernous fistula (CCF), we performed BMT of the internal carotid artery (ICA) and the common carotid artery (CCA), then examined the neurological findings, wedge pressure of ICA and CCA, and flow direction of ICA under CCA occlusion by the balloon catheter. These cases were classified into six types as follows. Type 1, BMT of ICA and CCA were both negative and flow direction of ICA during CCA occlusion was retrograde. Type 2, BMT of ICA was negative, BMT of CCA was positive, and flow direction of ICA was retrograde. Type 3, BMT of ICA and CCA were both positive and flow direction of ICA was retrograde. Type 4, BMT of ICA and CCA were both negative and flow direction of ICA was antegrade. Type 5, BMT of ICA was positive, BMT of CCA was negative, and flow direction of ICA was antegrade. Type 6, BMT of ICA and CCA were both positive and flow direction of ICA was antegrade. In cases of Type 1, ICA occlusion can be performed safely, because the collateral flow has the pressure to send the blood to the external carotid system. In cases of aneurysms of Type 4, subclinical ischemia may exist after ICA occlusion, because the external carotid system works as the collateral flow. Therefore, bypass surgery is recommended. In cases of aneurysms of Type 5 and 6, ICA occlusion cannot be performed without bypass surgery. Type 2 and 3 did not exist in our series. The flow direction of ICA can be used to show the presence of subclinical ischemia in patients with a negative BMT.

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A case of occlusion at the higher cervical level of the carotid artery with a homolateral persistent primitive hypoglossal artery was reported.
A 72 year-old male was admitted because of progressive consciousness disturbance with left side hemiplegia. CT findings, recorded the day after the incident, revealed a marked shift of the midline structure from the right to the left, compression of the right lateral ventricle and a larger low density area over the right cerebral hemisphere. These findings suggested ischemia due to occlusion of the main trunk of a cerebral artery such as the internal carotid artery. Angiograms showed that the internal carotid artery diverged from the common carotid artery at the level of the third cervical vertebral body, and then an aberrant artery branched at the level of the first cervical vertebral body, in an upward and posterior direction. The internal carotid artery was obstructed at a point immediately after divergence from the aberrant artery. This aberrant artery went in the cephalad direction and continued to the basilar artery. The right vertebral artery could not be observed by retrograde brachial angiography but the left artery was hypoplastic. The aberrant artery, which diverged from the right internal carotid artery, was thought to be a persistent primitive hypoglossal artery judging from its characteristic figure.
It is well known that the most common site of arterial stenosis or obstruction of the extracranial portion of the internal carotid artery ranges within 1.5cm distal from its origin. Therefore, the obstructive site of this case was very uncommon, and no previous case reports of a case like this could be found in the literature. The authors supposed the causes of this higher cervical obstruction to be as follows: as at other arterial bifurcations, turbulence and eddy blood stream, which differs from ordinary laminar flow, had crippled the smooth endothelium, and atheromatous deposition was caused at the subendothelial layer. Then arterial stenosis, caused by thickening of arterial wall, and ultimately total occlusion of the internal carotid artery had occured. Following the same process, it was presumed that occlusion of the higher cervical internal carotid artery, immediately after it diverged from the persistent primitive hypoglossal artery, had occured.

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