Surgical approaches for medially oriented internal carotid artery aneurysms include the ipsilateral pterional approach, the contralateral pterional approach, the interhemispheric approach, and the interhemispheric-subfrontal approach. In the ipsilateral pterional approach, the internal carotid artery obstructs direct visualization of the aneurysmal neck. In the contralateral pterional approach, the aneurysmal dome is exposed before dissection of the aneurysmal neck. In the interhe-mispheric and interhemispheric-subfrontal approaches, the aneurysmal neck can be seen without mobilization of the internal carotid artery or aneurysmal dome. The interhemispheric-subfrontal approach requires too much exposure of the brain to deal with this type of aneurysm microsurgically.
There are two kinds of interhemispheric approaches, i.e., the anterior interhemispheric approach (AIH) and the basal interhemispheric approach (BIH). The basal interhemispheric approach was initially developed as an approach for high-positioned anterior communicating artery aneurysms. Compared with the AIH, the BIH can provide a wider view without additional brain retraction. We applied the BIH to 3 cases of medially oriented internal carotid artery aneurysms.
Two cases of carotid-ophthalmic aneurysms and one case of an aneurysm arising from the origin of the duplicated middle cerebral artery were operated on. All aneurysms were successfully clipped. Postoperative complications included cerebrospinal fluid rhinorrhea (1 case), transient oculomotor palsy (1 case), ipsilateral visual disturbance (1 case) and anosmia (2 cases). The patients were discharged in the state of ADLs 1, 2 and 3.
The advantage of the BIH for medially oriented internal carotid artery aneurysms is direct visualization of the aneurysmal neck, with better anatomical orientation for surrounding structures. With decompression of the optic canal, mobilization of the optic nerve and removal of the sphenoid sinus wall, medially oriented aneurysms arising between the carotid bifurcation and the carotid cave can be clipped completely.
Disadvantages of the BIH are opening of the frontal sinus, injury to the olfactory nerve, and a narrow and deep operative field. In our cases, no serious complications such as meningitis were encountered.
he basal interhemispheric approach is a useful approach for medially oriented internal carotid artery aneurysms, especially those with a small neck.

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

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The clinical significance of intracerebral hematoma (ICH) following rupture of a middle cerebral artery (MCA) aneurysm was studied in 31 surgical patients having a mean age of 52 years. Sixteen patients were not included in this study, because of massive intraventricular bleeding (2), postoperative complications (7), operation trouble (5), and symptomatic vasospasm (2). One patient died in postoperative period. The remaining 30 patients were followed for a mean of 3.7 years postoperatively. Sixteen patients almost fully recovered, nine were self-sufficient with some deficits, two were partially dependent, one was fully dependent, and three died. The locations of the ICH were as follows: temporal lobe in 18 cases; frontal lobe in five; frontal and temporal lobes in three; temporal and parietal lobes in four; and temporal lobe and internal capsule in one. Fourteen patients had permanent neurological deficits. Left homonymous hemianopsia occurred in one patient who had a large hematoma in the right temporal lobe but became self-sufficient. Motor disturbances were mild in 11 cases, and severe in three (hemiplegia in two and tetraparesis in one). Six of the 11 patients with dominant hemispheric ICH experienced motor dominant aphasia and one had global aphasia. Although there was no definite correlation between hemisphere and outcome, patients with medium to large ICH in the dominant hemisphere tended to develop motor dominant aphasia. In terms of motor disturbance and aphasia due to ICH following MCA aneurysm rupture, the prognosis appears fairly good because these ICH are originally subcortical.

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Surgery was performed in particular cases of ruptured intracranial aneurysms accompanied by the insidious occlusion of the main cerebral artery. Such surgery was performed in 1.14% of 701 patients found to have ruptured intracranial aneurysms after the introduction of a CT scanner in our institute.
There were eight men and one woman, whose mean age was 58. In these nine patients, three of the ruptured aneurysms were located in the anterior communicating artery, five at the internal carotid-posterior communicating junction, and one at the internal carotid-anterior choroidal junction.There were four cases with multiple aneurysms.
There were five internal carotid occlusions, three middle cerebral (at the horizontal portion) occlusion and one occlusion of the common carotid artery. The site of the aneurysms and the previous occlusion of the main cerebral artery appeared well correlated, indicating a hemodynamic process for aneurysmal formation. None of the patients had ever experienced a cerebral ischemic event before the attack of aneurysmal subarachnoid hemorrhage.
Surgical treatment for five of these patients consisted of aneurysmal clipping, and that for the remaining four consisted of aneurysmal clipping + STA-MCA bypass. One patient died, four were fully recovered at the time of discharge, and four needed further treatment. Clinical deterioration of these cases was chiefly due to the severe cerebral ischemia at the occluded site after the development of vasospasms. When the degree of subarachnoid hemorrhage seemed too severe to avoid subsequent spasms, bypass surgery, in addition to acute aneurysmal clipping, was considered suitable.

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 A series of 105 patients presenting with multiple aneurysms and subarachnoid hemorrhage (SAH) were operated on for ruptured and unruptured aneurysms between 1976 and 1984. Clinical factors other than the severity of SAH affecting the outcomes included: 1) Misdiagnosis of the location of a ruptured aneurysm among multiple aneurysms resulted in poor outcomes because of multiple surgical approaches or rebleeding during the acute period. 2) Combinations of aneurysmal locations requiring multiple surgical approaches, such as interhemispheric and transsylvian, during the acute stage caused worse outcomes than with multi-stage surgeries. If an unruptured aneurysm could not be reached during the initial exposure, multi-stage surgery was safe if the ruptured aneurysm had been clipped during the acute period. 3) Complications occurring during unruptured aneurysm surgery. The patient's age, the location and size of the unruptured aneurysms were significant factors in the clinical prognosis. Surgery for unruptured aneurysm caused 1.8% morbidity in patients between 28 and 55 years, but 18.0% morbidity in patients over 56 years of age. Surgery for internal carotid artery aneurysms resulted in 14.8% overall morbidity. Surgery for middle cerebral and anterior cerebral artery aneurysms caused below 5% morbidity. Postoperative morbidity in patients with aneurysms less than 5 mm in diameter was 1.3%, and with aneurysms measuring 10 mm or more, 20%. The optimum treatment for multiple aneurysms with SAH should be based on all factors of the patient's condition, including the unruptured aneurysms.

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One hundred fourteen serious cases of ruptured intracranial aneurysms were studied clinically with special reference to prognosis and surgical indication. In this series, 57 cases underwent radical surgery in the acute stage and 57 cases were treated conservatively (including cases only treated with continuous ventricular drainage). The criterion for these serious cases was designated as semicoma or coma state just before operation in the radically treated group, and at admission in the conservative group. CT findings were divided into the following four types based on the cause of the severe disturbance of consciousness: 1) subarachnoid hemorrhage (SAH) type having only severe subarachnoid clot, 2) intraventricular hemorrhage (IVH) type having packed intraventricular hematoma, 3) intracerebral hematoma (ICH) type which showed massive ICH, and 4) subdural hematoma (SDH) type which showed massive SDH.
All patients in the conservatively treated group died except for one vegetative case. On the other hand, the outcome in 57 surgically treated cases was as follows: four (7.0%) fully recovered; 10 (17.5%) were capable of self management; 22 (38.6%) were partially of fully dependent, and 21 (36.8%) died. In the radically treated cases, we investigated preoperative factors that might predict clinical outcome, such as neurological grade, brain stem response, CT findings, response after injection of 20% Mannitol (300-900ml), and time from the last bleeding episode to the operation. It was recognized that there is no relationship between the neurological grade just before radical operation and the outcome in these serious cases. Results were good in patients in each of the following sub-groups: 1) Neurological symptom improved after rapid administration of 20% Mannitol even though the patient was still comatose. 2) Cases in which brain stem responses such as the ciliospinal reflex and oculocephalic reflex were preserved. 3) Surgery could be performed within six hours of the last bleeding episode.
If surgery is performed when any of the above conditions prevail, we feel that completely successful early surgery can be expected. It is important to emphasize, in addition, that our experience shows that a great deal of unfavorable outcome can be eliminated by the evacuation of clots at the time of clipping of the neck of the ruptured aneurysms. Thus, evacuation of the following four types of clots should be included in the surgical procedure: ICH, SDH, IVH and SAH.

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The authors have applied the microsurgical anterior interhemispheric approach (AIH, developed by Z. Ito in 1981) as a surgical approach for anterior communicating artery aneurysms (Aco-AN). AIH has several benefits: brain compression is minor, clot evacuation in the interhemispheric fissure and frontal lobes is possible without significant additional brain retraction; and approaches to the Aco-AN are possible without removal of a part of the brain tissues, such as the rectal gyrus. However, in cases of high- or posterior-positioned Aco-AN and aneurysms proximal to the knee portion in the anterior cerebral arteries (ACA), more interhemispheric dissection and brain retraction cannot be avoided in the aneurysmal operation if AIH is applied.
In these instances, the microsurgical basal interhemispheric approach (BIH) seems to be reasonable in order to make the dissection less extensive since the Aco-AN can be approached more inferiorly than in AIH. BIH was developed for anterior lesions of the third ventricle by N. Yasui, one of the authors. BIH could have the same benefits as AIH, mentioned above, and additional benefits accrue in that interhemispheric dissection is minimal in extension and distance and clot evacuation from the subchiasmatic to the prepontine cistern is possible without additional dissection or brain retraction. The purpose of this paper is to describe the practice of BIH and elucidate its characteristics compared with AI H.
The subjects were 19 patients with ruptured Aco-AN admitted to the authors' hospital from January 1985 to February 1986; BIH was applied in each case. The mean age of the subjects was 56 years. The interval from the last bleeding to the aneurysmal operation was from four hours to six days, with 15 of the patients being operated on within 24 hours. Preoperative consciousness levels showed alertness in nine, drowsiness in nine and semicoma in one. In six patients out of the 19, all the basal cisterns were packed with subarachnoid hematoma detected by CT scan. The operations were initiated under bifrontal craniotomy, applying the same methods as in AIH. In addition, a bilateral vertical craniotomy was performed at the frontal base, approximately 2cm away from the midline, and the anterior wall of the frontal sinus was removed. The first step in the interhemispheric dissection was not performed toward the knee portion of ACA compared with AIH, but to the planum sphenoidale and tuberculumn sellae directly. After aneurysmal clipping, clot evacuation from the subchiasmatic to the prepontine cistern was performed in 11 out of the 19 patients to establish the cerebrospinal fluid (CSF) pathway.
The patients were followed (mean: 6.1 months) and their outcomes were evaluated. Operative results were full recovery in 15 and self-management in four. Postoperative infection, cosmetic problems and olfactory nerve injuries were not experienced. These good outcomes could be the result of factors such as the minimal procedures employed during the operations and the easy establishment of the CSF pathway.
In conclusion, BIH is superior to AIH in cases with a high-positioned Aco-AN. But, it is stressed that both approaches should be undertaken with minimum brain retraction and sharp dissection, especially at the acute stage of subarachnoid hemorrhage.

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Computed tomographyで典型的な被殼出血の所見を呈した破裂中大脳動脈瘤の1例を報告した.症例は44歳の男性, 路上に倒れているところを発見され島根県立中央病院脳神経外科に搬入された.初診時の神経学的重症度はHunt & Hessで3, 左片麻痺と左半身の知覚障害があった.Computed tomographyで右の被殻に高吸収域を認めた.右内頚動脈撮影にて中大脳動脈瘤破裂と診断し, 入院当日に動脈瘤のクリッピングと血腫除去術を施行した.術後, 意識は清明となり左片麻痺に対しリハビリテーションを行った後独歩退院した.本症例は, くも膜下出血を伴わず被殼部の脳内血腫のみで発症した稀な脳動脈瘤破裂の症例と思われる.

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The operative field of the anterior interhemispheric approach depends on the frontopolar vein, height of the endofrontal eminence, and the lamina cribrosa. We measured the distances between the frontopolar vein and the nasion (F-N distance) and the frontopolar vein and the lamina cribrosa (F-C distance) in lateral view of both carotid angiograms (subtraction films) in 67 cases. The frontopolar vein drained bilaterally into the superior sagittal sinus at the frontal pole in 59 cases (88%). In the remaining 8 cases, the frontopolar vein entered into the well-developed frontal cortical vein instead of the superior sagittal sinus and drained into the superior sagittal sinus at the rolandic area. These configurations were found in 2 cases with both sides, in 3 with the right and in 3 with the left side. The F-N distance averaged 4.2cm (ranging from 3 to 6cm) and the F-C distance 5.3cm (ranging from 4 to 7cm). Before using the anterior interhemispheric approach, it is very important and necessary to know the relationship between the frontopolar vein and structures (the endofrontal eminence, the lamina cribrosa and nasion) of the anterior cranial fossa

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Factors affecting the outcome of early surgery (within 72 hours) for ruptured intracranial aneurysms were compared in an elderly and a younger population, and the causes of the relatively poor results among the elderly patients were analyzed. In this study, “elderly” was defined as 65 years of age or older, since the outcome was significantly poorer in these patients. There were 41 elderly patients (13 males and 28 females; 68±3 years old) and 179 younger patients (97 males and 82 females; 52±8 years old). The postoperative outcome, evaluated 3 months after onset, was rated in terms of the ability to carry out daily activities. Dependent and deceased patients were graded as having a poor outcome. The preoperative neurological status was graded according to the classification of Hunt and Kosnik, excluding the factor of serious systemic diseases. The proportion of elderly patients of grades 3-5 was significantly higher than that of younger patients (P<0.05). There was no significant difference in outcome among patients of grade 2, regardless of age. However, among patients of grades 3-5, the outcome was significantly poorer in the elderly group (p<0.05) . Therefore, the possible causes of the poor outcome among elderly patients of grades 3-5 were examined. Medical history, aneurysm rerupture, preoperative computed tomographic findings, surgical complications, vasospasm, and general and neurological postoperative complications were studied in particular. Vasospasm and general postoperative complications were identified as significant causes of poor outcome among the elderly. In addition, the incidence of severe vasospasm was significantly higher in the elderly group (p<0.025). In terms of general postoperative complications, the incidence of heart failure was significantly higher in the elderly patients (p<0.005). All patients who developed general complications also had vasospasm, and five of the seven elderly patients with heart failure developed severe vasospasm. These results suggest that, among elderly patients, poor outcome following early surgery for ruptured intracranial aneurysm is attributable to high incidences of poor preoperative neurological status, vasospasm, and general postoperative complications.

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We have treated 25 cases of ruptured intracranial aneurysms with intracerebral hematoma. There were nine male and 16 female patients, and the mean age was 51 years old. The ruptured aneurysms were located in the middle cerebral artery (MCA) in nine cases, the anterior communicating artery and the distal anterior cerebral artery (ACA) in 14 cases, and the internal carotid artery in two cases. Five of 25 patients died of rebleeding in the preoperative period. Fourteen of 18 patients who were surgically treated were operated on within three days after admission. Preoperatively, one patient was classified as Hunt and Kosnik Grade I, two as Grade II, 12 as Grade III and three as Grade IV. Grade I and II patients had a favorable outcome. Half of Grade III patients had a favorable outcome. However, the other half had an unfavorable outcome mainly due to postoperative symptomatic vasospasm. All Grade IV patients had MCA aneurysms, and had an unfavorable outcome, partly because of delay of surgery or intraoperative complications. In MCA aneurysms. the mass effect of intracerebral hematoma was thought to affect the prognosis; therefore, earlier operation might have improved the outcome of the patients. On the other hand, in ACA aneurysms. a poor outcome was thought to be due to symptomatic vasospasm, not to the presence of hematoma. The extent and gravity of subarachnoid hemorrhage had a great influence on the prognosis in cases where intracerebral hematoma was in ruptured aneurysms without hematoma. In ruptured aneurysms with intracerebral hematoma, especially in MCA aneurysms, early surgery including evacuation of the hematoma might improve the morbidity and mortality of patients.

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We report 4 cases of giant aneurysms in the basilar tip region, comprising 1 large and 3 giant aneurysms located in the basilar tip (2 cases), basilar-SCA (1 case), and PCA (1 case). One of the 4 was ruptured (basilar tip aneurysm). The symptoms were headache (3 cases) and oculomotor palsy (1 case; basilar-SCA). All aneurysms had unilateral internal carotid artery occlusion. In all cases the aneurysms were clipped following EC-RA-M2 bypass to prevent ischemia at the area of the occluded internal carotid artery and to reduce hemodynamic stress within the aneurysm. The clinical courses of 2 basilar tip aneurysms were good but 1 basilar-SCA aneurysm re-grew and ruptured 4 years later after incomplete clipping of the aneurysm. In 1 PCA aneurysm a new basilar tip aneurysm occurred that grew progressively. We consider that the cause of these aneurysms was hemodynamic stress due to internal carotid artery occlusion. It is suggested that the internal carotid artery should not be occluded without an EC-RA-M2 bypass.

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The effect of intracerebral hematoma (ICH) on the clinical manifestations and prognosis was studied in 486 consecutive cases with ruptured aneurysm at the acute stage. Grade III and IV cases were investigated with special interest because the indication of early surgery for these groups is thought to be still in controversy. Conclusions obtained from this study are as follows: 1) The poorer the grade from II to V on admission, the higher the incidence of ICH is.
2) ICH is rarely seen in cases with aneurysms in the vertebro-basilar system. In the anterior circulation, middle and anterior cerebral artery aneurysms are more often accompanied with ICH than those on the internal carotid and anterior communicating arteries.
3) At grade III and IV, cases with major neurological deficit (ND) such as hemiparesis or aphasia more frequently have ICH. Prognosis evaluated on the Glasgow outcome scale, however, is not worse in cases with ND or ICH than those without these seemingly harmful factors provided that they are managed properly.
4) Incidence of symptomatic vasospasm is less frequent in cases with ICH than those without it, and the differce between these two groups is statistically significant at Grade IV.

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The only way to prevent venous brain injury is to meticulously preserve the veins. In every surgical approach, there are various bridging veins blocking access to the subarachnoid space. It is necessary to understand venous anatomy, such as frontal bridging veins for the interhemispheric approach, sylvian veins for the pterional approach, and temporal bridging veins for the subtemporal approach. High-quality cerebral angiography is necessary for adequate pre-operative evaluation of venous anatomy.
With the advent of new-generation CT scanning, 3D-CT angiograms using 64 slice scanners offer an alternative means of preoperative evaluation of the venous system. Indeed, CT venogram might be superior to conventional cerebral angiography in obtaining 3D anatomical information before surgery. Meticulous microsurgical technique is essential to preserve the venous structure during surgery, as are the appropriate use of high magnification and good illumination, moist operative field, careful dissection and minimized retraction.
Vein preservation must be a critical part of surgical strategy, and perhaps the most important point in vein preservation is to keep the importance of those veins in mind at all times. To learn several techniques of vein preservation aids in the surgical strategy, and keeps the skills of the surgeon polished.

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脳主幹動脈の閉塞性病変を合併したくも膜下出血の症例に対して, 脳動脈瘤クリッピングと同時に行う脳血行再建術の意義について検討した.くも膜下出血にて発症した症例のうち, 頸動脈あるいは中大脳動脈に高度狭窄, 閉塞を合併していた5症例 (総頸動脈閉塞症1例, 内頸動脈閉塞症1例, 中大脳動脈狭窄症3例) を対象とした.頸動脈閉塞症の2例ではWillis動脈輪を介する良好な側副血行路が認められたため, 脳血行再建術は行わなかった.症例性脳血管攣縮は生じなかった.中大脳動脈狭窄症1例で脳血行再建術を行わなかったところ, 1週間後, その領域に広範な脳梗塞が出現し重篤な神経症状が残存した.ほかの2例に対しては脳動脈瘤クリッピングと同時に浅側頭一中大脳動脈吻合術を行ったところ, 症候性脳血管攣縮は生じず経過良好であった.このような症例に対する脳血行再建術は, 適応を明確にした上で行えばきわめて有効と考えられた.

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