An intracranial artery dissection has been recognized as a proper and definite clinical entity associated with subarachnoid hemorrhage (SAH), but true clinicopathological features of this disease have not been adequately elucidated. In this study, we investigated the pathological features ith angiographic correlates of 10 autopsied cases of an intracranial artery dissecting aneurysm and related lesions with SAH, including a case of dorsal wall aneurysm of the internal carotid artery or unknown-origin SAH.
Pathological study revealed that all 10 patients had a ruptured site on the lateral wall of the basal artery, and these lesions were classified into the following 3 categories: 1) fusiform dilatation, 2) lateral protrusion, 3) no dilatation. Three lesions of “fusiform dilatation” formed anenlarged aneurysm with false lumen and were thought to be a typical dissecting aneurysm. Four lesions of “lateral protrusion,” including ICA dorsal aneurysm, had no false lumen and formed a pseudoaneurysm at the arterial wall not related to the arterial divisions. Three other lesions of “no dilatation” were clinically diagnosed as SAH of unknown origin, although angiographic finding of diffuse narrowing was oberved at the ruptured site. Intra-wall dissecting hemorrhage without luminal connection was histopathologically identified as an origin of SAH.
Some characteristic information revealed in the previous reports was included in this classification, and good correlation between the pathological features and angiographic findings was seen. We conclude that this classification should be useful in discussions of the various clinicopathological subjects of the intracranial artery dissection.

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The retrogradely investigated results of 80 surgical treatments of unruptured cerebral aneurysms. The aneurysms were located at the internal carotid artery (35 aneurysms), the middle cerebral artery (32), the anterior communicating artery (9) and the vertebrobasilar artery (6). There were 17 large or giant aneurysms involving 3 middle cerebral arteries and 4 vertebrobasilar arteries. Somatosensory evoked potential (SEP) was intraoperatively recorded in 42 patients. Amplitude of N20/P25 was especially observed. The operative field was observed using an optic fiberscope in some patients. Blood flow in aneurysm or parent artery was examined by Doppler microvascular sonography.
Seven of 38 patients without SEP monitoring had postoperative neurologic deteriorations, including 3 patients with permanent neurologic deficits. On the other hand, 5 of 42 patients with SEP monitoring had reversible postoperative neurologic signs but no permanent deficits. Changes in SEP of these 5 patients were significant decrease in the amplitude of N20/P25 or disappearance of the N20. However, these changes in SEP were recovered at the end of the operations. Patients who demonstrated no significant decrease in the amplitude of N20/P25 had no neurologic deterioration.
Causes of significant decrease in the amplitude of N20/P25 included retraction of the brain (5 patients), temporary clipping (2), retraction of the internal carotid artery (2), occlusion of the middle cerebral artery (1), and occlusion of the perforating artery of the posterior cerebral artery (1). Seven of 16 patients with large or giant aneurysm demonstrated significant decrease in the amplitude of N20/P25. Doppler flowmetry was useful for detecting incomplete occlusion of aneurysm and patency of the parent artery. The optic fiberscope was also useful for confirming no sacrifice of the vessels near the aneurysm.
We conclude that SEP monitoring is a reliable method for safe operation of unruptured aneurysms, especially large or giant aneurysms, and in the patients with ischemic vascular disease. In addition microvascular sonography Doppler and optic fiberscope are helpful in decreasing operative complications.

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We report the experience of drill-off of the endostosis of the posterior clinoid process in clipping the aneurysms around the basilar bifurcation. Elimination of the endostosis is effective in cases with aneurysms around the basilar bifurcation, which is accessible in the pterional approach, and with endostosis of the posterior clinoid process, which obstructs access to the interpeduncular cistern. For the meticulous drilling procedure, it is necessary to make a wide working space by thorough opening of the sylvian fissure. It is also important not to use protectors such as cottonoid and multiple rubber dams, which can be caught in the drilling bar.

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We evaluated newly developed titanium clips for the treatment of cerebral aneurysm in terms of postoperative radiological findings and practical problems on the clinical application, as compared with cobalt alloy clips. Twenty-six patients with 29 saccular aneurysms operated on using Yasargil titanium clips (AESCULAP Co.) were analyzed. Titanium clips produced far fewer artifacts on both CT and MR images than cobalt alloy clips did, which enables postoperative radiological evaluation on the brain and vascular structure around the clips. However, 5 aneurysms that normally could be clipped by single conventional clip required multiple clips because of insufficient closing forces of the first clip. In addition, two clips were distorted easily during repeated clip application, which we never experienced in conventional clips. These facts suggested that titanium clips might be inferior to cobalt alloy clips in mechanical characteristics in contrast with their superiority in radiological features. We conclude that titanium aneurysm clips should only be used in selected cases and not considered for routine use in aneurysm surgery.

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To evaluate the clinical outcome of microsurgery, gamma-knife radiosurgery, and conservative treatment, we retrospectively reviewed 96 consecutive patients with cerebral arteriovenous malformation (AVM) in the thalamus and basal ganglia, treated at our institute between 1971 and 1995.
Among 16 patients treated conservatively, 10 patients (62.5%) bled during the follow up period (2-11 years). Eight of these 10 patients with a history of bleeding had rebleeding. The mortality of hemorrhage was 60.0% and morbidity was 20%.
In 15 patients who underwent surgical resection, no patients showed deterioration of pre-existing hemiparesis after surgery, while newly developed mild hemiparesis was recorded in 4 of 7 patients who showed no paresis before surgery. Speech dysfunction was persisted after resection in only 1 of 6 patients with dominant side AVM. Visual field defect permanently persisted after surgery in 5 patients.
Sixty patients underwent gamma knife radiosurgery. The actuarial obliteration rate of AVM was 28.8% at 1 year, and 85.7% at 2.5 years. Radiation induced brain edema was observed in 12 patients (20.0%). However, permanent neurological deterioration after radiosurgery was observed in only 3 patients (5.0%), who showed deterioration of pre-existing hemiparesis. Hemorrhage during the latency interval occurred in 3 patients (5.0%). In 1 patient, deterioration of hemiparesis associated with optic visual loss was permanently recorded after hemorrhage.
Patients' final outcome after surgery was good except for 1 patient who suffered intracranial hemorrhage during rehabilitation. No patient experienced a deterioration in activity of daily living after gamma knife radiosurgery, except for 1 patient who suffered rebleeding. As a result, overall management outcome for AVM in the thalamus and basal ganglia improved after gamma knife installation, because inoperable AVMs were successfully treated radiosurgically.
In conclusion, prognosis of patients with a history of hemorrhage was poor if conservatively treated. Such patients should be treated to prevent further bleeding. Patients with hematoma cavity around the nidus who present hemiparesis should be surgically extirpated, especially if the nidus is located in the thalamus and caudate nucleus. Patients without a clinical history of hemorrhage, or patients without neurological deficits should be radiosurgically treated, if the nidus is small. Patients with large nidus and a history of hemorrhage should be first treated with embolization, and then treated by either surgical resection or irradiation.

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We report 2 cases with occlusion of the parent artery after wrapping of cerebral aneurysm. In a 57-year-old male patient, infundibular dilatation of the posterior communicating artery was wrapped with Bemsheets (Bemlyse, 100% cotton linter) applied to the entire internal carotid artery (IC) circumferentially. Two months later, he presented with right hemiplegia and aphasia. Angiography revealed total occlusion of the IC. In another 55-year-old female patient, a left middle cerebral artery (MCA) aneurysm was clipped and the residual dome was wrapped with Bemsheets including MCA trunk, with an additional coating of fibrin glue. Disappearance of aneurysm and occlusion of the MCA was visualized on angiography two months after surgery.
Although Bemsheets are one of the best wrapping materials for cerebral aneurysm, inflammatory granulation develops, causing delayed stenosis or occlusion of the parent arteries. These occlusive complications should be avoided by wrapping without including the entire parent artery.

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The embolization of the cerebral arteriovenous malformation (AVM) is useful to prevent bleeding from the nidus under direct surgery. But various factors, such as emergency cases due to massive bleeding or when preoperative embolizations are difficult, have prevented it.
Over the past 4 years we attempted embolization using fibrin glue and pyoktanine during direct surgery for such cases.
In this procedure the craniotomy is done in the usual manner and the main feeder of the AVM is cannulated.
Angiography is done prior to embolization via this cannulation tube. Then fibrinogen mixed with tiny amounts of pyoktanine and thrombin with contrast material is injected simultaneously. The feeders and the niduses of the AVM are clearly distinguished from the surrounded structures and hematoma after embolization because they are stained with pyoktanine. In addition the softness of the AVM is maintained. This makes ease of the AVM removal without destruction of the surrounding glial tissue. No cases showed massive bleeding after embolization during the removal. This embolization method with fibrine glue is very useful for several reasons. We can use this method for the emergency operations without special catheters. The AVM is very distinguishable visually because it is stained with pyoktanine.
The problem of this method is transient hypotension just after the injection of fibrin glue and pyoktanine. This hypotension was observed in 2 of seven cases. We cannot explain the cause, but the fibrine glue and pyoktanine may be involved. This phenomenon is just transient. The blood pressure recovered immediately. In addition pulmonary embolism was not observed in these cases. This phenomenon should be studied further.

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Surgical treatment of internal carotid artery aneurysms around the carotid siphon is an art that is described elaborately in this paper. The surgical approach to the aneurysms in this region, is as follows: 1) A fronto-temporal approach with the patient in a 45° semi-sitting position to decrease venous pressure. 2) A Dolenc's approach cutting a part of the dura mater of the superior orbital fissure to facilitate removal of the anterior clinoid process and unroofing of the optic canal. 3) Opening of the medial triangle followed by transection of the optic canal dural sheath. Carotid siphon aneurysms can be divided into 3 groups anatomically: aneurysms of the ophthalmic segment (C2), those of the clinoid segment (C3), and those of the horizontal segment (C4). We present 34 cases of aneurysms arising from the C2 or C2/3 segment, 15 cases arising from the C3 or C3/4 segment, and 11 cases arising from the C4 segment. Anatomic localization of the aneurysms was established preoperatively by angiography and three-dimensional CT imaging. Small aneurysms of the ophthalmic segment projecting inferomedially can be clipped using a contralateral approach via the prechiasmatic root.
Aneurysms of the ophthalmic segment projecting superiorly can be clipped following resection of the anterior clinoid process. The clinoid process should be resected intradurally with direct visualization of the aneurysms. Straight side-angled clips are suitable for these aneurysms. Carotid cave aneurysms, which include aneurysms of the ophthalmic segment oriented inferomedially and of the clinoid segment projecting postero-medially, can be clipped using curved fenestrated clips via Dolenc's extradural approach. For accurate clipping, opening of the medial triangle and full mobilization of the IC at the clinoid segment and optic nerve by unroofing the optic canal are required.
Aneurysms of the horizontal portion are clipped after full exposure of the artery in the cavernous sinus only when the aneurysms are large and symptomatic. We used the fronto-temporal and Dolenc's approaches and applied fenestrated clips to aneurysms oriented postero-medially and straight or oblique clips to aneurysms projecting antero-laterally. Out of 52 aneurysms that underwent surgical clipping, 46 resulted in good post-operative recovery. There were 3 deaths secondary to complications of vasospasm and 3 cases with postoperative visual loss. We highlight the classification of these aneurysms and the surgical techniques we had employed.

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We analyze surgical results of 32 consecutive patients with intradural giant aneurysms. Using temporary clipping of parent artery, dome decompression by needle aspiration, and multiple clipping, 28 of 32 aneurysms were clipped. Proximal artery occlusion was performed for 2 vertebral aneurysms, and dome coating was done for 1 basilar aneurysm and 1 vertebral aneurysm. Surgical outcome was excellent in 17 patients, good in 7, fair in 3, poor in 1, with 4 death. The location of aneurysm had the biggest influence on the surgical outcome, and aneurysms located in the posterior cranial fossa tended to have poor results. The preoperative grade also influenced the results of ruptured cases. Another factor affecting the results was premature rupture during aneurysmal manipulation.
Five internal carotid artery aneurysms, 3 middle cerebral artery aneurysms, 1 basilar tip aneurysm, and 2 vertebral artery aneurysms harbored intra-aneurysmal thrombi. The thrombosed aneurysms of the internal carotid artery were successfully clipped, but some of those in the middle cerebral and basilar arteries showed poor outcome.
In conclusion, we recommend direct surgery for intradural giant aneurysm in the anterior circle of Willis, even for thrombosed aneurysms. For cases with giant basilar artery aneurysm, especially thrombosed one, strong brain protection with deep hypothermia, barbiturate administration, etc. should be considered during surgical intervention.

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A minor modification of Sugita's fenestrated angled aneurysm clip allows complete neck clipping, especially for the ophthalmic segment aneurysms (suprasellar and paraclinoid variants). The blade of this clip is curved upward to just fit the medial-to-lateral bend of the internal carotid artery (C3-C2 portion), where the aneurysm neck is located. Since it is not rare to be unable to clip the aneurysm neck properly with the existent style of clip due to the presence of surrounding structures and the bend of the parent artery (both anterior-to-posterior and medial-to-lateral), this simple modification by curving the blade of Sugita's fenestrated angled aneurysm clip might be particularly useful for the complete aneurysm neck clipping of the ophthalmic segment aneurysms.

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High positioned basilar top aneurysms (BTAs) present especial technical problems when approached by the conventional pterional or subtemporal approach. Particularly when the aneurysm is posteriorly projected, visualization of the perforating branches is extremely difficult even by the use of newly devised zygomatic approaches. We recently had a 60-year-old female patient with such a BTA, which was discovered in the course of a checkup for sudden headache.
While the the patient wanted surgery after having been well informed, the use of conventional approaches requiring overt brain retraction was considered extremely dangerous because a small infarct in the right basal ganglia was found in the preoperative MRI scan. Therefore, we decided to use the anterior transcallosal approach (ATA), which makes it possible to view the aneurysm and the perforating branches from above, namely through the floor of the IIIrd ventricle. The aneurysm was successfully and easily clipped by this approach. The postoperative course was uneventful except for a transient disturbance of recent memory. We describe the technical features of this approach and discuss its feasibility for the treatment of high positioned BTAs.

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