The internal carotid artery was occluded by means of intravascular balloon or surgical ligation in 12 cases with negative study of proceeded balloon Matas tests. Of 12 cases, 7 were cerebral aneurysms, 4 carotid-cavernous fistulas (CCF), and one cavernous sinus meningioma. Delayed ischemic symptoms appeared in three of those during the follow-up period after the occlusion. One of them developed hemiplegia 4 days after the proximal ligation, another patient suffered numbness of the left upper extremity a few weeks after occlusion of the ICA, and the third cases sustained a transient ischemic attack 5 years after the operation. Mean stump pressure (MSP) and/or tomographic cerebral blood flow (CBF) measured after ICA occlusion were slightly decreased, but still above the critical value. A focal ischemic region was found in the territory of perforating arteries in 2 of 3 cases. In those patients, postocclusion blood pressure and/or flow studies turned out to be of less value in predicting delayed ischemic symptoms, because the perforating arteries rather than the cortical branches seemed to take part in the symptomatic ischemia. Antiplatelet agents might be necessary to prevent the delayed ischemic complication after permanent ICA occlusion.

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The surgical technique of the transcondylar approach (TCA) for midline vertebral aneurysms is presented, and the differences in the surgical fields between TCA and the lateral suboccipital approach (LSA) are highlighted. Extradural resection of the lateral wall of the foramen magnum, from the occipital condyle to the jugular tubercule, was the most important element for exposure of the aneurysm in this area. Effective bone resection using the TCA enlarged the subarachnoid space around the lower cranial nerves, and offered more surgical space than that of LSA for aneurysm clipping between the nerves. The total length of the vertebral artery was observed with minimal retraction on those nerves. Resection of the JT was necessary when the aneurysm was located close to the vertebro-basilar junction (VBJ), in the area less than 10 mm from the midline on the A-P view of the angiogram, and closer than 12 mm to the internal auditory meatus on the lateral X-ray. One of the shortcomings of the TCA was the necessity of sacrificing or exposing the cervical venous plexus, which continues from the jugular bulb through the supracondylar emissary vein. A preoperative thin-slice bone CT scan offered important information about the variation of the venous system and the size of the JT in each case.

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A retrolabyrinthine presigmoid approach was employed successfully in four patients with aneurysms around the vertebral union. This approach allows excellent access to the vertebral union without resection of the sigmoid sinus, with minimum retraction of the cerebellum and brain stem. This approach can be recommended for not only aneurysms of vertebral union and lower basilar trunk, but also VA-PICA aneurysms that are located close to the midline, in high position from the foramen magnum, and far from the clivus.

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The authors report two AVM cases to establish that the draining veins of the AVMs lead from individual and partly overlapping compartments in the nidus.
The first case was a 62-years-old man who had a large AVM in the left Rolandic area. Its main feeding arteries were the left central sulcus artery, the anterior parietal artery and the lenticulostriate artery. The AVM had two major draining veins; one ran superiorly to connect with the superior sagittal sinus and the other ran inferiorly to empty into the sylvian and basal veins. The anterior parietal artery, feeding the AVM, was treated by preoperative embolization, however, the central sulcus artery was not treated. During the operation, the left anterior parietal artery, lower half of the nidus and a draining vein that was directed inferiorly were thrombosed. However, the central sulcus artery, upper half of the nidus and a draining vein that emptied into the superior sagittal sinus were patent.
The second case was a 19-year-old student who had a medium-size AVM in the right parietal lobe and complained of convulsive seizures. He was admitted to our hospital for embolization. The feeding arteries of this AVM were the middle cerebral artery and anterior cerebral artery. Two major draining veins emptied into the superior sagittal sinus. As the feeding arteries were so long and tortuous that the embolization was difficult using Seldinger's method, embolization via the craniotomy was performed. During surgery, when the contrast medium was injected at the anterior part of the nidus, the anteriorly directed draining vein was visible. When the contrast medium was injected at the posterior part of the nidus, the posteriorly directed draining vein was visible.
As a result of these findings, we concluded that the nidus of the AVM was divided into compartments.
This compartmentalization of the nidus can be determined by the draining veins. The DSA and embolization have clarified the anatomical and functional vascular structures of AVMs, especially the relationships between feeding arteries, compartments of the nidus and draining veins. This concept will help the investigation of vascular structures of AVMs. Application of this concept will allow for safer embolization, lower hemorrhagic risk and improved planning for AVM surgery.

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We have experienced six cases of arteriovenous malformation (AVM) treated by intravascular embolization followed by surgical removal. The embolic materials we used were liquid form of polyvinyl alcohol in which we suspended silk thread, ethylene vinyl alcohol copolymer, methylcellulose, and lipiodol. The surgical removal was done 1 week to 5 months after surgery. The best advantage of preoperative embolization is to change high-flow AVM to low-flow status. Besides this, embolization simplified the surgical approach because feeder occlusion was not needed. The occluded artery changed its color to dark red, indicating a surgical orientation was the right choice. Small feeders from deep perforators were not occluded by embolization and remained troublesome. Preoperative embolization was useful for removal of AVM if keep in mind its benefits and disadvantages.

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Saccular intracranial aneurysms almost always arise at arterial bifurcations; however, ventral paraclinoid carotid aneurysms arising from the internal carotid artery in the segment between the ophthalmic artery and the posterior communicating artery (“ophthalmic segment”) may have no obvious arterial branches at their origin. The superior hypophyseal arteries usually arise from the ophthalmic segment and pass ventrally and medially beneath the optic nerve to irrigate the optic nerve, pituitary stalk, and the hypophysis. We have documented intraoperatively three cases of saccular aneurysms arising from the superior hypophyseal artery take-off from the internal carotid artery. The age at presentation was 62, 50 and 63 years old, respectively. All three patients were female. Two patients experienced subarachnoid hemorrhage attributable to their superior hypophyseal artery aneurysms. The remaining patient presented with subarachnoid hemorrhage related to another aneurysm, and in the course of evaluation was found to have a second, incidental superior hypophyseal artery lesion. Angiographically, superior hypophyseal artery aneurysms were invariably noted on the inferior medial surface of the internal carotid artery slightly distal to the ophthalmic artery origin. At surgery, exposure of the cervical internal carotid was performed to gain proximal arterial control. The anterior clinoid process and optic canal roof were removed to provide proximal visualization of the neck of the aneurysm. In two cases, the aneurysm was easily obliterated with angled fenestrated clips, the blade of which passed over and then ran parallel to the internal carotid artery. All three patients were discharged without neurological deficit.

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So far there has been two ways of performing intraarterial thrombolysis for acute embolic stroke: regional and local thrombolysis. If thrombolysis is done with a catheter tip placed in the cervical cerebral artery, it is called regional thrombolysis, and if it is done with a catheter tip placed in the intracranial cerebral artery, it is called local thrombolysis.
In this report, we introduce a new technique for the further improvement of efficacy of intraarterial thrombolysis. This technique could be briefly summarized as follows: first, a tip a 0.016″radifocus GT guide wire was passed beyond an embolus with the aid of DSA roadmaps, then a radifocus GT catheter was advanced and a tip of the catheter was placed just distal to the embolus, where injection of a fibrinolytic agent was initiated to dissolve an embolus from distally. We have modified and refined this technique, introduced by Herman Zeumer, and called this technique “central thrombolysis” to stress the closed relationship of catheter tip to embolus. Points of prime importance to prevent perforation of vessel wall are as follows:
1) Meticulous manipulation of a catheter and a guide wire with the aid of:
2) high quality roadmap on DSA,
3) high-torque and low-friction guide wire, and low friction and floppy catheter.
The advantages of “central thrombolysis” were confirmed on clinical cases, i.e. a greater number of arteries were recanalized with fewer doses of fibrinolytic agent and less time.

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Paramedian vertebral aneurysms in the lower third clival region are one of the most difficult lesions to access surgically. Although several approaches with drilling of the skull base have been considered for aneurysms in this region, successful clipping in the acute stage without permanent neurological deficits is thought to be extremely rare. We experienced a case of VA-PICA aneurysm located 6 mm across the midline that was successfully clipped in the acute stage via the far-lateral suboccipital approach. The usefulness of this approach is reported in this paper.
A 52-year old female was admitted to our hospital suffering from severe headache. Right vertebral angiography revealed a right VA-PICA aneurysm located 6 mm across the midline towards the left. The pre-operative condition of this patient was classified as Hunt and Kosnik's grade 1. Direct clipping was completed on day 0 via the far-lateral suboccipital approach. The long straight clip (Sugita No. 18) was applied above the hypoglossal nerve by left hand, permiting microscopic visualization of the aneurysm below the hypoglossal nerve. Transient vagal and hypoglossal nerve palsy noted post-operatively were restored within a week. The post-operative vertebral angiography revealed complete clipping of this aneurysm.
The far-lateral suboccipital approach, in which the postero-medial third of the occipital condyle is drilled out, permits access to the midline, lower third clival region from the extreme infero-lateral direction. Excessive retraction against the brainstem and obstruction of the operative view by the lower cranial nerves are therefore minimal with this approach. The wide longitudinal operative field afforeded by this approach allows insertion of the clip from various directions and acute stage operation. An additional drilling of the jugular tubercle should also be considered depending on the height of the aneurysm.

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Preservation of large draining veins bridging the cortex and sinuses is extremely important for prevention of postoperative intracerebral hemorrhage. The vein of Labbé is also important and has been preserved during subtemporal approach using the arachnoid dissecting technique, partial cortex removing technique and intermittent retraction technique. But these techniques have absolute limitations because the subtemporal approach passes through a space between the tentorium and the temporal cortex.
We have performed the presigmoidal transpetrosal transtentorial approach preserving the vein of Labbé by the following technique. After completion of lateral suboccipital craniectomy and temporal craniotomy, the sigmoid sinus has been completely exposed to the jugular bulb epidurally. The superior petrosal sinus has been ligated and cut between two ligatures. The tentorium has been completely cut.
In some instances, there are small bridging veins draining into the tentorium. In these cases, tentoriotomy is performed in front of the entrance of these veins. After cutting the tentorium, the sigmoid sinus has been mobilized posteriorly and the tentorium, the transverse sinus, the vein of Labbé and the temporal lobe superiorly. In this technique, the vein of Labbé and the temporal cortex can be mobilized together in the same direction and there is no traction force between them. This technique is quite important and useful for preservation of the vein of Labbéduring skull base surgery.

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