Endovascular treatment of cerebral aneurysm has been established with the development of Guglielmi electrolytically detachable coils (GDC). The GDC system has become the gold standard for endovascular occlusion of intracranial aneurysms. Recent advancements in imaging technology and biomedical engineering also contribute to the safety and effectiveness of endovascular neurosurgery. In this paper, we review advancements in endovascular technology and training systems.

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Ischemic cerebrovascular disease is one of the most common diseases in Japan. Recent advancements in neuroradiological diagnostic modalities enabled us to make a precise pathophysiological diagnosis with each patient in the acute stage. Moreover, various drugs are available to treat patients on a pathophysiological basis. However, in clinical settings, progressing stroke, seen in 5% to 15% of cerebral infarction, is a major problem that worsens patients' outcomes. Rho kinase inhibitor may be a new option among the various treatment drugs for cerebral ischemia in the acute stage.

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We report on 4 patients surgically treated for ruptured aneurysm after incomplete coil embolization. Aneurysm was found in the anterior communicating artery in 3 patients and in the middle cerebral artery in 1. However, follow-up angiography revealed refilling of the aneurysm or enlargement of the residual neck. Prior to neck clipping, the coils were removed in 3 patients. Neck clipping was possible without coil removal in the remaining patient. There was no surgical morbidity and their final outcome was satisfactory. We discuss unique technical difficulties and pitfalls for neurosurgeons, and emphasize the possibility of the staged care strategy for poor-grade patients with subarachnoid hemorrhage

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There are many studies about asymptomatic unruptured cerebral aneurysms (AUAn), but we still have no evidence for those treatments. We report the management and treatment results for patients with AUAn in our department.
In principle, the decision to operate for AUAn was based on the guideline of the Japanese Society for Detection of Asymptomatic Brain Diseases. As regards informed consent, hemorrhage risk of AUAn was explained with the use of a table showing lifetime risk for patients with AUAn. Intraoperative digital subtraction angiography (DSA) and microvascular Doppler sonography had been routinely utilized since May 1997 in surgical clipping. A portable DSA unit (Siremobil 2000, SIEMENS) was used for intraoperative DSA.
We reviewed clinical features of 88 cases with 111 AUAns (30 males, 58 females, 63 years old±11 years) that were diagnosed and underwent angiography between January 1992 and July 2003. Fifty-one cases (58%) were treated, and 37 cases (42%) were untreated. Fifty-five aneurysms were treated with clipping and 1 aneurysm was treated with endovascular coil embolization.
By introduction of informed consent with the guideline and lifetime risk for AUAn, the patients who did not choose an operation had increased. Moreover, the patients aneurysmal size under 4mm in diameter and the patients aged over 70 years had tended to follow up without surgery. Of the 28 aneurysms evaluated by intraoperative DSA, there was no complication with the technique of angiography. After introduction of intraoperative DSA and microvascular Doppler sonography, the morbidity had decreased from 15.4% to 7.1%.
Informed consent with the guideline and lifetime risk for AUAn is useful whether patients choose an operation or not. We believe the use of intraoperative DSA and microvascular Doppler sonography is effective because it improves the result of clipping.

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We evaluated the feasibility of using Split-dose iodine-123-IMP SPECT for identifying the hemodynamic status in patients with bilateral carotid artery occlusive diseases. We studied 8 patients with angiographically-confirmed bilateral severe occlusive lesions (occlusion or >70% stenosis) in the cervical carotid artery. Of these patients, we performed carotid artery stenting (CAS) for carotid artery stenosis in 4 patients with contralateral carotid occlusion and for the symptomatic side in 1 patient with bilateral carotid stenosis. The remaining 3 patients were medically treated. The rest regional cerebral blood flow (rCBF) and cerebrovascular reactivity (CVR) were quantitatively evaluated twice by the split dose method before and after CAS. CAS for 1 side in patients with bilateral carotid artery occlusive diseases improves cerebral hemodynamics not only on the side of CAS but also on the other side.
Split-dose iodine-123I-IMP SPECT is useful for evaluating the hemodynamic status in bilateral carotid artery occlusive diseases.

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We evaluated treatment results of 109 patients with ruptured cerebral aneurysms when we employed endosaccular coil embolization instead of surgical clipping if sufficient obliteration rate was predicted. Endosaccular coil embolization was applied to 14 (12.8%) and surgical clipping was used for the other 95 patients. The reasons why endosaccular coil embolization was not indicated were presence of intracranial mass lesions such as intracerebral, intraventricular or subdural hematoma in 15, renal failure in 1, uncertain ruptured site in multiple aneurysms in 13, possibility of dissection in 3, inaccessibility in 2 and inadequate size and configuration in 61. Eighty-three of 109 (76.1%) patients were assessed as modified Rankin scale better than 2 in 3 months. Sufficient obliteration rate such as complete or neck remnant was achieved in 12 of 14 (85.1%) patients treated with endosaccular coil embolization. Occurrence and severity of cerebral vasospasm, secondary hydrocephalus and hospital days were less in patients treated with coil embolization.
When endosaccular coil embolization was used to treat ruptured aneurysms if a sufficient obliteration rate was predicted and surgical clipping was employed for others, indication of endosaccular coil embolization was still limited but treatment results were acceptable. Improvement of technique for complete obliteration in endosaccular coil embolization will expand the indication of coil embolization for patients with ruptured cerebral aneurysms, and it may help reduce cerebral vasospasm, secondary hydrocephalus and hospital days.

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Since 1997, we have used a preoperative surgical scoring for the surgical indication of unruptured cerebral aneurysms. The score includes aneurysm size (0: below 14 mm, 1: 15-24 mm, 2: over 25 mm), location (2: posterior fossa, 1: carotid cave, 0: others), associated systemic disease (0: none, 1: one, 2: two or more), and multiplicity (0: single approach, 1: multiple surgery). We investigated whether indication and complication differ before and after induction of scoring. There were 84 operated cases before induction of scoring and 55 cases after induction of scoring.
Compared to cases before induction of scoring, the age was higher than cases after induction of scoring. Posterior circulation aneurysms increased after induction of scoring, but 5 of 6 cases were treated with intravascular surgery. Major surgical complication (Rankin scale of III or more) decreased from 3.6 to 1.8% after induction of scoring. The minor complication (Rankin scale below II) did not decrease after induction of scoring.
The results indicate that intravascular surgery in cases of having a high preoperative score can reduce surgical complications.

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We retrospectively analyzed the complication of embolization for cerebral saccular aneurysms in 139 cases.
Sixty-six cases were ruptured aneurysms and 73 cases were unruptured aneurysms. There were 48 men and 91 women, ranging in age from 26 to 90 years (mean age 62.1 years). The clinical Hunt and Hess grades of 66 ruptured cases were as follows: Grade I, 22 cases; Grade II, 7 cases; Grade III, 5 cases; Grade IV, 13 cases and Grade V, 19 cases. The symptoms in 73 unruptured cases were cranial nerve dysfunction in 19 cases and no symptoms in 54 cases. The 114 cases used GDC, 18 cases used IDC and 7 cases used Cook's detachable coil for embolization. The mean follow-up period was 17 months.
There were complications in 11 of our cases (7.9%): bleeding complication in 5 cases (3.7%) and embolic complication in 6 cases (4.3%). The bleeding complications occurred during embolization. The embolic complications were infarction in 4 cases (2.9%) and TIA in 2 cases (1.4%). Permanent morbidity occurred in 6 cases (4.3%) and mortality in 1 (0.72%).
In conclusion, it is important that embolization of aneurysms be done carefully and blood pressure be controlled at operation to prevent bleeding complications. It is essential that anti-coagulation therapy be done at embolization or after embolization for at least 6 months.

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Low molecular dextran is often used in post-operative management of subarachnoid hemorrhage (SAH) to induce hypervolemia and hemodilution; however, its associated complications are not well-known. We retrospectively analyzed prothrombin time (PT%), activated partial thromboplastin time (APTT%), and fibrinogen level as coagulation markers in patients with subarachnoid hemorrhage who developed delayed intracranial hemorrhagic complications after undergoing craniotomy for clipping to examine the effect of long-term use of low molecular dextran on bleeding tendencies.
Fifty-two patients with SAH who underwent craniotomy were divided into 2 groups: 26 without post-operative use of low molecular dextran (Group 1) and 26 to whom low molecular dextran was administered for more than 5 consecutive days (Group 2). Group 2 was further divided into 2 subgroups: those who developed hemorrhagic complications (Group 2A) and those without complications (Group 2B). The frequency of complications in Group 2A was 19% (5/26; 3 with subdural hematoma and epidural hematoma, 1 with epidural hematoma, and 1 with intracerebral hematoma). Complications appeared 7.6 days on average after starting low molecular dextran. Compared with Group 1, PT% and APTT% as well as pre-and post-low molecular dextran administration fibrinogen levels significantly decreased in Group 2A.
Low molecular dextran is known to decrease fibrinogen levels, and patients' clinical conditions and changes in fibrinogen levels should be closely monitored to detect bleeding tendencies when low molecular dextran must be used for long periods.

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The surgery of direct neck clipping of basilar tip aneurysm is still a challenge among various aneurysm surgeries. In this surgery, the transsylvian approach is preferred to the subtemporal approach. There are several tactics to improve operative results. A wider surgical field can be obtained by dissecting the sylvian fissure from the distal segment. And anterior clinoidectomy and unroofing of the optic canal widen the space around the internal carotid artery and its cisternal cavity. Dividing the posterior communicating artery is crucial to managing the procedure. For low-position aneurysms, posterior clinoidectomy by surgical drill is inevitable to secure the temporary clipping on the basilar artery.
The key issue of neck clipping is how to preserve the perforators originating from the basilar tip and P1 segment of posterior cerebral artery. In the first step of clipping, we prefer incomplete dome or neck clipping, which makes detachment of perforators away from the aneurysm much easier. By gently pushing cottonoid or Surgicel underneath the aneurysm, a second clip can be applied for complete neck clipping.
With these tactics, the result of direct neck clipping of basilar tip aneurysm is excellent as long as the aneurysm is smaller than 10 mm.

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We describe techniques for removing previously placed clips. First, the parent artery should be secured to effect proximal flow control. Adherent tissues are dissected by sharp dissecting method using a small knife or microscissors. Then, we open the blade of the clip as little as possible using the clip applier, and the aneurismal clip can be carefully slid out along the line where the clip blade had been. Rough surgical technique might result in rupture of aneurysms. Bypass is also helpful to reduce the risk of ischemia during proximal flow control.

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