To improve the safety of aneurysmal clipping as well as to develop neurosurgical skills of residents simultaneously, we present the technical details and setting adopted in our institution. Between 2006 and 2011, we experienced 379 aneurysmal clipping surgeries (209 ruptured, 170 unruptured) at Fuji Brain Institute and Hospital. With daily thorough in-vitro microsurgical training, we performed standard-sized craniotomies with open fissures such as the sylvian fissure or interhemispheric fissure, to obtain a safe wide surgical field for clipping to compensate for the lack of experience in young neurosurgeons. We made every effort to be meticulous rather than fast to maintain treatment safety. To enhance the understanding for the surgical setting, method and strategy, we standardized procedures in detail to maximize the practice effect for residents with a limited amount of surgical experience. We discuss our institutional experiences in developing the surgical skills of young neurosurgeons, with the aim of having residents perform real neurosurgical micro-operations under the supervision of a staff doctor without compromising safety.

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We describe the basic methods of clipping of cerebral aneurysms in our hospital, as follows:
1) Examine the cerebral angiography carefully and practice the procedures in advance before operations.
2) Prepare various monitoring procedures such as motor evoked potential (MEP), ICG video-angiography, and vascular Doppler to support safe and accurate operations.
3) Perform the very precise microscopic technique under magnification while also remaining aware of the whole operative field.
4) Develop the necessary operative field with dissecting vessels which to belong.
5) Prepare steps to deal with aneurysmal rupture at all times throughout operations.
6) Dissect branches and perforators adhered to the aneurysm as thoroughly as possible.
7) Master the skill of anastomosis in case of neck tearing or direct revascularization.

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Background: Surgical clipping of the internal carotid artery–anterior choroidal artery aneurysm (ICA–AchA AN) has some risk of ischemic complications. One reason for this is the multiplicity of the AchA branches. We report our experience with the surgical clipping of the ICA–AchA ANs.
Methods: We treated 36 cases of ICA–AchA AN between May 2007 and April 2012, and classified them based on the origin of the AchA by intraoperative investigation. We used two techniques for clipping the ICA–AchA AN. The rotation technique was used to observe the origin of the AchA behind the aneurysm, and the blading technique was used to visualize the neck of the aneurysm by tipping the clip blade back and forth. Clipping was performed with motor evoked potential (MEP) monitoring in 13 cases of unruptured aneurysms, indocyanine green (ICG) videoangiography in 27 cases, and doppler sonography in all cases.
Results: There were no postoperative ischemic complications. The origins of the AchA were at the proximal neck in 29 cases (80.6%), at the proximal and distal necks in three cases (8.3%), and in a direct branch from the aneurysmal dome in four cases (11.1%). Not all branches were visible on preoperative CT angiography and 3D-rotational angiography. We applied clips carefully to preserve any AchA branch, and no changes in MEP waves were observed. In one case, we repositioned the clips because the ICG videoangiography findings were inconclusive. Postoperative courses were uneventful in all patients, except for seizure in two and transient oculomotor palsy in two.
Conclusion: To avoid ischemic complications after clipping of the ICA–AchA ANs, microscopic visualization of the origin and the direction of the AchA is very important. Moreover, using Doppler sonography, ICG videoangiography and MEP monitoring can produce good surgical results.

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The indications for surgical treatment in spontaneous intracerebral hemorrhage has been controversial. The objective of this study is to evaluate the less invasive hematoma evacuation technique by using the endoscope improving the functional outcome for the patient with spontaneous putaminal hemorrhage.
Materials and Methods: We retrospectively reviewed patients with spontaneous putaminal hemorrhage treated in Juntendo University Shizuoka Hospital between 2001 and 2011. A treatment group using endoscope (n=44) was compared with a patient group treated by the conventional surgery (n=14) or conservative therapy (n=21). In all patients, the hematoma volume prior to surgery was between 30 ml and 59 ml. Surgical hematoma evacuation had been performed within 72 hours after onset. Patient severity was recorded in ICH scores. The outcome was evaluated by modified Rankin scale (m-RS) and the 30-day mortality in each group.
Results: The patient populations did not statistically differ in any of the groups. Patient severity was similar in all three groups. The functional outcome in the endoscopic group was significantly better than in both the craniotomy surgery group and the conservative treatment group (p<0.05). Thirty-day mortality in the conservative group was higher than in the surgical treatment groups.
Conclusion: The neuro-endoscope is safe and useful for the surgical treatment of intracerebral hemorrhage. As optimal surgical indications for the endoscopic hematoma evacuation, the hematoma volume should be from 30 ml to 59 ml in patients with moderate neurological deficits. As further study, a randomized controlled trial must be conducted in the future.

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Objective: Patients with spontaneous intracerebral hematoma (ICH) often develop symptoms associated with hematoma expansion, which worsens their prognosis. We evaluated the risk factors for the enlargement of hematoma.
Materials and Methods: Stroke patients are diagnosed by CT followed by perfusion CT and 3D-CT angiography as a department policy. We retrospectively reviewed 123 patients hospitalized between Apr. 2008 and Dec. 2010. Among them, 27 patients (22.0%) showed hematoma enlargement within 24 hours after hospitalization. We compared the clinical characteristics of patients with and without hematoma enlargement.
Results: There were significant differences in the initial size of the hematoma, spot sign, and pretreatment with anticoagulants, but not in hypertension, diabetes mellitus, or pretreatment with antiplatelets.
Conclusions: We confirmed that the initial size, spot sign, and anticoagulants were risk factors for hematoma enlargement. Careful follow-up is needed for ICH patients with these factors.

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A double cerebral protection system can resolve the intolerance to flow blockage, which is a problem with proximal protection devices. The goal of this study was to investigate the efficacy of a double cerebral protection system using distal filter and proximal embolic protection devices in carotid artery stenting (CAS). Diffusion-weighted MR imaging (MR-DWI) and major adverse events were used to evaluate this protective procedure. Between April 2008 and February 2010, CAS was performed for 69 sides. Twenty-one patients with high-risk lesions underwent CAS with double cerebral protection. New cerebral ischemic lesions were detected on MR-DWI in 14% (3/21) of the patients. There were no strokes, deaths, or myocardial infarctions within 30 days after the procedure. Three patients did not tolerate carotid artery flow reversal. However, a double cerebral protection system can easily be overcome to realize successful stenting. High-risk lesions can be safely treated with CAS using a double cerebral protection system.

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The surgical skill of STA-MCA anastomosis has been reported to be trainable through several off-the-job practices, including suturing gauze fibers. We report a new method using a raw STA graft that can be obtained during routine STA-MCA bypass surgery, when preparing an STA stump. The raw STA graft was used to practice end-to-side anastomosis with a silicone tube used to simulate a recipient artery. Using a raw graft allowed the trainee to practice removing the connective tissue from the STA stump, which is good training for blunt dissection using microforceps. A raw graft also provides the trainee with real sensory input when penetrating the vessel wall, which made the practice closer to a real operation, resulting in good pre-operation simulation for training neurosurgeons. A raw STA graft makes a good material for training young neurosurgeons.

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Background: Extracranial-intracranial (EC-IC) bypass is a powerful tool for treating complex cerebral aneurysm. Ruptured aneurysms at the non-branching site of the internal carotid artery (ICA), the so-called blister-like aneurysm, have been treated with high flow EC-IC bypass and aneurysmal trapping, but postoperative cerebral hemodynamics following flow conversion have remained unclear.
Methods: The present study investigated six cases with ruptured blister-like ICA aneurysm, who were managed by high flow EC-IC (ECA-M2 or CCA-M2) bypass using interposed saphenous vein graft followed by microsurgical aneurysmal trapping. Postoperative cerebral blood flow (CBF) was evaluated by N-isopropyl-p-[¹²³I]iodoamphetamine single-photon emission computed tomography (SPECT) in the acute stage. Routine magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) were also performed in the acute stage.
Results: No patient suffered from intra-operative aneurysmal rupture, and no patient manifested procedure-related ischemic complications. Postoperative SPECT in the acute stage (1‐3 days after surgery) demonstrated a mild decrease in CBF in the operated hemisphere. Postoperative MRA demonstrated apparently patent EC-IC bypass in all cases. One patient manifested a delayed vasospasm and required a diagnostic angiogram and an intra-arterial infusion of fasudil hydrochloride. The clinical outcome was as follows: GR (good recovery) in four patients, and MD (moderately disabled) in two patients.
Conclusion: High flow EC-IC bypass followed by aneurysmal trapping (ICA trapping) was found to be a safe and effective treatment for ruptured blister-like ICA aneurysm. We recommend postoperative SPECT and MRI/MRA in the acute stage to monitor cerebral hemodynamics after flow conversion.

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Intraoperative motor evoked potential monitoring using transcranial electrical stimulation (TC-MEP) has been used to prevent postoperative motor deficits. However, postoperative motor deficits without intraoperative TC-MEP changes, (false negative MEP results), have been reported. We hypothesize that false negative TC-MEP results are a consequence of inadequate stimulation of the corticospinal tract. To activate the motor cortex only, stimulation intensity can be set at 20 V above the threshold level. Optimization of stimulation intensity resulted in fewer false negative TC-MEP results. In addition to stimulation intensity, there are three important points to be considered during intraoperative TC-MEP monitoring. First, stimulation threshold levels fluctuate during surgery; therefore, the threshold must be measured at each stage of the operation. Secondly, muscle evoked potentials must be recorded from the ipsilateral side as well as the contralateral side. Finally, when TC-MEP is recorded from the ipsilateral side, we should doubt TC-MEP findings.

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We reviewed nine (consecutive) cases of brainstem cavernous malformations surgically treated in Okayama University Hospital between 1994 and 2011, and evaluated the surgical approach used for each lesion, its accessibility, and the pre- and post-operative neurological statuses. All cases that were referred for surgery had a pre-surgical history of progressive or persistent neurological deficits caused by repeated episodes of hemorrhage. Of our nine cases, four of the cavernous malformations were dorsal lesions, three were lateral, and two were ventral. The dorsal lesions were treated using a trans 4th ventricular approach, the lateral lesions were treated using a retrosigmoid approach, and the ventral lesions were treated using an anterior petrosal approach in one patent and a presigmoid approach in the other. Total removal was carried out in seven patients, partial removal in one, and cauterization in one patient. Long-term follow-ups (mean: 78.2 months) showed no recurrent hemorrhages, and the mean modified Rankin Stroke Scale was 1.7. These findings indicate that direct surgery for brain stem cavernous malformation can be successfully performed by appropriate selection of surgical approaches under careful monitoring. The brainstem cavernous malformations require a skull-base approach and additional techniques based on considerations of local anatomy and surrounding structures.

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Distal anterior cerebral artery (DACA) aneurysm accounts for 6‐8% of all intracranial aneurysms. DACA was divided in four segments (A2‐5) by Dashi. We modified that aneurysm of A2 segment extends from the fronto-orbital artery branch origin to the border between rostrum and inferior genu, which is called infracallosal aneurysm. The A2 segment of DACA accounts for 8‐10% of all DACA. There are almost no detailed descriptions of infracallosal aneurysms in the literature. Infarcallosal aneurysms in five of our cases revealed a few features. The first was that the dome of the aneurysm in four of five cases projected posteriorly and superiorly. The second was that aneurysms in three cases were not associated with the branch on the A2 trunk. Two of the five cases were complicated with azygos artery or fenestration. Furthermore, almost all aneurysms had a relatively broad neck. It is very difficult to occlude infracallosal aneurysms because the A2 segment is in the deepest portion of the DACA running and tight between both inner frontal lobes.
A wide working space for the approach to the infarcallosal aneurysm should be maintained when using the basal anterior and distal interhemispheric procedure.

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