A retrospective analysis of 70 patients with moyamoya disease (MMD), 56 of whom received direct bypass, suggested direct bypass did not significantly reduce the occurrence of cerebral hemorrhage but did reduce ischemic stroke. A prospective analysis of 50 patients with 3-tesla magnetic resonance (MR) imaging indicated that the presence of multiple microbleeds is an independent risk factor of subsequent cerebral hemorrhage in MMD. An analysis with co-registrated imaging between MR images and cerebral blood flow (CBF) images suggested an inverted correlation between the decrease of regional CBF before surgery and the postoperative increase of CBF. Co-registrated imaging also preoperatively identified a recipient artery at the site with decreased CBF in direct bypass surgery. Results of 15 cases with this “target bypass” method appeared to be feasible.

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We analyzed the effect of superficial temporal to middle cerebral artery (STA-MCA) bypass to prevent future strokes based on the data of the clinical course and the course of the collateral circulation.
Thirty-five patients with hemorrhagic type moyamoya disease were examined during the follow-up period with a mean of 6.3 years after the initial intracranial hemorrhage. Eighteen patients were conservatively managed, 12 patients underwent STA-MCA bypass, and the last 5 patients underwent encephaloduroarteriosynangiosis (EDAS). The ophthalmic artery flow was examined as the collateral circulation using the color Doppler flow imaging (CDFI).
During the follow-up period, 13 patients (43%, 5.86%/patient/year) experienced a cerebral event such as ischemia or rebleeding. The incidence of a future stroke event in the patients treated with STA-MCA bypass (p<0.05) was significantly lower than that in the patients conservatively managed or treated with EDAS using the log-rank test. At the initial stage, the hemorrhagic side ophthalmic artery CDFI showed a high-flow pattern and a significantly high peak systolic flow velocity (Vs) compared to the opposite side (p<0.05). During the follow-up period, in the conservatively managed patients, the Vs value did not change markedly. On the other hand, in the patients treated with STA-MCA bypass, the Vs value decreased significantly (p<0.05).
Clinical symptoms and ophthalmic artery CDFI findings confirmed that STA-MCA bypass in patients with hemorrhagic type moyamoya disease prevents future strokes.

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We intraoperatively monitored visual evoked potential (VEP) in 6 aneurysm clipping surgeries for 2 IC paraclinoid, 2 IC-posterior communicating artery (IC-PCoA) and 2 posterior cerebral artery (PCA) aneurysms, which had potential risk of optic pathway damage. Stable waveform was acquired throughout the procedures in all cases under total intravenous anesthesia with propofol. Reproducible transient VEP waveform decrease was observed during temporary artery occlusion, which recovered after release of temporary artery occlusion in 3 patients. No visual disturbance was encountered in this group postoperatively. On the contrary, VEP waveform decreased permanently during aneurysm dissection from the optic nerve in an IC paraclinoid aneurysm patient. The patient had severe visual dysfunction postoperatively. Our series revealed that transient ischemic dysfunction of the optic pathway caused from artery occlusion was detectable within a reversible time window; however, it seems difficult to detect mechanical damage of the optic nerve damage in a reversible time window. Intraoperative monitoring of VEP predicts postoperative visual function; reversible change in VEP means visual function is preserved, especially when the change is caused by ischemia that occurs when the artery that supplies the optic apparatus is temporarily occluded.

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We will outline our surgical techniques and treatment strategies of CEA to prevent peri-operative complications. Between 1997 and 2006, 234 CEAs were performed on 205 patients, 128 of which were symptomatic, while 106 were asymptomatic. Prior to surgery, all patients were screened by cardiologists to elucidate congestive and/or ischemic heart disease (IHD). If coronary artery stenosis was present, it was treated before surgery. CEA was performed under general anesthesia using a “hitch-up” maneuver and with or without shunting according to a number of intraoperative parameters. For high-risk cases with higher carotid bifurcation, we prepared a special mouthpiece to achieve mandibular subluxation and expose the distal ICA for easy access. For patients with long-segmental lesions or contralateral ICA occlusion, and for those who seemed to be intolerant to intraoperative temporary occlusion of the ICA, we used an extracorporeal circulation technique. Postoperative management was as follows: 1) Overnight sedation with intubation to avoid postoperative bleeding and airway obstruction, and 2) SPECT on postoperative days (POD) 1 and 4 to predict hyperperfusion syndrome.
Among 128 symptomatic cases, perioperative stroke occurred in 5 (minor stroke in 3 and cerebral hemorrhage in 2 cases), making surgical morbidity and the mortality rate within 1 month of the CEAs 1.7% and 0.4%, respectively. Cranial nerve palsies were seen in 8 cases (6.2%), but all recovered within 1 month. Conversely, 106 asymptomatic cases had no surgical morbidity or mortality except for temporary cranial nerve palsies (6 cases: 5.7%). During the long-term follow-up of 32 months, minor stroke occurred in 2 patients (1.0%), and 12 patients (5.1%) died of causes other than stroke, including 1 myocardial infarction. As for high-risk cases (92 cases), cumulative incidence of adverse events (death, stroke, or myocardial infarction) at 30 days and 1 year after CEAs were 3.2% and 5.4%, respectively, which seemed to be acceptable compared with other clinical trials.
CEA prevents strokes (even for high-risk patients) quite effectively if carried out with consistent treatment strategies and appropriate technical devices.

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We review clinical results after surgical revascularization in 164 patients with moyamoya disease. The surgical procedures include superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis and indirect synangiosis using STA, dura mater, temporal muscle and pericranium. There were no significant differences in the incidence of perioperative morbidity among surgical procedures. Indirect synangiosis induced surgical collaterals in most of the pediatric patients, but in only 60% of adult patients. Postoperative angiography and SPECT/PET studies revealed that the development of surgical collaterals through indirect synangiosis depended on the operated areas. During follow-up periods, 10 of 164 patients (6.1%) experienced ischemic (n=3) or hemorrhagic stroke (n=7) after surgery. Completed stroke and “small craniotomy” surgery were significantly associated with poor intellectual outcome in pediatric patients.

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Dissection of the interhemispheric fissure via a basal interhemispheric approach (BIHA) is one of the most difficult skills for young neurosurgeons to acquire. We reviewed operative videos of 30 BIHAs performed by 4 residents in our institute, and investigated how the pia mater or pial capillary vessels were injured. Furthermore, after comparing these procedures with those of senior neurosurgeons in our institute, we discussed factors causing injury of the pia mater or pial capillary vessels and effective remedies to improve skills.
As a result, causes of pial injury were roughly divisible into 3 types: microscissor problems; excessive tension on trabecullae; and inappropriate hemostatic technique. Learning the transformation of the interhemispheric fissure accompanying cerebrospinal fluid decreases and the anatomical characteristics of interhemispheric fissure is important for acquiring appropriate brain retraction. Training to find trabecullae to be cut in the narrow microsurgical field is also an important skill to acquire for BIHA.

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Recently, intraoperative monitoring of the motor evoked potential (MEP) has become essential during aneurysm surgery to avoid the occurrence of motor deficit. The MEPs are commonly recorded from upper or lower limb muscles after electrical stimulation of the motor cortex. On the other hand, we monitor the MEPs recorded from the spinal cord at the cervical epidural space after the electrical stimulation of the motor cortex during aneurysm surgery. In this study, we describe the usefulness of corticospinal MEP monitoring in aneurysm surgery.
Corticospinal MEPs were recorded in 31 patients during aneurysm surgery. Twenty-two patients had internal carotid artery aneurysms, including 12 ruptured aneurysms, and 17 patients had middle cerebral artery aneurysms, including 10 ruptured aneurysms.
Preoperatively, an epidural lead for the MEP recording was inserted into the cervical epidural space under radiographic guidance and under general anesthesia with muscle relaxants. After craniotomy, a subdural grid was placed over the sensory and motor cortices and optimum contacts for the electrical stimulation were selected according to the waveforms of somatosensory evoked potentials. Corticospinal MEPs, which were elicited by cortical stimulation and consisted of a D-wave followed by 2 or 3 I-waves were recorded from an epidural lead (bipolar recording).
Among these 31 patients, 11 (35.5%) had changes in MEPs. An amplitude reduction less than 50% of the control was observed in 6 patients. An amplitude augmentation of more than 50% was also observed in 5 patients. These MEP changes recovered to the control level after the release of temporary clip or reclipping of aneurysms. MEP monitoring thereby prevented motor deficits.
Corticospinal MEPs were constantly recorded and they showed a sensitive response to the blood flow insufficiency of the arteries during aneurysm surgery.
Corticospinal MEP monitoring is therefore considered to safely and effectively prevent motor deficits caused during aneurysm surgery.

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In recent years, the stent technology available for endovascular treatment of aortic dissections has advanced tremendously. It is now possible to apply this minimally invasive technique to a wider range of pathology. The aim of this study was to develop anti-thrombogenic coronary stent using ion-beam technology. Our previous study indicted that He⁺-irradiated collagen surface with a fluence of 1×10¹⁴ ions/cm² has excellent antithrombogenicity and cell attachment property.
The ion beam irradiated collagen-coated Ni-Ti and available SUS stents demonstrated a high anti-thrombogenicity and endothelialization in animal studies. The implantation of ions into a collagen-coated surface is a promising approach for developing a new stent. It is therefore very likely that ion-implanted collagen-coated stents will be clinically applicable.

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Vascular reconstruction for moyamoya disease can be achieved by STA-MCA anastomosis, STA-ACA anastomosis as direct revascularization, EDAMS (encephalo-duro-arterio-myo-synangiosis) and EGAS (encephalo-galeo-arterio-synangiosis) as indirect vascular reconstruction. We revascularized 19 hemispheres of 13 patients—4 pediatric and 9 adult patients—using STA-ACA and STA-MCA anastomosis, EGAS for the medial frontal lobe, and EDAMS for the lateral frontal lobe. All of these procedures improved cerebral blood flow in the frontal lobe, resulting in improved mental and intellectual acuity in pediatric patients, which was apparent from obviously improved concentration and intellectual ability soon after surgery.

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Patients receiving anticoagulants occasionally suffer from intracranial hemorrhage. Initially, it is important to control the coagulation time for such patients, because of the possible need for emergency surgery. Previously, vitamin K and FFP (fresh frozen plasma) were administered to such patients; however, it took 3 to 6 hours to normalize the PT-INR (Prothrombin Time, International Normalized Ratio), and thus the bleeding could increase and the patients’ condition might then become critical. To correct the coagulation time quickly and evacuate the hematoma as soon as possible, ninth factor complex (PPSB-HT) was administered to 5 patients who had taken Warfarin and suffered from intracranial hemorrhage. In all patients, the PT-INR quickly normalized within 10 to 20 minutes, and they were thereafter successfully treated surgically.
The administration of PPSB-HT is critical to correct the coagulation time in patients taking Warfarin and requiring emergency surgery.

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We report a 61-year-old Japanease man with a superior petrosal sinus dural arteriovenous fistula (AVF) with a rapidly growing varix presenting as intracranial hemorrhage. He complained of headache and cerebellar ataxia. A computed tomography (CT) study revealed a huge high-density mass in the left cerebellar hemisphere. The mass had not been detected on a CT scan obtained elsewhere a month earlier. Magnetic resonance imaging revealed a huge flow void in the left cerebellopontine angle, and angiography showed a dural AVF located adjacent to the left superior petrosal sinus. It was supplied by the external carotid arteries and drained via the vein of Galen and a huge varix. After preoperative NBCA embolization of the feeding vessels, he underwent direct surgical ligation of the draining vein. However, as the size of the varix did not decrease and he developed brainstem symptoms, we excised the thrombosed varix. Ours is very rare case of superior petrosal sinus dural AVF resulting in consciousness disturbance due to brainstem compression by a huge varix. We postulate that the development of an intrathrombotic vascular channel and repeated recanalization may have been important factors in the rapid growth of the huge varix.

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