In recent years, exoscopes have been shown to be more useful than microscopes in reducing surgeon fatigue, sharing information, and educating young neurosurgeons. In this study, we investigated whether microscopes could be replaced by exoscopes during cerebrovascular surgery.

The study included 149 cases of cerebrovascular surgery in which direct surgery was performed using an exoscope between July 31, 2021, and August 31, 2023 (clipping: 45 ruptured cerebral aneurysms, 64 unruptured cerebral aneurysms, 1 unruptured cerebral aneurysm trap + bypass, removal of 14 intracerebral hematomas, 5 arteriovenous malformations, 10 superficial temporal artery [STA]-middle cerebral artery (MCA) anastomoses, 9 carotid endarterectomies, and 1 arteriovenous fistula).

When comparing exoscopes and microscopes for ruptured and unruptured cerebral aneurysms, no clear difference was observed in the time required for clipping surgery. For STA-MCA anastomosis, the number of cases of thrombus formation during surgery was lower in the exoscope group, and the postoperative patency rate and operation time tended to be better in the exoscope group.

During four-hands surgery, if the operator was on the left side, the assistant’s monitor display was inverted and rotated counterclockwise. If the operator was on the right side, the display was not inverted but was rotated counterclockwise, allowing the assistant to operate the device without discomfort. Although this was the first time all surgeons had used an exoscope, they were able to complete the surgeries without switching to a microscope. Compared with a microscope, an exoscope offers several advantages, including a more comfortable posture for the operator, improved information sharing, and better feasibility for four-hands surgery. Therefore, a complete transition from a microscope to an exoscope was determined to be possible.

Anterior choroidal artery (AchA) aneurysms clipping carries a high risk of ischemic complications due to several factors: the small diameter of the AchA, cases in which the AchA branches off from the aneurysm wall, and frequent adhesion of the AchA to the dorsal wall of the aneurysm. To reduce the risk of clipping the AchA aneurysm and subsequently decrease blood flow to the AchA, we intentionally left a small remnant of the aneurysm during the clipping procedure to preserve blood flow. The remaining aneurysmal wall was then coated with a small number of Bemsheets and fibrin glue. We retrospectively investigated the treatment outcomes and long-term outcomes of this surgical strategy. Between 2007 and 2018, we performed direct surgery on 63 patients with AchA aneurysms, enrolling 25 patients (mean age, 60 years; 76% females) in whom coating was applied to the residual aneurysm wall after clipping. These patients could perform daily activities independently postoperatively. The aneurysm sizes ranged from 2 to 7 mm (mean, 4 mm), with 18 unruptured aneurysms. Parallel clipping was performed in 88% of the patients. There were no cases of ischemic complications associated with this surgical technique. During the average follow-up period of 7.6 years, we observed no cases of ischemia in the AchA region, recurrence, or bleeding from residual aneurysms. In conclusion, clipping an AchA aneurysm while intentionally leaving a small remnant of the neck to preserve the AchA blood flow is a safe technique with significant therapeutic benefits. Additionally, coating the aneurysm remnant with a small amount of Bemsheets and fibrin glue may prevent recurrence and bleeding.

The primary goal in managing subarachnoid hemorrhage (SAH) caused by ruptured cerebral aneurysms is to prevent re-rupture. We analyzed 478 consecutive cases of ruptured aneurysms treated with craniotomy clipping at Sapporo Teishinkai Hospital from April 2012 to March 2024. We examined preoperative imaging, intraoperative findings, surgical techniques, and postoperative outcomes in patients who experienced re-bleeding within six months of rupture. Only one case (0.2%) of postoperative re-bleeding involving a vertebral artery dissecting aneurysm was observed. The very low rates of re-treatment and re-bleeding were achieved by ensuring direct visualization and hemostasis of the rupture point.

The RNF213 gene mutation is the primary susceptibility factor for moyamoya disease, with the p.R4810K mutation present in over 80% of Japanese patients. While other risk factors, such as low HDL levels, have been reported, the pathogenesis of the disease remains poorly understood. RNF213 has been shown to play a role in immune responses against pathogens such as bacteria and viruses, suggesting a potential involvement of these pathogens in moyamoya disease. To explore this, we conducted a study to determine whether past viral infections or the gut microbiota are linked to the disease. The results revealed a significantly lower infection rate of the HHV6 virus in patients and a significant increase in the relative abundance of the gut microbiota Ruminococcus gnavus. Both factors were found to be associated with the disease, independent of the p.R4810K mutation. Previous reports indicate that HHV6 suppresses IL-13 and IL-5, cytokines involved in type 2 inflammation, while Ruminococcus gnavus increases these levels. This suggests that while atherosclerosis is primarily driven by type 1 inflammation, moyamoya disease may be predominantly characterized by type 2 inflammation.

Objective: Three-dimensional printing technology is undergoing progressive development for the endovascular treatment of cerebral aneurysms. Microcatheter (MC) shaping is important for safety and efficacy in the treatment of aneurysms. In contrast to conventional middle-lumen models, we created a 3D mandrel mold (3DMM) that is inexpensive and quick to create and investigated its effectiveness.

Methods: Among the patients who underwent endovascular treatment for cerebral aneurysms at Saiseikai Fukuoka General Hospital between January 2021 and December 2023, 10 patients were included in the manual group, in which MCs were shaped by the operator based on imaging results, and 10 consecutive patients were included in the 3DMM group, in which 3DMMs were used. The following variables were evaluated: treatment method, reshaping, time to implantation of MC into the aneurysm, need for guidewire precedence at MC implantation, MC stability, volume embolization rate (VER), operative time, and complications associated with treatment.

Results: No differences were observed between the two groups in patient background or aneurysm morphology. Compared to those in the manual group, reshaping was significantly less frequent and time to MC placement into the aneurysm was significantly shorter in the 3DMM group (11.4 ± 3.4 vs. 15.5 ± 4.5 min, p<0.05). In the 3DMM group, the guidewire was used less frequently to place the MC into the aneurysm, and stability was higher (95.1 ± 10.4 vs 78.2 ± 21.4%, p<0.05). No significant differences were observed between groups in VER, operative time, or complications.

Conclusion: As we proposed, the novel shaping technique of the MC using a 3DMM facilitates guidance of the MC into the aneurysm and contributes to improved safety.

The use of endoscopy in the treatment of brainstem cavernous malformations (BCMs) has been reported in a limited number of cases. Given its ability to provide a broad and bright field of view even in deep regions, endoscopy is considered effective for treating deep-seated lesions, such as BCMs, and has been actively utilized in our institute.

This study retrospectively reviewed 32 cases of BCMs treated with endoscopic techniques (midbrain, 7 cases; pons, 22 cases; and medulla, 3 cases). The approach routes to the brainstem were based on the “Two Point Method,” primarily utilizing the nearby safe entry zones. Surgical removal was performed through transnasal procedures in 5 cases and craniotomy in 27 cases, with 25 of these employing small diameter cylinders to secure the surgical corridor. Gross total resection was achieved in 30 cases (93.8%). Postoperative complications were observed in five cases. The average Karnofsky Performance Status improved from 62.2 preoperatively to 84.4 3 months postoperatively, with improvements in 26 cases, no change in 5 cases, and deterioration in 1 case. Surgical treatments for BCMs are predominantly performed under a microscope; however, the outcomes of endoscopic surgery in this study showed favorable neurological prognoses compared with the findings of previous reports. The use of endoscopy facilitated the minimization of surgical pathways and enabled underwater surgery, thereby establishing a novel approach that is not preferably available in microscopic surgery. Underwater intraoperative observation, a distinctive feature of endoscopic surgery, was highly effective in identifying residual lesions and achieving hemostasis. Despite its advantages, endoscopy presents challenges, prompting ongoing developments and improvements in surgical instruments and techniques. Although this technique is still evolving, the utility of endoscopy for treating BCMs is promising.

A woman in her 50s presented with a subarachnoid hemorrhage and three bilateral aneurysms involving the posterior inferior cerebellar arteries (PICAs): one on the left side and two on the right side. The aneurysm of the left PICA was diagnosed as the rupture site, as vessel wall enhancement was observed on magnetic resonance imaging, suggesting a dissecting aneurysm. Bilateral occipital artery-PICA bypass was planned, but only a unilateral bypass was performed to treat a distal aneurysm of the right PICA. The remaining two aneurysms were successfully clipped. Postoperatively, the patient developed ischemic complications at the skin flap, necessitating additional skin transplantation. Identifying the rupture site in cases of multiple aneurysms can be challenging to diagnose. In such situations, vessel wall enhancement on magnetic resonance imaging may aid in diagnosis. Multiple aneurysms affecting bilateral PICAs presenting with subarachnoid hemorrhage can be surgically managed through a combination of bypass surgery and aneurysm clipping, with careful preoperative planning and consideration of ischemic risks at the skin flap.

The adequate exposure of the distal portion of the internal carotid artery is not always easy, especially in high-positioned carotid endarterectomy. The layered structure surrounding the internal carotid artery consists of the retromandibular space, which includes the parotid gland, deep cervical fascia, sternocleidomastoid muscle, carotid sheath, and lymph nodes wrapped in fat tissue over the internal jugular vein. A precise understanding of these complex layered structures is essential for performing carotid endarterectomy safely. Dissection around the parotid gland along with the deep cervical fascia from the anterior edge of the sternocleidomastoid muscle is a crucial technique in high-positioned carotid endarterectomy. This procedure facilitates a wide opening of the retromandibular space. Dissecting between the deep cervical fascia and the lymph nodes wrapped in fat tissue prevents damage to the parotid gland in the retromandibular space.

This procedure also facilitates early exposure of the posterior belly of the digastric muscle, hypoglossal nerve, and the distal portion of the external carotid artery. Their early exposure greatly improves intraoperative orientation and ensures safe dissection of the deep cervical lymph nodes wrapped in fat tissue over the internal jugular vein. These dissection procedures, based on the cervical layer structure, consistently ensure a wide opening of the upper portion of the retromandibular space and adequate exposure of the distal portion of the internal carotid artery, even in high-positioned carotid endarterectomy.

Superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis is a common intracranial revascularization procedure. Because the STA is one of the primary feeding vessels of the scalp, harvesting it can reduce scalp blood supply and lead to wound complications. These complications include delayed wound healing, alopecia, necrosis, and scalp ulceration. The risk of wound complications is particularly high in double anastomoses, where both the frontal and parietal branches are used⁶⁾.

To prevent operative wound complications, we employed the following strategies: 1. minimizing skin incisions, 2. avoiding thermal coagulation and excessive hemostatic manipulation of the wound surface, 3. using wide sutures, and 4. implementing meticulous postoperative wound care. This study included 37 patients who underwent STA-MCA double anastomoses between February 2017 and September 2024 using a previously described surgical technique. All patients underwent skin staple removal on the seventh postoperative day without wound healing delays.

Our surgical techniques appear effective in preventing postoperative wound complications.