Revascularization for extracranial vertebral artery (VA) dissection or VA atherosclerotic occlusive lesions caused by vertebrobasilar insufficiency or cerebral infarction is relatively rare. For VA origin stenosis, VA transposition surgery has traditionally been performed, but in recent years endovascular treatment has also been considered.

On the other hand, when bypassing from cervical external carotid artery (EC) or common carotid artery (CC) using a radial artery (RA) or saphenous vein (SV) graft, it is difficult to determine whether the recipient site should be V2 or V3 portion.

In Case 1, bilateral internal carotid occlusion and bilateral VA stenosis were treated with ischemia, and superficial temporal artery to middle cerebral artery bypass was performed followed by two-stage VA transposition. In Case 2, cervical EC-RA-V3 bypass was performed for bilateral extracranial VA dissection with onset of ischemia, and cervical CC-SV-V3 bypass was added 12 days later. In Case 3, cervical EC-RA-V2 bypass was performed for arteriosclerotic bilateral extracranial VA occlusion.

We present a case of VA transposition for VA origin stenosis and a case of posterior fossa revascularization using VA V3 and V2 portions, and report that it is important to consider each case in selecting V3 and V2 portion.

Surgical clipping remains the gold standard for treating selected intracranial aneurysms regarding treatment durability, maneuverability of surrounding normal arteries, and certainty of bleeding control. Over the past 10 years, 663 procedures were performed in 629 patients with unruptured anterior circulation aneurysms. Neuroradiological images were thoroughly reviewed to evaluate the cerebrospinal fluid (CSF) space of the access route, venous drainage pattern, and surrounding structures, including perforating arteries, using constructive interference in steady state (CISS) magnetic resonance (MR) imaging and cerebral angiography to narrow down the indications for surgery in cases that met the following criteria: 1) ensuring operability to preserve normal vessels, especially perforating arteries; 2) the ability to secure both the proximal and distal vessels of the aneurysm, allowing precise control of blood flow; 3) comprehensive multidirectional visualization of the aneurysm; and 4) provision of sufficient angle and space for optimal clip application, including combinations of multiple clips. During surgery, preservation of the vein and avoidance of brain damage were top priorities, with the principle being to dissect the aneurysm circumferentially. However, if the perforating artery exhibited strong adhesions, aggressive dissection was not performed. No symptomatic complications were associated with the surgical procedures. Early postoperative MRI revealed diffusion-weighted imaging hyperintensity in the territories of the perforating branches in 5.4% of cases and T2 changes within the brain parenchyma in 20.8% of cases. Postoperative computed tomography angiography (CTA) showed no residual necks in 94.9% of cases, with residuals of 2 mm or less in 5.1%. During long-term follow-up of 371 patients (up to 10 years, average 6.4 years), no local recurrence of the aneurysm was observed. One of the important roles of direct aneurysm surgery is to provide a favorable long-term prognosis without surgical complications by limiting the indications to lesions that meet the above requirements.

Endoscopic evacuation of intraventricular hematomas is reportedly effective for shortening the drainage period and improving prognosis. Herein, we present our efforts to standardize procedures for safe and effective surgery based on the characteristics of rigid and flexible endoscopes in dry and wet fields. Twenty-five patients with intraventricular hemorrhage who were treated for six years were retrospectively evaluated. The casting hematoma in the lateral ventricle was removed under a dry field using a rigid endoscope. Once the ventricular cavity narrowed under dry fields, the procedure was switched to wet fields under irrigation with artificial cerebrospinal fluid. Hematomas in the third ventricle and aqueduct were removed using a flexible scope under wet field. There were no intraoperative complications, and the mean hematoma removal rate was 70.4%. Postoperative complications included rebleeding in one case (4%), cerebral hemorrhage at a different site in one case (4%), intracranial infection in one case (4%), medical complications in three cases (8%), pneumonia in two cases (8%), and liver failure in one case (4%). Optimum selection and procedure of a rigid or flexible scope with dry or wet field according to each situation are useful for standardizing procedures for the endoscopic evacuation of ventricular hematoma.

The number of superficial temporal artery-to-middle cerebral artery (STA-MCA) bypass procedures that young neurosurgeons can perform is limited, making off-the-job training (OJT) crucial for acquiring surgical skills. Based on the authors’ training methods and surgical outcomes, this study explored how young neurosurgeons develop these skills. The study focused on end-to-side anastomosis training using a silicon tube that the author employed for OJT. Emphasis was placed on the setup of the anastomosis, defining the roles of the right and left hands in each phase, and continuously refining the surgical procedures. The diameter of the silicon tube and depth of the surgical field were adjusted to simulate actual surgery. Over a four-year period, 807 training sessions were conducted, and 10 cases of 12 STA-MCA bypasses were performed. After 119 sessions, the time for end-to-side anastomosis on the silicon tube was reduced to under 20 min, with the learning curve leveling off thereafter. Although the anastomosis time temporarily increased when the training conditions were altered, it quickly decreased again. A high correlation was observed between the number of training sessions and the middle cerebral artery occlusion time during surgery, following a power approximation curve (r = 0.90). In the fifth case, the occlusion time was reduced to < 20 min. In the ninth case, despite encountering a problem, the occlusion time remained under 20 min. The study demonstrated that with thorough and repeated training, the speed of the anastomosis improved, and the simulated problems also helped foster the ability to remain calm and manage complications. However, maintaining consistent practice can be challenging. It is important to uphold consistent training methods, devise ways to prevent boredom or habituation, and integrate training into routine clinical practice.

Direct surgery is safe and reliable for various types of cerebral aneurysms. However, frontotemporal craniotomy, frequently used in the treatment of cerebral aneurysms, sometimes causes aesthetic problems, such as temporal muscle atrophy, skin depressions causing bone atrophy, hair loss along the scalp incision, protrusion of artificial materials, and facial nerve palsy. Various techniques have been reported over the years; however, they have not been widely accepted because they require sufficient experience and skill to perform safely. At our institution, we maintain aesthetic results without sacrificing the conventional craniotomy size by modifying the conventional open and closed procedures. Our main surgical modifications were as follows: 1) Use of a local anesthetic with epinephrine in the skin incision area reduces bleeding during skin incision. 2) The incisions for the periosteum and temporalis muscle were designed to obtain a sufficient craniotomy area while avoiding manipulation of the temples, where temporal muscle atrophy is often prominent. After using a monopolar electrocautery device for temporal muscle incisions, the periosteum and temporalis muscles were peeled off gently using a periosteal elevator. 3) A craniotomy was performed without wasting the bone by creating a fracture line on the sphenoid ridge before fracturing the bone. For craniotomy margins, the use of foreign materials, such as bone wax, which prevents bone fusion, is avoided as much as possible. 4) In the closing phase, the bone defect was filled with bone powder obtained during craniotomy and was closed tightly with the periosteum and temporalis muscles, without exposing the craniotomy edge.

This study included 66 patients (44 with unruptured cerebral aneurysms and 22 with ruptured cerebral aneurysms) who underwent clipping between July 2017 and November 2023. We categorized the degree of temple depression, seen on CT images, into three classes: excellent in 58 cases, good in six cases, and poor in two cases. The thickness of the temporalis muscle and subcutaneous tissue, and that of the subcutaneous tissue considering the titanium plate, compared to the preoperative conditions, suggested that, the greater the thickness of the titanium plate, the better aesthetics were maintained. These attempts resulted in satisfactory aesthetic effects, both subjectively and statistically (p = 0.0008, p = 0.0046, and p = 0.0057, respectively). Our technique requires no special skills and can be performed by residents. In addition, this technique has been widely adapted for various cerebral aneurysms, because the conventional craniotomy area is obtained. Given that our technique maintains surgical opportunities, it is also effective in surgical education.

With the increase in life expectancy, the number of surgeries for unruptured aneurysms in older patients is increasing. However, the effects of clipping surgery on their cognitive function have not yet been adequately studied. Herein, we report our results and review the risk factors for postoperative cognitive decline in these patients. This study included 97 patients aged 75 years or older who underwent clipping surgery for unruptured aneurysms in our hospital between 2018 and 2022. We examined the Mini-Mental State Examination (MMSE) and Hasegawa's Dementia Scale-Revised (HDS-R) scores preoperatively and within 2 weeks postoperatively as well as the risk factors for patients with a decrease of score of at least 3 points in either of the assessments. Of the 97 patients, 11 were male and 86 were female, and the mean age was 78.4 years. The average aneurysm size was 5.9 mm, and the aneurysms were located in the anterior cerebral, middle cerebral, and internal carotid arteries (approximately 30% each) and in the posterior circulation (6%). The average MMSE scores were 27.1 points preoperatively and 26.4 points postoperatively, and the average HDS-R scores were 27.1 points preoperatively and 26.4 points postoperatively, with no significant decrease postoperatively in either assessments. Diabetes mellitus and preoperative modified Rankin Scale score ≥ 1 were risk factors for postoperative cognitive decline. In conclusion, with proper patient selection, clipping surgery can be performed in older patients without compromising their cognitive function..

Objective: Perioperative antiplatelet therapy is crucial for preventing complications during the treatment of cerebral aneurysms with a flow diverter (FD). We retrospectively compared the perioperative use of clopidogrel and prasugrel.

Methods: We evaluated 43 consecutive patients who had undergone FD treatment at our institution between April 2020 and August 2023 (clopidogrel group, n = 20; prasugrel group, n = 23). Dual antiplatelet therapy, consisting of acetylsalicylate and a thienopyridine, was initiated two weeks prior to FD treatment. The P2Y₁₂ reaction unit (PRU) was measured using the VerifyNow system the day before and one week after surgery. The therapeutic window was defined as 60 < PRU < 200. If the PRU value fell outside the therapeutic window, the thienopyridine antiplatelet drug was changed, its dose was adjusted, or cilostazol was added before FD treatment. VerifyNow measurements were repeated until the PRU was within the therapeutic window following treatment or if symptoms potentially related to the antiplatelet drugs occurred.

Results: The number of patients within the PRU therapeutic window preoperatively, postoperatively, and at the final assessment were 12/20, 9/20, and 18/20 in the clopidogrel group and 22/23, 21/23, and 22/23 in the prasugrel group, respectively (p = 0.007, 0.002, and 0.590, respectively). The median number of VerifyNow measurements was 3.0 (interquartile range [IQR]: 2.00–3.75) in the clopidogrel group and 2.0 (IQR: 2.00–2.00) in the prasugrel group (p < 0.001). The number of patients who required dose adjustments or a change in the thienopyridine antiplatelet drug was 16/20 in the clopidogrel group and 2/23 in the prasugrel group (p < 0.001).

Conclusion: Prasugrel effectively stabilized the PRU within the therapeutic window during the perioperative period of FD treatment. We suggest that prasugrel may be more suitable than clopidogrel for use in FD treatment.

Symptomatic thrombosed vertebral artery aneurysms are challenging to treat due to their anatomical location, particularly concerning the brainstem and vital cranial nerves. We report a case in which “hybrid surgery” combining craniotomy and endovascular surgery was attempted.

The patient was a man in his 50s who presented to our hospital with stuttering and dizziness. Magnetic resonance imaging (MRI) revealed a thrombosed aneurysm with a maximum diameter of 34 mm in the right vertebral artery, which was compressing the brainstem.

The initial surgery was conducted in a hybrid operating room to occlude the right vertebral artery using both endovascular treatment and direct surgical intervention. Thrombectomy was performed in a second stage via direct surgery to decompress the brainstem area.

In thrombosed aneurysms, the vasa vasorum is a significant contributor to thrombus enlargement, making it challenging to treat with endovascular methods alone. Direct surgery plays a crucial role in interrupting the vasa vasorum.

In posterior cranial fossa surgery, where surgical manipulation is restricted, combined endovascular surgery offers a minimally invasive treatment option that can effectively occlude the parent vessel.

Proximal posterior cerebral artery (PCA) fusiform aneurysms are challenging to treat due to their deep-seated location and the need to maintain distal blood flow whilst preserving the perforating branches. In this case, a subarachnoid hemorrhage occurred due to fusiform dissection of PCA P1-P2 segments, with the dissection involving the posterior communicating artery (Pcom) and perforating branches. The posterior thalamoperforating artery originated from the contralateral PCA P1 segment. On the day of onset, evaluation of collateral circulation through balloon occlusion testing at the terminal portion of the basal artery was attempted, but precise assessment of collateral circulation due to occlusion of the dissected portion was not possible, because temporary occlusion of the right Pcom could not be achieved. Stent-assisted coil embolization was performed on the same day, but recurred on the 19th day of illness. On the 25th day, superficial temporal artery to PCA P2 bypass surgery was performed, followed by endovascular treatment for aneurysmal occlusion and proximal occlusion on the 27th day. However, the patient developed a midbrain-thalamic infarction due to the occlusion of the long circumflex branch at the dissection site. After 1 year and 6 months, the patient had residual mild hemiparesis and ocular movement disorder but achieved social reintegration. Treatment of PCA P1-P2 segment dissection remains challenging both surgically and endovascularly due to the need to occlude the dissected portion while preserving collateral circulation and perforating branches, necessitating individualized treatment decisions.

Dural arteriovenous fistulas (dAVFs) in the tentorium of the cerebellum are often difficult to treat, particularly the medial type near the vein of Galen, which has numerous leptomeningeal feeding vessels and is associated with increased bleeding after endovascular treatment. Treatment remains challenging, even with direct surgery or gamma knife radiosurgery. Therefore, it is essential to consider treatment strategies for dAVFs in this region. We report a case of a medial tentorial dAVF with an arteriovenous malformation (AVM) nidus-like component in which intracerebral hemorrhage occurred during surgery despite nearly complete occlusion achieved through direct puncture of the middle meningeal artery via a small craniotomy.