BACKGROUND: Trapping an aneurysm after the establishment of an extracranial to intracranial high-flow bypass is considered the optimal surgical strategy for ruptured blood blister-like aneurysms (BBAs) of the internal carotid artery (ICA). For high-flow bypass surgeries, a radial artery graft is generally preferred over a saphenous vein graft (SVG). However, SVGs can be advantageous in acute-phase surgeries because of their greater length, easy manipulability, ability to act as high-flow conduits, and reduced risk of vasospasms. In this study, the authors presented five cases of ruptured BBAs treated with high-flow bypass using an SVG followed by BBA trapping, and they reported on surgical outcomes and operative nuances that may help avoid potential pitfalls.
METHODS: After the surgeries, there were no ischemic or hemorrhagic complications, including symptomatic vasospasms. In three of the five cases, postoperative modified Rankin scale scores were between 0 and 2 at the 3-month follow-up. In one case, the SVG spontaneously occluded after surgery while the protective superficial temporal artery (STA) to middle cerebral artery (MCA) bypass became dominant, and the patient experienced no ischemic symptoms.
CONCLUSIONS: High-flow bypass using an SVG with a protective STA-MCA bypass followed by BBA trapping is a safe and effective treatment strategy.

BACKGROUND: Selecting therapeutic options for moyamoya disease (MMD)-associated anterior communicating artery (ACoA) aneurysm, a rare pathology in children, is challenging because its natural course remains unclear.
METHODS: A 4-year-old boy exhibiting transient ischemic attacks was diagnosed with unilateral MMD accompanied by an unruptured ACoA aneurysm. Although superficial temporal artery to middle cerebral artery anastomosis eliminated his symptoms, the aneurysm continued to grow after surgery. Since a previous craniotomy and narrow endovascular access at the ACoA precluded both aneurysmal clipping and coil embolization, the patient underwent a surgical anastomosis incorporating an occipital artery graft between the bilateral cortical anterior cerebral arteries (ACAs). This was intended to augment blood flow in the ipsilateral ACA territory and to reduce the hemodynamic burden on the ACoA complex. The postoperative course was uneventful, and radiological images obtained 12 months after surgery revealed good patency of the bypass and marked shrinkage of the aneurysm in spite of the intact contralateral internal carotid artery.
CONCLUSIONS: Various clinical scenarios should be assessed carefully with regard to this pathology. Bypass surgery aimed at reducing flow to the aneurysm might be an alternative therapeutic option when neither coiling nor clipping is feasible.

BACKGROUND: Virtual reality (VR) offers an interactive environment for visualizing the intimate three-dimensional (3D) relationship between a patient\'s pathology and surrounding anatomy. The authors present a model for using personalized VR technology, applied across the neurosurgical treatment continuum from the initial consultation to preoperative surgical planning, then to intraoperative navigation, and finally to postoperative visits, for various tumor and vascular pathologies.
METHODS: Five adult patients undergoing procedures for spinal cord cavernoma, clinoidal meningioma, anaplastic oligodendroglioma, giant aneurysm, and arteriovenous malformation were included. For each case, 360-degree VR (360°VR) environments developed using Surgical Theater were used for patient consultation, preoperative planning, and/or intraoperative 3D navigation. The custom 360°VR model was rendered from the patient\'s preoperative imaging. For two cases, the plan changed after reviewing the patient\'s 360°VR model from one based on conventional Digital Imaging and Communications in Medicine imaging.
CONCLUSIONS: Live 360° visualization with Surgical Theater in conjunction with surgical navigation helped validate the decisions made intraoperatively. The 360°VR models provided visualization to better understand the lesion\'s 3D anatomy, as well as to plan and execute the safest patient-specific approach, rather than a less detailed, more standardized one. In all cases, preoperative planning using the patient\'s 360°VR model had a significant impact on the surgical approach.

BACKGROUND: Limb-shaking transient ischemic attacks (LS-TIAs) are a rare form of TIAs that present as involuntary movements of the limbs and indicate severe cerebral hypoperfusion. LS-TIAs are often reported in patients with carotid artery stenosis but can also affect patients with intracranial artery stenosis and moyamoya disease (MMD).
METHODS: A 72-year-old woman presented with repeated episodes of involuntary shaking movements of the right upper limb. Cerebral angiography revealed complete occlusion of the M1 segment of the left middle cerebral artery (MCA), and the left hemisphere was supplied by moyamoya vessels. She was treated with left direct revascularization without complications, and her involuntary movements subsided. However, she demonstrated involuntary shaking movements of the right lower limb 2 months postoperatively. Cerebral angiography revealed complete occlusion of the A1 segment of the left anterior cerebral artery (ACA). The multiple burr hole opening (MBHO) procedure was performed to improve perfusion in the left ACA territory and after 3 months, the patient\'s symptoms resolved.
CONCLUSIONS: This case demonstrated that LS-TIAs can also develop as ischemic symptoms due to MMD. Moreover, instances of LS-TIA of the upper and lower limbs developed separately in the same patient. The patient\'s symptoms improved with direct revascularization and MBHO.

BACKGROUND: Unlike in aneurysms of the adult-type posterior cerebral artery (PCA), in aneurysms of the fetal-type PCA, parent artery occlusion (PAO) results in vascular insufficiency and major ischemic strokes. Preservation or reconstruction of fetal-type PCAs is necessary to prevent these complications. Furthermore, it is necessary to select an appropriate bypass method and approach for revascularization of the PCA.
METHODS: The authors report 2 cases of aneurysms of fetal-type PCAs that were successfully treated with PAO with revascularization. A 38-year-old man with a large unruptured right PCA aneurysm at the postcommunicating (P2) segment underwent trapping with superficial temporal artery-PCA bypass via the anterior temporal and subtemporal approaches. In addition, a 45-year-old woman with a left PCA aneurysm at the quadrigeminal (P3)-cortical (P4) segments resulting in subarachnoid hemorrhage underwent proximal clipping of the P3 segment via the occipital interhemispheric approach with an occipital artery-PCA bypass. Although she had perforator infarction, major ischemic stroke was prevented, and aneurysm occlusion was accomplished in both cases.
CONCLUSIONS: Aneurysms of fetal-type PCAs pose a risk of ischemia due to PAO. The combined use of bypass and revascularization should be considered to prevent major ischemic stroke after occlusion of the fetal-type PCA. However, perforator infarction is a concern.

BACKGROUND: Aplastic or twig-like middle cerebral artery (Ap/T-MCA) is a congenital MCA anomaly. It may present with symptoms of both hemorrhage and ischemia, similar to moyamoya disease, and hemodynamic stress may play an essential role in the development of symptoms in both clinical entities. The optimal treatment remains controversial in symptomatic patients with Ap/T-MCA. This report discussed the treatment method for a patient with Ap/T-MCA with unruptured aneurysms who presented with intraventricular hemorrhage (IVH) treated by aneurysm clipping and bypass surgery.
METHODS: In a 46-year-old woman with a sudden headache, computed tomography showed left IVH. Magnetic resonance angiography showed a left MCA aneurysm and MCA trunk stenosis. Three-dimensional angiography demonstrated a plexiform arterial network and multiple aneurysms arising from the MCA and in the plexiform network, leading to the diagnosis of Ap/T-MCA harboring unruptured aneurysms. The patient was successfully treated by craniotomy with aneurysm clipping and bypass surgery to prevent further intracranial hemorrhages and/or aneurysm rupture.
CONCLUSIONS: Especially in cases such as Ap/T-MCA, in which hemodynamic stress has a significant effect, the optimal treatment method should be based on vascular morphology and the impact of hemodynamic stress.

BACKGROUND: The bonnet bypass was initially described for common carotid artery occlusion. Considered a second-generation bypass, it augments intracranial perfusion with contralateral external carotid artery flow through an interposition graft running over the scalp vertex. However, the traditional first-generation low-flow superficial temporal artery (STA)-M4 middle cerebral artery (MCA) bypass may be enhanced by performing a side-to-side (S-S) bypass with an intraluminal suture technique (fourth-generation bypass) to increase perfusion through antegrade and retrograde flow.
METHODS: The authors present a reimagined S-S STA-M4 bypass in the case of a patient with symptomatic common carotid occlusion, in which the ipsilateral STA filled in a reverse fashion from the contralateral external carotid branches over the scalp vertex (bonnet collaterals). By performing an S-S anastomosis, the authors were able to improve cerebral perfusion and avoid the multiple anastomosis sites of the bonnet bypass.
CONCLUSIONS: The patient had a good recovery with resolution of his preoperative symptoms. Follow-up angiography showed a patent bypass supplying the MCA territory through retrograde flow in the frontal and parietal limbs of the STA, converging at the anastomosis site. In this report, the authors present a new fourth-generation bypass dubbed the \"S-S reverse STA-M4 MCA bypass.\"

BACKGROUND: Aplastic or twiglike middle cerebral artery (Ap/T-MCA) is a rare anomaly characterized by a unilateral MCA occlusion with plexiform vessels that causes hemorrhagic and (less commonly) ischemic strokes. The reasons for this are rarely discussed, and thus optimal treatment for ischemic Ap/T-MCA remains controversial. Here, the authors report a case of Ap/T-MCA with transient ischemic attacks treated by bypass surgery and discuss the mechanism of ischemic development and treatment methods.
METHODS: A 62-year-old hypertensive man with transient, recurrent left hemiparesis visited the authors\' hospital. Magnetic resonance angiography showed proximal occlusion of the right MCA and stenosis in the left MCA. Digital subtraction angiography revealed occlusion of the right MCA and abnormal vascular networks, leading to a diagnosis of Ap/T-MCA with contralateral MCA stenosis. Antiplatelet therapy with aspirin was insufficient, and a superficial temporal artery-MCA bypass was performed. There were no ischemic or hemorrhagic events postoperatively.
CONCLUSIONS: Atherosclerosis seems to have a significant impact on the development of ischemic stroke in patients with Ap/T-MCA, and the presence of coexisting atherosclerotic stenotic vascular lesions outside the Ap/T-MCA site is substantial in its development. Bypass surgery is a promising treatment option for ischemic Ap/T-MCA.

Numerous recent technological advances offer the potential to substantially enhance the MRI evaluation of moyamoya disease (MMD). These include high-resolution volumetric imaging, high-resolution vessel wall characterization, improved cerebral angiographic and perfusion techniques, high-field imaging, fast scanning methods, and artificial intelligence. This review discusses the current state-of-the-art MRI applications in these realms, emphasizing key imaging findings, clinical utility, and areas that will benefit from further investigation. Although these techniques may apply to imaging of a wide array of neurovascular or other neurological conditions, consideration of their application to MMD is useful given the comprehensive multidimensional MRI assessment used to evaluate MMD. These MRI techniques span from basic cross-sectional to advanced functional sequences, both qualitative and quantitative.The aim of this review was to provide a comprehensive summary and analysis of current key relevant literature of advanced MRI techniques for the evaluation of MMD with image-rich case examples. These imaging methods can aid clinical characterization, help direct treatment, assist in the evaluation of treatment response, and potentially improve the understanding of the pathophysiology of MMD.

Postoperative neurological deficits impair the overall outcome of revascularization surgery for patients with moyamoya disease (MMD). dl-3-n-butylphthalide (NBP) is approved for the treatment of ischemic stroke in China. This pilot study evaluated the effect of NBP on perioperative stroke and neurological deficits in patients with MMD.
The authors studied cases in which patients underwent combined revascularization surgery for MMD at their institution, with or without NBP administration. The overall study group included 164 patients (213 surgically treated hemispheres), including 49 patients who received NBP (25 mg twice daily) for 7 postoperative days. The incidence of perioperative stroke and transient neurological deficit (TND) and the severity of neurological deficits were compared between 49 propensity score-matched case pairs with or without NBP treatment. Subgroup analyses by type of onset and preoperative neurological status were also performed to determine specific characteristics of patients who might benefit from NBP administration.
In the overall cohort, baseline characteristics differed with respect to preoperative stroke and modified Rankin Scale (mRS) score between patients who received NBP and those who did not receive it. In the 49 propensity score-matched pairs, postoperative stroke was observed in 11 patients and TND occurred in 21 patients, with no significant difference in incidence between the 2 groups. However, the TND was less severe in the NBP-treated group (p = 0.01). At 1 month after surgery, the neurological outcome was more favorable (p = 0.001) and the disability-free recovery rate was higher in patients with NBP treatment (p < 0.001). The number of patients who experienced an improved neurological function, compared to preoperative function, as measured by mRS, was greater in the NBP group than in the no-NBP group (p < 0.001). Multivariable analysis revealed that NBP administration was associated with decreased severity of TND (OR 0.28, p = 0.02), improved neurological function (OR 65.29, p = 0.04), and lower postoperative mRS score (OR 0.06, p < 0.001). These beneficial effects of NBP remained significant in ischemic type MMD and patients with preoperative mRS scores of 2 or greater.
Postoperative administration of NBP may alleviate perioperative neurological deficits after revascularization surgery for MMD, especially in patients with ischemic MMD and unfavorable preoperative status. The results of this study suggest that randomized controlled trials to assess the potential benefit of NBP in patients with MMD may be warranted.