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Objective: Bifrontal craniotomy often involves the bony opening and mucosal disruption of the frontal sinus (FS), which can lead to cerebrospinal fluid (CSF) leakage and meningitis. These complications are particularly associated with surgical treatments for skull base tumors and anterior cerebral artery aneurysms. The authors initially reported on the basic technique in 2014 with 51 cases. This study presents a detailed description of their technique and postoperative management for sealing the exposed FS during bifrontal craniotomy, including long-term follow-up results and outcomes. To objectively evaluate the effectiveness of suturing FS mucosa in preventing CSF leakage during bilateral frontal craniotomy, the authors focused only on anterior cerebral artery aneurysms. This limitation was necessary as other conditions, like extensive tumors or trauma, might lack intact FS mucosa or require its removal due to infection., Methods: The records of 34 consecutive patients (median age 62.0 years, mean 60.4 years, range 33-78 years) who underwent bifrontal craniotomy for anterior cerebral artery aneurysms between January 2014 and December 2023 were retrospectively analyzed. All patients had bony opening and mucosal injury of the FS (with exposure to the nasal cavity) that required mucosal suturing. This technique for sealing the exposed FS involves careful dissection of the mucosa from the entire sinus, sterilization with iodine-soaked surgical cotton, and preparation for closure. After the microsurgical procedure is completed, the exposed mucosa is sealed with 6-0 nylon sutures and further secured with fibrin glue-soaked Gelfoam. The bony exposure is covered with an autologous bone flap created from the inner table of the craniotomy bone flap. Finally, the frontal periosteal flap is sutured to the frontal base dura mater. Patients were instructed not to blow their noses for 2 months postoperatively., Results: Two patients experienced transient non-CSF leakage from the nasal cavity, likely due to irrigation fluid, which resolved within 2 days postoperatively. No recurrence was observed during a mean follow-up period of 52.8 ± 41.7 months (median 49 months, range 3-127 months). No cases of meningitis or other intracranial infections were reported., Conclusions: The long-term results demonstrate the sustained effectiveness of this technique in preventing postoperative complications related to FS exposure during bifrontal craniotomy.

We report a case of distal anterior cerebral artery (DACA) aneurysm presenting with subdural hematoma (SDH) without subarachnoid hemorrhage (SAH). A patient in his fifties presented with headache. Fluid-attenuated inversion recovery magnetic resonance imaging revealed SDH in the interhemispheric fissure and left frontotemporal region. SAH was not detected. Computed tomographic angiography revealed aneurysms in the left internal carotid artery (ICA) and DACA. The patient underwent frontotemporal craniotomy, which confirmed an unruptured ICA aneurysm, followed by bilateral frontal craniotomy for clipping of DACA aneurysm. The left DACA aneurysm was identified as the source of the SDH. Intraoperative findings showed adhesion between the aneurysm body and falx cerebri, explaining the SDH formation. Literature review identified only six reported cases of SDH without SAH due to DACA aneurysm. Evidence suggests that DACA aneurysms have a relatively higher propensity to cause SDH without SAH, likely due to the anatomical characteristics of the parent vessel and aneurysm projection., Competing Interests: The authors have no conflict of interest to declare., (Published by Oxford University Press and JSCR Publishing Ltd. © The Author(s) 2025.)

Background: Because of ischemic symptoms, intracranial internal carotid artery (IICA) dissection has no established treatment guidelines. The authors report a case of IICA dissection in which an emergency superficial temporal artery-middle cerebral artery (STA-MCA) bypass was performed., Observations: A 46-year-old woman presented with a headache and left hemiplegia. Her cortical symptoms appeared on day 10, and an STA-MCA bypass was performed because of cerebral hypoperfusion. Her postoperative patency was good, and cortical symptoms improved. Contrast-enhanced magnetic resonance imaging (MRI) was performed in the acute phase with wall contrast. From day 18, the internal carotid artery delineation improved, and the patient was transferred for rehabilitation without worsening symptoms. A literature review of spontaneous IICA dissection with revascularization procedures was conducted to discuss the indications, timing, treatment modalities, and surgical outcomes., Lessons: The STA-MCA bypass provides supplemental cerebral blood flow and can prevent critical complications. Contrast-enhanced MRI in the acute phase of dissection can show a wall contrast effect and assist in predicting disease progression. https://thejns.org/doi/10.3171/CASE24332.

Background: Fat is commonly used for preventing cerebrospinal fluid (CSF) leakage during endoscopic transsphenoidal surgery (ETSS). However, fat is soft, slippery, and sometimes not easy to handle. The present study aimed to examine the efficacy of our Surgicel ® wrapping method, which allows for better fat handling, in preventing the occurrence of CSF leakage among patients undergoing ETSS., Methods: We used fat tissues removed from the abdomen. The fat was cut with scissors into pieces that were approximately 5 mm in size. Surgicel ® was also cut into 2.5 cm 2 . The fat tissues were encased with these Surgicel ® squares and slightly moistened with a saline solution., Results: Between January 2023 and August 2024, 34 patients aged 18-86 years (average 54.9 years) underwent ETSS. Among these patients, 20 had pituitary tumors, 6 had Rathke's cysts, and 8 had other conditions. None of the patients had CSF leakage postoperatively. The use of Surgicel ® -wrapped fat during ETSS is better than the use of fat alone., Conclusion: The Surgicel ® wrapping method allows for better fat handling during ETSS., Competing Interests: There are no conflicts of interest., (Copyright: © 2024 Surgical Neurology International.)

Background:  Gentian violet ink is used as a skin marker in various surgical procedures, including neurosurgery. The dye is also used to visualize the edges of blood vessels during bypass surgery. However, gentian violet ink carries the risks of carcinogenicity and venous injury, which causes microvascular thrombosis. In this study, we compare the gentian violet-free dye C.I. Basic Violet 4 (BV4) and gentian violet. The usefulness, in terms of color, and formation of microvascular thrombosis in anastomosis were compared., Methods:  We used the gentian violet-free dye in 20 cases involving 3 vascular anastomoses. The bone cutting lines on the bone surface, superior temporal artery, and middle cerebral artery were drawn using BV4 and gentian violet ink., Results:  The colors of BV4 and gentian violet ink were similar. No thrombus formation was observed at the vascular anastomosis when using BV4., Conclusion:  BV4 can be used similarly to gentian violet ink. No adverse effects such as thrombus formation in microvascular anastomosis were experienced when BV4 was used., Competing Interests: None declared., (Thieme. All rights reserved.)

(1) Background Cerebral revascularization is necessary to treat intracranial arterial stenosis caused by moyamoya disease, atherosclerosis, or large complex aneurysms. Although various donor vascular harvesting methods have been reported safe, there are no reports on the histological evaluation of donor vessels for each disease, despite the variety of diseases wherein vascular anastomosis is required. (2) Methods Pathological findings of the superficial temporal artery (STA), radial artery (RA), occipital artery (OA), and saphenous vein (SV) harvested at the institution were analyzed. Patients classified according to aneurysm, atherosclerosis, and moyamoya disease were assessed for pathological abnormalities, medical history, age, sex, smoking, and postoperative anastomosis patency. (3) Results There were 38 cases of atherosclerosis, 15 cases of moyamoya disease, and 30 cases of aneurysm in 98 donor vessels (mean age 57.2) taken after 2006. Of the 84 STA, 11 RA, 2 OA, and 1 SV arteries that were harvested, 71.4% had atherosclerosis, 11.2% had dissection, and 10.2% had inflammation. There was no significant difference in the proportion of pathological findings according to the disease. A history of hypertension is associated with atherosclerosis in donor vessels. (4) Conclusions This is the first study to histologically evaluate the pathological findings of donor vessels according to disease. The proportion of dissection findings indicative of vascular damage due to surgical manipulation was not statistically different between the different conditions.

Moyamoya disease (MMD) is a cerebrovascular disorder that is predominantly observed in women of East Asian descent, and is characterized by progressive stenosis of the internal carotid artery, beginning in early childhood, and a distinctive network of collateral vessels known as "moyamoya vessels" in the basal ganglia. Additionally, a prevalent genetic variant found in most MMD cases is the p.R4810K polymorphism of RNF213 on chromosome 17q25.3. Recent studies have revealed that RNF213 mutations are associated not only with MMD, but also with other systemic vascular disorders, including intracranial atherosclerosis and systemic vascular abnormalities such as pulmonary artery stenosis and coronary artery diseases. Therefore, the concept of "RNF213-related vasculopathy" has been proposed. This review focuses on polymorphisms in the RNF213 gene and describes a wide range of clinical and genetic phenotypes associated with RNF213-related vasculopathy. The RNF213 gene has been suggested to play an important role in the pathogenesis of vascular diseases and developing new therapies. Therefore, further research and knowledge sharing through collaboration between clinicians and researchers are required.

A patient with trigeminal neuralgia due to venous compression was successfully treated by transposition achieved by drilling the suprameatal tubercle. A 53-year-old woman presented with classical trigeminal neuralgia affecting the maxillary division of the right trigeminal nerve. MRI and CT revealed a bony prominence, called the suprameatal tubercle, above the opening of the internal acoustic meatus. MRI showed a thick venous flow void interposed between the suprameatal tubercle and trigeminal nerve. The patient underwent retrosigmoid craniotomy. The bony prominence restricted transposition of the compressed vein, so the compressed vein was successfully transposed after drilling the prominence. The patient's symptoms resolved completely. Drilling the suprameatal tubercle is useful for transposing sandwiched compression vessels.

Ruptured cerebral aneurysms that occur in the anterior wall of the internal carotid artery (ICA) are known as blood blister-like aneurysms (BBAs); they have been reported to account for 0.3% to 1% of all ruptured ICA aneurysms. In this report, we describe the treatment of an unusual traumatic BBA (tBBA) with high-flow bypass using a radial artery graft, which resulted in a favorable outcome. A 59-year-old female suffered from an acute epidural hematoma, traumatic subarachnoid hemorrhage, and traumatic carotid-cavernous sinus fistula (tCCF) after being involved in a motor vehicle accident. Her angiography results showed tCCF and a tBBA on the anterior wall of the right ICA. On the fourth day after injury, we found rebleeding from the tBBA and performed an emergency high-flow bypass using a radial artery graft with lesion trapping as a curative procedure for the tCCF and tBBA. Postoperatively, right abducens nerve palsy appeared, but no other neurological symptoms were noted; the patient was thereafter transferred to a rehabilitation hospital 49 days after injury. Traumatic ICA aneurysms commonly occur close to the anterior clinoid process, form within 1 to 2 weeks of injury, and often rupture around 2 weeks after trauma. This case was considered rare as the ICA was likely injured and bleeding at the time of injury, resulting in a form of tBBA; this allowed early detection and appropriate treatment that resulted in a good outcome., Competing Interests: The authors and all co-authors have no conflicts of interest to declare. Authors who are members of the Japan Neurosurgical Society have registered online for self-reported COI Disclosure Statement Forms., (© 2023 The Japan Neurosurgical Society.)

Middle cerebral artery (MCA) dissection is rare, and various clinical presentations, including hemorrhage, ischemia, or comorbidities, and the changes in imaging findings over time hinder treatment decisions. The European Stroke Organization guidelines exclude MCA dissection. Few cases have been reported with no review of the relevant literature. Therefore, we reviewed the relevant literature and our own experience with non-traumatic MCA dissection cases to determine appropriate treatment strategies. At our institution and affiliated institutions, we encountered six cases of MCA dissection-five with infarction and one with hemorrhage. Two patients underwent revascularization, and one underwent an aneurysmectomy. We reviewed English and Japanese articles in PubMed and Medical Journal Web and summarized the results based on the relationships among age, sex, location, the presence of an aneurysm, the presence of angiography, history, treatment, and mode of onset. The clinical course, changes in imaging, treatment strategies, and prognosis were discussed. Eighty cases were included in the review. Cerebral aneurysms were more common distal to the M2 area (p = 0.00) and were correlated with hemorrhage (p < 0.001). Most hemorrhagic cases with aneurysms were treated surgically, while ischemic cases were treated with antithrombotic agents, and both had a similar neurological prognosis. There were some cases of rebleeding after antithrombotic therapy, especially in older adults.Surgical treatment is recommended in cases of hemorrhage and confirmed aneurysms, particularly for lesions distal to the M2 area. Patients with aneurysm-associated ischemia should be followed up, and antithrombotic treatment should be considered with particular care in older adults., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Transorbital endoscopic approaches have been described for pathologies of anterior and middle fossae. Standard lateral orbitotomy gives access to mesial temporal lobe, but the axis of work is partially obscured by the temporal pole and working corridor is limited., Objective: To evaluate the usefulness of an inferolateral orbitotomy to provide a more direct corridor to perform a transuncal selective amygdalohippocampectomy., Methods: Three adult cadaveric specimens were used for a total of 6 dissections. A step-by-step description and illustration of the transuncal corridor for a selective amygdalohippocampectomy were performed using the inferolateral orbitotomy through an inferior eyelid conjunctival incision. The anatomic landmarks were demonstrated in detail. Orbitotomies and angles of work were measured from computed tomography scans, and the area of resection was illustrated by postdissection MRI., Results: Inferior eyelid conjunctival incision was made for exposure of the inferior orbital rim. Inferolateral transorbital approach was performed to access the transuncal corridor. Endoscopic selective amygdalohippocampectomy was performed through the entorhinal cortex without damage to the temporal neocortex or Meyer's loop. The mean horizontal diameter of the osteotomy was 14.4 mm, and the vertical one was 13.6 mm. The mean angles of work were 65° and 35.5° in the axial and sagittal planes, respectively. Complete amygdalohippocampectomy was achieved in all 6 dissections., Conclusion: Transuncal selective amygdalohippocampectomy was feasible in cadaveric specimens using the inferolateral transorbital endoscopic approach avoiding damage to the temporal neocortex and Meyer's loop. The inferior eyelid conjunctival incision may result in an excellent cosmetic outcome., (Copyright © Congress of Neurological Surgeons 2023. All rights reserved.)

Crystal violet (CV) ink has been used as a skin marker worldwide. It has been reported to be useful for vessel wall visualization of microvascular anastomoses. Contrastingly, it has been found to be carcinogenic and inhibit migration and proliferation of venous cells. In some countries, its use in the medical field has been restricted. Therefore, it is necessary to consider alternatives to CV. In this present study, we compared the time required for the anastomosis of a 0.8-1 mm diameter vessel in the chicken wrist artery using CV and a CV-free dye (ethyl violet; EV). The surgeon, microscope, and anastomosis microsurgical tools were standardized for comparison. CV and EV were changed for each anastomosis. The same surgeon performed 30 anastomoses using each dye. No visually obvious differences were noted in the vascular transections with CV and EV. As per the results, no statistically significant difference was observed in the time required for anastomosis using CV and EV. EV conforming to California Proposition 65 may be an effective alternative to CV for vascular visualization of microvascular anastomoses. However, further studies on the effectiveness of the EV in clinical cases are needed.

Background: Few studies have used simulation models to examine long-term improvement in microsurgical technique. We investigated whether improvement in surgical technique could be assessed by continuous, objective, contest-format evaluation of the same microsurgical task., Methods: Since 2014, neurosurgeons with 1-10 years of experience participated in a biannual competition-format test. The task involved creating as many sutures as possible during the 5-minute interval after arteriotomy of a 1-mm artificial vessel. A modified version of the Objective Structured Assessment of Technical Skills examination was created and used. Changes and differences in scores over time were examined for each evaluator., Results: Overall, 103 neurosurgeons participated in the study at least once, and those who participated more than once were divided into two groups: those who had the highest score in each contest and those who had the lowest score. The linear regression equations for the highest and lowest scorers were y=7.62x+81.56 (R 2 =0.628) and y=1.94x+67.93 (R 2 =0.0433), respectively. High scorers had high scores from the first time they participated, and their scores tended to increase further, while scores for low scorers tended not to increase with additional experience. Scores for the four evaluators did not significantly differ., Conclusions: Our results suggest that technical improvement in surgery can be assessed by long-term, continuous evaluation of microsurgical technique and that the present evaluation system might help increase surgical safety.

Objective: Concerns about the approach-related morbidity of the extradural anterior petrosal approach (EAPA) have been raised, especially regarding temporal lobe and venous injuries, hearing impairment, facial nerve palsy, cerebrospinal fluid fistula, and seizures. There is lack in the literature of studies with detailed analysis of surgical complications. The authors have presented a large series of patients who were treated with EAPA, focusing on complications and their avoidance., Methods: The authors carried out a retrospective review of patients who underwent EAPA at their institution between 2012 and 2021. They collected preoperative clinical characteristics, operative reports, operative videos, findings on neuroimaging, histological diagnosis, postoperative course, and clinical status at last follow-up. For pathologies without petrous bone invasion, the amount of petrous apex drilling was calculated and classified as low (< 70% of the volume) or high (≥ 70%). Complications were dichotomized as approach related and resection related., Results: This study included 49 patients: 26 with meningiomas, 10 brainstem cavernomas, 4 chondrosarcomas, 4 chordomas, 2 schwannomas, 1 epidermoid cyst, 1 cholesterol granuloma, and 1 osteoblastoma. The most common approach-related complications were temporal lobe injury (6.1% of patients), seizures (6.1%), pseudomeningocele (6.1%), hearing impairment (4.1%), and dry eye (4.1%). Approach-related complications occurred most commonly in patients with a meningioma (p = 0.02) and Meckel's cave invasion (p = 0.02). Gross-total or near-total resection was correlated with a higher rate of tumor resection-related complications (p = 0.02) but not approach-related complications (p = 0.76). Inferior, lateral, and superior tumoral extension were not correlated with a higher rate of tumor resection-related complications. No correlation was found between high amount of petrous bone drilling and approach- or resection-related complications., Conclusions: EAPA is a challenging approach that deals with critical neurovascular structures and demands specific skills to be safely performed. Contrary to general belief, its approach-related morbidity seems to be acceptable at dedicated skull base centers. Morbidity can be lowered with careful examination of the preoperative neuroradiological workup, appropriate patient selection, and attention to technical details.

The extended endoscopic endonasal approach(EEA)has been expanding in recent years with the development of instruments and surgical techniques. Basically, sela, extradural, and intranasal lesions such as pituitary tumor, craniopharyngioma, chordoma, chondrosarcoma, and cholesterol granuloma are indicated. Intradural lesions or lesions that extend laterally or downward to the craniocervical junction are more difficult to operate. In addition, cases of hard tumor with calcification of the tumor, cases in which the tumor involves important blood vessels, re-operative cases, and cases after radiotherapy are also difficult cases and should be considered preoperatively. In recent years, we have been trying to keep the nasal structures as much as possible without removing nasal structure, but in cases where the tumor has invaded and destroyed the nasal structures, extended EEA is necessary. The anatomy of the extended EEA is complicated and not common among neurosurgeons. In this chapter, we present the basic anatomy and surgical cases to be understood in extended EEA and explain the pitfalls.

•The transorbital approach combining eyebrow incision and crescent-shaped craniotomy increases the surgical freedom to access the anterior and middle skull-base.•The technic allows the use of both endoscope and microscope.•The concept is at the crossroad between the supraorbital keyhole and endoscopic trans-orbital approach., (© 2022 Published by Elsevier B.V. on behalf of EUROSPINE, the Spine Society of Europe, EANS, the European Association of Neurosurgical Societies.)

Background: Maintaining the patency of extracranial-to-intracranial (EC-IC) bypass is critical for long-term stroke prevention. However, reports on the factors influencing long-term bypass patency and quantitative assessments of bypass patency are limited., Objective: To quantitatively evaluate blood flow in EC-IC bypass using four-dimensional (4D) flow magnetic resonance imaging (MRI) and investigate factors influencing the long-term patency of EC-IC bypass., Methods: Thirty-six adult Japanese patients who underwent EC-IC bypass for symptomatic internal carotid or middle cerebral artery occlusive disease were included. We examined the relationships between decreased superficial temporal artery (STA) blood flow volume and perioperative complications, long-term ischemic complications, patient background, and postoperative antithrombotic medications in patients for whom STA flow could be quantitatively assessed for at least 5 months using 4D flow MRI., Results: The mean follow-up time was 54.7 ± 6.1 months. One patient presented with a stroke during the acute postoperative period that affected postoperative outcomes. No recurrent strokes were recorded during long-term follow-up. Two patients died of malignant disease. Seven cases of reduced flow occurred in the STA, which were correlated with single bypass (P = .0294) and nonuse of cilostazol (P = .0294). STA occlusion was observed in 1 patient during the follow-up period. Hypertension, age, smoking, dyslipidemia, and diabetes mellitus were not correlated with reduced blood flow in the STA., Conclusion: Double anastomoses and cilostazol resulted in long-term STA blood flow preservation. No recurrence of cerebral infarction was noted in either STA hypoperfusion or occlusion cases., (Copyright © Congress of Neurological Surgeons 2022. All rights reserved.)