A novel predictor of ischemic complications in the treatment of ruptured middle cerebral artery aneurysms: Neck-branching angle.

Objective: The risk factors of procedural cerebral ischemia (CI) in ruptured middle cerebral artery (MCA) aneurysms are unclear. This study proposed the neck-branching angle (NBA), a simple quantitative indicator of the aneurysm neck and branch vessels, and analyzed its usefulness as a predictor of procedural CI in ruptured MCA aneurysms. Methods: We retrospectively analyzed 128 patients with ruptured saccular MCA aneurysms who underwent surgical or endovascular treatment between January 2014 and June 2021. We defined the NBA as the angle formed by the MCA aneurysm neck and M2 superior or inferior branch vessel line. The superior and inferior NBA were measured on admission via three-dimensional computed tomography angiography on admission. We divided the patients into clipping (106 patients) and coiling (22 patients) groups according to the treatment. Risk factors associated with procedural CI were analyzed in each group. Results: Both groups showed that an enlarged superior NBA was a significant risk factor for procedural CI (clipping, P < 0.0005; coiling group, P = 0.007). The receiver operating characteristic curve showed the closed thresholds of the superior NBA with procedural CI in both groups (clipping group, 128.5°, sensitivity and specificity of 0.667 and 0.848, respectively; coiling group, 130.9°, sensitivity and specificity of 1 and 0.889, respectively). Conclusion: The NBA can estimate the procedural risk of ruptured MCA aneurysms. In addition, an enlarged superior NBA is a risk factor for procedural CI in both clipping and coiling techniques.

Bimodal artificial intelligence using TabNet for differentiating spinal cord tumors-Integration of patient background information and images.

We proposed a bimodal artificial intelligence that integrates patient information with images to diagnose spinal cord tumors. Our model combines TabNet, a state-of-the-art deep learning model for tabular data for patient information, and a convolutional neural network for images. As training data, we collected 259 spinal tumor patients (158 for schwannoma and 101 for meningioma). We compared the performance of the image-only unimodal model, table-only unimodal model, bimodal model using a gradient-boosting decision tree, and bimodal model using TabNet. Our proposed bimodal model using TabNet performed best (area under the receiver-operating characteristic curve [AUROC]: 0.91) in the training data and significantly outperformed the physicians' performance. In the external validation using 62 cases from the other two facilities, our bimodal model showed an AUROC of 0.92, proving the robustness of the model. The bimodal analysis using TabNet was effective for differentiating spinal tumors.

Feasibility of Metal Artifact Reduction on CT Angiography for Planning Direct Surgery of Tentorial dAVF after Onyx Embolization.

Although Onyx is approved as an embolic material for arteriovenous malformation (AVM) and dural arteriovenous fistula (dAVF), metal artifacts due to Onyx on CT remain problematic. We report the feasibility of a metal artifact reduction (MAR) algorithm on CT angiography (CTA) in the planning of direct surgery of dAVF after transarterial Onyx embolization. A 45-year-old male patient presented with right pulsatile tinnitus, and cerebral angiography demonstrated right tentorial dAVF. As the dAVF had not completely disappeared even after Onyx transarterial embolization, we planned direct surgery. Evaluation of the lesion was difficult on normal preoperative CTA because of Onyx artifacts, but CTA using MAR enabled a detailed planning of direct surgery. Direct surgery was performed through right retrosigmoid craniotomy. Referencing CTA using MAR, we identified the draining veins originating from the main drainer, which were coagulated and cut, achieving complete occlusion of the dAVF. His symptoms disappeared with no postoperative complications. CT angiography using MAR was useful for planning direct surgery after Onyx embolization. As the incidence of direct surgery after transarterial Onyx embolization for AVM or dAVF is increasing, MAR on CTA will become more important.

Crossbow Bolt Penetrating the Neck Removed with the Assistance of an Endovascular Approach: A Case Report and Literature Review.

Penetrating neck injury by a crossbow bolt is extremely rare and can be life-threatening. When removing a crossbow bolt from the neck, it is necessary to protect against fatal bleeding from the carotid vessels. We report removing a crossbow bolt penetrating the neck, with an endovascular approach. A 49-year-old woman was shot in the neck by a crossbow and was transferred to our hospital. On presentation, the crossbow bolt totally penetrated the neck from right to left. Her level of consciousness was clear, with no significant neurological deficits except for right peripheral facial palsy. Neck contrast-enhanced computed tomography revealed the crossbow bolt in contact with bilateral external and internal carotid arteries and that the bolt caused dissection of the left main trunk of the external carotid artery. Under general anesthesia, the crossbow bolt was removed under fluoroscopy with the assistance of an endovascular approach. First, we performed coil embolization for the dissected external carotid artery. Second, we prepared for fatal bleeding from the carotid arteries during crossbow bolt removal under protection using guiding catheters placed in bilateral common carotid arteries. The bolt was removed successfully without significant bleeding, and no complications occurred during the procedure. We report the successful removal of a crossbow bolt penetrating the neck. When removing a crossbow bolt penetrating the neck, endovascular assistance may be feasible to protect against fatal bleeding from the carotid arteries.

Midline suboccipital approach to a vertebral artery-posterior inferior cerebellar artery aneurysm from the rostral end of the patient using ORBEYE.

Background: The midline suboccipital approach with the patient in the prone position is safe and effective for clipping vertebral artery-posterior inferior cerebellar artery (VA-PICA) aneurysms. Using a conventional surgical microscope from the rostral end of the patient for this approach without an extreme head-down position requires the surgeon to overhang the visual axis of the microscope and perform surgical manipulations in an uncomfortable posture. We report performing the midline suboccipital approach from the rostral end with slight head-down position using ORBEYE, a new high-definition (4K) three-dimensional exoscope. Case Description: A 65-year-old woman was admitted for clipping of a right unruptured VA-PICA aneurysm (maximum diameter, 5mm) located medially and ventral to the hypoglossal canal. After induction of general anesthesia, the patient was placed in the prone position with the head titled slightly downward. A midline suboccipital approach was performed from the rostral end of the patient using ORBEYE. Clipping was safely accomplished in a comfortable posture. No operative complications occurred. Postoperative computed tomography angiography showed complete aneurysmal obstruction. Conclusion: Exoscopic surgery using ORBEYE is feasible for a midline suboccipital approach to VA-PICA aneurysms from the rostral end of the patient with the patient in the prone with slight head-down position.

Carotid-carotid crossover bypass after mechanical thrombectomy for internal carotid artery occlusion due to plaque from stenosed innominate artery.

BACKGROUND: The treatment for internal carotid artery occlusion (ICAO) due to innominate artery stenosis is not well established. We herein describe a case of carotid-carotid crossover bypass and common carotid artery (CCA) ligation after mechanical thrombectomy for ICAO due to a plaque from the stenosed innominate artery. CASE DESCRIPTION: A 70-year-old man was transferred to our hospital because of left-sided hemiparalysis. Head magnetic resonance imaging/angiography showed a cerebral infarction in the right middle cerebral artery area and the right ICAO due to a plaque from the stenosed innominate artery. Immediately, we performed mechanical thrombectomy and successfully attained partial revascularization (Thrombolysis in Cerebral Infarction Grade 2B). After a conference with cardiovascular group, we performed carotid-carotid crossover bypass and the right CCA ligation. The treatment was successful, and no complications occurred. CONCLUSION: Carotid-carotid crossover bypass and CCA ligation may be a better option for innominate artery stenosis in selected patients.

Exoscopic carotid endarterectomy using movable 4K 3D monitor: Technical note.

BACKGROUND: Carotid endarterectomy (CEA) using conventional surgical microscope has been already established as golden standard. Recently, exoscope was introduced into the field of neurosurgery, and various merits of it have been reported. We report the experiences of exoscopic CEA using a movable 4K 3D monitor and discuss the feasibility of it. METHODS: We report a consecutive series of 15 cases of exoscopic CEA for internal carotid artery (ICA) stenosis using a movable 4K 3D monitor between January 2020 and April 2021. We utilized ORBEYE as an exoscope system and a 31-inch movable 4K 3D monitor, which was installed in the Maquet Moduevo ceiling supply unit. RESULTS: In all 15 cases, the procedures were accomplished only using the ORBEYE. There were no operative complications due to the use of the exoscope. In response to the operative site, the 4K 3D monitor was moved to face the operator. Even when the angle of the visual axis of the exoscope against the horizontal plane was small during the surgical manipulation in the distal portion of ICA, the operator was able to maintain a comfortable posture. CONCLUSION: Using the movable 4K 3D monitor, exoscopic CEA can be performed ergonomically. The operator can manipulate the distal portion of the ICA or proximal portion of the common carotid artery in a comfortable posture and face the monitor by adjusting its position.

Four Hands Surgery for Intracerebral Hemorrhage using Orbeye: Educational Values and Ergonomic Advantages - A Technical Note.

We have developed a new educational approach to microsurgery in which a trainee and supervisor can cooperate with "4 hands" using the exoscope. We evaluated 4-hands surgery for intracranial hemorrhage (ICH) using the exoscope to validate the educational value and ergonomic advantages of this method. Thirty consecutive patients who underwent surgery for ICH using the exoscope between December 2018 and May 2020 were studied retrospectively. All operations were performed by a team comprising a supervisor (assistant) and a trainee (main operator). The assistant set the visual axis of the exoscope, and adjusted focus and magnification as a scopist. After setting the ORBEYE, the supervisor helped retract the brain and withdraw and irrigate the hematoma using suction tubes or brain retractors. Moreover, the trainee evacuated the hematoma with a suction tube and coagulated using bipolar forceps. Patient background and results of treatment were evaluated. Intraoperative postures of the operators were observed, and schemas compared with the use of a conventional microscope were developed. All microsurgical procedures were accomplished by a trainee with a supervisor using only the exoscope. During the surgery, the surgeons could work in a comfortable posture, and the supervisor and trainee could cooperate in microsurgical procedures using their four hands. The results of the present case series concerning evacuation of ICH were not inferior to those described in previous reports. To increase opportunities for education in microsurgery, 4-hands surgery for ICH using the exoscope appears feasible and safe and offered excellent educational value and ergonomic advantages.

Balloon anchoring to traverse the sigmoid sinus for delivery of large-caliber venous stents: A technical note.

BACKGROUND: In the reconstruction of the superior sagittal sinus or transverse sinus, it is desirable to place a large-diameter guiding catheter into the transverse sinus to introduce the stent delivery system smoothly. The utility of an anchoring technique with a percutaneous transluminal angioplasty (PTA) balloon for navigating an 8 F guiding catheter into the transverse sinus is demonstrated.Case Descriptions: Two dural arteriovenous fistula (dAVF) cases (Cognard type II a +b, Borden type II) that underwent sinus stenting are presented. In both cases, when the 8 F guiding catheter was placed in the jugular vein, the stent delivery system could not enter the transverse sinus because it could not pass through the transverse-sigmoid sinus junction. Introduction of an 8 F guiding catheter into the transverse sinus was attempted but failed. An 8-mm or 9-mm PTA balloon was used as a distal anchor, and this technique allowed easier guiding of catheter advancement into the transverse sinus. In both cases, Carotid WALLSTENTS were placed in the sinus easily, with no complications. CONCLUSION: Balloon anchoring in the venous system is useful for achieving large-caliber catheter access across difficult anatomy and is technically feasible.

Retrosigmoid Approach in the Supine Position Using ORBEYE: A Consecutive Series of 14 Cases.

One of the merits of recently introduced exoscopes, including ORBEYE, is that they are superior to a conventional microscope in terms of ergonomic features. Taking advantage of it, the retrosigmoid approach can be performed in the supine position using ORBEYE. We report a consecutive series of 14 operations through the retrosigmoid approach in the supine position using ORBEYE. Fourteen consecutive patients who underwent surgery through the retrosigmoid approach for cerebellopontine (CP) angle lesions in the supine position using ORBEYE were targeted, and surgical outcomes and complications were examined. We evaluated the posture of the operator and the surgical field during this approach compared with those using a conventional microscope. In all 14 cases, all operative procedures were accomplished only using the ORBEYE. There were no operative complications due to this approach. Using ORBEYE, even when the angle of the operative visual axis was horizontal, the operators could manipulate in a comfortable posture. They were not forced to be in an uncomfortable posture that extended their arms, as is often the case with a conventional microscope. Therefore, they could use shorter surgical instruments. As the cerebellum shifted downward with gravity even using slight retraction during this approach, the working space of the surgical field was easily secured. Through this approach, the operators can perform stable microsurgery of CP angle lesions in a comfortable posture. This approach can reduce the burden on the operator and the patient, leading to a refined surgical procedure.

Reduction of radiation exposure using low pulse rate fluoroscopy during neuroendovascular surgery.

INTRODUCTION: Endovascular surgery is minimally invasive, but the radiation exposure can be problematic. There is no report assessing whether radiation exposure can be reduced by using a low pulse rate during carotid artery stenting (CAS). The aim of this study was to evaluate whether reducing the pulse rate from 7.5 to 4 frames per second (f/s) can reduce the radiation exposure while maintaining safety during CAS procedure. METHODS: We retrospectively reviewed the radiation data and clinical features of all 100 patients who underwent CAS between 2014 and 2019. We changed the pulse rate from 7.5 to 4 f/s in 2017. The fluoroscopic time (FT), dose area product (DAP), and total air kerma (AK) were collected. Statistical analyses were performed between the pulse rate and clinical outcomes, including radiation exposure.

Sphenoid Ridge Keyhole Approach Using the Lone Star Retractor System in Clipping of Unruptured Middle Cerebral Artery Aneurysms: Technical Note.

BACKGROUND: We report a technique for the sphenoid ridge keyhole approach using the Lone Star (LS) retractor system as an extracranial tissue retractor in microsurgical clipping of unruptured middle cerebral artery aneurysms. METHODS: The LS retractor system is used as the extracranial tissue retractor. A skin incision (50-60 mm) without shaving is made. The temporal fascia is cut, and skin and fascia flap are reflected anteriorly. On the temporal muscle, keyhole craniotomy is registered using the navigation system such that the lateral edge of the sphenoid ridge is the center of the craniotomy. After the temporal muscle is split in the direction of the muscle fiber, keyhole craniotomy of approximately 30 mm in diameter is created. After dural incision, the Sylvian fissure is dissected by a standard microsurgical technique using brain retractors, and the target aneurysm is clipped. RESULTS: By precise registration of the sphenoid ridge keyhole craniotomy, the Sylvian fissure emerged in the center of the keyhole. Using the LS retractor system, a flat and shallow operative field was obtained. There were no complications using this method. CONCLUSIONS: We optimized the craniotomy, manipulating the target aneurysm in the center of the keyhole. It did not interfere with conventional microsurgical techniques.

Microsurgery "Under the Eaves" Using ORBEYE: A Case of Dural Arteriovenous Fistula of the Anterior Cranial Fossa.

BACKGROUND: One of the merits of exoscopes, including ORBEYE, is that they are superior to a microscope in terms of ergonomic features. We report a case of dural arteriovenous fistula (dAVF) that was cured by direct surgery using the ergonomic advantages of ORBEYE. CASE DESCRIPTION: A 78-year-old man was found to have dAVF of the anterior cranial fossa incidentally. We performed direct surgery via bifrontal craniotomy. Because the frontal sinus was large, we reserved the frontal bone-like eaves in order not to open the frontal sinus. The vertex of his head was sufficiently down to shift the frontal lobe downward with gravity. During surgery, we set the angle of the operative visual axis of ORBEYE approximately horizontal to avoid the reserved frontal bone. We performed a stable operation using ORBEYE in a comfortable posture. CONCLUSIONS: ORBEYE facilitates ergonomic microsurgery, even under the eaves, with the angle of the operative visual axis approximately horizontal using gravity.

Feasibility of Smart Metal Artifact Reduction Algorithm on Computed Tomography Angiography for Clipping of Recurrent Aneurysms After Coil Embolization.

BACKGROUND: The number of patients with a history of clipping of recurrent aneurysms after coil embolization has increased. The aim of this article was to report the feasibility of CT angiography using a commercial metal artifact reduction algorithm (Smart Metal Artifact Reduction [MAR]) for patients who underwent clipping of recurrent aneurysms after coil embolization. METHODS: Six cases of clipping of recurrent aneurysms after coil embolization were examined with CT angiography using MAR between 2015 and 2018 at a single institution. Conventional CT angiography and three-dimensional digital subtraction angiography data were compared, and depiction of the status of treated aneurysms using MAR was estimated. RESULTS: Conventional CT angiography was unable to depict the status of treated aneurysms in the patients with a history of clipping of recurrent aneurysms after coil embolization because of metal artifacts. With MAR, metal artifacts were greatly reduced, and the status of treated aneurysms was able to be depicted, although depiction was inferior to three-dimensional digital subtraction angiography. CONCLUSIONS: For patients with a history of clipping of recurrent aneurysms after coil embolization, CT angiography using MAR is feasible, although further development of imaging techniques is needed.

Clipping of Recurrent Cerebral Aneurysms After Coil Embolization.

BACKGROUND AND AIMS: To assess the technical points of surgical clipping for recurrent aneurysms after coiling, we examine a consecutive series of 14 patients who underwent re-treatment. MATERIALS AND METHODS: From 2009 to 2016, 27 recurrent aneurysms after coiling were re-treated with endovascular treatment or surgical clipping. Of these, 14 were re-treated surgically. In cases where the remnant neck was sufficiently large, neck clipping was chosen. Where the remnant neck was too small and the border between the thrombosed and non-thrombosed portion was distinct, partial clipping was chosen. Surgical clipping was attempted without removing the coils when technically feasible. RESULTS: Among the 14 cases, neck clipping was performed in 11, partial clipping in 2, and trapping with bypass in 1 case. Clipping without removal of coils was accomplished in all cases. No neurological deterioration occurred after surgical clipping in any case. CONCLUSION: Clipping of recurrent aneurysms after coiling can compensate for the failure of initial endovascular therapy. For clipping without removal of coils, precise evaluation of the remnant neck is required. Bypass surgery is key to treatment in the case of aneurysm trapping.

Freehand Technique of an Electromagnetic Navigation System Emitter to Avoid Interference Caused by Metal Neurosurgical Instruments.

BACKGROUND: Electromagnetic (EM) navigation has been reported to be a noninvasive and easy-to-use technique. However, the use of metal neurosurgical instruments (e.g., skin hooks, head frames, brain retractors systems) can interfere with the magnetic fields of such systems. We present the freehand technique, a new technique involving the manual manipulation of the emitter of an EM navigation system, which helps to prevent interference caused by metal instruments during surgery. METHODS: The AxiEM Electromagnetic StealthStation Navigation System (Medtronic) was used in this study. The emitter was placed in the sterilized surgical field, which allowed it to be moved freely during surgery. When navigation was necessary during the procedure, the assistant held the emitter at an appropriate angle to the sterile surgical field to avoid interference caused by the metal neurosurgical instruments. RESULTS: During surgery involving metal surgical instruments, all of the functions of the EM navigation system were available throughout the procedure. The accuracy of the navigation system was sufficient to allow craniotomy and intradural manipulation to be conducted. CONCLUSIONS: During the use of EM navigation systems, the freehand technique with the emitter can prevent interference caused by metal instruments.

Direct Surgery of Previously Coiled Large Internal Carotid Ophthalmic Aneurysm for the Purpose of Optic Nerve Decompression.

Background Progressive visual loss after coil embolization of a large internal carotid ophthalmic aneurysm has been widely reported. It is generally accepted that the primary strategy for this complication should be conservative, including steroid therapy; however, it is not well known as to what approach to take when the conservative therapy is not effective. Case Presentation We report a case of a 55-year-old female presenting with progressive visual loss after the coiling of a ruptured large internal carotid ophthalmic aneurysm. As the conservative therapy had not been effective, we performed neck clipping of the aneurysm with optic canal unroofing, anterior clinoidectomy, and partial removal of the embolized coils for the purpose of optic nerve decompression. After the surgery, the visual symptom was improved markedly. Conclusions It is suggested that direct surgery for the purpose of optic nerve decompression may be one of the options when conservative therapy is not effective for progressive visual disturbance after coil embolization.

Utility of the Lone Star Retractor System in Microsurgical Carotid Endarterectomy.

BACKGROUND: The retractor system is an important device in carotid endarterectomy (CEA). We applied the Lone Star (LS) Retractor System, which is a self-retaining retractor originally designed for improved visualization in many other surgical fields, in microsurgical CEA. METHODS: The LS disposal retractor (14.1 cm × 14.1 cm) and LS elastic stays (5-mm sharp hook) were used as a retractor system in 38 consecutive CEAs. RESULTS: Using the LS retractor system, a shallow operative field could be obtained by lifting up the connective tissue surrounding the deep structures hooked by the LS elastic stays. The LS elastic stays were quick and easy to handle in the microsurgical operative field. There were no complications using the LS retractor system. CONCLUSIONS: The application of the LS retractor system in microsurgical CEA is feasible. An additional merit is that it is single use.

Traumatic Entrapment of the Vertebral Artery Demonstrated by a 3D Angiographic Study.

BACKGROUND: Vertebrobasilar artery entrapment resulting from a clivus fracture is rare. The entrapped lesions are not radiographically depicted precisely because they are only identified by autopsy or completely occluded. In addition, no changes in the features have been revealed clearly because radiologic examinations were performed only in the acute stage. CASE DESCRIPTION: We report a case of traumatic entrapment of the vertebral artery depicted precisely by a three-dimensional angiographic study in the subacute stage, presenting the serial changes in the morphologic features and a review of the published cases. CONCLUSION: It is necessary to manage vertebrobasilar artery entrapment cautiously because it is suggested that the entrapped lesion is accompanied by arterial dissection.

Retreatment of Recurrent Internal Carotid-Posterior Communicating Artery Aneurysm after Coil Embolization.

Internal carotid-posterior communicating artery (IC-PC) aneurysms account for more than 20% of all intracranial aneurysms. As a result of the increase in coiling, there has also been an increase in recurrent IC-PC aneurysms after coiling. We present our experience of 10 recurrent IC-PC aneurysms after coiling that were retreated using surgical or endovascular techniques in order to discuss the choice of treatment and the points of clipping without removal of coils. From 2007 to 2014, 10 recurrent IC-PC aneurysms after coiling were retreated. When the previous frames covered the aneurysms all around or almost around except a part of the neck, coiling was chosen. In other cases, clipping was chosen. Clipping was attempted without removal of coils when it was technically feasible. Among the 10 IC-PC aneurysms retreated, 3 were retreated with coiling and 7 were retreated with clipping. In all three cases retreated with coiling, almost complete occlusion was accomplished. In the seven cases retreated with clipping, coil extrusion was observed during surgery in six cases. In most of them, it was necessary to dissect strong adhesions around the coiled aneurysms and to utilize temporary occlusion of the internal carotid artery. In all seven cases, neck clipping was accomplished without the removal of coils. There were no neurological complications in any cases. The management of recurrent lesions of embolized IC-PC aneurysms requires appropriate choice of treatment using both coiling and clipping. Clipping, especially without the removal of coils, plays an important role in safe treatment.