Microscope-based augmented reality with diffusion tensor imaging and fluorescein in insular glioma resection

Maximal safe resection is the goal of insular glioma surgery. The combination of intraoperative augmented reality (AR) diffusion tensor imaging (DTI) fiber tracking with fluorescein dye (F) helps achieve this goal throughout a microscope-based visualization of the tumor and white matter fiber tracts. The aim of the present video article was to show the technical key aspects of DTI-F microscope-based AR-assisted surgery during the gross-total resection of an insular Berger-Sanai type I+IV high-grade glioma in a 63-year-old patient, performed through a pterional transsylvian approach. The video can be found here: https://stream.cadmore.media/r10.3171/2021.10.FOCVID2157

Optic Foraminotomy for Clipping of Superior Carotid-Ophthalmic Aneurysms

Background: Carotid-ophthalmic aneurysms usually cause visual problems. Its surgical treatment is challenging because of its anatomically close relations to the optic nerve, carotid artery, ophthalmic artery, anterior clinoid process, and cavernous sinus, which hinder direct access. Despite recent technical advancements enabling risk reduction of this complication, postoperative deterioration of visual function remains a significant problem. Therefore, the goal of preserving and/or improving the visual outcome persists as a paramount concern.Objective: We propose optic foraminotomy as an alternative microsurgical technique for dorsal carotid-ophthalmic aneurysms clipping. As a secondary objective, the step by step of that technique and its benefits are compared to the current approach of anterior clinoidectomy.Methods: We present as an example two patients with superior carotid-ophthalmic aneurysms in which the standard pterional craniotomy, transsylvian approach, and optic foraminotomy were performed. Surgical techniques are presented and discussed in detail with the use of skull base dissections, microsurgical images, and original drawings.Results: Extensive opening of the optic canal and optic nerve sheath was successfully achieved in all patients allowing a working angle with the carotid artery for correct visualization of the aneurysm and further clipping. Significant visual acuity improvement occurred in both patients because of decompression of the optic nerve.Conclusion: Optic foraminotomy is an easy and recommended technique for exposing and treating superior carotid-ophthalmic aneurysms and allowing optic nerve decompression during the first stages of the procedure. It shows several advantages over the current anterior clinoidectomy technique regarding surgical exposure and facilitating visual improvement.

Intraoperative epileptogenic network visualization using gamma oscillation regularity correlation analysis in epilepsy surgery

Background: We have recently demonstrated that gamma oscillation (30–70 Hz) regularity (GOR) analysis accurately localized epileptogenic focus using intraoperative electrocorticographic data. In this report, we assessed whether GOR correlation analysis could depict epileptogenic networks intraoperatively. Dual foci in temporal lobe epilepsy without hippocampal structural abnormalities are difficult to diagnose. Using our GOR correlation analysis, we aimed to intraoperatively visualize such dual foci and epileptogenic networks. Case Description: A 56-year-old man suffered from pharmacoresistant focal impaired awareness seizures. Magnetic resonance imaging demonstrated an 8 × 12-mm cavernoma in the right inferior temporal gyrus without any structural changes in the hippocampus. Since ictal semiology indicated a high probability of epileptogenicity in the right hippocampus, we reached the hippocampus using a transsylvian approach and assessed intraoperative GOR correlation analysis in the lateral temporal lobe where the cavernoma was located and the hippocampus, simultaneously. High GORs suggestive of epileptogenicity were identified in both the lateral temporal lobe and the hippocampus. Furthermore, they were connected using GOR correlation networks. When the high GOR locations in the lateral temporal lobe and the cavernoma were removed, high GORs and those networks were found within the hippocampus only. After additional hippocampal transection, high GORs and these networks were absent. The patient became seizure-free after the surgery. Conclusion: Our GOR correlation analysis may be a powerful tool for intraoperative evaluation of epileptogenic networks in epilepsy surgery.

Microsurgical Resection of a Chiasmatic Cavernoma: 3-Dimensional Operative Video

According to reports from the literature,1,2 depending on the location where cavernomas appear, range from the very common locations to unusual. Cavernous malformations arising from the optic nerve and chiasm are rare, with only few cases reported to date.3-5 We present a case of a 28-yr-old man who suddenly started with sever visual loss in the right eye and homonymous lateral hemianopia in the left eye. Because of the acute symptomatology, a brain MRI was immediately performed in order to diagnose the etiology. The MRI showed a chiasmatic mass with right extension, heterogeneous on T1 and T2 sequences, without enhancement after gadolinium. The surgery was carried out a week after the diagnosis. A right pterional transsylvian approach was performed and the cavernoma was resected with microsurgical maneuvers, preserving the optic nerve fibers, chiasm, and optic tract. The patient evolved favorably, improving the visual deficit in the postoperative period as can be observed in the postoperative visual field study 7 mo after the surgery. The patient signed an informed consent for the procedure and agreed with the use of his images and surgical video for research and academic purposes. Our surgical case emphasizes the importance of a prompt diagnosis and surgery for chiasmatic cavernomas3 associated to visual loss, providing early decompression of the optic apparatus and improvement of the visual field defects after surgery.

The anterior incisural width as a preoperative indicator for intradural space evaluation: An anatomical investigation

Background: The opticocarotid triangle (OCT) and the carotico-oculomotor triangle (COT) are two anatomical triangles used in accessing the interpeduncular region. Our objective is to evaluate if the anterior incisural width (AIW) is an indicator to predict the intraoperative exposure through both triangles. Methods: Twenty sides of 10 cadaveric heads were dissected and analyzed. The heads were divided into the following: Group A – narrow anterior incisura and Group B – wide anterior incisura – using 26.6 mm as a cutoff distance of the AIW. Subsequently, the area of the COT and the OCT in the transsylvian approach was measured, along with the maximum widths through the two trajectories in modified superior transcavernous approach. Results: The COT in the wide group was shown to have a significantly larger area compared with the COT in the narrow group (38.4 ± 12.64 vs. 58.3 ± 15.72 mm, P < 0.01). No difference between the two groups was reported in terms of the area of the OCT (50.9 ± 19.22 mm vs. 63.5 ± 15.53 mm, P = 0.20), the maximum width of the OCT (6.6 ± 1.89 vs. 6.5 ± 1.38 mm, P = 1.00), or the maximum width of the COT (11.7 ± 2.06 vs. 12.2 ± 2.32 mm, P = 0.50). Clinical cases were included. Conclusion: An AIW <26.6 mm is an unfavorable factor related to a limited COT area in a transsylvian approach for pathologies at the interpeduncular fossa. Preoperative identification and measurement of a narrow AIW can suggest the need to add a transcavernous approach.

Surgical morbidity of transsylvian versus transcortical approaches to insular gliomas

OBJECTIVEThe choice of transsylvian versus transcortical corridors for resection of insular gliomas remains controversial. Functional pathway compromise from transcortical transgression and vascular injury during transsylvian dissection are the primary concerns. In this study, data from a single-center experience with both approaches were compared to determine whether one approach was associated with a higher rate of morbidity than the other.METHODSThe authors identified 100 consecutive patients who underwent resection of pure insular gliomas at the Barrow Neurological Institute. Volumetric analysis was performed using FLAIR and contrast-enhanced T1-weighted MRI for low- and high-grade gliomas, respectively, for extent of resection (EOR) and diffusion-weighted sequences were used to detect for postoperative ischemia. Step-wise logistic regression analysis was performed to identify predictors of neurological morbidity.RESULTSData from 100 patients with low-grade or high-grade insular gliomas were analyzed. Fifty-two patients (52%) underwent a transsylvian approach, and 48 patients (48%) underwent a transcortical approach. The mean (± SD) EOR was 91.6% ± 12.4% in the transsylvian group and 88.6% ± 14.2% in the transcortical group (p = 0.26). Clinical outcome metrics for the 2 groups were similar. Overall, 13 patients (25%) in the transsylvian group and 10 patients (21%) in the transcortical group had evidence of ischemia on postoperative MR images. For both approaches, high-grade histology was associated with permanent morbidity (p = 0.01). For patients with gliomas located within the superior-posterior quadrant of the insula, development of postoperative ischemia was associated with only the transsylvian approach (46% vs 0%, p = 0.02).CONCLUSIONSAreas of restricted diffusion are common on postoperative MRI following resection of insular gliomas, but only a minority of these patients develop permanent neurological deficits. Insular glioma patients with high-grade histology may be at particular risk for developing symptomatic postoperative ischemia. Both the transcortical and transsylvian corridors are associated with reasonable morbidity profiles, although gliomas situated within the superior-posterior quadrant of the insula are more safely accessed with a transcortical approach.

Burr Hole-Assisted Direct Transsylvian Venous Catheterization for Carotid-Cavernous Fistula Embolization: A Case Report

BACKGROUND AND IMPORTANCE Carotid-cavernous fistulas (CCF) are pathological connections between carotid artery branches and the cavernous sinus. They can lead to a variety of symptoms, such as chemosis and double vision, or more insidious events, such as vision loss and intracranial hemorrhage. Although these patients are often treated by endovascular means, we describe a case in which the patient's CCF was not able to be accessed by usual methods and required an open surgical approach. CLINICAL PRESENTATION The patient had progressive chemosis, double vision, and periorbital pain. Angiogram showed an indirect type D CCF with cortical venous drainage with a large sylvian vein that was directly draining the fistula. The patient did not have a dilated superior ophthalmic vein, and the petrosal sinuses could not be catheterized. Therefore, because of the patient's increased risk for intracranial hemorrhage, she was taken to the operating room for an image guided burr hole for direct catheterization of the sylvian vein. From this point, the fistulous point could be catheterized, and the CCF was embolized using onyx. Follow-up angiogram showed complete occlusion. CONCLUSION This is the first report in literature of an indirect CCF being treated through a transsylvian approach with onyx. This combined open-surgical-and-endovascular approach was necessary to get full resolution of the lesion, and patient had rapid improvement of symptoms.