Transorbital neuroendoscopic surgery for treatment of sphenoid wing meningiomas extending to the cavernous sinus: clinical implications and a technical illustration.

OBJECTIVE: The aim of this study was to evaluate the efficacy and safety of transorbital neuroendoscopic surgery (TONES) in the management of sphenoid wing meningiomas (SWMs) with cavernous sinus and orbital invasion. METHODS: The authors conducted a retrospective review of 32 patients with SWMs treated at Gazi University using TONES from October 2019 to May 2023. The study includes clinical applications to elucidate the endoscopic transorbital approach. Surgical techniques focused on safe subtotal resection, aiming to minimize residual tumor volume for subsequent radiosurgery. Data were collected on patient demographics, tumor characteristics, surgical procedures, complications, and postoperative outcomes, including radiological imaging and ophthalmological evaluations. RESULTS: Surgical dissections delineated a three-phase endoscopic transorbital approach: extraorbital, intraorbital, and intracranial. In the clinical application, gross-total resection was not achieved in any patient because of planned postoperative Gamma Knife radiosurgery. The mean follow-up period was 16.3 months. Of 30 patients with preoperative proptosis, 25 experienced postoperative improvement. No new-onset extraocular muscle paresis or visual loss occurred postoperatively. The average hospital stay was 1.15 days, with minimal complications and no significant morbidity or mortality. CONCLUSIONS: Total resection of SWMs invading the cavernous sinus and orbit is associated with substantial risks, particularly cranial nerve deficits. TONES offers a minimally invasive alternative, reducing morbidity compared with transcranial approaches, and represents a significant advancement in the surgical management of SWMs, especially those extending into the cavernous sinus and orbit. The approach provides a safe, effective, and patient-centric approach, prioritizing subtotal resection to minimize neurological deficits while preparing patients for adjunctive radiosurgery. This study positions TONES as a transformative surgical technique, aligning therapeutic efficacy with neurovascular preservation and postoperative recovery.

[Carotid-cavernous fistulas]. / Sinus-cavernosus-Fisteln.

BACKGROUND: Carotid cavernous fistulas (CCFs) are rare but clinically significant vascular anomalies characterized by abnormal connections between the cavernous sinus and arteries. This overview presents a comprehensive analysis of anatomy, classification, clinical presentation, diagnosis, imaging, and therapy of CCFs. The cavernous sinus, a central venous structure in the brain, is of critical importance for understanding CCFs due to its proximity to key structures such as the internal carotid artery and cranial nerves. CLASSIFICATION: CCFs are classified into direct and dural types, with direct fistulas typically being high-flow and dural fistulas being low-flow. The symptomatology varies greatly and can range from noises in the head, diplopia, red eye, tearing, to blurred vision and headaches. The diagnostic assessment requires a combination of detailed medical history, neurological and ophthalmological examination, and the use of imaging techniques. METHODS: In imaging, computed tomography (CT) and magnetic resonance imaging (MRI) are crucial for depicting the anatomical structures and blood vessels, while digital subtraction angiography (DSA) is considered the gold standard for accurate representation of the fistula. The treatment of CCFs is complex and depends on the type of fistula, location, and clinical condition of the patient. CONCLUSION: This overview emphasizes the importance of precise diagnosis and individualized therapy to achieve optimal results and avoid complications. Ongoing developments in medical imaging and treatment techniques will continuously improve the treatment outcomes of patients with CCFs.

Carotid-cavernous fistula: A potential treatable cause of bilateral abducens palsy and conjunctival hyperemia.

OBJECTIVE: Carotid cavernous fistulas (CCFs) represent uncommon and anomalous communications between the carotid artery and the cavernous sinus. MATERIALS AND METHODS: Case report RESULTS: We present the clinical details and successful management of a previously healthy 44-year-old patient who presented with one-month worsening headache, bilateral abducens palsy and conjunctival injection. Imaging modalities including magnetic resonance imaging (MRI) with contrast and digital subtraction angiography (DSA) facilitated the diagnosis of CCF. The patient underwent endovascular coiling of the CCF, leading to neurological recovery and symptom remission. CONCLUSION: This case highlights the importance of promptly CCF diagnosis in patients with multiple cranial nerve palsies and conjunctival hyperemia. Moreover, it emphasizes the efficacy of endovascular coiling in achieving symptom remission.

Multi-center application of a convolutional neural network for preoperative detection of cavernous sinus invasion in pituitary adenomas.

OBJECTIVE: Cavernous sinus invasion (CSI) plays a pivotal role in determining management in pituitary adenomas. The study aimed to develop a Convolutional Neural Network (CNN) model to diagnose CSI in multiple centers. METHODS: A total of 729 cases were retrospectively obtained in five medical centers with (n = 543) or without CSI (n = 186) from January 2011 to December 2021. The CNN model was trained using T1-enhanced MRI from two pituitary centers of excellence (n = 647). The other three municipal centers (n = 82) as the external testing set were imported to evaluate the model performance. The area-under-the-receiver-operating-characteristic-curve values (AUC-ROC) analyses were employed to evaluate predicted performance. Gradient-weighted class activation mapping (Grad-CAM) was used to determine models' regions of interest. RESULTS: The CNN model achieved high diagnostic accuracy (0.89) in identifying CSI in the external testing set, with an AUC-ROC value of 0.92 (95% CI, 0.88-0.97), better than CSI clinical predictor of diameter (AUC-ROC: 0.75), length (AUC-ROC: 0.80), and the three kinds of dichotomizations of the Knosp grading system (AUC-ROC: 0.70-0.82). In cases with Knosp grade 3A (n = 24, CSI rate, 0.35), the accuracy the model accounted for 0.78, with sensitivity and specificity values of 0.72 and 0.78, respectively. According to the Grad-CAM results, the views of the model were confirmed around the sellar region with CSI. CONCLUSIONS: The deep learning model is capable of accurately identifying CSI and satisfactorily able to localize CSI in multicenters.

Cavernous Sinus Syndrome Caused by Noninvasive Fungal Maxillary Sinusitis.

It is rare that cavernous sinus complications are caused by maxillary sinus lesions because the locations of these lesions are some distant from each other. The authors describe an unusual presentation that the primary lesion was located in the maxillary sinus and triggered cavernous sinus syndrome and optic nerve symptoms. The most likely possibility was that the infection traveled retrograde along the vascular plexus. Removal of maxillary sinus lesions and establishment ventilation may achieve source control.

The learning curve for cavernous sinus surgery illustrated by symptomatic intracavernous aneurysm clipping through a pretemporal transcavernous approach.

OBJECTIVE: The anatomy of the cavernous sinus (CS) has been well studied in the laboratory for decades; however, performing surgery in and around the CS is still a challenge. To reveal the learning curve for CS surgery via the pretemporal transcavernous approach (PTTC), surgical procedures were examined. The authors proposed 4 levels of surgical difficulty in opening the walls of the CS through this approach. Details of the approach were illustrated by surgical videos of symptomatic intracavernous aneurysm clipping. METHODS: Four levels of surgical difficulty were proposed. The higher the level, the more the CS walls were opened. Pathologies corresponding to each level of difficulty in and around the CS were categorized in each level together with explanations. From 2015 to 2021, 5 patients with symptomatic intracavernous aneurysms (diplopia due to compressive cranial neuropathy) underwent the PTTC at the authors' institute and served as representative cases in opening the walls of the CS. All CS cases from 2009 to 2021 were reviewed and categorized to demonstrate the learning curve. RESULTS: Four levels of surgical difficulty are as follows: level 1, a basic Dolenc extradural approach, which involves opening the anterior third of the superior and lateral walls of the CS; level 2, mobilizing the internal carotid artery (ICA) and opening the proximal dural ring to enter the roof of the CS and treat lesions around the clinoid and upper cavernous ICA; level 3, opening the entire aspect of the superior and lateral walls of the CS, which involves opening the oculomotor triangle and peeling the lateral wall of the CS to the tentorial incisura; and level 4, mobilizing cranial nerves III, IV, and V1 to gain access to the supra-/infratrochlear triangles to have proximal ICA control and opening the posterior wall as the last step to enter the posterior fossa. Surgical steps were described and illustrated with surgical videos of symptomatic intracavernous aneurysm clipping. CONCLUSIONS: The learning curve for CS surgery is long. The authors use 4 levels of surgical difficulty to describe applications of the PTTC in CS surgery. This approach serves as an effective workhorse in treating CS pathologies with low morbidity and high success rates when performed by experienced neurosurgeons.

The lateral transorbital approach to the medial sphenoid wing, anterior clinoid, middle fossa, cavernous sinus, and Meckel's cave: target-based classification, approach-related complications, and intermediate-term ocular outcomes.

OBJECTIVE: The lateral transorbital approach (LTOA) is a relatively new minimal access skull base approach suited for addressing paramedian pathology of the anterior and middle fossa. The authors define target zones for this approach and describe a series of cases with detailed measurements of visual outcomes, including those obtained with exophthalmometry. METHODS: The authors performed a retrospective analysis of a consecutive series of LTOA patients. Seven target zones were identified: 1) the orbit, 2) the lesser sphenoid wing and anterior clinoid, 3) the middle fossa, 4) the lateral wall of the cavernous sinus and Meckel's cave, 5) the infratemporal fossa, 6) the petrous apex, and 7) the anterior fossa. The authors used volumetric analyses of preoperative and postoperative MR and CT imaging data to calculate the volume of bone and tumor removed and to provide detailed ophthalmological, neurological, and cosmetic outcomes. RESULTS: Of the 20 patients in this cohort, pathology was in zone 2 (n = 10), zone 4 (n = 6), zone 3 (n = 2), zone 1 (n = 1), and zone 5 (n = 1). Pathology was meningioma (n = 10), schwannoma (n = 2), metastasis (n = 2), epidermoid (n = 1), dermoid (n = 1), encephalocele (n = 1), adenoma (n = 1), glioblastoma (n = 1), and inflammatory lesion (n = 1). The goal was gross-total resection (GTR) in 9 patients, all of whom achieved GTR. Subtotal resection (STR) was the goal in 8 patients (5 spheno-orbital meningiomas, 1 giant cavernous sinus/Meckel's cave schwannoma, 1 cavernous sinus prolactinoma, and 1 cavernous sinus dermoid), 7 of whom achieved STR and 1 of whom achieved GTR. The goal was biopsy in 2 patient and repair of encephalocele in 1. Visual acuity was stable or improved in 18 patients and worse in 2. Transient early postoperative diplopia, ptosis, eyelid swelling, and peri-orbital numbness were common. All 9 patients with preoperative diplopia improved at their last follow-up. Seven of 8 patients with preoperative exophthalmos improved after surgery (average correction of 64%). There were no cases of clinically significant (> 2 mm) postoperative enophthalmos. The most frequent postoperative complaint was peri-orbital numbness (40%). There was 1 CSF leak. Most patients were satisfied with their ocular (84%-100% of patients provided positive satisfaction-related responses) and cosmetic (75%-100%) outcomes. CONCLUSIONS: The LTOA is a safe minimal access approach to a variety of paramedian anterior skull base pathologies in several locations. Early follow-up revealed excellent resolution of exophthalmos with little risk of clinically significant enophthalmos. Transient diplopia, ptosis, and peri-orbital numbness were common but improved. Careful case selection is critical to ensure good outcome.

Paradoxical worsening of ocular symptoms after transvenous embolization of cavernous sinus dural arteriovenous fistula due to coil-induced perifocal inflammation: A case report.

Ocular symptoms usually completely resolve after successful transvenous embolization of cavernous sinus dural arteriovenous fistulas (CS-dAVFs). Herein, we report a case of CS-dAVF in which sinus packing of the superior ophthalmic vein (SOV) caused coil-induced inflammation in orbital tissue, leading to deteriorating ocular symptoms. A 73-year-old woman presented with right-eye exophthalmos and chemosis. Cerebral angiography demonstrated right CS-dAVF, which retrogradely drained into the right SOV. We conducted sinus packing with coils via the right inferior petrosal sinus, resulting in obliteration of the shunts. One day after sinus packing, right exophthalmos and chemosis progressed, suggesting dAVF recurrence. However, no residual angiographic shunts were observed. Orbital magnetic resonance imaging (MRI) revealed edema in intraorbital tissue and gadolinium contrast enhancement of SOV wall. We presumed that the coils in SOV induced perifocal inflammation at the venous wall and surrounding orbital tissue, leading to aggravation of ocular symptoms. Following steroid therapy for 2 months, ocular symptoms and contrast enhancement on orbital MRI significantly improved without anticoagulant treatment. Posttreatment paradoxical worsening of ocular symptoms could be caused by coil-induced inflammation of the SOV wall near the orbital tissue. Steroid therapy could be effective in reducing orbital inflammatory reactions.

Role of Cavernous Sinus Extension and MRI T2 Hypointensity in the Extent of Resection following Trans-Sphenoidal Surgery for Giant Pituitary Adenomas.

Background: Giant pituitary adenomas (GPA) pose a significant neurosurgical challenge. In this study, we present an experience of 60 consecutive patients with GPA operated by trans-sphenoidal surgery (microscopic/endoscopic). Objective: The aim of this study was to elucidate preoperative factors predicting extent of resection (EOR) following transsphenoidal surgery for GPA. Materials and Methods: The study was a retrospective evaluation of 60 adult patients (>18 years) with GPA operated over a decade. The patients were analyzed for their clinical presentation, EOR, radiology, visual outcome, endocrinological outcome, and complications. Results: The mean age of the cohort was 41.5 ± 13.3 years, mean tumor volume was 38.2 ± 19.1 cm3, and mean follow-up was 30.6 ± 21.7 months. Improvement in vision was seen in forty patients (66.7%), while another 16 (26.7%) had stable vision as prior to surgery. Duration of visual symptoms was found to be statistically significantly associated with postoperative improvement of vision (P = 0.001). Twenty-four patients (40.0%) underwent subtotal resection (STR), while the remaining 36 patients (60.0%) underwent either gross total or near-total resection. Factors associated with STR were retrosellar (P = 0.04), subfrontal (P = 0.02), Knosp 3,4 cavernous sinus extension (P = 0.03), and MRI T2 hypointensity (P = 0.02). During follow-up, eight patients (13.3%) had radiological evidence of growth of residual tumor. Conclusions: Most cases of GPA can be adequately handled by trans-sphenoidal surgery. The presence of retrosellar, subfrontal, cavernous sinus extensions, and T2 hypointensity should alert the surgeon for likelihood of STR, postoperative residual tumor hemorrhage and need for second-stage endonasal or transcranial surgery. However, utilization of extended endoscopic route has allowed good debulking of tumors having subfrontal and parasellar extensions, which was not possible previously using traditional microscopic transsphenoidal surgery.

Embolization of Cavernous Sinus Dural Arteriovenous Fistula with Liquid Materials Under Transarterial Balloon Protection.

AIM: To analyze the clinical and angiographic outcomes of interventional embolization under transarterial balloon protection technique in patients with cavernous sinus dural arteriovenous fistulas. MATERIAL AND METHODS: In a single-center cohort of 30 patients undergoing cavernous sinus dural arteriovenous fistulas embolization under balloon protection. We collected their clinical symptoms, complications, mid-term follow-up angiographic results, and long-term clinical outcomes for the baseline characteristics. RESULTS: Thirty patients with 31 lesions were included in this study. Immediate applications of angiographies after embolization indicated that complete obliteration occurred in 29 lesions (93.5% of 31 lesions). Two cases with permanent trigeminal nerve palsy were treated by arterial approach. Onyx dispersed into the internal carotid artery in one process, and salvage stent implantation was performed to prevent parent artery occlusion. CONCLUSION: Interventional embolization with intra-arterial balloon protection is effective and safe with rarely occurring complications.

Microscopic with Endoscopic Surgery via Subtemporal Approach for Cavernous Sinus Cholesteatomas.

OBJECTIVE: The aim of this study was to retrospectively analyze the clinical data of 16 patients with cavernous sinus cholesteatomas, explore the surgical outcomes, and summarize the surgical experience. METHODS: Patients with cavernous sinus cholesteatomas underwent surgery between June 2016 and June 2022 at the Department of Neurosurgery at the First Affiliated Hospital of Soochow University. Clinical data were obtained from all patients for analysis. RESULTS: Common preoperative symptoms included headache, dizziness, diplopia, ptosis, and facial numbness. There were 7 patients with 2 or more symptoms. There were 13 patients with total resection and 3 patients with subtotal resection. There were 5 patients with improved postoperative symptoms, 10 patients with no significant change, and 1 patient with worse symptoms. New postoperative cranial nerve defects occurred in 4 patients. During the follow-up, all patients had favorable prognosis without progression. CONCLUSIONS: Using "double-scope" technique, the subtemporal approach, a surgical strategy for cavernous sinus cholesteatomas, was sufficient to completely resect the tumors.

An algorithm for the treatment of concurrent pituitary adenoma and cavernous sinus aneurysm: A systematic review & case report.

BACKGROUND: Rarely, Pituitary adenomas (PA) can co-occur with intrasellar or intracavernous aneurysms. There is currently no clear guidance for the management of this dual pathology. We attempt to provide an algorithm to help guide clinical decision making for treatment of PAs co-occurring with adjacent cerebral aneurysms. METHODS: A comprehensive literature search was conducted following PRISMA guidelines using various databases. Search terms included "(Pituitary Adenoma OR Prolactinoma OR Macroadenoma OR Adenoma) AND (ICA OR Internal Carotid Artery OR paracliniod OR clinoid) Aneurysm AND (Intra-cavernous OR intracavernous OR intrasellar OR Cavernous)." RESULTS: A total of 24 studies with 24 patients were included. Twelve (50%) patients experienced visual symptoms. Ten patients (42%) had an aneurysm embedded within the adenoma. Fourteen patients (58%) had an aneurysm adjacent to the adenoma. Embedded aneurysms were significantly associated with rupture events. CONCLUSION: Vision loss is the most pressing determinant of treatment. In the absence of visual symptoms, the aneurysm should be treated first by coil embolization. If not amenable to coiling, place flow diverting stent followed by six months of anticoagulation and antiplatelet therapy. If visual loss is apparent, the adenoma-aneurysm spatial relationship becomes critical. In cases of an adjacent aneurysm, the adenoma should be removed transsphenoidally with extreme care and aneurysm rupture protocols in place. If the aneurysm is embedded within the adenoma, then a BTO is favored with permanent ICA occlusion followed by transsphenoidal resection if adequate collateral supply is demonstrated. If there is inadequate collateral supply, then an open-approach for amenable aneurysms with transcranial adenoma debulking should be performed.

Endovascular treatment in bilateral cavernous sinus dural arteriovenous fistulas: a systematic review and meta-analysis.

Few studies have discussed the disease nature and treatment outcomes for bilateral cavernous sinus dural arteriovenous fistula (CSDAVF). This study aimed to investigate the clinical features and treatment outcomes of bilateral CSDAVF. Embase, Medline, and Cochrane library were searched for studies that specified the outcomes of bilateral CSDAVF from inception to April 2022. The classification, clinical presentation, angiographic feature, surgical approach, and treatment outcomes were collected. Meta-analysis was performed using the random effects model. Eight studies reporting 97 patients were included. The clinical presentation was mainly orbital (n = 80), cavernous (n = 52) and cerebral (n = 5) symptoms. The most approached surgical route was inferior petrosal sinus (n = 80), followed by superior orbital vein (n = 10), and alternative approach (n = 7). Clinical symptoms of 88% of the patients (95% CI 80-93%, I2 = 0%) were cured, and 82% (95% CI 70-90%, I2 = 7%) had angiographic complete obliteration of fistulas during follow up. The overall complication rate was 18% (95% CI 11-27%, I2 = 0%). Therefore, endovascular treatment is an effective treatment for bilateral CSDAVF regarding clinical or angiographic outcomes. However, detailed evaluation of preoperative images and comprehensive surgical planning of the approach route are mandatory owing to complexity of the lesions.

Video article: the subtemporal extradural approach to cavernous sinus tumour.

OBJECTIVE: Here we demonstrate via operative video the subtemporal extradural approach to a tumour in the cavernous sinus. METHODS: The extradural approach is performed here in a paediatric patient (a 15-year-old child) via a right extended pterional osteoplastic craniotomy with removal of the zygomatic arch. The operative microscope is introduced, and the dura is divided at the superior orbital fissure into endosteal and meningeal layers using a diamond knife. The middle cranial fossa floor is drilled flat to increase access, and the plane is further developed towards the cavernous sinus. The tumour is seen bulging from within the cavernous sinus, and the cavernous sinus is opened in the anteromedial triangle between cranial nerves Vi and Vii. After biopsy, the tumour is debulked with an ultrasonic aspirator. Doppler is used to identify the internal carotid artery and preserve it. The bone flap is replaced, and the wound is closed in layers in standard fashion. RESULTS: The patient recovered well and was discharged on post-operative day 3. Persistent sixth nerve palsy (present pre-operatively) was present; however, otherwise, there was good recovery from surgery. Good resection of tumour is demonstrated on post-operative MR imaging. CONCLUSIONS: This approach is uncommon but important as it enables extradural access to the cavernous sinus, minimising the complications associated with an intradural approach such as cortical injury. In this video, we also demonstrate the fundamental anatomy using annotation and cadaveric images to enhance understanding required for the neurosurgeon to successfully complete this approach. The patient consented to the procedure in the standard fashion.

Lateral Transorbital Endoscope-Assisted Approach to the Cavernous Sinus.

BACKGROUND AND OBJECTIVES: Surgical access to the cavernous sinus (CS) poses a unique challenge to the neurosurgeon given the concentration of delicate structures in the confines of a very small anatomic space. The lateral transorbital approach (LTOA) is a minimally invasive, keyhole approach that can provide direct access to the lateral CS. METHODS: A retrospective review of CS lesions treated by a LTOA at a single institution was performed between 2020 and 2023. Patient indications, surgical outcomes, and complications are described. RESULTS: Six patients underwent a LTOA for a variety of pathologies including a dermoid cyst, schwannoma, prolactinoma, craniopharyngioma, and solitary fibrous tumor. The goals of surgery (ie, drainage of cyst, debulking, and pathological diagnosis) were achieved in all cases. The mean extent of resection was 64.6% (±34%). Half of the patients with preoperative cranial neuropathies (n = 4) improved postoperatively. There were no new permanent cranial neuropathies. One patient had a vascular injury repaired endovascularly with no neurological deficits. CONCLUSION: The LTOA provides a minimal access corridor to the lateral CS. Careful case selection and reasonable goals of surgery are critical to successful outcome.

Endoscopic Extended Transsphenoidal Surgery Aiming for Radical Resection of Skull Base Tumors Involving Cavernous Sinus: Assessment of Resectability and Risks of Complications.

BACKGROUND AND OBJECTIVES: Surgical resection of tumors invading the cavernous sinus (CS) still shows therapeutic challenges. For "nonadenomatous" skull base tumors invading in CS, there were only a few reports showing the outcomes of radical resection. Therefore, the outcomes of endoscopic transsphenoidal surgery (ETS) aiming for radical resection thus remain largely unknown regarding resectability and functional results of the cranial nerves. METHODS: We performed ETS aiming for radical resection in 35 skull base tumors involving CS (17 chondrosarcomas, 12 chordomas, 3 meningiomas, and 3 trigeminal schwannomas; median follow-up 36.5 months ranging from 12 to 91 months). Gross total resection (GTR) is attempted in all the cases for real-time findings from electrophysiological monitoring of the cranial nerves. When the tumor was strongly adherent to the cranial nerves or internal carotid artery, maximum volume reduction of the tumor was attempted. RESULTS: GTR was achieved in 28 patients (80.0%), subtotal resection in 3 (8.6%), and partial resection in 4 (11.4%). One patient experienced internal carotid artery injury during surgery. After ETS, 15 patients showed symptom improvement (51.7% in all 29 patients with preoperative cranial nerve symptoms, CNS). Four (11.4%) transiently developed abducens nerve palsy, and one required repair surgery for cerebrospinal leakage. In univariate analyses, extension to the lateral compartment of CS ( P = .04) was significantly associated with reduced achievement of GTR. Previous transcranial surgery was associated with reduced possibility of improvement and worsening in CNS. Eleven patients underwent stereotactic radiosurgery, at a median of 12 months after ETS. 32 patients (91.4%) did not show recurrence at the final follow-up. CONCLUSION: ETS can achieve sufficient surgical resection in most of the patients, with acceptable neurological complications. For patients with CNS, ETS may offer the opportunity for improving CNS. We should also always prioritize avoidance of critical situations by preventing internal carotid artery injury.

How we do it? Performing a protective superficial temporal artery-middle cerebral artery bypass with endoscopic transnasal cavernous sinus lesion operation.

BACKGROUND: To describe the concept of a protective superficial temporal artery-middle cerebral artery (STA-MCA) bypass performed prior to endoscopic transnasal cavernous sinus (CS) lesion resection in order to reduce the risk of perioperative cerebral ischemia due to internal carotid artery (ICA) vasospasm, occlusion, and even injury. METHOD: We illustrated the procedure of a 14-year-old female accepting a protective STA-MCA bypass with endoscopic transnasal CS lesion resection. CONCLUSION: A protective bypass may be a prophylactic strategy in selected endoscopic transnasal CS surgery cases, particularly where the diagnosis is uncertain, or the risk of ICA injury or occlusion is high.