Nonaneurysmal perimesencephalic subarachnoid hemorrhage on noncontrast head CT: An accuracy, inter-rater, and intra-rater reliability study.

BACKGROUND AND PURPOSE: To evaluate the reliability and accuracy of nonaneurysmal perimesencephalic subarachnoid hemorrhage (NAPSAH) on Noncontrast Head CT (NCCT) between numerous raters. MATERIALS AND METHODS: 45 NCCT of adult patients with SAH who also had a catheter angiography (CA) were independently evaluated by 48 diverse raters; 45 raters performed a second assessment one month later. For each case, raters were asked: 1) whether they judged the bleeding pattern to be perimesencephalic; 2) whether there was blood anterior to brainstem; 3) complete filling of the anterior interhemispheric fissure (AIF); 4) extension to the lateral part of the sylvian fissure (LSF); 5) frank intraventricular hemorrhage; 6) whether in the hypothetical presence of a negative CT angiogram they would still recommend CA. An automatic NAPSAH diagnosis was also generated by combining responses to questions 2-5. Reliability was estimated using Gwet's AC1 (κG), and the relationship between the NCCT diagnosis of NAPSAH and the recommendation to perform CA using Cramer's V test. Multi-rater accuracy of NCCT in predicting negative CA was explored. RESULTS: Inter-rater reliability for the presence of NAPSAH was moderate (κG = 0.58; 95%CI: 0.47, 0.69), but improved to substantial when automatically generated (κG = 0.70; 95%CI: 0.59, 0.81). The most reliable criteria were the absence of AIF filling (κG = 0.79) and extension to LSF (κG = 0.79). Mean intra-rater reliability was substantial (κG = 0.65). NAPSAH weakly correlated with CA decision (V = 0.50). Mean sensitivity and specificity were 58% (95%CI: 44%, 71%) and 83 % (95%CI: 72 %, 94%), respectively. CONCLUSION: NAPSAH remains a diagnosis of exclusion. The NCCT diagnosis was moderately reliable and its impact on clinical decisions modest.

Chiasmapexy for secondary empty sella syndrome: diagnostic and therapeutic considerations.

PURPOSE: Secondary empty sella syndrome (SESS) following pituitary surgery remains a diagnostic and therapeutic challenge. The aim of this study was to specify the diagnostic criteria, surgical indications and results of chiasmapexy in the SESS. METHODS: Three cases from two experienced neurosurgical centers were collected and the available literature was reviewed. RESULTS: The 3 patients were operated for a giant non-functioning pituitary adenoma, a cystic macroprolactinoma, and an arachnoid cyst respectively. Postoperative visual outcome was initially improved, and then worsened progressively. At the time of SESS diagnosis, visual field defect was severe in all cases with optic nerve (ON) atrophy in 2 cases. Patients were operated via an endoscopic endonasal extradural approach. One patient was re-operated because of early fat reabsorption. Visual outcome improved in 1 case and stabilized in 2 cases. Statistical analyses performed on 24 cases from the literature review highlighted that patient age and severity of the preoperative visual defect were respectively significant and nearly significant prognostic factors for visual outcome, unlike the surgical technique. CONCLUSION: T2-weighted or CISS/FIESTA sequence MRI is mandatory to visualize adhesions, ON kinking and neurovascular conflict. TS approach is the most commonly used approach. The literature review could not conclude on the need for an intra or extradural approach suggesting case by case adapted strategy. Intrasellar packing with non-absorbable material such as bone should be considered. Severity of the visual loss clearly decreases the visual outcome suggesting early chiasmapexy. In case of severe and long standing symptoms before surgery, benefits and surgical risks should be carefully balanced.

Extradural anterior temporal fossa approach to the paranasal sinuses, nasal cavities through the anterolateral and anteromedial triangles: Combined microscopic and endoscopic strategy.

OBJECTIVE: To demonstrate the utility and limitations of the extradural endoscopic-assisted anterior temporal fossa approach to the pterygopalatine fossa (PPF), infratemporal fossa (ITF), paranasal sinuses (PS), parapharyngeal region (PPR), nasal cavities (NC), epipharynx (EP), and clivus. METHODS: A frontotemporal orbitozygomatic craniotomy is performed. The dura is elevated from the cavernous sinus (CS). The anterior temporal fossa floor is drilled. Foramen rotundum and ovale are opened. The PPF is exposed and the lateral margin of inferior orbital fissure (IOF) is removed. The anterolateral triangle (ALT) is drilled and the vidian nerve (VN) is exposed. Drilling between the maxillary nerve (V2) and the VN provides access to the sphenoid sinus (SphS). The medial pterygoid plate is drilled exposing the EP. The maxillary sinus (MaxS) is opened anterior to the PPF. V2 is transposed laterally to enlarge the anteriomedial triangle (AMT). The orbital muscle of Muller is removed as well as the medial margin of the IOF, which opens the SphS. Anteriorly, the posterior ethmoid air cells are opened. Morphometric measurements evaluating the size of the ALT were done and the PS, NC, EP were explored with the endoscope. RESULTS: The ALT and AMT triangle provides a wide exposure of the PPF, ITF, PPR. In addition, those triangles represent a deep entry point to explore the PS, NC, and EP. CONCLUSION: The ALT and AMT are useful corridors to access to the SphS, MaxS, PS, NC, and EP via a transcranial approach. The use of the endoscope through this corridor widely extend the extradural anterior temporal fossa approach which may be considered as a valuable alternative to the extended endoscopic endonasal approach for selected skull base lesions extending both intracranial and into the PS, NC and EP.

Endoscopic endonasal approach to the mesial temporal lobe: anatomical study and clinical considerations for a selective amygdalohippocampectomy.

BACKGROUND: Selective amygdalohippocampectomy (AH) is a surgical option for patients with medically intractable seizures from mesial temporal lobe pathology. The transcranial route is considered the best method to achieve this goal. However, the standard approach through the neocortex is still invasive. The risks can be minimized if the mesial temporal lobe is resected while preserving the lateral temporal lobe and the Meyer's loop. This study explores the feasibility of selective AH by endoscopic endonasal approach (EEA) in cadaveric specimens. METHODS: The endoscopic anatomy of the mesial temporal lobe and the feasibility of a successful selective AH were studied in six hemispheres from three injected human cadavers. Quantitative analyses on the extent of resection and angles of exposure were performed based on CT and MRI studies of pre- and post-selective AH and measurements taken during dissections. RESULTS: The EEA V1-V2 corridor provided a direct and logical line of access to the mesial temporal lobe, following its natural trajectory with no brain retraction and minimal exposure of the pterygopalatine fossa. The components of the mesial temporal lobe were resected just as selectively and easily as the transcranial route, but without compromising the structures of the lateral temporal lobe or the Meyer's loop. CONCLUSIONS: The EEA V1-V2 corridor demonstrated its selective resectability and accessibility of the mesial temporal lobe in cadaveric specimens. The clinical value of this approach should be explored responsibly by a surgeon with both competent microsurgical skills and experiences in EEA.

Internal Audit of Compliance with a Perioperative Checklist in a Tertiary Care Neurosurgical Unit.

BACKGROUND: In 1999, the Institute of Medicine reported that, in the United States, 44,000 to 98,000 people die annually as a result of avoidable medical errors. Among the many initiatives undertaken to stem avoidable surgical errors, the World Health Organization (WHO) Surgical Safety Checklist has certainly been one of the most successful. Many surgical units have implemented adapted versions of the WHO Surgical Safety Checklist, audited their performance and discussed issues relating to the implementation process. However, such literature is still lacking in neurosurgery. METHODS: A prospective observational study of 171 neurosurgical cases was conducted over an 8-week period. An independent observer assessed compliance with and completeness of the three steps in the perioperative checklist: Sign-in, Time-out and Sign-out. Factors that may reduce compliance were also analyzed. RESULTS: Compliance with the Sign-in, Time-out and Sign-out steps was 82%, 99% and 93% respectively. On average, 92% of the Time-out elements were verified. The emergent nature of a surgery was the only factor that caused a statistically significant reduction in compliance with the checklist. Overall compliance diminished during the observation period. CONCLUSION: In this internal audit study, compliance with the preoperative checklist reached a satisfactory level. Further work is still needed, however, on some aspects of our surgical strategy, namely, a relatively low compliance rate with the Sign-in process was recorded and emergent cases were associated with decreased performance.

Anatomy of the craniocervical junction - A review.

An in-depth understanding of the anatomy of the craniocervical junction (CCJ) is indispensable in skull base neurosurgery. In this paper, we discuss the osteology of the occipital bone, the atlas (C1) and axis (C2), the ligaments and the muscle anatomy of the CCJ region and their relationships with the vertebral artery. We will also discuss the trajectory of the vertebral artery and review the anatomy of the jugular foramen and lower cranial nerves (IX to XII). The most important surgical approaches to the CCJ, including the far lateral approach, the anterolateral approach of Bernard George and the endoscopic endonasal approach, will be discussed to review the surgical anatomy.

Spontaneous intracranial vertebral artery dissections presenting with subarachnoid hemorrhage.

BACKGROUND: Vertebral artery dissection (VAD) is an infrequent source of subarachnoid hemorrhage (SAH), with a high mortality rate, primarily due to the risk of rebleeding both before and after medical intervention. This paper provides a comprehensive analysis of the anatomy, pathophysiology, clinical presentation, treatment strategies, and outcomes of intracranial vertebral artery dissections that result in subarachnoid hemorrhage. METHODS: Comprehensive five-year literature review (2018-2022) and a retrospective analysis of patient records from our institution between 2016 and 2022. We included studies with a minimum of 5 patients. RESULTS: The study incorporated ten series from the literature and 22 cases from CHUM. Key anatomical factors increasing the risk of VAD include the vertebral artery's origin from the aortic arch, asymmetry of the vertebral artery, and its tortuosity. Patients may display specific collagen and genetic abnormalities. The occurrence of VAD appears to be more prevalent in men. Those with a ruptured intracranial VAD typically show prodromal symptoms and present with severe SAH. Rebleeding within the first 24 h is frequent. While standard imaging methods are usually adequate for VAD diagnosis, they may not provide detailed information about the perforator anatomy. Treatment approaches include both deconstructive and reconstructive methods. CONCLUSION: Ruptured VAD is a critical, life-threatening condition. Many patients have a poor neurological status at presentation, and rebleeding prior to treatment is a significant concern. Deconstructive techniques are most effective in preventing rebleeding, whereas the efficacy of reconstructive techniques needs more investigation.

Surgical management of tumors of the cervical spine and craniovertebral junction involving the vertebral artery: A narrative review.

BACKGROUND: The vertebral artery (VA) is in close proximity to bony structures, nerves and nerve sheaths of the cervical spine and craniovertebral junction (CVJ). These structures can be sources of tumors that are responsible for displacement, encasement and sometimes invasion of the VA. Removing these tumors while minimizing the risk of vascular injury requires thorough knowledge of the vascular anatomy, risk factors of vascular injury, the relationships of each tumor type with the VA, and the different surgical approaches and techniques that result in the best outcomes in terms of vascular control, tumoral exposure and resection. OBJECTIVE: To present an overview of preoperative and anatomical considerations, differential diagnoses and various approaches to consider in cases of tumors in close relationship with the VA. METHOD: A review of recent literature was conducted to examine the anatomy of the VA, the tumors most frequently affecting it, surgical approaches, and the necessary pre-operative preparations for ensuring safe and maximal tumor resection. This review aims to underscore the principles of treatment. CONCLUSION: Tumors located at the CVJ and the cervical spine intimately involved with the VA, pose a surgical challenge and increase the risk of incomplete removal of the lesion. Detailed knowledge of the patient-specific anatomy and a targeted pre-operative work-up enable optimal planning of surgical approach and management of the VA, thereby reducing surgical risks and improving extent of resection.

Craniovertebral and spinal adhesive arachnoiditis: a late complication of ruptured vertebral and posterior inferior cerebellar arteries aneurysms.

BACKGROUND: Adhesive arachnoiditis is a rare yet serious complication that may occur following subarachnoid hemorrhage (SAH). In this circumstance, it is mainly due to ruptured vertebral artery (VA) or posterior inferior artery (PICA) aneurysms. It disrupts cerebrospinal fluid (CSF) flow leading to complications such as spinal arachnoiditis, syringomyelia, trapped 4th ventricle, or a combination of these conditions. Evidence for effective treatment strategies is currently limited. We aimed to review the epidemiology, clinical characteristics, treatment, complications, outcomes, and prognosis of cranio-vertebral junction and spinal adhesive arachnoiditis resulting from ruptured VA and PICA aneurysms. METHODS: This study involved a comprehensive literature review and complemented by our own case. We focused on adult cases of arachnoiditis, syringomyelia, and trapped 4th ventricle with SAH caused by ruptured VA or PICA aneurysms, excluding cases unrelated to these aneurysms and those with insufficient data. RESULTS: The study included 22 patients, with a mean age of 52.4 years. Symptoms commonly manifest within the first year after SAH and timely diagnosis requires a high index of suspicion. Treatment approaches included lysis of adhesions and various shunt procedures. Most patients showed improvement post-treatment, though symptom recurrence is significant. CONCLUSION: Adhesive arachnoiditis is a critical complication following SAH, most commonly from ruptured VA and PICA aneurysms. Early detection and individualized treatment based on the type of arachnoiditis and CSF flow impact are crucial for effective management. This study underscores the need for tailored treatment strategies and further research in this field.

The Rostral Mucosa: The Door to Open and Close for Targeted Endoscopic Endonasal Approaches to the Clivus.

BACKGROUND: Extended endoscopic endonasal approaches (EEAs) have progressively widened the armamentarium of skull base surgeons. In order to reduce approach-related morbidity of EEAs and closure techniques, the development of alternative strategies that minimize the resection of normal tissue and alleviate the use of naso-septal flap (NSF) is needed. We report on a novel targeted approach to the clivus, with incision and closure of the mucosa of the rostrum, as the initial and final step of the approach. OBJECTIVE: To present an alternative minimally invasive approach and reconstruction technique for selected clival chordomas. METHODS: Three cases of clival chordomas illustrating this technique are provided, together with an operative video. RESULTS: The mucosa of the rostrum is incised and elevated from the underlying bone, as first step of surgery. Following tumor resection with angled scope and instruments, the mucosa of the sphenoid sinus (SS) is removed and the tumor cavity and SS are filled with abdominal fat. The mucosal incision of the rostrum is then sutured. A hangman knot is prepared outside the nasal cavity and tightened after the first stitch and a running suture is performed. CONCLUSION: We propose, in this preliminary report, a new targeted approach and reconstruction strategy, applying to EEAs the classic concept of skin incision and closure for transcranial approaches. With further development in the instrumentations and visualization tools, this technique may become a valuable minimally invasive endonasal approach for selected lesions.

Use of high dose cyproterone acetate and risk of intracranial meningioma in women: cohort study.

OBJECTIVE: To assess the risk of meningioma associated with use of high dose cyproterone acetate, a progestogen indicated for clinical hyperandrogenism. DESIGN: Observational cohort study. SETTING: Data from SNDS, the French administrative healthcare database, between 2007 and 2015. PARTICIPANTS: 253 777 girls and women aged 7-70 years living in France who started cyproterone acetate between 2007 and 2014. Participants had at least one reimbursement for high dose cyproterone acetate and no history of meningioma or benign brain tumour, or long term disease status. Participants were considered to be exposed when they had received a cumulative dose of at least 3 g during the first six months (139 222 participants) and very slightly exposed (control group) when they had received a cumulative dose of less than 3 g (114 555 participants). 10 876 transgender participants (male to female) were included in an additional analysis. MAIN OUTCOME MEASURE: Surgery (resection or decompression) or radiotherapy for one or more intracranial meningiomas. RESULTS: Overall, 69 meningiomas in the exposed group (during 289 544 person years of follow-up) and 20 meningiomas in the control group (during 439 949 person years of follow-up) were treated by surgery or radiotherapy. The incidence of meningioma in the two groups was 23.8 and 4.5 per 100 000 person years, respectively (crude relative risk 5.2, 95% confidence interval 3.2 to 8.6; adjusted hazard ratio 6.6, 95% confidence interval 4.0 to 11.1). The adjusted hazard ratio for a cumulative dose of cyproterone acetate of more than 60 g was 21.7 (10.8 to 43.5). After discontinuation of cyproterone acetate for one year, the risk of meningioma in the exposed group was 1.8-fold higher (1.0 to 3.2) than in the control group. In a complementary analysis, 463 women with meningioma were observed among 123 997 already using cyproterone acetate in 2006 (risk of 383 per 100 000 person years in the group with the highest exposure in terms of cumulative dose). Meningiomas located in the anterior skull base and middle skull base, particularly the medial third of the middle skull base, involving the spheno-orbital region, appeared to be specific to cyproterone acetate. An additional analysis of transgender participants showed a high risk of meningioma (three per 14 460 person years; 20.7 per 100 000 person years). CONCLUSIONS: A strong dose-effect relation was observed between use of cyproterone acetate and risk of intracranial meningiomas. A noticeable reduction in risk was observed after discontinuation of treatment.

From the Occipital Condyle to the Sphenoid Sinus: Extradural Extension of the Far Lateral Transcondylar Approach with Endoscopic Assistance.

BACKGROUND: Surgical management of extensive skull base tumors, such as chordoma and chondrosarcoma, remains very challenging. The need for gross total removal to improve survival must be weighed against the risk of injury to neurovascular structures and the loss of stability at the craniovertebral junction. In cases of tumors that are already compromising craniovertebral junction stability, the occipital condyle can be exploited as a deep keyhole to reach the clivus, petrous apex, and sphenoid sinus. METHODS: We performed an anatomic study on 7 cadaveric specimens to describe the main landmarks and boundaries of the corridor. We also provide a clinical case to demonstrate the feasibility of the approach. RESULTS: In all specimens, using the space provided by the condyle, it was possible to drill the petrous bone up to the posterior wall of the sphenoid sinus following the direction of the inferior petrosal sinus. To successfully complete the approach, after the hypoglossal canal was exposed, endoscopic assistance was needed to overcome the narrowing of the visual field provided by the microscope. CONCLUSIONS: In cases of invasive skull base tumor involving the craniovertebral junction and affecting its stability, the occipital condyle can be exploited as a deep keyhole to the homolateral and contralateral petrous apex, clivus, and sphenoid sinus.

Supracerebellar transtentorial resection of a ruptured thalamomesencephalic cavernous malformation.

Thalamomesencephalic cavernous malformations are located high in the brainstem and may be difficult to reach. We present a case of such a lesion which was successfully approached via the supracerebellar transtentorial route. Our enclosed video provides elements to justify this posterior approach and illustrates the steps required for the cavernoma's safe removal, which include opening of the tentorium and gentle retraction of the exposed temporal lobe. The video can be found here: https://youtu.be/Ex5OfLyBzPY.

Visualization of Dark Side of Skull Base with Surgical Navigation and Endoscopic Assistance: Extended Petrous Rhomboid and Rhomboid with Maxillary Nerve-Mandibular Nerve Vidian Corridor.

BACKGROUND: Lesions located at the petrous apex, cavernous sinus, clivus, medial aspect of the jugular foramen, or condylar regions are still difficult to fully expose using the operating microscope. Although approaches to this region through the middle cranial fossa have been previously described, these approaches afford only limited visualization. We have confirmed a transcranial infratemporal fossa combined microsurgical and endoscopic access to the petrous apex, clivus, medial aspect of the jugular foramen, and occipital condyle. We have presented the results of a micro-anatomical cadaver dissection study and its clinical application. METHODS: Ten latex-injected cadaveric specimens (20 twenty sides) underwent dissection with navigational guidance to achieve an extended anterior petrosal approach combined with a far vidian corridor approach (between the foramen rotundum and foramen ovale). We performed anatomical dissections to confirm the surgical anatomy and the feasibility and limitations of this approach. Anatomical dissections were performed in the skull base laboratory of Lariboisière Hospital and Duke University Medical Center. This approach was then applied to some clinical cases. RESULTS: The combination of the microscope and endoscope, aided by surgical navigation, was extremely effective and provided a wide view of the petrous rhomboid, the entire clivus, and the medial condylar regions. The extended extradural anterior petrosal approach provided a large corridor to petrous and clival lesions. Endoscopic assistance allows for wide and deep exposure of the middle to lower clivus, epipharyngeal space, and bilateral condylar regions. This approach successfully provided adequate surgical access for resection of tumors located in these regions. The depth of the medial aspect of the jugular foramen was 16.3 ± 1.2 mm deep from the geniculate ganglion. The emerging point of the inferior petrosal sinus in the jugular foramen was 16.5 ± 1.8 mm deep from the geniculate ganglion. The hypoglossal canal was 21.6 ± 2.2 mm deep from the geniculate ganglion. The foramen magnum was located 31.5 ± 2.4 mm deep from the gasserian ganglion. The inferior petrosal sinus was found to be a reliable landmark to identify the medial portion of the jugular bulb. The introduction of the endoscope through the middle fossa rhomboid enabled visualization of the medial aspect of the jugular bulb, which otherwise would be hampered by the internal auditory canal under the microscope. CONCLUSION: After microscopic exposure of the middle fossa rhomboid, neuronavigational endoscopic assistance facilitated visualization of the ventral cavernous region, petrous apex, retropharyngeal space, and middle and inferior clivus down to the medial aspect of the jugular bulb and condyle regions. Additional maxillary nerve-mandibular nerve vidian corridor visualization provides a lateral transsphenoidal approach to upper clivus lesions.

Combined Nasoseptal and Inferior Turbinate Flap for Reconstruction of Large Skull Base Defect After Expanded Endonasal Approach: Operative Technique.

BACKROUND: Increasing indications for endoscopic endonasal approaches have led neurosurgeons to develop new reconstruction techniques for larger skull base defects. Vascularized grafts have been a great adjunction to reduce the rate of cerebrospinal fluid leak and can also be used to cover exposed critical structures such as the internal carotid artery. The nasoseptal flap and the inferior or middle turbinate flap are thus widely used in endoscopic skull base surgery, but may be insufficient for very large defects. OBJECTIVE: To present a new mucosal flap used to cover large skull base defects in which the mucosa of the inferior turbinate, inferior meatus, nasal floor, and nasal septum is harvested in 1 piece keeping both vascular pedicles intact (inferior turbinate and septal arteries). METHODS: We describe a surgical technique to harvest a combined inferior turbinate-nasoseptal flap. RESULTS: Technical pearls and surgical pitfalls are described through 2 clinical cases in which the nasoseptal mucosa was partially damaged during a previous surgery, rendering the nasoseptal flap insufficient by itself. The flap is harvested thanks to 2 mucosal cuts: a first circular cut around the choanal arch and the junction between the hard and the soft palate, and a second one combining classical cuts of the nasoseptal flap and the inferior turbinate flap. CONCLUSION: The inferior turbinate-nasoseptal flap can be a useful alternative in patients whose septal mucosa was partially damaged and/or with very large postoperative skull base defects.

Efficacy of antiseizure prophylaxis in chronic subdural hematoma: a cohort study on routinely collected health data.

OBJECTIVE: Chronic subdural hematoma (CSDH) is a common neurosurgical condition that can result in significant morbidity. The incidence of epileptic events associated with CSDH reported in the literature varies considerably and could potentially increase morbidity and mortality rates. The effectiveness of antiepileptic prophylaxis for this indication remains unclear. The primary objective of this study was to assess the relevance of anticonvulsant prophylaxis in reducing seizure events in patients with CSDH. METHODS: All consecutive cases of CSDH from January 1, 2005, to May 30, 2014, at the Hôpital de l'Enfant-Jésus in Quebec City were retrospectively reviewed. Sociodemographic data, antiepileptic prophylaxis use, incidence of ictal events, and clinical and radiological outcome data were collected. Univariate analyses were done to measure the effect of antiepileptic prophylaxis on ictal events and to identify potential confounding factors. Multivariate logistic regression was performed to evaluate factors associated with epileptic events. RESULTS: Antiepileptic prophylaxis was administered in 28% of the patients, and seizures occurred in 11%. Univariate analyses showed an increase in the incidence of ictal events in patients receiving prophylaxis (OR 5.92). Four factors were identified as being associated with seizures: septations inside the hematoma, membranectomy, antiepileptic prophylaxis, and a new deficit postoperatively. Antiepileptic prophylaxis was not associated with seizures in multivariate analyses. CONCLUSIONS: Antiepileptic prophylaxis does not seem to be effective in preventing seizures in patients with CSDH. However, due to the design of this study, it is difficult to conclude definitively about the usefulness of this prophylactic therapy that is widely prescribed for this condition.

A Staged Strategy for Craniocervical Junction Chordoma with Combination of Endoscopic Endonasal Approach and Far Lateral Approach with Endoscopic Assistance: Case Report.

Objective While the endoscopic endonasal approach (EEA) has gained widespread acceptance for the resection of clivus chordomas, conventional transcranial approaches still have a crucial role in craniocervical junction (CCJ) chordoma surgery. In repeat surgery, a carefully planned treatment strategy is needed. We present a surgical treatment plan combining an EEA and a far-lateral craniotomy with endoscopic assistance (EA) in the salvage surgery of a recurrent CCJ chordoma. Case Presentation A 37-year-old woman who had undergone partial resection of a chordoma extending from the mid-clivus to the CCJ. Technique A two-stage surgical intervention was planned. First, we opted for an EEA with the intention of removing only the extradural and medial compartments of the lesion. The rationale was to avoid intradural dissection of possibly adherent tissues from the previous procedures and to minimize the cerebrospinal fluid leak risk. One month after the first endonasal stage, a far lateral craniotomy was performed. After removal of the lateral mass and pedicle of C1, a large surgical corridor to the tumor was obtained. Tumor loculations disseminated in and around the CCJ and located in the areas blind to microscopic examination were then successfully resected with EA. An occipito-cervical fusion was then performed during the same procedure. Conclusion In addition to the exact location and morphology of the tumor, history of previous surgery was an important factor in devising a treatment strategy in this case of clivus chordoma. EA was also found to be instrumental in improving the reach of the far lateral approach.

The Occipital Artery as an Alternative Donor for Low-Flow Bypass to Anterior Circulation After Internal Carotid Artery Occlusion Failure prior to Exenteration for an Atypical Cavernous Sinus Meningioma.

BACKGROUND: In skull base tumors involving the cavernous sinus, indications for aggressive resection are sparse and must be carefully examined because of their invasiveness. With careful evaluation, techniques including internal carotid artery sacrifice with or without extracranial-intracranial bypass may still be an option in some cases. Moreover, previous surgery with the sacrifice of potential donor vessels requires adjusting the revascularization strategy. We describe an occipital artery-middle cerebral artery bypass before skull base tumor resection. CASE DESCRIPTION: A 47-year-old woman with a recurrent cavernous sinus meningioma was referred to our department. Because of tumor recurrence after radiotherapy and its rapid progression, radical resection, including part of the cavernous sinus, was planned. A balloon test occlusion was performed and showed good tolerance. An endovascular internal carotid artery occlusion was performed. The patient eventually experienced motor deficits and aphasia after surgery. Therefore, bypass surgery using an occipital artery-middle cerebral artery anastomosis was performed. The patient showed no exacerbation of symptoms after bypass surgery and subsequently underwent tumor resection. CONCLUSIONS: The reliability of balloon test occlusion in the management of giant aneurysms may not be similarly applicable to skull base tumors. If hypoperfusion symptoms occur after occlusion of the internal carotid artery, a surgical revascularization procedure should be considered because of the risk of ischemic stroke following tumor resection. For patients whose superficial temporal artery is not available, the occipital artery can be a valuable alternative donor for low-flow bypass.

The Posterior Transpetrosal Approach in a Case of Large Retrochiasmatic Craniopharyngioma: Operative Video and Technical Nuances.

Objectives To discuss the use of the posterior petrosal approach for the resection of a retrochiasmatic craniopharyngioma. Design Operative video. Results In this case video, the authors discuss the surgical management of a large craniopharyngioma, presenting with mass effect on the third ventricle and optic apparatus. A first surgical stage, through an endoscopic endonasal transtubercular approach, allowed satisfactory decompression of the optic chiasma and nerves in preparation for adjuvant therapy. However, accelerated growth of the tumor, with renewed visual deficits and mass effect on the hypothalamus and third ventricle, warranted a supplementary resection. A posterior transpetrosal 1 2 (also called "retrolabyrinthine transtentorial") was performed to obtain a better exposure of the tumor and the surrounding anatomy (floor and walls of the third ventricle, perforating vessels, optic nerves, etc.) 3 . Nuances of technique and surgical pearls related to the posterior transpetrosal are discussed and illustrated in this operative video, including the posterior mobilization of the transverse-sigmoid sinuses junction, preservation of the venous anatomy during the tentorial incision, identification and preservation of the floor of the third ventricle during tumor resection, and a careful multilayer closure. Conclusion Retrochiasmatic craniopharyngiomas are difficult to reach tumors that often require skull base approaches, either endoscopic endonasal or transcranial. The posterior transpetrosal approach is an important part of the surgical armamentarium to safely resect these complex tumors. The link to the video can be found at: https://youtu.be/2MyGLJ_v1kI .

Resection of an Optic Canal Meningioma through a Contralateral Subfrontal Approach with Endoscopic Assistance: A 2D Operative Video.

Objective To review the use of the contralateral subfrontal approach for the resection of an optic canal meningioma. Design Operative video. Results A meningioma, located in the inferomedial side of the optic canal ( Fig. 1 ), was found to cause significant visual deterioration. The subfrontal route was preferred to expose the tumor without mobilization of the optic nerve. Drilling of the anterior limb of the chiasmatic sulcus (limbus sphenoidale) provided adequate exposure of the medial aspect of the optic canal. Gross total resection (Simpson II) of the tumor was accomplished, and endoscopic assistance allowed identification and coagulation of an infiltrated dura mater in the chiasmatic sulcus and tuberculum sellae. Conclusion The subfrontal approach grants an optimal surgical trajectory to the contralateral chiasmatic sulcus and optic nerve. When the medial side of the optic canal is drilled, tumors extending into the optic canal can be safely resected, under direct visualization of the inferomedial side of the optic nerve. Breach into the sphenoid sinus can occur during drilling of the anterior limb of the chiasmatic sulcus. Endoscopic assistance can provide a better view on blind areas of the surgical field, including the depth of the optic canal ( Fig. 2 ). The link to the video can be found at: https://youtu.be/fS2udUCPH1g .