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.

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.

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.

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.

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.

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.

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.

Surgery and protontherapy in Grade I and II skull base chondrosarcoma: A comparative retrospective study.

OBJECTIVE: Skull base chondrosarcoma is a rare tumour usually treated by surgery and proton therapy. However, as mortality rate is very low and treatment complications are frequent, a less aggressive therapeutic strategy could be considered. The objective of this study was to compare the results of surgery only vs surgery and adjuvant proton therapy, in terms of survival and treatment adverse effects, based on a retrospective series. METHODS: Monocentric retrospective study at a tertiary care centre. All patients treated for a skull base grade I and II chondrosarcoma were included. We collected data concerning surgical and proton therapy treatment and up-to-date follow-up, including Common Terminology Criteria for Adverse Events (CTCAE) scores. RESULTS: 47 patients (23M/24F) were operated on between 2002 and 2015; mean age at diagnosis was 47 years-old (10-85). Petroclival and anterior skull base locations were found in 34 and 13 patients, respectively. Gross total resection was achieved in 17 cases (36%) and partial in 30 (64%). Adjuvant proton therapy (mean total dose 70 GyRBE,1.8 GyRBE/day) was administered in 23 cases. Overall mean follow-up was 91 months (7-182). Of the patients treated by surgery only, 8 (34%) experienced residual tumour progression (mean delay 51 months) and 5 received second-line proton therapy. Adjuvant proton therapy was associated with a significantly lower rate of relapse (11%; p = 0.01). There was no significant difference in 10-year disease specific survival between patients initially treated with or without adjuvant proton therapy (100% vs 89.8%, p = 0.14). Difference in high-grade toxicity was not statistically significant between patients in both groups (25% (7) vs 11% (5), p = 0.10). The most frequent adverse effect of proton therapy was sensorineural hearing loss (39%). CONCLUSION: Long-term disease specific survival was not significantly lower in patients without adjuvant proton therapy, but they experienced less adverse effects. We believe a surgery only strategy could be discussed, delaying as much as possible proton therapy in cases of relapse. Further prospective studies are needed to validate this more conservative strategy in skull base chondrosarcoma.

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.

Regression of Giant Olfactory Groove Meningioma and Complete Visual Acuity Recovery after Discontinuation of Cyproterone Acetate.

PURPOSE: To report on the medical management of meningioma with compression of the optic chiasm associated with the use of cyproterone acetate (CA). CASE REPORT: A 65-year-old woman who was being treated with CA presented with a recent decrease in visual function, leading to discovery of a giant olfactory groove meningioma with compression of the optic chiasm. CA was discontinued immediately, and her visual function improved dramatically. At 13 months, in addition to a significant improvement in visual and neurocognitive symptoms, the tumor volume was reduced by 50%. CONCLUSION: In meningiomas associated with CA, treatment cessation may result in prompt improvement in symptoms and a reduction in tumor volume, even if the tumor is large and causing neurologic impairments.

The Chopsticks Technique for Endoscopic Endonasal Surgery-Improving Surgical Efficiency and Reducing the Surgical Footprint.

BACKGROUND: Variations and additions to the endoscopic endonasal exposure have been proposed around a modular strategy. These extensions are often necessary to provide additional working space and reduce conflict between the instruments and the endoscope. Resection of endonasal structures, which affects negatively the sinonasal quality of life, is thus undertaken not only to obtain tumor exposure but also to improve the maneuverability of the instruments. OBJECTIVE: Our objective was to achieve the same skull base exposures and tumor resections and limit the surgical footprint on sinonasal structures and patients' quality of life. METHODS: Our team developed a surgical technique in which the endoscope and a malleable rotative aspirator are held by the nondominant hand and the other main instrument in the dominant hand. This modification, which we call the chopsticks technique, allows the surgeon to use minimalistic exposures with an improved dynamic perception of the surgical field and reduced conflicts between the instruments. The endonasal structures that are left intact help support the instruments. The same surgical objectives, in terms of exposure and resection, are achieved. We describe our technique and a series of patients operated with this uninarial 3-instruments technique to discuss relevant operative nuances. CONCLUSIONS: We propose a technical modification that allows the surgeons to benefit from the advantages of a bimanual technique while still holding the endoscope. In our opinion, this technique may improve dynamic understanding of the anatomy and surgical efficiency and reduce the footprint of the surgery.

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 .

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 .

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.

Tentorial meningioma supplied by a marginal tentorial artery arising from the superior cerebellar artery: Anatomic and technical considerations.

Background and importance The marginal tentorial artery runs over the free edge of the tentorium. Different origins have been described, always involving branches of the carotid artery. We report the superior cerebellar artery as an unknown origin of this artery. We developed our strategy in a case of a tentorial meningioma mainly supplied by this artery. Clinical presentation A 53-year-old man was admitted in our institution for the surgical treatment of a large tentorial and petroclival meningioma. A 2D conventional angiogram was insufficient to detect the tumoral blush. A 3D digital subtraction angiogram (DSA) of the vertebral artery highlighted a blush arising from a marginal tentorial artery fed by the superior cerebellar artery. Selective embolization of this branch led to significant devascularization of the tumor. A total tumor resection was performed 24 h after embolization without complication. The dural medial tentorial artery of the superior cerebellar artery is relatively unknown and courses at the inferior surface of the tentorium. We report the first case in which the marginal tentorial artery arises from this artery. Major bleeding may result from its section or its avulsion from the superior cerebellar artery during surgery; its preoperative diagnosis is thus essential. In this case, a 3D-DSA with dual volume visualization was more sensitive than a 2D conventional angiogram to detect such an anatomic variant. Conclusion The marginal tentorial artery may originate from the superior cerebellar artery. The recognition of this anatomic variant may be essential to avoid hemorrhagic complications during surgery of hypervascular tumors of the tentorium.

Clivus chordomas: a systematic review and meta-analysis of contemporary surgical management.

INTRODUCTION: Chordomas are rare bony lesions arising from notochordal remnants. Technical advances in endoscopic surgery have allowed the median endonasal corridor to be used for a larger number of chordoma cases. However, very few studies have critically examined the data in support of the anterior midline approach (AMA), as compared to lateral and posterolateral transcranial corridors. EVIDENCE ACQUISITION: A systematic search of the literature was done in March 2016 using EMBASE and PubMed for articles published between January 2006 and March 2016 to identify surgical series of clivus chordomas. Only articles describing chordomas cases arising from the clivus of craniocervical junction were included in the analysis. EVIDENCE SYNTHESIS: Twenty-seven articles were included in this systematic review, amounting to a total of 1050 patients. The weighted mean rate of GTR was 39.9% (range 0-78.3%) in this patient population. The surgical approaches were described in 16 papers, with 6 series reporting on surgeries done exclusively through the midline corridor (116 patients). In the remaining 10 series (495 patients), the AMA was used in a mean of 56.8% of cases. In studies including patients operated solely through an AMA, a higher GTR rate was obtained (60.7% vs. 42.0%). Postoperative complications were also different between the two cohorts, with lower cranial nerves deficits and CNS infections but higher incidence of CSF leak in the AMA group than in mixed surgical series. In a weighted mean follow-up time of 52.1±21.9 months, recurrences were observed in 38.2% of the total population of patients. Among 423 patients, the weighted 5-year PFS was 49.9±12.1% and the 5-year OS was 73.9±11.2% (N.=391). A random effects model was performed, combining data from studies reporting recurrence rates in GTR and non-GTR (N.=610), with a total odds ratio of having a recurrence for patients who had GTR vs non-GTR of 0.289 (95CI 0.184-0.453). CONCLUSIONS: In this systematic review and meta-analysis of studies published in the last decade, an estimated 5-year PFS of 49.9% and 5-year OS of 73.9% were obtained. The weighted mean GTR rate in the included study was 39.9%, with a significantly reduced occurrence of recurrence in complete resections. Although anterior midline approaches may allow for higher GTR rates and fewer neurological morbidity than traditional transcranial routes, their impact of long-term survival and disease control remains largely unknown.

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.

Predicting success of endoscopic third ventriculostomy: validation of the ETV Success Score in a mixed population of adult and pediatric patients.

OBJECT: Endoscopic third ventriculostomy (ETV) has become the first line of treatment in obstructive hydrocephalus. The Toronto group (Kulkarni et al.) developed the ETV Success Score (ETVSS) to predict the clinical response following ETV based on age, previous shunt, and cause of hydrocephalus in a pediatric population. However, the use of the ETVSS has not been validated for a population comprising adults. The objective of this study was to validate the ETVSS in a "closed-skull" population, including patients 2 years of age and older. METHODS: In this retrospective observational study, medical charts of all consecutive cases of ETV performed in two university hospitals were reviewed. The primary outcome, the success of ETV, was defined as the absence of reoperation or death attributable to hydrocephalus at 6 months. The ETVSS was calculated for all patients. Discriminative properties along with calibration of the ETVSS were established for the study population. The secondary outcome is the reoperation-free survival. RESULTS: This study included 168 primary ETVs. The mean age was 40 years (range 3-85 years). ETV was successful at 6 months in 126 patients (75%) compared with a mean ETVSS of 82.4%. The area under the receiver operating characteristic curve was 0.61, revealing insufficient discrimination from the ETVSS in this population. In contrast, calibration of the ETVSS was excellent (calibration slope = 1.01), although the expected low numbers were obtained for scores < 70. Decision curve analyses demonstrate that ETVSS is marginally beneficial in clinical decision-making, a reduction of 4 and 2 avoidable ETVs per 100 cases if the threshold used on the ETVSS is set at 70 and 60, respectively. However, the use of the ETVSS showed inferior net benefit when compared with the strategy of not recommending ETV at all as a surgical option for thresholds set at 80 and 90. In this cohort, neither age nor previous shunt were significantly associated with unsuccessful ETV. However, better outcomes were achieved in patients with aqueductal stenosis, tectal compressions, and other tumor-associated hydrocephalus than in cases secondary to myelomeningocele, infection, or hemorrhage (p = 0.03). CONCLUSIONS: The ETVSS did not show adequate discrimination but demonstrated excellent calibration in this population of patients 2 years and older. According to decision-curve analyses, the ETVSS is marginally useful in clinical scenarios in which 60% or 70% success rates are the thresholds for preferring ETV to CSF shunt. Previous history of CSF shunt and age were not associated with worse outcomes, whereas posthemorrhagic and postinfectious causes of the hydrocephalus were significantly associated with reduced success rates following ETV.