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Transpetrosal approaches are technically complex and require a complete understanding of surgical and radiological anatomy. A careful evaluation of pre-operative magnetic resonance imaging and computed tomography scan is mandatory, because anatomical or pathological variations are common and may increase the risk of complications related with the approach.Pre-operative characteristics of venous and petrous bone anatomy were analysed and correlated with intraoperative findings, using injected magnetic resonance imaging and thin-slices computed tomography scan. These data regularly checked before each transpetrosal approach were progressively included in the presented checklist.Transpetrosal approaches have been used in 101 patients. Items included in the checklist were petrous bone pneumatization, angle between petrous apex and clivus, dehiscence of petrous carotid artery, dehiscence of geniculate ganglion, distance between superior semicircular canal and middle fossa floor, distance between cochlea and middle fossa floor, sigmoid sinus dominance, transverse sigmoid sinus junction depth to the outer cortical bone, jugular bulb height (high or low), location of the vein of Labbé, characteristics of superior petrosal vein complex.The presented checklist provides a systematic scheme of consultation of characteristic of venous and petrous bone anatomy for transpetrosal approaches. In our experience, the use of this checklist reduces the risk of complications related with approach, by minimizing the neglect of crucial information.

Purpose The purpose of this study was to assess the accuracy of computed tomography angiography (CTA) for quantification of cerebral vasospasm following aneurysmal subarachnoid hemorrhage in proximal and middle segments of intracranial arteries. Materials and methods Twenty consecutive patients (7 men, 13 women; mean age, 47 ± 7 [SD] years; age range: 27–78 years) with aneurysmal subarachnoid hemorrhage who underwent CTA and digital subtracted angiography (DSA) with a 6-hour window at baseline and during vasospasm period were included. Twelve artery segments were analyzed in each patient. Vasospasm was blindly quantified on CTA and digital subtracted angiography (DSA) by two independent readers with discordance > 10% resolved by open data consensus. Inter-reader and inter-test correlations with DSA as reference, and causes of discordant readings were analyzed. The best sensitivity and specificity of CTA for determination of vasospasm ≥ 50% on DSA was determined using receiver operating curve analysis. Results Two-hundred-and-ten arterial segments were analyzed after exclusion of 30 segments with missing data or metallic artifacts. An inter-reader discordance >10% was observed in 82 segments (82/210; 39% [95% CI: 32–46]). Inter-test discordances >10% were observed respectively in 115 segments (115/210; 55% [95% CI: 49–62]) with the junior reader and in 73 segments (73/210; 35% [95% CI: 29–42]) with the senior reader. They were related to reader error in 55 (55/210; 26% [95% CI: 20–32]) with the junior reader and 13 (13/210; 6% [95% CI: 3–9]) with the senior reader, as well systematic biases in 8 (8/210; 4% [95% CI: 1–6]), and intrinsic limitation in 52 (52/210; 25% [95% CI: 19–31]). Best sensitivity and specificity of CTA were observed for a threshold value of 30% (sensitivity = 88% [95% CI: 78–97%]; specificity = 84% [95% CI: 77–90%]; area under curve = 0.92 [95% CI: 0.86–0.97]). On a patient basis, sensitivity was 100% (specificity = 60% [95% CI: 38–81%]; area under curve = 0.97 [95% CI: 89–100%] for this same threshold. Conclusion Our study shows a moderate accuracy of CTA for the quantification of cerebral vasospasm, mostly related to challenging interpretation and intrinsic limitations. CTA may rule-out angiographic vasospasm ≥ 50% when no segment has vasospasm over than 30%.

OBJECTIVE Craniocervical junction (CCJ) chordomas are a neurosurgical challenge because of their deep localization, lateral extension, bone destruction, and tight relationship with the vertebral artery and lower cranial nerves. In this study, the authors present their surgical experience with the endoscope-assisted far-lateral transcondylar approach (EA-FLTA) for the treatment of CCJ chordomas, highlighting the advantages of this corridor and the integration of the endoscope to reach the anterior aspect and contralateral side of the CCJ and the possibility of performing occipitocervical fusion (OCF) during the same stage of surgery. METHODS Nine consecutive cases of CCJ chordomas treated with the EA-FLTA between 2013 and 2020 were retrospectively reviewed. Preoperative characteristics, surgical technique, postoperative results, and clinical outcome were analyzed. A cadaveric dissection was also performed to clarify the anatomical landmarks. RESULTS The male/female ratio was 1.25, and the median age was 36 years (range 14–53 years). In 6 patients (66.7%), the lesion showed a bilateral extension, and 7 patients (77.8%) had an intradural extension. The vertebral artery was encased in 5 patients. Gross-total resection was achieved in 5 patients (55.6%), near-total resection in 3 (33.3%), and subtotal resection 1 (11.1%). In 5 cases, the OCF was performed in the same stage after tumor removal. Neither approach-related complications nor complications related to tumor resection occurred. During follow-up (median 18 months, range 5–48 months), 1 patient, who had already undergone treatment and radiotherapy at another institution and had an aggressive tumor (Ki-67 index of 20%), showed tumor recurrence at 12 months. CONCLUSIONS The EA-FLTA provides a safe and effective corridor to resect extensive and complex CCJ chordomas, allowing the surgeon to reach the anterior, lateral, and posterior portions of the tumor, and to treat CCJ instability in a single stage.

Background Chordomas are rare malignant bone cancers of the skull-base and spine. Patient survival is variable and not reliably predicted using clinical factors or molecular features. This study identifies prognostic epigenetic chordoma subtypes that are detected noninvasively using plasma methylomes. Methods Methylation profiles of 68 chordoma surgical samples were obtained between 1996 and 2018 across three international centers along with matched plasma methylomes where available. Results Consensus clustering identified two stable tissue clusters with a disease-specific survival difference that was independent of clinical factors in a multivariate Cox analysis (HR = 14.2, 95%CI: 2.1–94.8, P = 0.0063). Immune-related pathways with genes hypomethylated at promoters and increased immune cell abundance were observed in the poor-performing “Immune-infiltrated” subtype. Cell-to-cell interaction plus extracellular matrix pathway hypomethylation and higher tumor purity were observed in the better-performing “Cellular” subtype. The findings were validated in additional DNA methylation and RNA sequencing datasets as well as with immunohistochemical staining. Plasma methylomes distinguished chordomas from other clinical differential diagnoses by applying fifty chordoma-versus-other binomial generalized linear models in random 20% testing sets (mean AUROC = 0.84, 95%CI: 0.52–1.00). Tissue-based and plasma-based methylation signals were highly correlated in both prognostic clusters. Additionally, leave-one-out models accurately classified all tumors into their correct cluster based on plasma methylation data. Conclusions Here, we show the first identification of prognostic epigenetic chordoma subtypes and first use of plasma methylome-based biomarkers to noninvasively diagnose and subtype chordomas. These results may transform patient management by allowing treatment aggressiveness to be balanced with patient risk according to prognosis.

Background The behavior of meningiomas under influence of progestin therapy remains unclear. Objective To investigate the relationship between growth kinetics of intracranial meningiomas and usage of the progestin cyproterone acetate (PCA). Methods This study prospectively followed 108 women with 262 intracranial meningiomas and documented PCA use. A per-meningioma analysis was conducted. Changes in meningioma volumes over time, and meningioma growth velocities, were measured on magnetic resonance imaging (MRI) after stopping PCA treatment. Results Mean follow-up time was 30 (standard deviation [SD] 29) mo. Ten (4%) meningiomas were treated surgically at presentation. The other 252 meningiomas were followed after stopping PCA treatment. Overall, followed meningiomas decreased their volumes by 33% on average (SD 28%). A total of 188 (72%) meningiomas decreased, 51 (20%) meningiomas remained stable, and 13 (4%) increased in volume of which 3 (1%) were surgically treated because of radiological progression during follow-up after PCA withdrawal. In total, 239 of 262 (91%) meningiomas regressed or stabilized during follow-up. Subgroup analysis in 7 women with 19 meningiomas with follow-up before and after PCA withdrawal demonstrated that meningioma growth velocity changed statistically significantly (P = .02). Meningiomas grew (average velocity of 0.25 mm3/day) while patients were using PCA and shrank (average velocity of -0.54 mm3/day) after discontinuation of PCA. Conclusion Ninety-one percent of intracranial meningiomas in female patients with long-term PCA use decrease or stabilize on MRI after stopping PCA treatment. Meningioma growth kinetics change significantly from growth during PCA usage to shrinkage after PCA withdrawal.

BACKGROUND Currently, different postoperative predictors of chordoma recurrence have been identified. Tumor growth rate (TGR) is an image-based calculation that provides quantitative information of tumor's volume changing over time and has been shown to predict progression-free survival (PFS) in other tumor types. OBJECTIVE To explore the usefulness of TGR as a new preoperative radiological marker for chordoma recurrence. METHODS A retrospective single-institution study was carried out including patients reflecting these criteria: confirmed diagnosis of chordoma on pathological analysis, no history of previous radiation, and at least 2 preoperative thin-slice magnetic resonance images available to measure TGR. TGR was calculated for all patients, showing the percentage change in tumor size over 1 mo. RESULTS A total of 32 patients were retained for analysis. Patients with a TGR ≥ 10.12%/m had a statistically significantly lower mean PFS (P

Introduction Endoscopic endonasal approaches (EEAs) provide improved access and operative visualization for resection of pituitary adenomas. Although the technique has gained wide acceptance, there is a paucity of data regarding late recurrence. Objective We aim to assess long-term outcomes of patients with nonfunctioning pituitary adenomas (NFPAs) who underwent EEA. Methods We reviewed 269 patients operated on for an NFPA between 2005 and 2015. Clinical and radiologic factors including those potentially related to higher chances of recurrence were analyzed. Progression-free survival was analyzed using the Kaplan-Meier method, and univariate and multivariate survival were analyzed using a Cox regression model. Results The study included 269 patients. The gross total resection rate was 46.0% (n = 124) but cavernous sinus involvement was present in almost half the patients (n = 115). The probability of recurrence at 5 years and 10 years was 22.0% and 47.2%, respectively. The median time to recurrence was 10 years for patients without cavernous sinus involvement and 6 years for those with cavernous sinus involvement. Univariate and multivariate analysis showed that tumor size, cavernous sinus invasion, anterior skull base extensions, and residual tumor were significantly associated with recurrence. Conclusions Recurrence rate of NFPA remains high despite the better visualization offered by EEA, especially in those tumors involving the cavernous sinus and/or previously operated on. Repeat surgery is adequate for tumor debulking and decompression of the optic apparatus but is unlikely to achieve gross total resection if a successful previous EEA has been performed. Radiation therapy is an effective option for management of recurrent tumors.

Background: The type of sellar barrier observed between a pituitary tumor and cerebrospinal fluid (CSF) on preoperative magnetic resonance imaging (MRI) may predict intraoperative CSF leak during endonasal pituitary surgery. This is the first multicentric prospective cohort trial to study the sellar barrier concept and CSF leak rate during endoscopic pituitary surgery. Methods: This multi-center, international study enrolled patients operated for pituitary adenomas via fully endoscopic endonasal surgery over a period of 4 months. The independent variable was the subtype of sellar barrier observed on preoperative MRI (strong, mixed or weak); the dependent variable was the presence of an intraoperative CSF leak. The primary goal was to determine the association between a particular type of sellar barrier and the risk of intraoperative CSF leak. Appropriate statistical methods were then applied for data analysis. Results: Over the study period, 310 patients underwent endoscopic endonasal surgery for pituitary tumor. Preoperative imaging revealed a weak sellar barrier in 73 (23.55%), a mixed sellar barrier in 75 (24.19%), and a strong sellar barrier in 162 (52.26%) patients. The overall rate of intraoperative CSF leak among all patients was 69 (22.26%). A strong sellar-type barrier was associated with significantly reduced rate of intraoperative CSF leak (RR = 0.08; 95% CI 0.03–0.19; p < 0.0001), while a weak sellar barrier associated with higher rates of CSF leak (RR = 8.54; 95% CI 5.4–13.5; p < 0.0001). Conclusions: The preoperative MRI of pituitary patients can suggest intraoperative CSF leak rates, utilizing the concept of the sellar barrier. Patients with a weak sellar barrier carry a higher risk for an intraoperative CSF leak, whereas a strong sellar barrier on MRI seems to mitigate intraoperative CSF leak. We propose that preoperatively assessment of the sellar barrier can prepare surgeons for intraoperative CSF leak repair.

Background Vascular encasement by skull base chordomas can increase surgical risk and hinder completeness of resection. However, the evidence behind this remains anecdotic. Objective To give a better portrayal of chordomas encasing vertebrobasilar arteries mainly in regard of surgical vascular risk and its impact on extent of resection. Methods A retrospective cohort study comparing skull base chordomas with encasement (≥180o encirclement) of the vertebrobasilar arteries to a control group of skull base chordomas with intradural extension. Data gathered involved pre- and postoperative volumetric analysis of the tumor, degree of encasement of involved vessel, occurrence of complication, and survival data including progression-free survival (PFS) and overall survival (OS). Results A total of 24 patients with vertebrobasilar encasement were included in the study and an equal number of control cases were randomly selected from the same time period, totalizing 48 patients. Lower clival tumors with condyle involvement were more likely to have encasement. Gross total resection (GTR) rate was significantly lower in the encasement group (13% vs 42%, P = .023). Rates of postoperative new neurological deficit, CFS leak and 30 d postoperative mortality were not statistically different between groups. There was no statistically significant difference in mean PFS (P = .608) and OS (P = .958). Conclusion Skull base chordomas encasing vertebrobasilar arteries are highly challenging tumors. This study demonstrates that although safe resection is possible, GTR is hindered by the presence of encasement. We advocate letting the tumor's adherence to vessels lead the resection, leaving a small piece of tumor behind if adherent to the vessels.

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.

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. 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. 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. 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.

Background The use of nonadhesive liquid embolic agents (NALEAs) has gained great popularity in the treatment of brain vascular malformations, with a lower rate of local complications than surgery. However, we describe the formation of brain abscesses after endovascular treatment of a brain arteriovenous malformation (bAVM) and how important removal of the NALEAs was in the treatment of these abscesses. Case Description A 68-year-old man presented with seizures after being treated for an unruptured bAVM using Squid (Emboflu), an NALEA. Radiologic imaging revealed brain lesions suspicious of abscesses around the previously treated bAVM. A surgical excision of the bAVM and the embolized material was performed as was drainage of the brain abscesses. Bacterial cultures were positive for Enterococcus faecalis, and the patient left the hospital with an appropriate antibiotic regimen without new deficits. Conclusions This is the first reported case of a bAVM treated with Squid complicated with brain abscesses, a rare but very serious complication. This complication should be treated not only using antibiotherapy but with complete safe removal of the embolic material.

Objective To investigate on the feasibility and safety of a new approach which consists of delaying instrumentation after destabilizing craniovertebral junction (CVJ) chordoma surgery, allowing proton beam radiotherapy to be performed in a metal-free tumoral cavity. Design This is a retrospective series of a prospectively maintained database. Participants Five consecutive patients operated on for a CVJ chordomas for which instrumentation after tumor resection was deferred to after radiotherapy treatment. Main Outcome Measures The main outcome consisted of measurements of the following parameters: C0–C2 angle, atlanto-dens interval (ADI), condylar gap, and the position of the dens relative to McGregor's line and coronal inclination, performed at 3 different times for all patients: before tumor surgery (baseline), before instrumentation surgery, and after instrumentation surgery. Results For all patients, CVJ parameters deteriorated during the delay period, but stayed within normal limits for most. Because of radiological instability, one patient necessitated instrumentation before receiving radiotherapy. All parameters except condylar gap were partially corrected after instrumentation. No new neurological symptom or evolving neck pain occurred during the delay period. Conclusion Delayed instrumentation of CVJ chordomas can be a safe alternative that might lead to improved subsequent radiotherapeutical treatment. Patient's selection and close clinical and radiological follow-up are mandatory for the success of this approach.

Purpose Long-term use of cyproterone acetate (CPA) is associated with an increased risk of developing an intracranial meningioma. Discontinuation of CPA most often induce stabilization or regression of the tumor. The exact mechanism of regression is unknown as well as the reason why some meningiomas are still growing after CPA discontinuation.We are reporting four patients with multiple meningiomas, showing opposite tumor evolutions after stopping the CPA highlighting the underlying histologic and genetic features.MethodsPatients presenting several meningiomaswith opposite evolutions following the discontinuation of CPA were identified. The clinical and radiological data’s were reviewed. A retrospective volumetric analysis of the meningiomas was performed. All the growing meningiomas were operated. Each tumor was characterized histopathologically and by molecular and genetic analyses.ResultsFour female withmultiple meningiomas and opposite tumor volume evolution after CPA discontinuation were identified. The histopathological results found fibroblastic meningiomas for tumorsgrowinglocated in the convexity and a morefibrousmeningioma in the skull-base tumor which decreased. Meningothelial and transitional meningiomaswere found in two skull-base growing meningiomas.The molecular characterization found twoNF2-mutations among the 4 growing meningiomas. In one patient who presented both patterns, the shrinking skull-basetumor harbored a PIK3CA-mutation whereas the growing tumor, a NF2-mutation.ConclusionTo our knowledge, this is the first report of such an atypical tumor evolution of CPA-associated meningiomatosis after CPA discontinuation in the same patient. Underlying biological mechanisms explaining this observationespecially, the close relationship between mutational landscapes and the meningeal embryologyin CPA-related meningiomasrequire further research.

Background: Associations between progestins and meningiomas is now well established. While the link between cyproterone acetate (CA) and meningioma was thoroughly studied, there is far less available data regarding the link between chlormadinone acetate (CHA) or nomegestrol acetate (NA) and risk of intracranial meningiomaMethods: We are presenting a series of 28 patients diagnosed with single or multiple meningiomas while treated with CHA-NA, in which the clinical and radiological course were analyzed after treatment discontinuation.Results: 28 women, with a mean age of 56 years old, were diagnosed with one or multiple meningioma while being treated with either CHA or NA. After stopping treatment, 89.3% showed either tumor shrinkage or tumor stabilization on follow-up MRIs. Multiple meningiomas were more likely observed in patients with long periods of treatment (>10 years, p 0.03) and seem to have a better clinical course (p 0.01). Most of the lesions were located on the skull base (55.4%). Four patients with multiple meningiomas showed discordant tumors evolution, with some tumors growing while others were decreasing. Most of the growing meningiomas were either convexity or midline lesions and more posteriorly located. Conclusion: Our study demonstrated a significant percentage of tumor diminution or stabilization after NA and CHA discontinuation. Therefore, treatment discontinuation with close monitoring should be the first measure taken if urgent surgery is not indicated. However, our results seem to be less encouraging than previously described in patients treated by CA, with more patients showing tumor growth despite treatment discontinuation. Further studies are needed to differentiate the effect of the different progestins treatment on meningiomas.

Purpose The purpose of this study was to analyze the long-term efficacy and safety of intracranial venous sinus stenting in a large cohort of patients with any type of presentation of primary lateral venous sinus stenosis (VSS). Materials and methods A retrospective cohort study was performed including patients treated by venous sinus stenting for symptomatic VSS from 2012 to 2019. Successful primary resolution of symptoms without adjunctive treatment or recurrence, and complications after stenting were analyzed at the last follow-up time point. Results Two-hundred patients were included. There were 14 men and 186 women with a mean age of 39 ± 14 (SD) years (age range: 13–75 years). Presenting symptoms included venous pulsatile tinnitus in 168 patients (168/200; 84%), idiopathic intracranial hypertension in 100 patients (100/200; 50%) and/or spontaneous cerebrospinal fluid leak in 35 patients (35/200; 17%). The overall rate of successful primary resolution of any typical presenting symptoms was 79% (95% CI: 73–85%). This rate ranged from 74% to 93% depending on the symptom with no significant difference between patients with and those without idiopathic intracranial hypertension (P = 0.08). Recurrence rate was 10% (95% CI: 6–14%). No death or permanent morbidity were observed during a median follow-up of 2.2 years (Q1, Q3: 1.4, 3.3; range: 1–7.7 years). Conclusion Our study shows that venous sinus stenting has a low morbidity and high success rate at long-term follow-up for the treatment of idiopathic intracranial hypertension, venous pulsatile tinnitus or spontaneous cerebrospinal fluid leak associated with VSS. The excellent safety suggests considering this treatment as first-line treatment when medical management is ineffective or poorly tolerated.

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.

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. Three cases from two experienced neurosurgical centers were collected and the available literature was reviewed. 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. 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.

Introduction Although the indication of endoscopic approaches for anterior skull base meningiomas (ASBM) has been progressively refined, there remains a paucity of data on recurrence rates after resection. To analyze and compare recurrence rates of ASBM resected through endoscopic endonasal (EEE) versus transcranial (TCA) approaches. Material and Methods We performed a retrospective analysis of patients submitted to the EEE or TCA approach for ASBM resection from May 2006 to January 2016 in our center. Clinical, radiological, and pathology data were retrieved for analysis. Tumor size, location, surgical technique, extent of resection, and tumor grade were assessed. The 2 groups were compared to identify predictors and differences regarding tumor recurrence. Results Fifty-two patients (17 olfactory groove meningioma [OGM] and 35 tuberculum sellae meningioma [TSM]) were included; 26 (6 OGM and 20 TSM) underwent EEE and 26 (13 OGM and 13 TSM) TCA, with a mean follow-up of 41 months. Gross total resection was achieved in 38 (73%) patients (18 [69%] in EEE and 20 [77%] in TCA). Eight (15%) patients presented with recurrence: 5 (19%) in the EEE group and 3 (11.5%) in the TCA group without a statistical difference (P = 0.69). Among the recurrences, gross total resection had been achieved in 1 case of each group. In the EEE group, 1 patient underwent TCA for a recurrent tumor and another patient was referred for radiosurgery. Conclusions This study has shown an overall similar recurrence rate of ASBM regardless of the technique used. However, the analysis of larger series with longer follow-up is necessary to clearly define the indications and to fully validate the efficacy of EEE.

Objective The aim of this study was to identify key anatomic landmarks useful in gaining access to the anteromedial temporal region via the corridor formed by the inferior orbital fissure (IOF), the ophthalmic branch of the trigeminal nerve (V1), and the maxillary branch of the trigeminal nerve (V2) via an endoscopic endonasal approach (EEA). Methods An anatomic dissection of 6 cadaver heads was performed to confirm the feasibility and applicability of an EEA for accessing the anteromedial temporal region. Results After middle turbinectomy, the lateral recess of the sphenoid sinus was opened, the orbital apex was exposed, and the posterior wall of the maxillary sinus was removed, in sequence. The IOF and the pterygopalatine fossa (PPF) were then identified. After opening the foramen rotundum (FR) and removing the bony structure between the FR, V2 was transposed downward. The orbital muscle of Muller was removed. The PPF was mobilized downward exposing the greater wing of the sphenoid bone (GWS). The GWS between V1 and V2 was drilled, therefore exposing the temporal dura. With blunt dissection, the medial temporal dura was peeled away from the cavernous sinus to increase access to the anteromedial temporal region. Conclusions The anteromedial temporal fossa was exposed by drilling the V1-V2 triangle corridor via an EEA. Endoscopic endonasal exposure of the anteromedial temporal fossa is feasible and requires limited endonasal work. This approach may be considered as an alternate surgical corridor to the temporomesial lobe that offers the advantages of a direct route with less temporal lobe retraction.

International audience; 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.

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 long-term use of cyproterone acetate (CPA) is associated with an increased risk of developing intracranial meningiomas. CPA discontinuation most often induces a stabilization or regression of the tumor. The underlying biological mechanisms as well as the reasons why some meningiomas still grow after CPA discontinuation remain unknown. We reported a series of patients presenting CPA-induced meningiomatosis with opposed tumor evolutions following CPA discontinuation, highlighting the underlying histological and genetic features. Patients presenting several meningiomas with opposite tumor evolution (coexistence of growing and shrinking tumors) following CPA discontinuation were identified. Clinical and radiological data were reviewed. A retrospective volumetric analysis of the meningiomas was performed. All the growing meningiomas were operated. Each operated tumor was characterized by histological and genetic analyses. Four women with multiple meningiomas and opposite tumor volume evolutions after CPA discontinuation were identified. Histopathological analysis characterized the convexity and tentorial tumors which continued to grow after CPA discontinuation as fibroblastic meningiomas. The decreasing skull base tumor was characterized as a fibroblastic meningioma with increased fibrosis and a widespread collagen formation. The two growing skull base meningiomas were identified as meningothelial and transitional meningiomas. The molecular characterization found two NF2 mutations among the growing meningiomas and a PIK3CA mutation in the skull base tumor which decreased. To our knowledge, this is the first report describing an atypical tumor evolution of CPA-associated meningiomas after CPA discontinuation. The underlying biological mechanisms explaining this observation and especially the close relationship between mutational landscapes and embryologic origins of the meninges in CPA-related meningiomas as well as their clonal origin require further research.

BACKGROUND Chordomas are malignant bone cancers arising from the skull-base and spine that are rare but cause devastating central nervous system morbidities. Survival is highly variable despite surgery and radiotherapy as 10% live under 1 year and 30-35% survive over 20 years. There are currently no reliable prognostic factors and this limits our ability to tailor patient treatment to their risk. Accordingly, this work identifies epigenetic prognostic chordoma subgroups that are detectable non-invasively through plasma methylomes to guide treatment. METHODS A total of 68 chordoma surgical specimens resected between 1996-2018 across three international centres underwent DNA methylation profiling. Cell-free methylated tumor DNA immunoprecipitation and high-throughput sequencing was performed on available matched plasma samples. RESULTS Two stable tumor clusters were identified through consensus clustering of tissue methylation data. Clusters had statistically significantly different disease-specific survivals (log-rank p=0.0062) independent of clinical factors in a multivariable Cox analysis (HR=16.5, 95%CI: 2.8-96, p=0.0018). The poorer-performing “Immune-infiltrated” cluster had genes hypomethylated at promoters, typically resulting in transcription, within immune-related pathways and higher immune cell abundance within tumors. The better-performing “Cellular” cluster showed higher tumor cellularity plus cell-to-cell interaction and extracellular matrix pathway hypomethylation. Fifty chordoma-versus-other binomial generalized linear models built using plasma methylome data distinguished chordomas from meningiomas and spinal metastases, as representative clinical differential diagnoses, in random left-out 20% testing sets (mean AUROC=0.84, 95%CI: 0.52-1.00). Plasma-based methylation signatures were highly correlated with tissue-based signals within both poor-performing (median r=0.69, 95%CI: 0.66-0.72) and better-performing cluster tumors (median r=0.67, 95%CI: 0.62-0.72). CONCLUSIONS The first identification of two distinct prognostic epigenetic chordoma subgroups is shown here with “Immune-infiltrated” tumors having a poorer prognosis than “Cellular” tumors. Plasma methylomes can be utilized for non-invasive chordoma diagnosis and subtyping. This work may transform chordoma treatment decision-making by guiding surgical planning in advance to match resection aggressiveness with patient prognosis.

Background Investigation of the venous system surrounding a tumor that is invading a dural sinus is of great use for guiding the surgical excision. Non-invasive imaging is often inadequate since enhancement of the tumor causes it to blend with the contrast of the venous vascular structures. Conventional two-dimensional angiography is also often insufficient. Objective The objective of this study was to report regarding the potential of three-dimensional digital subtracted computed tomography angiography (3D DS-CTA) as a technique to preoperatively explore these tumors. Methods We retrospectively studied the radiological and surgical features of patients explored with 3D DS-CTA for a tumor invading a major dural sinus. Results Three patients were included in this study, one hemangiopericytoma and two meningiomas. 3D DS-CTA allows for accurate assessment of the patency of the sinus, the location of the secondary intra- and trans-osseous venous outlets, and surgical guidance by neuronavigation. Conclusion 3D DS-CTA could be a promising guiding and diagnostic tool for the pre- and intraoperative treatment of vascular tumors invading the dural sinuses, for which the venous morbidity and mortality is substantial.

Background Lateral sinus stenosis is a little-known cause for pulsatile tinnitus (PT). In several small series, stenting has been described as an effective treatment for disabling PT linked with this type of stenosis. Objectives To describe the clinical, radiological, and manometric characteristics of patients treated for disabling PT by lateral sinus stenosis. Assessment of the efficacy of stenting for this indication. Methods Retrospective study of patients treated for isolated PT by stenting of a lateral sinus stenosis in our institution, between 2009 and 2015. Results Fourteen patients were included in our study. All of them were women. The median age at the onset of symptoms was 39.0 (21.0) years. The median body mass index was 28.5 (7.0) kg/m 2 . Stenting of the lateral sinus led to the disappearance of PT without recurrence in 13 patients. In one patient, stenting did not modify the noise. In this case, another cause of PT was diagnosed after stent placement. Conclusion Lateral sinus stenosis is a curable cause of venous PT. Other causes of PT must be ruled out before an endovascular treatment is undertaken, due to the frequent asymptomatic nature of Pacchioni granulations in the lateral sinus. Treatment by stenting is effective in all cases, provided that stenosis underlies the PT.

Surgical treatment of lesions involving the ventral craniovertebral junction (CVJ) and the lower clivus, traditionally involved complex lateral or transoral approaches to the skull base. However, mid or upper clivus involvement requires more extensive lateral approaches. Recently, the endoscopic endonasal approach (EEA) has become the standard for upper CVJ lesions and medial clival, and a valuable alternative for those tumors extending in its upper third as well as laterally. However, the EEA is associated with an increased risk of post-operative CSF leakage and infection when the tumor is characterized by an intradural extension. Furthermore, whenever the tumor has significant lateral and/or inferior extension below the odontoid process, the chances for a complete resection decrease. To analyze the extent of exposure of a hybrid microscopic-endoscopic transcondylar antero-lateral approach to the CVJ and clival region, and to verify its effectiveness in terms of mid and upper clival access. Five silicone-injected cadaver heads were used. Following a standard antero-lateral approach, condylectomy and jugular tubercle drilling were performed, after which angled endoscopes were utilized to extend the bone resection to the clivus. A volumetric assessment of the amount of clival removal was carried out. A case of CVJ chordoma operated through this approach is presented. The hybrid antero-lateral transcondylar approach provides adequate exposure of the ventral CVJ, up to the dorsum sellae and the sphenoid sinus, the contralateral petrous apex, and the contralateral paraclival internal carotid artery (ICA). Approximately 60% of the total clival volume can be removed with this approach. The main limitation is the limited visualization of the ipsilateral paraclival ICA and petrous apex. The hybrid antero-lateral transcondylar approach is a valuable surgical option for CVJ tumor extending from C2 to the mid and upper clivus.

OBJECTIVE The anteromedial triangle (AMT) is the triangle formed by the ophthalmic (V1) and maxillary (V2) nerves. Opening of this bony space offers a limited access to the sphenoid sinus (SphS). This study aims to demonstrate the utility of the orbitopterygopalatine corridor (OPC), obtained by enlarging the AMT and transposing the contents of the pterygopalatine fossa (PPF) and V2, as an entrance to the SphS, maxillary sinus (MaxS), and nasal cavity. METHODS Five formalin-injected cadaveric specimens were used for this study (10 approaches). A classic pterional approach was performed. An OPC was created through the inferior orbital fissure, between the orbit and the PPF, by transposing the PPF inferiorly. The extent of the OPC was measured using neuronavigation and manual measurements. Two illustrative cases using the OPC to access skull base tumors are presented in the body of the article. RESULTS Via the OPC, the SphS, MaxS, ethmoid sinus (EthS), and nasal cavity could be accessed. The use of endoscopic assistance through the OPC achieved better visualization of the EthS, SphS, MaxS, clivus, and nasal cavity. A significant gain in the area of exposure could be achieved using the OPC compared to the AMT (22.4 mm2 vs 504.1 mm2). CONCLUSIONS Opening of the AMT and transposition of V2 and the contents of the PPF creates the OPC, a potentially useful deep keyhole to access the paranasal sinuses and clival region through a middle fossa approach. It is a valuable alternative approach to reach deep-seated skull base lesions infiltrating the cavernous sinus and middle cranial fossa and extending into the paranasal sinus.

The 2017 World Health Organization classification of pituitary tumors redefined pituitary null cell adenomas (NCAs) by restricting this diagnostic category to pituitary tumors that are negative for pituitary transcription factors and adenohypophyseal hormones. The clinical behavior of this redefined entity has not been widely studied, and this is a major shortcoming of the classification. This study evaluated the imaging and clinical features of NCAs from two pituitary centers and compared them with those of gonadotroph adenomas (GAs). Imaging, pathologic, and clinical characteristics of NCAs and GAs were retrospectively reviewed. Tumor immunohistochemistry was performed to confirm absence of adenohypophyseal hormones and pituitary transcription factor expression. Thirty-one NCAs were compared with 38 GAs. NCAs were more likely to invade the cavernous sinus (15/31 [48%] vs. 5/38 [13%], P = .003) and had a higher proliferative index (i.e., MIB-1 > 3%, 11/31 [35%] vs. 5/38 [13%], P = .04). Gross total resection was less likely in the NCA group (19/31 [61%] vs. 33/38 [87], P = .02). Progression-free survival was worse in the NCA cohort (5-year progression-free survival, 0.70 vs. 1.00; P = .011, by log-rank test). Compared with GAs, NCAs are more invasive at the time of presentation and have a more aggressive clinical course. This study provides evidence that NCAs represent a distinct clinicopathologic entity with behavior that differs adversely from that of GAs. This may inform clinical decision-making, including frequency of postoperative tumor surveillance and timing of adjunctive treatments.

Background: Over the past decade, stenting of lateral sinus stenosis has been used to treat idiopathic intracranial hypertension. Two types of stenoses have been identified: extrinsic and intrinsic. Objective: The aim of this study was to report the results of our use of this procedure to treat patients with extrinsic or intrinsic stenoses in idiopathic intracranial hypertension. Methods: We retrospectively studied clinical, radiological, and manometric data from patients with idiopathic intracranial hypertension who were treated at our institution between January 2009 and January 2015 by stenting of the lateral sinus. Results: Data were studied from 19 women and 2 men. Average body mass index was 29 kg/m 2 , and the median age at stenting was 33 years. Patients with extrinsic stenoses were younger than those with intrinsic stenoses. Transstenotic gradients measured with patients under general anesthesia were lower than those measured with patients under local anesthesia. In all cases, stenting was effective for papilledema and pulsatile tinnitus. Seventeen patients reporting headaches found that they disappeared completely after stenting. Two complications without long-term effects were reported. Conclusion: Irrespective of the type of stenosis, stenting of lateral sinus stenoses is an effective treatment for intracranial hypertension symptoms. At our institution, this treatment has replaced draining of cerebrospinal fluid when treatment with acetazolamide has proved to be ineffective.

The relationship between increased meningioma incidence and growth and long-term hormonal therapy with cyproterone acetate (CPA) in women has been recently established in literature. Following the raise in awareness from hormonal treatment, we describe a potential relationship between the progesterone agonist nomegestrol acetate (NOMAC) and meningioma growth. After implementation of a screening protocol to detect potential interactions between hormonal exposure and occurrence of meningioma, we identified patients taking NOMAC and newly diagnosed with a meningioma. NOMAC was stopped and those patients were followed tightly both clinically and radiologically. Retrospective volumetric analysis of the tumors was performed on the imaging. Three patients were identified for the study. After cessation of the NOMAC, tumor shrinkage was documented for all meningiomas within the first month. Up to 70% of tumor volume reduction was observed during the first year of follow-up in one of them. None of the patients developed new symptoms. We report the first cases of meningiomas responsiveness to discontinuation of hormonal therapy with NOMAC. Similarly to cases associated with long-term CPA intake, tumor reduction, and improvement of clinical symptoms can be observed after cessation of NOMAC.

Endoscopic techniques in neurosurgery have allowed an increasing number of skull base lesions to be treated through more limited exposures. In this chapter, we review the surgical anatomy of the craniocervical region and discuss the more recent advances in endoscopic endonasal and transcranial techniques as applied to lesions in this location. We will focus on the surgical treatment of chordomas, as these are the archetypal lesions encountered in this location.

International audience; BACKGROUND:Preoperative interpretation of resectability of diffuse nonenhancing glioma is primarily based on individual surgical expertise.OBJECTIVE:To compare the accuracy and precision between observed resections and preoperative estimates of neurosurgeons and a resection probability map (RPM). We hypothesize that the RPM estimates is as good as senior neurosurgeons.METHODS:A total of 234 consecutive patients were included from 2 centers, who had resective surgery with functional mapping between 2006 and 2012 for a supra-tentorial nonenhancing glioma. Extent of resection (EOR) and residual tumor volume (RTV) were segmented and an RPM was constructed in standard brain space. Three junior and three senior neurosurgeons estimated EOR and RTV, blinded for postoperative results. We determined the agreement between the estimates and calculated the diagnostic accuracy of the neurosurgeons and the RPM to predict the observed resections.RESULTS:Preoperative estimates of resection results by junior and senior neurosurgeons were significantly biased towards overestimation of EOR (4.2% and 11.2%) and underestimation of RTV (4.3 and 9.0 mL), whereas estimates of the RPM were unbiased (-2.6% and -.2 mL, respectively). The limits of agreement were wide for neurosurgeons and for the RPM. The RPM was significantly more accurate in identifying patients in whom an EOR >40% was observed than neurosurgeons.CONCLUSION:Neurosurgeons estimate preoperative resectability before surgery of a nonenhancing glioma rather accurate-with a small bias-and imprecise-with wide limits of agreement. An RPM provides unbiased resectability estimates, which can be useful for surgical decision-making, planning, and education.

Introduction: Chronic myelomonocytic leukaemia (CMML) is a clonal hematopoietic stem cell disorder characterized by the presence of an absolute monocytosis in the peripheral blood (>1 x 109/L) and the presence of myelodysplastic and myeloproliferative features in the bone marrow. Involvement of the central nervous system (CNS) is uncommon in CMML.Areas covered: Herein described is a case report of a CMML patient who presents with symptomatic chronic subdural collection overlying a haemorrhagic brain lesion, along with diffuse dural infiltration, after two cycles of azacytidine. Surgical intervention was performed to alleviate the mass effect on the brain, and obtain a tissue sample for diagnosis. Histopathological report confirmed brain infiltration with myeloid leukemic cells.Expert commentary: Despite its rarity, cerebral dissemination should be considered even in patients with CMML. A multidisciplinary approach, lead by a hematologist, is mandatory in order to correct the underlying haematological disorder, with specific attention to the coagulation profile. Surgical intervention is necessary for symptomatic patients, and should be performed once an improvement of clinical conditions has been achieved. Despite appropriate surgical and medical therapy, the prognosis remains poor with high risk of perioperative complications, such as rebleeding, and progressive systemic involvement.

The relationship between meningiomas and exogenous sex hormones is well known, but cyproterone acetate (CA), a progesterone agonist, seems to have a stronger influence on tumor growth. To show the close relationship between CA treatment and meningioma growth. Since 2010, all patients referred to our clinic for a suspicion of meningioma were questioned specifically about exogenous sex hormone intake and more specifically about CA intake. Twelve patients harboring one or multiple meningiomas and treated with CA were identified. CA was stopped in all cases. Tumor volumes and diameters were measured on serial MRIs and compared to the last MRI before CA withdrawal. Ten patients with multiple tumors had been taking the drug for a longer period of time (mean of 20.4 years) than the two patients with one tumor (10 years). Two patients with multiple tumors underwent surgery because of rapidly decreased visual acuity at the time of diagnosis. Discontinuation of CA led to tumor shrinkage in 11 patients and a stop in tumor growth in one [mean tumor volume reduction was around 10 cm3/year; range (0.00; 76)]. There was no regrowth during a mean follow-up period of 12 months (range: 5–35). For patients diagnosed with a meningioma and treated with CA, medication withdrawal followed by observation should be the first line of treatment. Care should be taken with long-term use of high doses of CA, and serial brain MRIs should be considered after several years of CA.

Les malformations arterioveineuses (MAV) cerebrales et les fistules durales arterioveineuses intracrâniennes sont des causes classiques d’hemorragie cerebrale. Elles peuvent egalement se manifester par une epilepsie, et surtout pour les fistules durales, par un oedeme cerebral par hyperpression veineuse. Ces complications peuvent entrainer des symptomes neurologiques necessitant une prise en charge du patient en reanimation. Les imageries non invasives, et notamment l’IRM cerebrale, permettent le plus souvent de poser ou de suspecter le diagnostic, mais l’arteriographie conventionnelle est toujours indispensable pour le confirmer et evaluer les possibilites therapeutiques. Certaines formes oedemateuses de fistules durales sont de diagnostic difficile et peuvent faire suspecter une pathologie inflammatoire du systeme nerveux central. En cas de doute, la realisation d’une arteriographie doit preceder la realisation de la ponction lombaire. La soustraction de liquide cephalorachidien peut en effet decompenser le drainage veineux de la fistule et aggraver les symptomes du patient, et la ponction peut provoquer une hemorragie intracanalaire par perforation d’une veine de drainage perimedullaire. Une fois le diagnostic de MAV ou de fistule durale pose, la prise en charge du patient est multidisciplinaire, et les decisions therapeutiques sont prises collegialement entre neuroradiologues interventionnels, neurochirurgiens et neuroreanimateurs. L’embolisation par voie endovasculaire est le plus souvent le traitement de premiere intention de ces pathologies. Elle doit etre realisee dans les 24 heures pour les fistules durales intracrâniennes. Elle est habituellement realisee de facon differee pour les malformations arterioveineuses. L’intervention endovasculaire ne doit pas retarder une chirurgie urgente de decompression (evacuation d’hematome, derivation de liquide cephalorachidien…).

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.