Abstract Introduction Post-operative cerebral venous sinus thrombosis (CVST) is increasingly recognised after lateral skull-base surgery. When centres use routine early venography, asymptomatic thrombi are commonly detected; clinically symptomatic events are less frequent. A single-centre experience applying a sinus-sparing strategy (Bill’s Island during TL exposure, avoidance of fixed venous-sinus retraction in all cases) with selective lumbar drainage (LD) reports observed CVST rates with selective venography. Methods Retrospective cohort of 54 consecutive vestibular schwannoma resections (translabyrinthine [TL] or retrosigmoid [RS]) at a tertiary neurosurgical centre from February 2016 to December 2023. Venography was selective, using CT venography (CTV) for clinical triggers. The primary outcome was clinical CVST, defined as symptomatic CVST with imaging confirmation. Secondary outcomes were radiological CVST detected under selective venography, longitudinal functional outcomes measured by the Modified Rankin Scale (mRS) and Barthel Index (BI), cerebrospinal-fluid (CSF) complications, lumbar-drain use, and other postoperative events. Functional outcomes were assessed at 3, 6, 12 and 24 months. Results Clinical CVST was 0/54 (one-sided 95% upper confidence limit 5.40%). Post-operative CTV was performed selectively in 15/54 patients (27.8%) at a median of postoperative day 2. Radiological CVST occurred in 1/15 (6.7%) among those imaged; this corresponded to 1 event in the full cohort (1/54, 1.9%; 95% CI 0.047%–9.89%), although this should not be interpreted as the true radiological incidence because venography was selective rather than protocolised. The single radiological CVST arose adjacent to a minor intra-operative sigmoid-sinus wall injury, was asymptomatic, and occurred in a case without prophylactic LD; anticoagulation was not used. Patients who did not undergo venography did not develop symptoms prompting imaging or meet criteria for clinical CVST during the recorded postoperative course. Median mRS improved from 2 (3–6 months) to 1 (12–24 months); BI median was 100 at all time-points. Conclusion In this selective-venography series using a sinus-sparing, retraction-avoiding operative strategy, no clinical CVST and a low rate of radiological thrombosis were observed. Because imaging was selective, the true burden of silent radiological thrombosis cannot be determined from this study. Prospective multicentre studies with protocolised venography and harmonised endpoints are warranted.

Background: Meningiomas arising from the choroid plexus of the foramen of Luschka (CPFOL) without dural attachment are an exceedingly rare subtype of intracranial tumor. They present a significant diagnostic challenge, as their clinical and radiological features can mimic more common pathologies of the cerebellopontine angle (CPA), such as vestibular or lower cranial nerve schwannomas. Case Description: We present the case of a 47-year-old female with a 1-year history of progressive glossopharyngeal neuralgia. Magnetic resonance imaging revealed a homogeneously enhancing lesion in the left CPA. Due to the absence of a dural tail or broad dural base, the lesion was presumptively diagnosed as a lower cranial nerve schwannoma. After documented interval growth, the patient underwent a left retrosigmoid suboccipital craniotomy for tumor resection. Intraoperatively, the tumor was found to originate from the choroid plexus protruding from the foramen of Luschka, with the lower cranial nerves splayed over its capsule. A near-total resection was achieved. Histopathological and molecular analyses confirmed a World Health Organization Grade 1 meningioma with a low-risk integrated molecular profile. The patient experienced a transient, mild postoperative lower cranial nerve palsy that resolved completely. At 12-month follow-up, imaging showed resolution of the small residual tumor, and the patient remained free of her preoperative neuralgic symptoms. Conclusion: CPFOL meningioma is a critical entity in the differential diagnosis of CPA masses, particularly those lacking classic dural-based features. A high index of suspicion, coupled with meticulous interpretation of neuroimaging, is essential for accurate preoperative assessment. This case underscores the importance of considering rare tumor origins to avoid diagnostic pitfalls and highlights the utility of multi-modal intraoperative neuromonitoring in achieving maximal safe resection with excellent functional outcomes.

OBJECTIVE:This study aimed to compare pain outcomes and complication rates between reexploration microvascular decompression (MVD), percutaneous rhizotomy (PR), and stereotactic radiosurgery (SRS) as second-line treatments for recurrent or persistent trigeminal neuralgia (TN) following an initial MVD. METHODS:A systematic review and meta-analysis was performed in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) and MOOSE (Meta-Analysis of Observational Studies in Epidemiology) guidelines. Studies were included if they reported outcomes of reexploration MVD, PR, or SRS in adult patients with classic or idiopathic TN after a failed initial MVD. Primary outcomes included early and long-term pain relief. Secondary outcomes included recurrence, facial numbness, and complications. Random-effects models were used for meta-analyses, and subgroup and sensitivity analyses were conducted. RESULTS:Twenty-seven studies including 886 patients were analyzed (MVD + MVD: 505; MVD + PR: 267; MVD + SRS: 114). Early pain relief rates were similar between the MVD + MVD (83%) and MVD + PR (88%) groups, but lower in the MVD + SRS (76%) group. Long-term pain relief was highest in the MVD + MVD (82%) group, followed by the MVD + PR (68%) and MVD + SRS (67%) groups. New facial numbness occurred most frequently in the MVD + PR (93%) group, compared with the MVD + MVD (29%) and MVD + SRS (12%) groups. Neurolysis during reexploration was associated with significantly improved pain outcomes (OR 4.0, p = 0.00017). No clinical variables significantly predicted early pain relief. CONCLUSIONS:Reexploration MVD provides durable long-term pain relief but carries a risk of complications. PR offers comparable short-term efficacy with higher rates of sensory disturbance but lower surgical morbidity. The benefit of nerve manipulation even in the absence of neurovascular compression highlights the need to better understand the pathophysiology of recurrent TN and supports the necessity for randomized controlled trials to inform treatment algorithms.

Diffuse gliomas are the commonest malignant primary brain tumour in adults. Herein, we present analysis of the genomic landscape of adult glioma, by whole genome sequencing of 403 tumours (256 glioblastoma, 89 astrocytoma, 58 oligodendroglioma; 338 primary, 65 recurrence). We identify an extended catalogue of recurrent coding and non-coding genetic mutations that represents a source for future studies and provides a high-resolution map of structural variants, copy number changes and global genome features including telomere length, mutational signatures and extrachromosomal DNA. Finally, we relate these to clinical outcome. As well as identifying drug targets for treatment of glioma our findings offer the prospect of improving treatment allocation with established targeted therapies.

The emergence of neurosurgery from the practice of cranial surgery between the eighteenth and the twentieth centuries in London, UK, is well documented, including the role of Sir Victor Horsley, the first neurosurgical appointee at the National Hospital Queen Square in 1886. The process of this transition elsewhere in London and the subsequent foundation of other neurosurgical units are less well described. In East London, the status of St. Bartholomew's Hospital (Barts) as the oldest London hospital still active on its original site and its comprehensive archives allow an unusually long history of surgical practice in the specialty to be studied. Using these archives and other primary and secondary sources, this article describes the transition of cranial surgery in East London from the general surgeons, limited to the treatment of brain and skull injury, to the specialized discipline of neurosurgery. We discuss the culmination of this process in the foundation of three neurosurgical units at London Hospital, Whitechapel, by Sir Hugh B. Cairns from 1927; at Barts Hospital, Smithfield, by John E. A. O'Connell from 1937; and at Oldchurch Hospital, Romford, by Leslie C. Oliver from 1945. Two modern neurosurgical units, in Whitechapel and Romford, have taken forward the work begun by this group.

Background Posterior fossa tumors (PFTs) comprise 15%-20% of adult brain tumors, with the reported frequency of hydrocephalus (HCP) ranging between 3.7% and 58%. Most HCP resolves after resection of PFTs, but studies report persistent or new-onset HCP occurring in between 2% and 7% of cases. Preoperative cerebrospinal fluid (CSF) diversion with a ventriculoperitoneal shunt (VPS), external ventricular drain (EVD), or endoscopic third ventriculostomy (ETV) has been shown to improve outcomes. Evidence regarding the efficacy of these techniques is limited.Methods A systematic literature search was performed in line with Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Data points were extracted from individual patient cohort data. A failure rate was determined by the number of patients requiring further postoperative CSF diversion.Results In total, 8863 records were identified. Thirteen studies consisting of 17 patient cohorts met our inclusion criteria. Across all individual cohort studies, 2976 patients underwent surgical resection of a PFT in whom the frequency of hydrocephalus at presentation was 22.98% (1.92%-100%), and persistent hydrocephalus following preoperative CSF diversion was 13.63% (0%-18%). Of the 684 hydrocephalic patients, 83.63% underwent CSF diversion in the form of ETV, EVD, or VPS. Between years 1992 and 2020, 1986 and 2021, and 1981and 2013, the pre-resection ETV, EVD, and VPS failure rates were 14.66% (17/116), 16.26% (60/369), and 0% (0/87), respectively.Conclusions This systematic review highlights that VPS has a better failure rate profile in minimizing postoperative hydrocephalus in adult patients with PFTs.

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Hydrocephalus (HC) is common in patients with vestibular schwannoma (VS). This can be managed with a cerebrospinal fluid (CSF) diversion procedure prior to VS resection or with VS resection, keeping CSF diversion in reserve unless required postoperatively. No clear consensus exists as to which approach is superior. This study identifies factors predictive of the development of HC, and analyses outcomes for those managed with primary CSF resection versus tumour resection. Single-centre retrospective cohort study of 204 consecutive adult patients with a unilateral VS from May 2009 to June 2021. Data was collected on patient and tumour demographics, management, and outcome. 204 patients, with a mean age at presentation of 59.5 (21–83), with 50

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

BACKGROUND The occurrence of hyperostotic bilateral spheno-orbital meningiomas (BSOMs) is very rare. Patients present with bilateral symptoms and require bilateral treatment. This series describes 6 patients presenting to 2 UK neurosurgical units and includes a literature review. To the best of the authors’ knowledge, this is the largest series documented. OBSERVATIONS This is a retrospective review of patients with BSOMs presenting between 2006 and 2023. Six females, whose mean age was 43 (range: 36–64) years, presented with features of visual disturbance. Bilateral sphen-oorbital meningiomas were identified. All patients underwent bilateral staged resections. The patients had an initial improvement in their symptoms. Extensive genetic testing was performed in 4 patients, with no variants in the NF2, LZTR1, SMARCB1, SMARCE1, and SMARCA4 genes or other variants detected. The mean follow-up was 100.3 (range: 64–186) months. Sixty-seven percent of patients had good long-term visual acuity. The progression rate was 75% and was particularly aggressive in 1 patient. Four patients required radiation therapy, and 2 needed further surgery. LESSONS Hyperostotic BSOMs are extensive, challenging tumors causing significant disability. They can recur, with significant patient impact. Multidisciplinary management and indefinite long-term follow-up are essential. The biology of these tumors remains unclear. As molecular testing expands, the understanding of BSOM oncogenesis and potential therapeutic targets is likely to improve.

We report a case of a 61-year-old lady presenting with several weeks of progressive left-sided weakness, and found to have a foramen magnum meningioma. She was counselled on surgical resection of the tumour, and a preoperative computed tomography angiogram (CTA) was obtained for operative planning purposes. CTA demonstrated incidental bilateral internal jugular vein (IJV) stenosis, with enlarged extracranial collateral vessels and elongated styloid processes. The main surgical concern was potential injury of the extracranial collateral vessels during operative exposure, which may compromise her intracranial venous outflow in light of the IJV stenosis. A doppler ultrasound scan of the IJVs was performed, which demonstrated that blood flow was still present through both vessels. Through careful soft tissue dissection during surgery, potential complications and injury to the extracranial collaterals were avoided. We performed a literature review of the incidence of IJV stenosis, its associated conditions, and potential surgical implications. Complications from injury to vital collateral extracranial vessels should be considered during preoperative planning in patients with anatomical variants or risk factors for IJV stenosis, as seen in this case.

Internal jugular vein (IJV) stenosis is being increasingly associated with certain neurological conditions, including benign intracranial hypertension, cerebrospinal fluid (CSF) disorders, multiple sclerosis and Alzheimer's disease. The role of surgery in IJV stenosis have typically been to manage the associated CSF disorders, or with IJV stents. We describe a case of a patient incidentally found to have bilateral possible IJV stenosis with dilated paraspinal collateral venous channels during pre-operative CT angiogram for a symptomatic craniocervical junction meningioma, and the associated operative considerations.

BACKGROUND: CRANIAL (CSF Rhinorrhoea After Endo nasal Intervention to the Skull Base) is a prospective multicenter observational study seeking to determine 1) the scope of skull base repair methods used and 2) corresponding rates of postoperative cerebrospinal fluid (CSF) rhinorrhea in the endonasal transsphenoidal approach (TSA) and the expanded endonasal approach (EEA) for skull base tumors. We sought to pilot the project, assessing the feasibility and acceptability by gathering preliminary data. METHODS: A prospective observational cohort study was piloted at 12 tertiary neurosurgical units in the United Kingdom. Feedback regarding project positives and challenges were qualitatively analyzed. RESULTS: A total of 187 cases were included: 159 TSA (85%) and 28 EEA (15%). The most common diseases included pituitary adenomas (n = 142/187), craniopharyngiomas (n = 13/187). and skull base meningiomas (n = 4/187). The most common skull base repair techniques used were tissue glues (n = 132/187, most commonly Tisseel), grafts (n = 94/187, most commonly fat autograft or Spongostan) and vascularized flaps (n = 51/187, most commonly nasoseptal). These repairs were most frequently supported by nasal packs (n = 125/187) and lumbar drains (n = 20/187). Biochemically confirmed CSF rhinorrhea occurred in 6/159 patients undergoing TSA (3.8%) and 2/28 patients undergoing EEA (7.1%). Four patients undergoing TSA (2.5%) and 2 patients undergoing EEA (7.1%) required operative management for CSF rhinorrhea (CSF diversion or direct repair). Qualitative feedback was largely positive (themes included user-friendly and efficient data collection and strong support from senior team members), demonstrating acceptability. CONCLUSIONS: Our pilot experience highlights the acceptability and feasibility of CRANIAL. There is a precedent for multicenter dissemination of this project, to establish a benchmark of contemporary practice in skull base neurosurgery, particularly with respect to patients u ndergoing EEA.

-BACKGROUND: During the coronavirus disease 2019 (COVID-19) pandemic, concerns have been raised regarding the increased risk of perioperative mortality for patients with COVID-19, and the transmission risk to healthcare workers, especially during endonasal neurosurgical operations. The Pituitary Society has produced recom-mendations to guide management during this era. We sought to assess contemporary neurosurgical practice and the effects of COVID-19. -METHODS: A multicenter prospective observational cohort study was conducted at 12 tertiary neurosurgical -nits (United Kingdom and Ireland). Data were collected from March 23 to July 31, 2020, inclusive. The data points collected included patient demographics, preoperative COVID-19 test results, operative modifications, and 30-day COVID-19 infection rates. -RESULTS: A total of 124 patients were included. Of the 124 patients, 116 (94%) had undergone COVID-19 testing preoperatively (transsphenoidal approach, 97 of 105 [92%]; expanded endoscopic endonasal approach, 19 of 19 [100%]). One patient (1 of 116 [0.9%]) had tested positive for COVID-19 preoperatively, requiring a delay in surgery until the infection had been confirmed as resolved. Other than transient diabetes insipidus, no other complications were reported for this patient. All operating room staff had worn at least level 2 personal protective equipment. Adapta-tions to surgical techniques included minimizing drilling, draping modifications, and the use of a nasal iodine wash. At 30 days postoperatively, no evidence of COVID-19 infection (symptoms or positive formal testing results) were found in our cohort and no mortality had occurred. -CONCLUSIONS: Preoperative screening protocols and operative modifications have facilitated endonasal neuro-surgery during the COVID-19 pandemic, with the Pituitary Society guidelines followed for most of these operations. We found no evidence of COVID-19 infection in our cohort and no mortality, supporting the use of risk mitigation strategies to continue endonasal neurosurgery in subse-quent pandemic waves.

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

BACKGROUND:Cavernous sinus tumours comprise 0.1-0.2% of all intracranial tumours, and are most commonly meningiomas or schwannomas. Central nervous system and cranial nerve granular cell tumours (GCTs) are extremely rare. We report the tenth case of a GCT arising from a cranial nerve, and the second case reported in a cavernous sinus location, and review the literature.CLINICAL PRESENTATION:A 67-year-old man presented with right sided trigeminal neuralgia. Imaging findings suggested a trigeminal schwannoma and he was treated with CyberKnife radiosurgery. Over a period of 41 months follow up, there was a progression in both symptoms and imaging findings, requiring debulking surgery. Histopathology identified a GCT.CONCLUSIONS:This is the first case of a cranial nerve GCT treated with stereotactic radiosurgery. Trigeminal nerve GCTs are a rare differential in cases of presumed schwannomas.

The acquisition of volumetric post-contrast MRI has clear advantages in the interpretation of neuro-oncology studies but has yet to find its way into routine clinical practice beyond planning scans for surgery and radiotherapy. This commentary briefly highlights the benefits of these techniques whilst dispelling some of the perceived disadvantages.

Abstract Background: Giant prolactinomas (GPs) are rare representing 2-3% of prolactinomas and only ~ 0.5% of all pituitary tumors. Various definitions have been proposed for GP but commonly accepted criteria is tumor dimension of ≥4 cm. GP is often associated with very high prolactin (PRL) ranging 1,000 -100,000 ng/ml, significant extrasellar extension and no concomitant growth hormone or ACTH secretion. Patients predominantly present with neurological symptoms rather than endocrine dysfunction, and so the primary goal of treatment is amelioration of neurological symptoms. The literature search reveals approximately 190 papers on this topic and most are single case reports or series describing only unusual clinical manifestations. Hence, evidence based recommendations for treatment are lacking. Dopamine agonist (DA) is considered first line of therapy, as these tumors are highly sensitive to medical therapy. Surgery and radiation may be warranted in special situations. Low starting doses of cabergoline (CAB) are generally recommended due to concern for complications of apoplexy and cerebrospinal fluid (CSF) leak from rapid tumor shrinkage. However, no recommendations for a specific starting dose exist. Objective: Individual tumor and hormonal response were assessed on 15 patients (pts) with GP on low dose CAB; 0.25-0.5 mg weekly to determine the effectiveness of DA therapy. Methods: 15 GP pts from two tertiary care centers, meeting the diagnostic criteria mentioned above, were reviewed. Reduction in tumor volume and maximal tumor diameter along with PRL, after initiation of CAB, at or before 6 months and 1 year post diagnosis, was calculated. Results: Presenting symptom: visual disturbance (56%), headache (20%), apoplexy (13%) and incidental finding (6%). Mean age at diagnosis: 61 years. Male to Female: 4: 1. Basal prolactin concentration: >2000 ng/dl (12/15pts), and > 900 ng/ml (2/15). Initial total CAB dose/week: 0.25-0.5 mg (13/15) and 1-2 mg (2/15). Cranial surgery: 4/15. Complications: CSF leak (1/15). Tumor volume assessed at 6 months (11/15) and 1 year (4/15) along with decrease in maximum tumor diameter in the same period of time. PRL assessed at or before 6 months (13/15) and at 1 year (2/15). Improvement in tumor size occurred promptly even with low dose CAB (0.25-0.5mg/week). 100% of patients initiated on low dose CAB responded to therapy. Mean reduction in tumor volume at or before 6 months was 47% in 11/15, and 52% at 1 year (10/15). Mean decrease in maximal tumor dimension was calculated as 0.95 cm at 6 months (12/15) and 1.4 cm at 1 year (9/15). The overall prolactin response rate at or before 6 months was > 90% in 7/15 patients (53%) and >50% in 11/15 patients (73%). Conclusion: Our data confirms excellent tumor response to low dose cabergoline therapy. Dose as low at 0.25 mg twice weekly is proven to be effective, leading to decrease in both tumor volume and PRL levels.