The Use of the Suboccipital Transtentorial Approach to the Posterior Inferior Incisural Space.

Objective To describe our experience with the microsurgical technique of the suboccipital transtentorial (SOTT) approach in the removal of posterior fossa lesions located in the posterior incisural space. Method Between 2002 and 2020 we reviewed all patients who underwent microsurgical resection of lesions of the posterior incisural space at the Department of Neurosurgery, Essex Neuroscience Centre, London, England (eight patients, male to female 3:5, mean age: 51, range 35-69). We describe the preoperative symptoms, radiological findings, surgical techniques, histology and postoperative outcomes in this cohort of patients. Results Eight patients with tumours located in the posterior incisural space underwent surgery during the study period including four meningiomas (50%), two haemangioblastomas (25%), one metastasis (13%) and one giant prolactinoma (13%). Gross or near total resection was achieved in six patients (75%): the giant prolactinoma could not be radically removed and one of the meningiomas required a small fragment to be left in place to protect the Vein of Galen. No patient developed a visual field deficit due to occipital lobe retraction. One patient developed a temporary trochlear nerve palsy (13%). Five patients had mild disability (Glasgow Outcome Scale (GOS) = 5), and four had moderate disability (GOS = 4). Conclusion In our series, the SOTT approach provided excellent access for all cases of tumours in the posterior incisural space. The tumour's size and relationship to the deep venous system contributed to the choice of approach and in one patient who had previously undergone surgery via the supracerebellar route, the SOTT approach enabled the avoidance of gliotic scar tissue. Success is dependent on careful case selection, though from our series of 8 patients, we conclude that this approach allows safe access to the posterior incisural space, with acceptable outcomes with regard to postoperative disability and cranial nerve palsy. As such, the approach should be in the armamentarium of any neurosurgeon who regularly deals with posterior fossa pathology.

The management of symptomatic hyperostotic bilateral spheno-orbital meningiomas: patient series.

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.

The value of repeated lumbar puncture to test for xanthochromia, in patients with clinical suspicion of subarachnoid haemorrhage, with CT-negative and initial traumatic tap.

OBJECTIVES: For the diagnosis of subarachnoid haemorrhage (SAH), the presence of cerebrospinal fluid (CSF) xanthochromia is still considered the gold standard for patients with a thunderclap headache, in the absence of blood on brain CT scan. However, a traumatic lumbar puncture (LP) typically results in high concentrations of oxyhaemoglobin in CSF, impairing the detection of xanthochromia and preventing the reliable exclusion of SAH. In this context, the value of a repeat lumbar puncture has not yet been described. MATERIALS AND METHODS: A retrospective case series of suspected SAH patients, with a negative CT scan and initial traumatic LP, managed with a repeat LP to assess for CSF xanthochromia. Clinical notes, laboratory and imaging results were reviewed. RESULTS: Between August 2011 and January 2020, 31 patients with suspected SAH were referred to our neurosurgical unit following negative CT and traumatic LP. A repeat LP was performed in 7 of the 31 patients, 2.4 days (±0.79 SD) after the first traumatic LP. CSF spectrophotometry analysis from repeated LP in all 7 patients was negative for xanthochromia. No adverse clinical events were recorded on average 18 months following discharge. CONCLUSION: A repeat LP performed following a traumatic tap can still yield xanthochromia-negative CSF, thereby, excluding SAH, avoiding unnecessary invasive angiography and overall promoting the safer management of these patients.

CSF-diverting shunts: Implications for abdominal and pelvic surgeons; a review and pragmatic overview.

The optimal management of patients with ventriculoperitoneal or lumboperitoneal shunts undergoing abdominal or pelvic surgery for unrelated reasons is often unclear due to the paucity of guidelines in this field. In this review, we outline key issues in managing these patients. Specifically, we address issues relating to pre-operative planning, avoidance of shunt-related complications such as infection and malfunction, and specific management of neurological symptoms in the post-operative period. A retrospective study was carried out analysing correspondence between general surgeons and a specialist hydrocephalus unit over a 4-year period relating to management of patients with ventriculoperitoneal and lumboperitoneal shunts undergoing abdominal or pelvic surgery. A literature review was carried out to identify available evidence in this field. 30 queries from general surgeons were identified comprising 12 main themes. 16 relevant publications were identified. We summarised these to answer these queries. The management of shunted patients may present challenges and uncertainties in an abdominal or pelvic surgery setting. This paper provides guidelines and clarity in this field by discussing and summarising reported data in the literature.

Intraoperative neurophysiological monitoring in paediatric Chiari surgery-help or hindrance?

INTRODUCTION: The role of intraoperative neurophysiological monitoring (IONM) during surgery for Chiari I malformation has not been fully elucidated. Questions remain regarding its utility as an adjunct to foramen magnum decompression surgery, specifically, does IONM improve the safety profile of foramen magnum decompression surgery and can IONM parameters help in intraoperative surgical decision-making. This study aimed to describe a single institution experience of IOM during paediatric Chiari I surgery. METHODS: The methodology comprised a retrospective review of prospectively collected electronic neurosurgical departmental operative database. Inclusion criteria were children under 16 years of age who had undergone foramen magnum decompression for Chiari I malformation with IONM. In addition to basic demographic data, details pertaining to presenting features and post-operative outcomes were obtained. These included primary symptoms of Chiari I malformation and indications for surgery. MRI findings, including the presence of syringomyelia on pre-and post-operative imaging, were reviewed. Details of the surgical technique for each patient were recorded. Only patients with either serial brainstem auditory evoked potential (BAEP) and/or upper limb somatosensory evoked potential (SSEP) recordings were included. Two time points were used for the purposes of analysing IONM data; initial baseline before skin incision and final at the time of skin closure. RESULTS: Thirty-seven children underwent foramen magnum decompression (FMD) with IONM. Mean age was 10.5 years (range 1-16 years) with a male:female ratio 13:24. The commonest clinical features on presentation included headaches (15) and scoliosis (13). Twenty-four patients had evidence of associated syringomyelia (24/37 = 64.9%). A reduction in the SSEP latency was observed in all patients. SSEP amplitude was more variable, with a decrease seen in 18 patients and an increase observed in 12 patients. BAEP recordings decreased in 13 patients and increased in 4 patients. There were no adverse neurological events following surgery; the primary symptom was resolved or improved in all patients at 3-month follow-up. Resolution or improvement in syringomyelia was observed in 19/24 cases. CONCLUSIONS: Our data shows that FMD for Chiari malformation (CM) is associated with changes in SSEPs and BAEPs. However, we did not identify a definite link between clinical outcomes and IONM, nor did syrinx outcome correlate with IONM. There may be a role for IONM in CM surgery but more robust data with better-defined parameters are required to further understand the impact of IONM in CM surgery.

Idiopathic intracranial hypertension: 120-day clinical, radiological, and manometric outcomes after stent insertion into the dural venous sinus.

OBJECTIVE Idiopathic intracranial hypertension (IIH) is commonly associated with venous sinus stenosis. In recent years, transvenous dural venous sinus stent (DVSS) insertion has emerged as a potential therapy for resistant cases. However, there remains considerable uncertainty over the safety and efficacy of this procedure, in particular the incidence of intraprocedural and delayed complications and in the longevity of sinus patency, pressure gradient obliteration, and therapeutic clinical outcome. The aim of this study was to determine clinical, radiological, and manometric outcomes at 3-4 months after DVSS in this treated IIH cohort. METHODS Clinical, radiographic, and manometric data before and 3-4 months after DVSS were reviewed in this single-center case series. All venographic and manometric procedures were performed under local anesthesia with the patient supine. RESULTS Forty-one patients underwent DVSS venography/manometry within 120 days. Sinus pressure reduction of between 11 and 15 mm Hg was achieved 3-4 months after DVSS compared with pre-stent baseline, regardless of whether the procedure was primary or secondary (after shunt surgery). Radiographic obliteration of anatomical stenosis correlating with reduction in pressure gradients was observed. The complication rate after DVSS was 4.9% and stent survival was 87.8% at 120 days. At least 20% of patients developed restenosis following DVSS and only 63.3% demonstrated an improvement or resolution of papilledema. CONCLUSIONS Reduced venous sinus pressures were observed at 120 days after the procedure. DVSS showed lower complication rates than shunts, but the clinical outcome data were less convincing. To definitively compare the outcomes between DVSS and shunts in IIH, a randomized prospective study is needed.

Intraparenchymal intracranial pressure monitoring for hydrocephalus and cerebrospinal fluid disorders.

BACKGROUND: Elective intraparenchymal intracranial pressure (ICP) monitoring is useful for the diagnosis and treatment of hydrocephalus and cerebrospinal fluid (CSF) disorders. This retrospective study analyzes median ICP and pulse amplitude (PA) recordings in neurosurgically naïve patients undergoing elective ICP monitoring for suspected CSF disorders. METHODS: Retrospective review of prospectively collated database of neurosurgically naïve patients undergoing elective ICP monitoring for suspected hydrocephalus and CSF disorders. Following extraction of the median ICP and PA values (separated into all, day and night time recordings), principal component analysis (PCA) was performed to identify the principal factors determining the spread of the data. Exploratory comparisons and correlations of ICP and PA values were explored, including by post hoc diagnostic groupings and age. RESULTS: A total of 198 patients were identified in six distinct diagnostic groups (n = 21-47 in each). The PCA suggested that there were two main factors accounting for the spread in the data, with 61.4% of the variance determined largely by the PA and 33.0% by the ICP recordings. Exploratory comparisons of PA and ICP between the diagnostic groups showed significant differences between the groups. Specifically, significant differences were observed in PA between a group managed conservatively and the Chiari/syrinx, IIH, and NPH/LOVA groups and in the ICP between the conservatively managed group and high-pressure, IIH, and low-pressure groups. Correlations between ICP and PA revealed some interesting trends in the different diagnostic groups and correlations between ICP, PA, and age revealed a decreasing ICP and increasing PA with age. CONCLUSIONS: This study provides insights into hydrodynamic disturbances in different diagnostic groups of patients with CSF hydrodynamic disorders. It highlights the utility of analyzing both median PA and ICP recordings, stratified into day and night time recordings.

Effect of venous stenting on intracranial pressure in idiopathic intracranial hypertension.

BACKGROUND: Idiopathic intracranial hypertension (IIH) is characterised by an increased intracranial pressure (ICP) in the absence of any central nervous system disease or structural abnormality and by normal CSF composition. Management becomes complicated once surgical intervention is required. Venous sinus stenosis has been suggested as a possible aetiology for IIH. Venous sinus stenting has emerged as a possible interventional option. Evidence for venous sinus stenting is based on elimination of the venous pressure gradient and clinical response. There have been no studies demonstrating the immediate effect of venous stenting on ICP. METHODS: Patients with a potential or already known diagnosis of IIH were investigated according to departmental protocol. ICP monitoring was performed for 24 h. When high pressures were confirmed, CT venogram and catheter venography were performed to look for venous stenosis to demonstrate a pressure gradient. If positive, venous stenting would be performed and ICP monitoring would continue for a further 24 h after deployment of the venous stent. RESULTS: Ten patients underwent venous sinus stenting with concomitant ICP monitoring. Nine out of ten patients displayed an immediate reduction in their ICP that was maintained at 24 h. The average reduction in mean ICP and pulsatility was significant (p = 0.003). Six out of ten patients reported a symptomatic improvement within the first 2 weeks. CONCLUSIONS: Venous sinus stenting results in an immediate reduction in ICP. This physiological response to venous stenting has not previously been reported. Venous stenting could offer an alternative treatment option in correctly selected patients with IIH.

Proton beam therapy in the management of skull base chordomas: systematic review of indications, outcomes, and implications for neurosurgeons.

BACKGROUND: Chordomas are rare tumours affecting the skull base. There is currently no clear consensus on the post-surgical radiation treatments that should be used after maximal tumour resection. However, high-dose proton beam therapy is an accepted option for post-operative radiotherapy to maximise local control, and in the UK, National Health Service approval for funding abroad is granted for specific patient criteria. OBJECTIVES: To review the indications and efficacy of proton beam therapy in the management of skull base chordomas. The primary outcome measure for review was the efficacy of proton beam therapy in the prevention of local occurrence. METHODS: A systematic review of English and non-English articles using MEDLINE (1946-present) and EMBASE (1974-present) databases was performed. Additional studies were reviewed when referenced in other studies and not available on these databases. Search terms included chordoma or chordomas. The PRISMA guidelines were followed for reporting our findings as a systematic review. RESULTS: A total of 76 articles met the inclusion and exclusion criteria for this review. Limitations included the lack of documentation of the extent of primary surgery, tumour size, and lack of standardised outcome measures. Level IIb/III evidence suggests proton beam therapy given post operatively for skull base chordomas results in better survival with less damage to surrounding tissue. CONCLUSIONS: Proton beam therapy is a grade B/C recommended treatment modality for post-operative radiation therapy to skull base chordomas. In comparison to other treatment modalities long-term local control and survival is probably improved with proton beam therapy. Further, studies are required to directly compare proton beam therapy to other treatment modalities in selected patients.

Improving neurosurgical communication and reducing risk and registrar burden using a novel online database referral platform.

OBJECTIVES: Documentation of urgent referrals to neurosurgical units and communication with referring hospitals is critical for effective handover and appropriate continuity of care within a tertiary service. Referrals to our neurosurgical unit were audited and we found that the majority of referrals were not documented and this led to more calls to the on-call neurosurgery registrar regarding old referrals. We implemented a new referral system in an attempt to improve documentation of referrals, communication with our referring hospitals and to professionalise the service we offer them. METHODS: During a 14-day period, number of bleeps, missed bleeps, calls discussing new referrals and previously processed referrals were recorded. Whether new referrals were appropriately documented and referrers received a written response was also recorded. A commercially provided secure cloud-based data archiving telecommunications and database platform for referrals was subsequently introduced within the Trust and the questionnaire repeated during another 14-day period 1 year after implementation. RESULTS: Missed bleeps per day reduced from 16% (SD ± 6.4%) to 9% (SD ± 4.8%; df = 13, paired t-tests p = 0.007) and mean calls per day clarifying previous referrals reduced from 10 (SD ± 4) to 5 (SD ± 3.5; df = 13, p = 0.003). Documentation of new referrals increased from 43% (74/174) to 85% (181/210), and responses to referrals increased from 74% to 98%. CONCLUSION: The use of a secure cloud-based data archiving telecommunications and database platform significantly increased the documentation of new referrals. This led to fewer missed bleeps and fewer calls about old referrals for the on call registrar. This system of documenting referrals results in improved continuity of care for neurosurgical patients, a significant reduction in risk for Trusts and a more efficient use of Registrar time.

Surgically managed idiopathic intracranial hypertension in adults: a single centre experience.

INTRODUCTION: Idiopathic intracranial hypertension (IIH) is a rare condition that is often managed conservatively. In patients with aggressive progression of the disease surgical options are considered. There are few data on the outcomes of these patients when surgically managed. We describe our experience of surgically managed IIH and the outcomes of these patients, in particular the surgical revision rate and interventions required for resolution of symptoms. METHODS: A retrospective review of all patient files coded with benign intracranial hypertension, idiopathic intracranial hypertension or pseudotumour cerebri was undertaken. Files were searched with the date of diagnosis and the date these patients were referred for surgical intervention. The surgical interventions and complications were then documented and note was made of the number of inpatient admissions and days spent in hospital. RESULTS: From 2000-2013, 79 patients were identified as patients with IIH that had required surgical intervention; 52 % required further surgical intervention. The average number of surgical interventions was 5.6. For patients requiring further intervention the average number of surgical interventions was 8.6. On average patients with IIH also spent 42 inpatient days in neurosurgical beds, whilst those patients who required further intervention spent 63 days on average in neurosurgical beds. The length of the average individual admission was longer for patients requiring repeated surgical interventions. CONCLUSION: Based on our experience, patients that require surgical management of IIH frequently require further surgical interventions to control symptoms and manage complications of CSF diversion surgery. Those that require such further intervention on average will have six further operations and spend significantly longer in hospital. Lumboperitoneal (LP) shunting is an effective first line surgical intervention for 52 % of our patient cohort. This sub-group of patients therefore requires specialist neurosurgical input for this long-term and challenging pathological process.

Evaluation of the impact of the Canadian subarachnoid haemorrhage clinical decision rules on British practice.

INTRODUCTION: Acute headache is among the commonest presenting complaints to emergency departments. While it is estimated that only 1-3% result from subarachnoid haemorrhage (SAH), because the disease carries such significant morbidity and mortality if missed, most clinicians have a low threshold for investigation. A recent prospective cohort study in Canada determined a number of high-risk clinical characteristics for SAH in patients with acute headache. We investigated the potential impact of incorporating the Canadian clinical decision rules on British practice. METHODS: A retrospective case note review on all adult patients presenting to our emergency department with acute headache between August and October 2011 was conducted. The Canadian decision rules for SAH were applied retrospectively to the cases identified, and the sensitivity, specificity and negative predictive values calculated. The two-tailed McNemar test was used to evaluate differences between proportions of patients undergoing investigations using the clinical decision rules against current practice. RESULTS: In all, 112 patients met the inclusion criteria in a 3-month period, of which 41 patients (36.6%) underwent unenhanced computed tomography and 4 (3.6%) were found to have SAH. Nine patients subsequently had a lumbar puncture and none demonstrated xanthochromia. None of the patients who were not fully investigated were readmitted to the regional neurosurgical centre within 6 months of discharge with missed SAH. Application of the Canadian clinical decision rules would have led to an investigation rate between 59% and 74%, compared to an actual rate of 37% (p < 0.05). CONCLUSION: The present study shows that application of the Canadian clinical decision rules for SAH would lead to more patients with acute headache being investigated than current British practice. However, much larger prospective studies are required to determine whether such clinical decision rules may identify patients at risk who would otherwise have been missed.

The dilemma of an incidental preoperative electrocardiogram showing a Brugada phenotype.

A Brugada pattern on routine electrocardiography is one of several features that can indicate the potential for life threatening rhythm disturbances. The authors describe such a scenario in an asymptomatic 38-year-old woman who required significant surgery under anaesthesia. The diagnosis and possible management routes are outlined with an emphasis on the incumbent psychosocial and familial issues that are encountered. The patient underwent her surgery and was then further investigated to 'prove' the diagnosis. Ultimately, the patient declined further investigations and interventions. This case highlights the dilemma faced by anaesthetists and clinicians, not to mention the patients and their family when a Brugada phenotype is identified on a routine ECG. Clinicians should seek an expert opinion but ultimately, as in this case, the patient should be positioned to make an informed decision on what route to follow.