Aberrant Arterial Anatomy at the Floor of the Third Ventricle: Video Case Report

A 65-year-old woman presented with a 2-month progressive history of forgetfulness, headaches, and decline in mobility. Imaging showed a large, enhancing pineal region tumor with triventricular hydrocephalus. She underwent an endoscopic third ventriculostomy and biopsy after appropriate consent was gained. Video 1 demonstrates the endoscopic procedure during which 2 aberrant arteries were identified at the floor of the third ventricle. The endoscopic third ventriculostomy was performed between these 2 arteries with great care to preserve them. The patient improved postoperatively with resolution of the hydrocephalus. Histology showed a metastatic malignant melanoma. To the best of our knowledge, no similar anatomy has been shown in an endoscopic procedure. We speculate that these are perforating arteries from the posterior communicating artery (premamillary artery) or a branch from the first part of the posterior cerebral artery P1 (thalamoperforators). Other options include perforators from the ophthalmic segment of the internal carotid artery, the communicating segment of the internal carotid artery, the superior hypophyseal artery, or a branch of the medial posterior choroidal arteries. We look at each in turn.

Hydrocephalus in patients with vestibular schwannoma

BACKGROUND

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.

METHODS

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.

RESULTS

204 patients, with a mean age at presentation of 59.5 (21-83), with 50% female, and a mean follow-up of 7.5 years (1.8-13.9) were included. 119 were managed conservatively, 36 with stereotactic radiosurgery only, and 49 with surgery. 30 (15%) patients had radiological HC, of which 23 (77%) were obstructive, and 7 (23%) were communicating. Maximum intracranial tumour diameter and Koos grade were higher in patients with HC. Of the patients with HC the majority (20, 67%) were managed initially with CSF diversion, with 12 patients undergoing subsequent tumour resection, and three patients avoiding primary resection. Nine (30%) were managed with primary surgical resection, of whom three required subsequent CSF diversion. Complication rates and Modified Rankin Scale (MRS) were comparable or lower in the CSF diversion group (8%, MRS ≤2 = 83%), versus the primary resection group (67%, MRS ≤2 = 67%), and the primary surgical resection without HC group (25%, MRS ≤2 = 86%).

CONCLUSIONS

CSF diversion prior to tumour resection is a safe and acceptable strategy compared to primary VS resection, with improved outcomes and reduced surgical complications. Randomized studies and national databases are needed to determine the long-term outcomes of patients treated with CSF diversion versus primary resection.

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.

Long-Term Outcomes of the Electrically Unresponsive, Anatomically Intact Facial Nerve Following Vestibular Schwannoma Surgery

Objective The study aimed to determine long-term outcomes in patients with intraoperative electrical conduction block in an anatomically intact facial nerve (FN).

Methods Single center retrospective review of prospectively collected database of all vestibular schwannoma surgeries between January 1, 2008 and August 25, 2015. Operative notes were reviewed and patients with anatomically intact FNs, but complete conduction block at the end of surgery were included for analysis.

Results In total, 371 patients had vestibular schwannoma surgery of which 18 met inclusion criteria. Mean follow-up was 34.28 months and average tumor size was 28.00 mm. Seventeen patients had House-Brackmann Grade VI facial palsy immediately postoperatively and one patient was grade V. At 1 year, three patients remained grade VI (17%), two improved to grade V (11%), seven to grade IV (39%), six to grade III (33%), and one patient to grade II (6%). On extended follow-up, five patients (28%) had additional 1 to 2 score improvement in facial function. Subset analysis revealed no correlation of tumor size, vascularity, adherence to nerve, operative approach, extent of resection, splaying of FN, and recurrent tumor or sporadic tumors to the extent of FN recovery.

Conclusion Intraoperative conduction block does not condemn a patient to permanent FN palsy. There is potential for a degree of recovery comparable with those undergoing nerve grafting. Our data do not clearly support a policy of same-surgery or early-postoperative primary nerve grafting in the event of a complete conduction block, and instead we favor monitoring for recovery in an anatomically intact nerve.

Potential Surgical Implications of Internal Jugular Stenosis in a Craniocervical Junction Meningioma

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.

CSF Rhinorrhea After Endonasal Intervention to the Skull Base (CRANIAL) - Part 2: Impact of COVID-19

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 recommendations 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 units (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. Adaptations 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 neurosurgery 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 subsequent pandemic waves.

Neurophysiological monitoring of the laryngeal adductor reflex during cerebellar-pontine angle and brainstem surgery

OBJECTIVE

To correlate intraoperative changes of the laryngeal adductor reflex (LAR), alone or in combination with corticobulbar motor evoked potential of vocal muscles (vocal-CoMEPs), with postoperative laryngeal function after posterior fossa and brainstem surgery.

METHODS

We monitored 53 patients during cerebellar-pontine angle and brainstem surgeries. Vocal-CoMEPs and LAR were recorded from an endotracheal tube with imbedded electrodes or hook-wires electrodes. A LAR significant change (LAR-SC) defined as ≥ 50% amplitude decrement or loss, was classified as either transient or permanent injury to the vagus or medullary pathways by the end of the surgery.

RESULTS

All patients with permanent LAR loss (n = 5) or LAR-SC (n = 3), developed postoperative laryngeal dysfunction such as aspiration/pneumonia and permanent swallowing deficits (5.6%). Vocal-CoMEP findings refined postoperative vocal motor dysfunction. All seven patients with transient LAR-SC or loss, reverted by changing the surgical approach, did not present permanent deficits.

CONCLUSIONS

Permanent LAR-SCs or loss correlated with postoperative laryngeal dysfunction and predicted motor and sensory dysfunction of the vagus nerve and reflexive medullary pathways. In contrast, a LAR-SC or loss, averted by a timely surgical adjustment, prevented irreversible damage.

SIGNIFICANCE

Monitoring of the LAR, with vocal-CoMEPs, may enhance safety to resect complex posterior fossa and brainstem lesions.

The importance of genetic counseling and screening for people with pathogenic SMARCE1 variants: A family study

Clear cell meningioma (CCM) is a rare variant of meningioma. In recent years, an association between cranial and spinal CCMs and germline loss of function mutations in the SMARCE1 gene (SWI/SNF chromatin remodeling complex subunit gene) has been discovered. We report a family with an incidental large spinal clear cell meningioma in a young adult following reflex screening for a germline loss of function pathogenic variant (PV) in the SMARCE1 gene. The index patient's mother and maternal grandfather were both also tested positive presymptomatically for SMARCE1. His mother developed intracranial and spinal meningiomas and his maternal grandfather developed a spinal CCM 4 years following a clear spinal MRI scan which required surgical excision. In this report we particularly emphasize the importance of genetic counseling and screening in siblings, parents and offspring of patients who are diagnosed with intracranial or spinal CCM in the context of SMARCE1 PVs. We recommend brain and spine Imaging screening of asymptomatic SMARCE1 PV carriers at least every 3 years, even if the baseline scan did not show any tumors.

CSF rhinorrhoea after endonasal intervention to the anterior skull base (CRANIAL): proposal for a prospective multicentre observational cohort study

BACKGROUND

The endonasal transsphenoidal approach (TSA) has emerged as the preferred approach in order to treat pituitary adenoma and related sellar pathologies. The recently adopted expanded endonasal approach (EEA) has improved access to the ventral skull base whilst retaining the principles of minimally invasive surgery. Despite the advantages these approaches offer, cerebrospinal fluid (CSF) rhinorrhoea remains a common complication. There is currently a lack of comparative evidence to guide the best choice of skull base reconstruction, resulting in considerable heterogeneity of current practice. This study aims to determine: (1) the scope of the methods of skull base repair; and (2) the corresponding rates of postoperative CSF rhinorrhoea in contemporary neurosurgical practice in the UK and Ireland.

METHODS

We will adopt a multicentre, prospective, observational cohort design. All neurosurgical units in the UK and Ireland performing the relevant surgeries (TSA and EEA) will be eligible to participate. Eligible cases will be prospectively recruited over 6 months with 6 months of postoperative follow-up. Data points collected will include: demographics, tumour characteristics, operative data), and postoperative outcomes. Primary outcomes include skull base repair technique and CSF rhinorrhoea (biochemically confirmed and/or requiring intervention) rates. Pooled data will be analysed using descriptive statistics. All skull base repair methods used and CSF leak rates for TSA and EEA will be compared against rates listed in the literature.

ETHICS AND DISSEMINATION

Formal institutional ethical board review was not required owing to the nature of the study - this was confirmed with the Health Research Authority, UK.

CONCLUSIONS

The need for this multicentre, prospective, observational study is highlighted by the relative paucity of literature and the resultant lack of consensus on the topic. It is hoped that the results will give insight into contemporary practice in the UK and Ireland and will inform future studies.

Granular cell tumour of the cavernous sinus: A rare cause of secondary trigeminal neuralgia

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.

SAT-474 Giant Prolactinoma Case Series Assessing Response on Initial Dose of Cabergoline

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.

Dumbell atypical teratoid/rhabdoid tumour (AT/RT) of the cervical spine

Spinal Atypical Teratoid/Rhabdoid Tumour (AT/RT) is a highly malignant tumour, and its prognosis is dismal especially for very young patients. In this article, we present the case of a teenage boy with AT/RT in the cervical spine and its multimodality management. A review of the literature on ATRT of the spine is also presented.

Atypical Presentation of a Sequestered Posterolateral Disc Fragment

Sequestered disc fragments typically occur ventrally but can also migrate dorsally or intradurally. At times, atypical disc herniations can be misinterpreted on imaging as other lesions, such as neoplasms, hematomas, or abscesses. We present an uncommon case of a patient presenting with cauda equina syndrome secondary to an enhancing sequestered disc fragment mimicking a tumor.

Necrotizing Fasciitis: A Life-threatening Complication of Intraoperative Electromyography

Intraoperative neurophysiological monitoring is a commonly used practice during spine surgery. Complications of electromyography (EMG) needle electrode placement are very uncommon. We present a patient who was infected with necrotizing fasciitis in her left thigh due to an EMG needle electrode during a two-stage complex spine procedure. This case demonstrates that providers should continue to meticulously adhere to protocol when inserting and removing EMG needles, but also be cognizant during postoperative observation of the possibility of infection caused by EMG needles.

A 3D endoscopic transtubular transcallosal approach to the third ventricle

OBJECT

Surgical approaches to deep-seated brain pathologies, specifically lesions of the third ventricle, have always been a challenge for neurosurgeons. In certain cases, the transcallosal approach remains the most suitable option for targeting lesions of the third ventricle, although retraction of the fornices and wall of the third ventricle have been associated with neuropsychological and hypothalamic deficits. The authors investigated the feasibility of an interhemispheric 3D endoscopic transcallosal approach through a minimally invasive tubular retractor system for the management of third ventricular lesions.

METHODS

Three-dimensional endoscopic transtubular transcallosal approaches were performed on 5 preserved cadaveric heads (10 sides). A parasagittal bur hole was placed using neuronavigation, and a tubular retractor was inserted under direct endoscopic visualization. Following observation of the vascular structures, fenestration of the corpus callosum was performed and the retractor was advanced through the opening. Transforaminal, interforniceal, and transchoroidal modifications were all performed and evaluated by 3 surgeons.

RESULTS

This approach provided enhanced visualization of the third ventricle and more stable retraction of corpus callosum and fornices. Bayonetted instruments were used through the retractor without difficulty, and the retractor applied rigid, constant, and equally distributed pressure on the corpus callosum.

CONCLUSIONS

A transtubular approach to the third ventricle is feasible and facilitates blunt dissection of the corpus callosum that may minimize retraction injury. This technique also provides an added degree of safety by limiting the free range of instrumental movement. The combination of 3D endoscopic visualization with a clear plastic retractor facilitates safe and direct monitoring of the surgical corridor.

Abdominal wall endometrioma in a patient with lumbo-peritoneal shunt: case report

Lumbo-peritoneal shunt as one of the modalities for management of benign intracranial hypertension is prone to complications. We are reporting a rare complication of lumbo-peritoneal shunt insertion in which our patient had developed a painful swelling on the scar site. Surgical exploration confirmed diagnosis of abdominal wall endometriosis. Abdominal wall swelling with variation in size and tenderness during menstrual cycle in female patients with shunt, especially lumbo-peritoneal shunt, should raise the suspicion of endometriosis.

Enterocutaneous fistulae presenting as a late complication of a non-functioning Ventriculo- Peritoneal shunt catheter

A patient with spina bifida and hydrocephalus who had undergone multiple shunt revisions, presented with a 9 month history of chronic discharging sinuses related to a retained shunt catheter not visible on x-ray. This case report demonstrates the importance of clinical history and investigation in patients with retained catheters presenting with cutaneous sinuses.

LONG-TERM OUTCOME OF SUBCUTANEOUSLY PRESERVED AUTOLOGOUS CRANIOPLASTY

OBJECTIVE

Decompressive craniectomy for intracranial hypertension mandates later cranioplasty. Autologous cranioplasties can be preserved either by freezing or placement in a subcutaneous pocket. There are few data on the long-term follow-up of patients treated in such a fashion.

METHODS

A retrospective study was conducted on 100 consecutive patients who underwent decompressive craniectomy and placement of the bone flap in a subcutaneous pocket in the abdominal wall between 2000 and 2005. Initial diagnosis, Glasgow Coma Scale score on admission, complications, and Glasgow Outcome Score were recorded.

RESULTS

Of the 100 patients who underwent autocranioplasty, the primary diagnosis was traumatic brain injury (76%), subarachnoid hemorrhage (17%), primary intracerebral hemorrhage (3%), and tumor (4%). The mean age of the sample was 39 years (age range, 10–72 years). The mean follow-up duration was 25 months. The average Glasgow Coma Scale score on admission was 7. Eight patients died before replacement of the bone flap. The average time between craniectomy and replacement of bone flap was 42 days. The mean Glasgow Outcome Score was 4 at the time of the 1-year follow-up evaluation. Seven of the 79 patients (9%) for whom 1-year review data were available had a cosmetic result that was unacceptable and required removal of the flap (bone flap infections in 5 patients, unacceptable bone flap resorption in 2 patients)

CONCLUSION

Our study indicates that storage of a cranioplasty flap in a subcutaneous pouch in the abdominal wall has a favorable long-term outcome.

Dialysis disequilibrium syndrome: a consideration in patients with hydrocephalus

Dialysis disequilibrium syndrome is a rare neurological manifestation of intermittent hemodialysis. Urea removal occurs more slowly across the blood-brain barrier than from the plasma, generating an osmotic gradient that promotes water movement into the brain and cerebral edema. The authors report the development of dialysis disequilibrium syndrome in a patient with spina bifida and an adequately functioning shunt.