Fully endoscopic approach for resection of brainstem cavernous malformations: a systematic review of the literature.

BACKGROUND: Brainstem cavernous malformations (BCMs) are benign lesions that typically have an acute onset and are associated with a high rate of morbidity. The selection of the optimal surgical approach is crucial for obtaining favorable outcomes, considering the different anatomical locations of various brainstem lesions. Endoscopic surgery is increasingly utilized in treating of BCMs, owing to its depth illumination and panoramic view capabilities. For intra-axial ventral BCMs, the best surgical options are endoscopic endonasal approaches, following the "two-point method. For cavernous hemangiomas on the dorsal side of the brainstem, endoscopy proves valuable by providing enhanced visualization of the operative field and minimizing the need for brain retraction. METHODS: In this review, we gathered data on the fully endoscopic approach for the resection of BCMs, and outlined technical notes and tips. Total of 15 articles were included in this review. The endoscopic endonasal approach was utilized in 19 patients, and the endoscopic transcranial approach was performed in 3 patients. RESULTS: The overall resection rate was 81.8% (18/22). Among the 19 cases of endoscopic endonasal surgery, postoperative cerebrospinal fluid (CSF) leakage occurred in 5 cases, with lesions exceeding 2 cm in diameter in 3 patients with postoperative CSF rhinorrhea. Among the 20 patients with follow-up data, 2 showed no significant improvement after surgery, whereas the remaining 18 patients showed significant improvement compared to their admission symptoms. CONCLUSIONS: This systematic literature review demonstrates that a fully endoscopic approach is a safe and effective option for the resection of BCMs. Further, it can be considered an alternative to conventional craniotomy, particularly when managed by a neurosurgical team with extensive experience in endoscopic surgery, addressing these challenging lesions.

Tectal Plate Glioma: A Clinical and Radiologic Analysis of Progression and Management in Adults.

BACKGROUND: Tectal plate gliomas (TPGs) are a heterogeneous group of uncommon brain tumors. TPGs are considered indolent and are usually managed conservatively but they have the potential to transform into higher-grade tumors. The aims of this study were to investigate the natural history of adult TPG, treatment outcomes, and overall survival. METHODS: A retrospective cohort analysis was performed of adult patients with TPG between 1993 and 2021. Baseline clinical, radiologic, and management characteristics were collected. The primary outcome was tumor progression, defined as increasing size on radiologic assessment or new gadolinium contrast enhancement. Secondary outcomes included management and mortality. RESULTS: Thirty-nine patients were included, of whom 23 (52.2%) were men. Median age at diagnosis was 35 years (interquartile range, 27-53). Radiologic tumor progression was observed in 8 patients (20.5%). The 10-year progression-free survival was 72.6% (95% confidence interval [CI], 0.58-0.91). The 10-year overall survival was 86.5% (95% confidence interval, 0.75-1.0). Cerebrospinal fluid diversion procedures were used in 62% of the cohort (n = 24). Seventeen patients (43.6%) underwent at least 1 endoscopic third ventriculostomy, whereas only 6 patients (15.4%) underwent at least 1 ventriculoperitoneal shunt. CONCLUSIONS: TPG has an overall favorable clinical prognosis, although progression occurs in 1 in 5 patients. Showing accurate factors by which patients with TPG may be risk stratified should be a key area of further research. A follow-up duration of 10 years would be a reasonable window based on the radiologic progression rates in this study; however, larger cohort studies are needed to answer both questions definitively.

Clinical characteristics and prognostic factors of surgical treatment in children with brainstem tumor.

OBJECTIVE: Brainstem tumors present a significant challenge in surgical treatment, and the prognostic factors in children are lacking. This study aimed to investigate clinical characteristics and prognostic factors of surgical treatment in children with brainstem tumors. PATIENTS AND METHODS: 50 children with brainstem tumors who underwent surgical treatment, including frameless- or frame-based stereotactic biopsy and resection, were included and followed up for clinical and biological analysis. Factors of outcomes were assessed by univariate and multivariate analysis. RESULTS: 27 cases (54.0%) underwent resection in all children with brainstem tumors. The rate of resection reached as high as 81.8% in children with non-diffuse intrinsic pontine glioma (DIPG), while in children with DIPG, biopsy was performed in the majority, and resection was obtained in the minority with focal necrosis. A rare complication was found following the surgery. Multivariate analysis considered World Health Organization (WHO) grade 3-4, with hazard ratio (HR)=4.48, 95% confidence interval (CI) of 2.84-8.69, p=0.001, H3K27M mutation (HR=2.50, 95% CI 1.73-5.69, p=0.015), and hydrocephalus (HR=2.17, 95% CI 1.08-5.32, p=0.014) as independent adverse prognostic factors. For Kaplan-Meier analysis, children with WHO grade 3-4, Ki-67 LI ≥ 20%, TP53 mutation, H3K27M mutation, DIPG, and hydrocephalus had significantly decreased overall survival (OS). CONCLUSIONS: A high rate of resection has been obtained in non-DIPG, and surgical intervention is remarkably safe and efficient for children with brainstem tumors. WHO grade 3-4, H3K27M mutation, and hydrocephalus indicate poor prognosis in children with brainstem tumors.

Recurrent haemorrhagic pontine cavernoma resection via a retrosigmoid microsurgical approach.

BACKGROUND: Brainstem cavernomas occasionally require surgical treatment. Appropriate patient selection and thorough understanding of the anatomy and technical nuances involved in microsurgical resection is a pre-requisite in undertaking these challenging cases. CASE DESCRIPTION: We present a video case of a patient with a recurrent haemorrhagic pontine cavernoma. A step-by-step commentary of surgical footage is provided along with clinical, anatomical and technical learning points pertinent to the safe surgical management of these lesions.

A multimodal imaging-based classification for pediatric diffuse intrinsic pontine gliomas.

OBJECT: Pediatric diffuse intrinsic pontine glioma (DIPG) is a radiologically heterogeneous disease entity, here we aim to establish a multimodal imaging-based radiological classification and evaluate the outcome of different treatment strategies under this classification frame. METHODS: This retrospective study included 103 children diagnosed with DIPGs between January 2015 and August 2018 in Beijing Tiantan Hospital (Beijing, China). Multimodal radiological characteristics, including conventional magnetic resonance imaging (MRI), diffuse tensor imaging/diffuse tensor tractography (DTI/DTT), and positron emission tomography (PET) were reviewed to construct the classification. The outcome of different treatment strategies was compared in each DIPG subgroup using Kaplan-Meier method (log-rank test) to determine the optimal treatment for specific DIPGs. RESULTS: Four radiological DIPG types were identified: Type A ("homocentric", n=13), Type B ("ventral", n=41), Type C ("eccentric", n=37), and Type D ("dorsal", n=12). Their treatment modalities were grouped as observation (43.7%), cytoreductive surgery (CRS) plus radiotherapy (RT) (24.3%), RT alone (11.7%), and CRS alone (20.4%). CRS+RT mainly fell into type C (29.7%), followed by type B1 (21.9%) and type D (50%). Overall, CRS+RT exhibited a potential survival advantage compared to RT alone, which was more pronounced in specific type, but this did not reach statistical significance, due to limited sample size and unbalanced distribution. CONCLUSION: We proposed a multimodality imaging-based radiological classification for pediatric DIPG, which was useful for selecting optimal treatment strategies, especially for identifying candidates who may benefit from CRS plus RT. This classification opened a window into image-guided integrated treatment for pediatric DIPG.

Role of Stereotactic Radiosurgery in Glial Tumors.

Glial tumors are a relatively new indication for stereotactic radiosurgery (SRS). Traditionally, SRS has been considered to be an inadequate treatment for glial tumors as these are diffuse tumors, but SRS is a highly focused treatment. Tumor delineation can be challenging given the diffuse nature of the gliomas. It has been recommended to include the T2/fluid-attenuated inversion recovery (FLAIR) altered signal intensity areas in addition to the contrast enhancing part in the treatment plan of glioblastoma in order to increase the coverage. Some have recommended to include 5 mm margins to cover up for the diffusely infiltrative nature of the glioblastoma. The most common indication of SRS in patients with glioblastoma multiforme is tumor recurrence. SRS has also been used as a boost to the residual tumor or tumor bed after surgical excision before conventional radiotherapy. The addition of bevacizumab has been recently tried along with SRS in patients with recurrent glioblastoma to decrease radiation toxicity. Besides, SRS has also been used in patients with low-grade gliomas following recurrence. Brainstem gliomas, which are usually low-grade gliomas, are another indication for SRS. Outcomes following the use of SRS are comparable with external beam radiotherapy in brainstem gliomas, whereas the risks of radiation-induced complications is less. SRS has also been used in other glial tumors such as gangliogliomas and ependymomas.

Intratumoral catheter placement in pediatric patients with diffuse midline gliomas.

INTRODUCTION: Diffuse midline brainstem gliomas have a poor prognosis and are generally not amenable to surgical resection. Occasionally, palliative surgical procedures can be performed to improve the quality of life of these patients. We describe three patients with solid-cystic brainstem gliomas in whom an Ommaya reservoir catheter was placed to reduce mass effect. OBJECTIVES: To describe the characteristics, indications for, and operative technique of Ommaya reservoir catheter placement in patients with solid-cystic diffuse midline glioma. MATERIALS AND METHODS: A review was conducted of the medical records of pediatric patients with solid-cystic diffuse midline glioma H3 K27-altered, treated with an Ommaya reservoir at Hospital J.P. Garrahan between 2014 and 2021 together with a search of the literature. RESULTS: Three cases of stereotaxic Ommaya placement in solid-cystic diffuse midline gliomas, H3 K27M-altered were identified. After the procedure, clinical improvement and reduction of the size of the tumor cyst size was achieved. No associated complications were seen. At the time of the study, one patient died, and the remaining two patients continued in follow-up at our hospital. CONCLUSION: We believe that the placement of an intratumoral Ommaya reservoir catheter may be considered a therapeutic option to improve symptoms and quality of life of selected patients with solid-cystic diffuse midline glioma.

Frameless Robotic-Assisted Biopsy of Pediatric Brainstem Lesions: A Systematic Review and Meta-Analysis of Efficacy and Safety.

BACKGROUND: Pediatric brainstem lesions are diagnoses that require tissue sampling to advance our understanding of them and their management. Frameless, robot-assisted biopsy of these lesions has emerged as a novel, viable biopsy approach. Correspondingly, the aim of this study was to quantitively and qualitatively summarize the contemporary literature regarding the likelihood of achieving tumor diagnosis and experiencing any postoperative complications. METHODS: Searches of 7 electronic databases from inception to September 2022 were conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Articles were screened against prespecified criteria. Outcomes were pooled by random-effects meta-analyses of proportions where possible. RESULTS: A total of 8 cohort studies satisfied all criteria. They described 99 pediatric patients with brainstem lesions in whom frameless, robot-assisted biopsy was involved in their work-up. There were 62 (63%) male and 37 (37%) female patients with a median age of 9 years at time of biopsy. Overall, all patients had sufficient tissue obtained by initial biopsy for evaluation. Pooled estimate of achieving tumor diagnosis was 100% (95% confidence interval [CI] 97%-100%) across all studies with a high degree of certainty. Across all studies, there were no cases of procedure-related mortality. The pooled estimates of transient and permanent complications after biopsy were 10% (95% CI 4%-19%) and 0% (95% CI 0%-2%), respectively, of very low and low degrees of certainty each. CONCLUSIONS: The contemporary metadata demonstrates the frameless, robot-assisted biopsy of pediatric brainstem lesions is both effective and safe when performed in an experienced setting. Further research is needed to augment robot and automated technologies into workup algorithms.

Endoscopic transventricular biopsy in brainstem diffuse midline glioma: how I do it.

BACKGROUND: Brainstem diffuse midline gliomas represent infiltrative and rare pediatric tumors with a dismal prognosis. Surgical biopsy is emerging as a valid technique to define diagnosis and molecular markers for future targeted therapies. METHOD: We describe the key steps of an endoscopic trans-ventricular biopsy of a brainstem diffuse midline glioma and associated ventriculomegaly. The relevant surgical anatomy along with an illustrative video is described. CONCLUSION: The endoscopic third ventriculostomy combined with a punch biopsy of a brainstem diffuse midline glioma associated with ventriculomegaly represent a feasible and low-risk procedure to simultaneously treat incipient hydrocephalus and molecular diagnosis for future treatment and research.

Biopsy of paediatric brainstem intrinsic tumours: Experience from a Singapore Children's Hospital.

BACKGROUND: Biopsy of intrinsic brainstem tumours presumed to be diffuse midline gliomas (previously known as DIPG) is controversial. Surgery has risks of injury to the eloquent brainstem and may not have direct benefit to the patient. Technological improvements in operative adjuncts have allowed the role of biopsy for paediatric brainstem lesions to be revisited with new insights. This study aims to evaluate our institutional experience in brainstem biopsy. METHODS: This is an ethics-approved retrospective study based in KK Women's and Children's Hospital. Patients diagnosed with intrinsic brainstem tumours and managed by the Neurosurgical Service were included. Variables of interest included patient demographics, neuroimaging features, type of surgery, histological and molecular diagnosis, treatment, and outcomes. RESULTS: From 2006 to 2021, a total of 27 brainstem intrinsic tumours were referred to the Neurosurgical Service. Eleven (40.7 %) patients underwent stereotactic biopsy and 10 (37 %) had open biopsies. Histologically, 10 (37 %) were confirmed to be high grade gliomas, eight (29.6 %) were low grade gliomas and 3 (11.1 %) were malignant embryonal tumours. No negative diagnostic results or permanent postoperative complications were encountered. Five patients went on to have their tumours interrogated via next-generation sequencing to look for targetable mutations. The remaining 6 (22.2 %) patients did not undergo biopsy, whereby 1 of them is still alive after 6 years. CONCLUSION: Biopsy of paediatric brainstem intrinsic tumours is a safe procedure that concurrs with accurate tissue diagnosis. This option can be offered to affected patients, especially to identify relevant markers for targeted therapy.

Frameless robot-assisted stereotactic biopsy: an effective and minimally invasive technique for pediatric diffuse intrinsic pontine gliomas.

PURPOSE: Diffuse intrinsic pontine gliomas (DIPGs) are prone to high surgical risks, and they could even lead to death due to their specific sites. To determine the value of frameless robot-assisted stereotactic biopsies of DIPGs, when compared it with microsurgical biopsies. METHODS: We conducted a retrospective study of 71 pediatric patients who underwent biopsies from January 2016 to January 2021. (i) group 1: microsurgical biopsies, and (ii) group 2: frameless robot-assisted stereotactic biopsies. Demographic information, neuroimaging characteristics, pathological diagnoses, operation time, postoperative intensive care unit (ICU) stay time, postoperative hospitalization time, complications, cost, and perioperative mortality rate (POMR) were collected for analyses. RESULTS: 32 Cases underwent microsurgical biopsies (group 1) and 39 cases underwent frameless robot-assisted stereotactic biopsies (group 2). All cases were accurately diagnosed after surgery. There was no significant difference in gender, age, symptom times and tumor volumes between the two groups (p > 0.05); operation time, postoperative ICU, stay time and postoperative hospitalization time were longer in group 1 than in group 2 (p < 0.001); the intraoperative bleeding volumes and cost were higher in group 1 than in group 2 (p < 0.001). Group 1 patients required more perioperative blood transfusion than group 2 (p = 0.001), and the new neurological impairments were more frequent in group 1 than in group 2 (p = 0.003). The POMR was 9.38% (3/32) in group 1 and 0 in group 2 (p = 0.087). CONCLUSIONS: Frameless robot-assisted stereotactic biopsy was an effective and minimally invasive technique for pediatric DIPGs.

3-Dimensional Exoscope for Far Lateral Approach to Pontomedullary Cavernous Malformation.

Brainstem cavernous malformations account for 15%-18% of all central nervous system cavernomas and are histologically characterized by thin-walled, low-pressure capillaries, classically without intervening brain tissue.1,2 Cavernomas may be sporadic, typically characterized by a single lesion, or inherited. The inherited form is most often autosomal dominant with incomplete penetrance and variable expression. Multiple cavernomas are associated with the familial form; although this is not always the case, genetic workup should be pursued.3,4 Clinical presentation typically includes focal neurologic deficit related to hemorrhage location, seizures, and rarely obstructive hydrocephalus.1,2 Indications for surgical management include severe or progressive neurologic dysfunction, lesion size ≥2 cm, recurring hemorrhages, and/or significant mass effect.5 Microsurgical resection of a cavernoma is associated with an overall 28% complication rate and perioperative neurologic morbidity upwards of 45% according to some series. Long-term surgical outcomes at 12 months are more reassuring: 84% reported their condition to have improved or remained the same, and the long-term morbidity rate is 14%.1,6 The location of the lesion dictates the approaches available-cavernomas in the pons or medulla are commonly approached via a retrosigmoid or retrolabyrinthine approach, while more ventral pathologies in this region necessitate a far lateral approach.1,5,7,8 In Videos 1 and 2, we describe our experience with an exoscope-assisted far lateral approach to a pontomedullary cavernoma in a 10-year-old male presenting with numerous cavernomas and confirmed gene mutation. We demonstrate the exoscope's unparalleled visualization of the anterolateral brainstem, with nominal condylar drilling. The patient and his parents consented to the procedure and publication.

The Role of Stereotactic Frame-Based Biopsy for Brainstem Tumors in the Era of Molecular-Based Diagnosis and Treatment Decisions.

Stereotactic frame-based brain tumor biopsy (SFB) is a potent diagnostic tool considering its minimal invasiveness, though its diagnostic power and safety for brainstem lesions remain to be discussed. Here, we aimed to examine the usefulness of SFB for brainstem tumors. Twenty-two patients with brainstem tumors underwent 23 SFBs at our institution during 2002-2021. We retrospectively analyzed patient characteristics, tumor pathology, surgical procedures, and outcomes, including surgery-related complications and the diagnostic value. Seven (32%) tumors were located from the midbrain to the pons, eleven (50%) in the pons only, and four (18%) from the pons to the medulla oblongata. The target lesions were in the middle cerebellar peduncles in sixteen procedures (70%), the cerebellum in four (17%), the inferior cerebellar peduncles in two (9%), and the superior cerebellar peduncles in one (4%). A definitive diagnosis was made in 21 patients (95%) at the first SFB. The diagnoses were glioma in seventeen (77%) cases, primary central nervous system lymphoma in four (18%), and a metastatic brain tumor in one (5%). The postoperative complications (cranial nerve palsy in three [13%] cases, ataxia in one [4%]) were all transient. SFB for brainstem tumors yields a high diagnostic rate with a low risk of morbidity.

Microsurgical Resection of Multiple Hemangioblastomas.

Hemangioblastoma, especially medulla oblongata hemangioblastoma, is a great challenge for neurosurgeons due to its highly vascularized property and neighbor to the pivotal neural structures of the brainstem.1,2 Surgical resection has been recommended as the main therapeutic option for symptomatic lesions.3,4 However, how to remove the huge solid tumor en bloc, instead of the relatively small cystic counterpart, without any neurologic dysfunction still remains elusive.5 Here, we demonstrate the case of a 28-year-old female who presented with headache for 2 months. A series of images illustrated multiple hemangioblastomas including a huge (maximum diameter >3 cm) solid medulla oblongata hemangioblastoma and a cerebellum hemangioblastoma. Surgical resection via the suboccipital approach was chosen because of the increasing risks of hydrocephalus and brainstem compression. According to the principle of hemangioblastoma resection, dissecting through the pia plane will ensure total removal of the tumor. Unfortunately, this is difficult to achieve when a tumor is huge and solid because the surgical plane is obscure and even vanishes. In Video 1, we demonstrated how to deal with the tumor in such a situation using blunt dissection and sharp dissection. In addition, appropriate traction assisted us in creating a detachable plane, collectively providing an opportunity to remove the tumor en bloc without uncontrollable bleeding and functional brain tissue injury. With the help of these technical nuances, a curative resection of the tumor was finally achieved and the patient preserved intact neurologic function. The patient gave informed consent for the procedure and verbal consent for the publication of her image.

Tectal Plate Gliomas Masquerading as Idiopathic Aqueduct Stenosis.

Aqueduct stenosis is a recognized cause of obstructive hydrocephalus in children and can be treated effectively with endoscopic third ventriculostomy. Preoperative magnetic resonance imaging is often diagnostic of the cause of aqueduct stenosis. We describe 2 pediatric cases with obstructive hydrocephalus secondary to a working diagnosis of idiopathic aqueduct stenosis. Following successful endoscopic third ventriculostomy, repeat magnetic resonance brain imaging revealed tectal plate glioma as the primary cause of obstruction. We believe these 2 reported cases demonstrate a previously unreported phenomenon whereby concealed tectal gliomas presenting with hydrocephalus are only unmasked following relief of hydrocephalus and decompression and normalization of the ventricular system. We aim to raise awareness about this unusual phenomenon and recommend routine postoperative interval imaging following endoscopic third ventriculostomy to avoid missing underlying pathology masquerading as aqueduct stenosis.

Endoscopic Endonasal Excision of a Ventral Exophytic Brainstem Glioma: A Technical Case Report.

BACKGROUND AND IMPORTANCE: Ventral midbrain glioma is an extremely rare lesion in adults. The endoscopic endonasal approach is potentially a better alternative to transcranial approach for this challenging lesion and has not been described in the literature. CLINICAL PRESENTATION: A 22-yr-old woman previously operated through an interhemispheric approach for ventral midbrain glioma with extension in the suprasellar cistern presented with severe headache and diplopia. Imaging revealed an increase in size of the residual lesion. The tumor was resected by using an extended endonasal approach. The patient had improvement in her diplopia with no endocrine complication. CONCLUSION: This case demonstrates the surgical technique of endoscopic endonasal resection of a ventral midbrain glioma.