Subependymomas: An analysis of Clinical and Imaging Features

Symptomatic Multi-Nodular Fourth Ventricular Choroid Plexus Papillary Fibrosis in the Context of Chiari II Malformation: Case Report and Literature Review

INTRODUCTION

Chiari II malformation (CM-II) is a congenital malformation characterized by the caudal displacement of the cerebellar tonsils, inferior cerebellar vermis, and fourth ventricle through the foramen magnum. Although rare, the association between CM-II and the development of a variety of mass lesions within the fourth ventricle and craniocervical junction has been described in the literature.

CASE PRESENTATION

We present the case of a 9-year-old boy with a history of mid-lumbar myelomeningocele, CM-II, and ventriculoperitoneal shunt-dependent hydrocephalus who was discovered to have a syringomyelia and numerous spherical/ovoid masses within the caudal fourth ventricle and dorsal cervicomedullary subarachnoid space on a surveillance brain MRI. On questioning, the patient endorsed a longstanding history of poor bilateral hand dexterity and grip strength. After further imaging workup, the patient underwent suboccipital craniectomy and C1 laminectomy for resection of the mass lesions arising from the fourth ventricular choroid plexus (CP) and performance of an expansile pericranial duraplasty. The patient tolerated surgery well and had progressive improvement in hand dexterity/strength as well as radiographic improvement in the cervical cord syrinx after surgery. Pathologic analysis of the resected mass lesions demonstrated the lesions to be predominantly characterized by dense nodular fibrosis of the CP stromal cores which we are describing as choroid plexus papillary fibrosis. A minority of the lesional stromal cores were noted to be edematous, imparting a more "reticular" appearance. There were no features to suggest a neoplastic or infectious process.

CONCLUSION

This combination of dysplastic/reactive CP histologic findings has not been previously reported in an extramedullary location. The unique pathology of this patient's CP lesions will be discussed, and previously reported fourth ventricular mass lesions seen in association with CM-II will be reviewed.

Cytological features of ependymal and choroid plexus tumours

Ependymal and choroid plexus tumours arise in anatomically related regions. Their intraoperative differential diagnosis is large and depends on factors such as age, tumour site and clinical presentation. Squash cytology can provide valuable information in this context. Cytological features of conventional ependymomas, subependymomas and myxopapillary ependymomas as well as choroid plexus tumours are reviewed and illustrated. Differential diagnostic considerations integrating morphological and clinical information are discussed.

Intraventricular Subependymoma With Obstructive Hydrocephalus: A Case Report and Literature Review

Subependymomas are benign tumors of the ventricles that grow from the ventricular wall into the cerebrospinal fluid spaces within the brain, obstructing the flow of the cerebrospinal fluid and causing obstructive hydrocephalus. It is estimated that ependymomas represent between 0.2% and 0.7% of all intracranial tumors. They arise most frequently in the fourth ventricle (50-60%) and the lateral ventricles (30-40%). We present the case of a 50-year-old patient, previously diagnosed with an intraventricular process, admitted in our clinic. At neurological examination, the patient was cooperative, bradylalic, and bradypsychic, with right hemiparesis, postural and balance disorders, and occasionally sphincteric incontinence. MRI with contrast described a left intraventricular tumor, in the frontal horn of the left lateral ventricle with homogeneous appearance, with a maximum diameter of 50 mm and base of insertion at the adjacent ependyma of the foramen of Monro, which determined obstructive hydrocephalus. Total resection of the left intraventricular cerebral tumor was achieved. Histopathological analysis revealed a subependymoma. Postoperative recovery was slowly favorable, with significant neurological improvement. At neurological examination at three-month follow-up, the patient's right hemiparesis and unsystematized balance disorders improved. A contrast-enhanced CT scan was performed, highlighting left frontal sequelae hypodensity corresponding to the operated tumor, enlarged left lateral ventricle without active hydrocephalus, and no sign of tumor recurrence. At six-month follow-up, clinico-radiologic findings coincide with those from three-month follow-up. Subependymomas are slow-growing (grade 1) tumors and generally have a favorable prognosis. Unfortunately, due to their anatomical level, multiple complications can arise, caused from obstructive hydrocephalus complications, such as cognitive dysfunction and incontinence. Tumor resection should be complete, a successful operation being a challenge for every neurosurgeon.

Subependymomas of the fourth ventricle: To operate or not to operate?

BACKGROUND

There is a paucity of literature regarding the clinical characteristics and management of subependymomas of the fourth ventricle due to their rarity. Here, we describe the operative and non-operative management and outcomes of patients with such tumors.

METHODS

This retrospective single-institution case series was gathered after Institutional Review Board (IRB) approval. Patients diagnosed with a subependymoma of the fourth ventricle between 1993 and 2021 were identified. Clinical, radiology and pathology reports along with magnetic resonance imaging (MRI) images were reviewed.

RESULTS

Patients identified (n = 20), showed a male predominance (n = 14). They underwent surgery (n = 9) with resection and histopathological confirmation of subependymoma or were followed with imaging surveillance (n = 11). The median age at diagnosis was 51.5 years. Median tumor volume for the operative cohort was 8.64 cm3 and median length of follow-up was 65.8 months. Median tumor volume for the non-operative cohort was 0.96 cm3 and median length of follow-up was 78 months. No tumor recurrence post-resection was noted in the operative group, and no tumor growth from baseline was noted in the non-operative group. Most patients (89 %) in the operative group had symptoms at diagnosis, all of which improved post-resection. No patients were symptomatic in the non-operative group.

CONCLUSIONS

Surgical resection is safe and is associated with alleviation of presenting symptoms in patients with large tumors. Observation and routine surveillance are warranted for smaller, asymptomatic tumors.

Disappearance of a Ruptured Feeding Artery Fusiform Aneurysm After the Resection of a Large Subependymoma: A Case Report

Aneurysm formation on the tumor-feeding artery is rare, and its treatment strategies are not yet settled. We herein report the case of a 49-year-old female with a large subependymoma in the left lateral ventricle presenting remote intracerebral hemorrhage at the left posterior cingulate gyrus. Digital subtraction angiography (DSA) revealed the presence of a 5.5 mm fusiform tumor-feeding artery aneurysm on the left parieto-occipital branch of the posterior cerebral artery, considered to be the source of the hemorrhage. Three months after total tumor resection, the aneurysm subsequently disappeared on the follow-up angiography. Subependymomas are generally known as tumors with low vascularity and seldom present with symptoms such as intracerebral hemorrhage. From the subsequent disappearance of the aneurysm after the complete tumor resection, the pathophysiological cause of the aneurysm formation is assumed to be flow-related hemodynamic vessel wall stress of the feeding artery. Tumor resection alone may be a favorable first treatment strategy to avoid unnecessary brain damage since subsequent disappearance of the aneurysm can be expected. The coexistence of feeding artery aneurysms should be kept in mind, especially in cases with remote hemorrhage.

Spinal Cord Subependymoma: A Subanalysis of the Neurospinal Society of Japan's Multicenter Study of Intramedullary Spinal Cord Tumors

OBJECTIVE

This study aimed to analyze the clinical characteristics, treatment strategies, and surgical outcomes of subependymoma patients from the 2022 Neurospinal Society of Japan multicenter intramedullary spinal cord tumor study.

METHODS

Twenty-six patients with spinal cord subependymoma who were included in the index study of 1,033 patients were retrospectively analyzed.

RESULTS

Mean patient age was 49.4 years. Seventeen patients were men and 9 were women. Sensory disturbance was reported in 22 patients and motor weakness in 18. Median duration of symptoms was 24 months. The tumor was eccentrically located in 19 patients (73.1%) and unilateral in 17 (65.4%). Gross total resection was achieved in 6 patients (23.1%). The same rate for ependymoma patients in the index study was significantly higher (74.8%). Median follow-up was 40.5 months (interquartile range, 18-68 months). In 2 patients who underwent only partial resection, reoperation was required owing to progression 68 and 90 months after surgery, respectively. No recurrence occurred in patients who underwent gross total resection. Five patients experienced neurological worsening after surgery.

CONCLUSION

Although spinal cord subependymoma can be difficult to distinguish from other intramedullary spinal cord lesions before surgery, it is characterized by an indolent clinical course and eccentric location. Surgical treatment should prioritize functional preservation because the prognosis is good even after subtotal resection.

The Ribbon Sign as a Radiological Indicator of Intramedullary Spinal Cord Subependymomas

OBJECTIVE

Intramedullary spinal cord (IMSC) subependymomas are rare World Health Organization grade 1 ependymal tumors. The potential presence of functional neural tissue within the tumor and poorly demarcated planes presents a risk to resection. Anticipating a subependymoma on preoperative imaging can inform surgical decision-making and improve patient counseling. Here, we present our experience recognizing IMSC subependymomas on preoperative magnetic resonance imaging (MRI) based on a distinctive characteristic termed the "ribbon sign."

METHODS

We retrospectively reviewed preoperative MRIs of patients presenting with IMSC tumors at a large tertiary academic institution between April 2005 and January 2022. The diagnosis was confirmed histologically. The "ribbon sign" was defined as a ribbon-like structure of T2 isointense spinal cord tissue interwoven between regions of T2 hyperintense tumor. The ribbon sign was confirmed by an expert neuroradiologist.

RESULTS

MRIs from 151 patients were reviewed, including 10 patients with IMSC subependymomas. The ribbon sign was demonstrated on 9 (90%) patients with histologically proven subependymomas. Other tumor types did not display the ribbon sign.

CONCLUSION

The ribbon sign is a potentially distinctive imaging feature of IMSC subependymomas and indicates the presence of spinal cord tissue between eccentrically located tumors. Recognition of the ribbon sign should prompt clinicians to consider a diagnosis of subependymoma, aiding the neurosurgeon in planning the surgical approach and adjusting the surgical outcome expectation. Consequently, the risks and benefits of gross-versus subtotal resection for palliative debulking should be carefully considered and discussed with patients.

Classification and neuroimaging of ependymal tumors

Ependymal tumors arise from the ependymal cell remnants of the cerebral ventricles, the central canal of the spinal cord, or the filum terminale or conus medullaris, although most pediatric supratentorial ependymomas do not exhibit clear communication or abutment of the ventricles. In this article, we discuss the classification, imaging characteristics, and clinical settings of these tumors. The WHO 2021 classification system has categorized ependymal tumors based on histopathologic and molecular features and location, in which they are grouped as supratentorial, posterior fossa (PF), and spinal. The supratentorial tumors are defined by either the ZFTA (formerly RELA) fusion or the YAP1 fusion. Posterior fossa tumors are divided into group A and group B based on methylation. On imaging, supratentorial and infratentorial ependymomas may arise from the ventricles and commonly contain calcifications and cystic components, with variable hemorrhage and heterogeneous enhancement. Spinal ependymomas are defined by MYCN amplification. These tumors are less commonly calcified and may present with the "cap sign," with T2 hypointensity due to hemosiderin deposition. Myxopapillary ependymoma and subependymoma remain tumor subtypes, with no change related to molecular classification as this does not provide additional clinical utility. Myxopapillary ependymomas are intradural and extramedullary tumors at the filum terminale and/or conus medullaris and may also present the cap sign. Subependymomas are homogeneous when small and may be heterogeneous and contain calcifications when larger. These tumors typically do not demonstrate enhancement. Clinical presentation and prognosis vary depending on tumor location and type. Knowledge of the updated WHO classification of the central nervous system in conjunction with imaging features is critical for accurate diagnosis and treatment.

Clinical Characteristics, Management, and Outcomes of Intramedullary Spinal Cord Ependymomas in Adults: A Systematic Review

BACKGROUND

Intramedullary spinal cord ependymomas (IMSCEs) are rare tumors that mostly occur in adults. Management strategies and related outcomes are heterogeneously reported across the literature, demanding a comprehensive analysis to standardize guidelines. We performed a systematic review of the literature on IMSCEs.

METHODS

A literature search was conducted using 6 databases from inception up to July 28, 2022. Studies with data on clinical characteristics, management strategies, and related outcomes in adult patients with histopathologically confirmed IMSCEs were pooled and analyzed.

RESULTS

The analysis included 69 studies comprising 457 patients (52.7% males). Mean age was 42.4 ± 7.4 years. Sensory deficit (58.0%) was the most prevalent symptom, followed by radicular pain (50.5%). Tumors mostly involved the cervical (64.4%) or thoracic (18.8%) spinal cord and were mostly World Health Organization grade II (80.5%) and classic subtype (72.4%). Gross total resection was performed in most cases (83.4%), with adjuvant radiotherapy delivered in 10.5% of cases. Progression-free survival ≥2 years was reported in 61.1% of cases, and tumor recurrence or progression was reported in only 7.0% of the patients. At last follow-up, 97.4% of patients were alive.

CONCLUSIONS

IMSCEs are uncommon tumors that frequently manifest with debilitating symptoms that require surgical treatment. When feasible, gross total resection may be pursued to improve the patient's functional status and prevent tumor progression, with adjuvant radiotherapy required only in some more aggressive grade III lesions. Future studies should investigate different growth patterns and prognoses based on different IMSCE subtypes.

A Case of Cerebellar Intraparenchymal Subependymoma with Next-Generation Sequencing Analysis

Subependymomas are rare, intraventricular glial tumors histologically characterized by clusters of small uniform cells distributed in an abundant fibrillary matrix. These tumors can arise in the parenchyma of the cerebrum, cerebellum, or spinal cord. Herein, we report an extremely rare case of cerebellar intraparenchymal subependymoma in a 62-year-old woman. The patient presented with dizziness for several years, and brain magnetic resonance imaging revealed a well-defined solid mass in the right cerebellum, upon which a stereotactic biopsy was performed. Histologically, the tumor showed a distinctive multinodular pattern with unevenly distributed glial cells and an abundant fibrillary matrix. Next-generation sequencing analysis showed balanced genomes without genetic alterations, including single-nucleotide variants, small insertions, deletions, or copy number alterations. Follow-up magnetic resonance imaging revealed that the size of the mass has not changed; the patient has not received any surgical treatments since the pathologic diagnosis and is living healthily.

Survival of patients and risk factors for subependymoma: a population-based study

OBJECTIVE

Given the paucity of data on the subependymoma, we aimed to evaluate its risk factors from the Surveillance, Epidemiology, and End Results (SEER) database.

METHODS

We collected survival and clinical information on patients with subependymoma diagnosed between 1975 and 2016 from the SEER database and screened them according to inclusion and exclusion criteria. Then, univariate and multivariate Cox regression analyses were used to identify significant prognostic factors, and nomograms were constructed to visualize the results. The concordance index (C-index), receiver operating characteristic (ROC), and calibration curves were used to assess the predictive ability of the nomogram. We divided the patient scores into two groups according to the high- and low-risk groups and constructed a survival curve using Kaplan-Meier analysis.

RESULTS

A total of 731 patients were initially enrolled, including 511 (69.9%) males and 220 (30.1%) females. After screening, a total of 581 patientswere further evaluated by statistical analysis. The 5- and 10-year survival estimates were 92.0% and 81.9%, respectively. Sex (male, p=0.018; HR=2.3547, 95% CI=1.158-4.788) and age (≥56 years, p<0.001; HR=5.640, 95% CI= 3.139-10.133) were identified as independent prognostic factors for overall survival. The nomogram contained 4 prognostic factors. The C-index was 0.741, and the ROC and calibration curves also indicated the good predictability of the nomogram.

CONCLUSION

In this large cohort, a significant association was noted between age/sex and outcome, which could serve an important role for patient education. Even though a significant association was not found between the extent of resection and outcome, the effect of surgery on prognosis should be further explored.Abbreviations: AUC: area under the curve; CI: confidence interval; C-index: concordance index; CNS: central nervous system; GTR: gross total resection; HR: hazard ratio; NOS: not specific; OS: overall survival; PTR: partial resection; ROC: receiver operating characteristic; SEER: Surveillance, Epidemiology, and End Results; STR: subtotal resection; WHO: World Health Organization.

Tumors of Choroid Plexus and Other Ventricular Tumors

Tumors arising inside the ventricular system are rare but represent a difficult diagnostic and therapeutic challenge. They usually are diagnosed when reaching a big volume and tend to affect young children. There is a wide broad of differential diagnoses with significant variability in anatomical aspects and tumor type. Differential diagnosis in tumor type includes choroid plexus tumors (papillomas and carcinomas), ependymomas, subependymomas, subependymal giant cell astrocytomas (SEGAs), central neurocytomas, meningiomas, and metastases. Choroid plexus tumors, ependymomas of the posterior fossa, and SEGAs are more likely to appear in childhood, whereas subependymomas, central neurocytomas, intraventricular meningiomas, and metastases are more frequent in adults. This chapter is predominantly focused on choroid plexus tumors and radiological and histological differential diagnosis. Treatment is discussed in the light of the modern acquisition in genetics and epigenetics of brain tumors.

Benign Glioma

Benign glioma broadly refers to a heterogeneous group of slow-growing glial tumors with low proliferative rates and a more indolent clinical course. These tumors may also be described as "low-grade" glioma (LGG) and are classified as WHO grade I or II lesions according to the Classification of Tumors of the Central Nervous System (CNS) (Louis et al. in Acta Neuropathol 114:97-109, 2007). Advances in molecular genetics have improved understanding of glioma tumorigenesis, leading to the identification of common mutation profiles with significant treatment and prognostic implications. The most recent WHO 2016 classification system has introduced several notable changes in the way that gliomas are diagnosed, with a new emphasis on molecular features as key factors in differentiation (Wesseling and Capper in Neuropathol Appl Neurobiol 44:139-150, 2018). Benign gliomas have a predilection for younger patients and are among the most frequently diagnosed tumors in children and young adults (Ostrom et al. in Neuro Oncol 22:iv1-iv96, 2020). These tumors can be separated into two clinically distinct subgroups. The first group is of focal, well-circumscribed lesions that notably are not associated with an increased risk of malignant transformation. Primarily diagnosed in pediatric patients, these WHO grade I tumors may be cured with surgical resection alone (Sturm et al. in J Clin Oncol 35:2370-2377, 2017). Recurrence rates are low, and the prognosis for these patients is excellent (Ostrom et al. in Neuro Oncol 22:iv1-iv96, 2020). Diffuse gliomas are WHO grade II lesions with a more infiltrative pattern of growth and high propensity for recurrence. These tumors are primarily diagnosed in young adult patients, and classically present with seizures (Pallud et al. Brain 137:449-462, 2014). The term "benign" is a misnomer in many cases, as the natural history of these tumors is with malignant transformation and recurrence as grade III or grade IV tumors (Jooma et al. in J Neurosurg 14:356-363, 2019). For all LGG, surgery with maximal safe resection is the treatment of choice for both primary and recurrent tumors. The goal of surgery should be for gross total resection (GTR), as complete tumor removal is associated with higher rates of tumor control and seizure freedom. Chemotherapy and radiation therapy (RT), while not typically a component of first-line treatment in most cases, may be employed as adjunctive therapy in high-risk or recurrent tumors and in some select cases. The prognosis of benign gliomas varies widely; non-infiltrative tumor subtypes generally have an excellent prognosis, while diffusely infiltrative tumors, although slow-growing, are eventually fatal (Sturm et al. in J Clin Oncol 35:2370-2377, 2017). This chapter reviews the shared and unique individual features of the benign glioma including diffuse glioma, pilocytic astrocytoma and pilomyxoid astrocytoma (PMA), subependymal giant cell astrocytoma (SEGA), pleomorphic xanthoastrocytoma (PXA), subependymoma (SE), angiocentric glioma (AG), and chordoid glioma (CG). Also discussed is ganglioglioma (GG), a mixed neuronal-glial tumor that represents a notable diagnosis in the differential for other LGG (Wesseling and Capper 2018). Ependymomas of the brain and spinal cord, including major histologic subtypes, are discussed in other chapters.

Ependymomas in Children and Adults

Ependymomas account for approximately 5% of all CNS tumors in adults and around 10% in the pediatric population. Contrary to traditional theories supporting that ependymomas arise from ependymal cells, recent studies propose radial glial cells as the cells of origin. In adults, half of the ependymomas arise in the spinal cord, whereas in the pediatric population, almost 90% of ependymomas are located intracranially. Most of the ependymomas are usually low-grade tumors except anaplastic variants and some cases of RELA-fusion-positive ependymomas, a molecular variant consisting the most recent addition to the 2016 World Health Organization (WHO) classification. Of note, the recently described molecular classification of ependymomas into nine distinct subgroups appears to be of greater clinical utility and prognostic value compared to the traditional histopathological classification, and parts of it are expected to be adopted by the WHO in the near future. Clinical manifestations depend on the location of the tumor with infratentorial ependymomas presenting with acute hydrocephalus. Gross total resection should be the goal of treatment. The prognostic factors of patients with ependymomas include age, grade, and location of the tumor, with children with intracranial, anaplastic ependymomas having the worst prognosis. In general, the 5-year overall survival of patients with ependymomas is around 60-70%.

Lateral Horizontal Head Position Approach for the Lateral and Anterior Third Ventricles: A Subependymoma Clinical Case and Literature Review

Subependymomas are benign, slow-growing, noninvasive solitary lesions of World Health Organization Grade I cerebral ependymal origin that are rare compared with other types of ependymomas. Anterior third ventricle subependymomas are usually detected during autopsies in cases of sudden death due to acute or intermittent obstruction of the cerebrospinal fluid passage. Different surgical approaches are used for these cerebral lateral and third ventricular lesions. Serious complications can occur, either because of brain edema and acute intracranial pressure due to the lesion itself or the chosen head position and continuous use of brain retractors during the surgical procedure. In this case report, we trust that the surgical principles we applied with the aid of two cotton pads, gravity assist, and lateral horizontal head position, and without continuous use of brain retractors in the third ventricular lesion in the transcallosal interhemispheric approach are safe and secure in preventing perioperative brain edema or early postoperative neurological complications.

Clinical features and surgical outcomes of intracranial and spinal cord subependymomas

OBJECTIVE

Subependymomas are low-grade ependymal tumors whose clinical characteristics, radiographic features, and postsurgical outcomes are incompletely characterized due to their rarity. The authors present an institutional case series and a systematic literature review to achieve a better understanding of subependymomas.

METHODS

Adult patients with histologically confirmed subependymoma or mixed subependymoma-ependymoma surgically treated at a tertiary hospital between 1992 and 2020 were identified. A systematic literature review of the PubMed, Embase, Web of Science, and Google Scholar databases from inception until December 4, 2020, was conducted according to PRISMA guidelines. Data extracted from both groups included demographics, radiographic features, tumor characteristics, management, and follow-up variables.

RESULTS

Forty-eight unique patients with subependymoma were identified by chart review; of these patients, 8 (16.7%) had mixed subependymoma-ependymoma tumors. The median age at diagnosis was 49 years (IQR 19.8 years), and 26 patients (54.2%) were male. Forty-two patients (87.5%) had intracranial subependymomas, and 6 (12.5%) had spinal tumors. The most common presentation was headache (n = 20, 41.7%), although a significant number of tumors were diagnosed incidentally (n = 16, 33.3%). Among the 42 patients with intracranial tumors, 15 (35.7%) had hydrocephalus, and the most common surgical strategy was a suboccipital approach with or without C1 laminectomy (n = 26, 61.9%). Gross-total resection (GTR) was achieved in 33 cases (68.7%), and 2 patients underwent adjuvant radiotherapy. Most patients had no major postsurgical complications (n = 34, 70.8%), and only 1 (2.1%) had recurrence after GTR. Of 2036 reports initially identified in the systematic review, 39 were eligible for inclusion, comprising 477 patients. Of 462 patients for whom tumor location was reported, 406 (87.9%) were intracranial, with the lateral ventricle as the most common location (n = 214, 46.3%). Spinal subependymomas occurred in 53 patients (11.5%), with 3 cases (0.6%) in multiple locations. Similar to the case series at the authors' institution, headache was the most common presenting symptom (n = 231, 54.0%) among the 428 patients whose presentation was reported. Twenty-seven patients (6.3%) were diagnosed incidentally, and 36 cases (8.4%) were found at autopsy. Extent of resection was reported for 350 patients, and GTR was achieved in 250 (71.4%). Fifteen of 337 patients (4.5%) had recurrence or progression.

CONCLUSIONS

The authors' case series and literature review demonstrate that patients with subependymoma are well managed with resection and generally have a favorable prognosis.

Diagnosis of symmetric bilateral lateral ventricular subependymomas: A case report

Subependymomas are rare benign tumors that are hypovascular and noninvasive. Subependymomas tend to present as solitary lesions in the fourth ventricle or the frontal horn of the lateral ventricle. When multiple lesions are present, determining the correct diagnosis between subependymoma and other intraventricular neoplasms can be challenging. The characterization of imaging features and enhancement patterns can help narrow down the list of potential differential diagnoses. In this article, we describe a case of bilateral subependymomas in the lateral ventricles in a 40-year-old Asian man, including the clinical features, imaging results from conventional magnetic resonance imaging, magnetic resonance spectroscopy, and magnetic resonance perfusion, histological outcomes, and the disease management approach.

Neuroimaging in cerebellar ataxia in childhood: A review

Ataxia is one of the most common pediatric movement disorders and can be caused by a large number of congenital and acquired diseases affecting the cerebellum or the vestibular or sensory system. It is mainly characterized by gait abnormalities, dysmetria, intention tremor, dysdiadochokinesia, dysarthria, and nystagmus. In young children, ataxia may manifest as the inability or refusal to walk. The diagnostic approach begins with a careful clinical history including the temporal evolution of ataxia and the inquiry of additional symptoms, is followed by a meticulous physical examination, and, depending on the results, is complemented by laboratory assays, electroencephalography, nerve conduction velocity, lumbar puncture, toxicology screening, genetic testing, and neuroimaging. Neuroimaging plays a pivotal role in either providing the final diagnosis, narrowing the differential diagnosis, or planning targeted further workup. In this review, we will focus on the most common form of ataxia in childhood, cerebellar ataxia (CA). We will discuss and summarize the neuroimaging findings of either the most common or the most important causes of CA in childhood or present causes of pediatric CA with pathognomonic findings on MRI. The various pediatric CAs will be categorized and presented according to (a) the cause of ataxia (acquired/disruptive vs. inherited/genetic) and (b) the temporal evolution of symptoms (acute/subacute, chronic, progressive, nonprogressive, and recurrent). In addition, several illustrative cases with their key imaging findings will be presented.

How I do it: minimally invasive resection of a sub-ependymoma of the fourth ventricle

BACKGROUND

A 54-year-old female was referred to our clinic with a lesion of the lower fourth ventricle extending to the median aperture. Here, we report the use a minimally invasive sub-occipital approach (MISA) as a safe and effective surgical management.

METHOD

We performed a MISA using a short midline incision and a 1-cm sub-occipital craniectomy. Dissection of the lesion was performed, and "en bloc" resection could be achieved. The lesion was confirmed to be a grade I sub-ependymoma.

CONCLUSION

MISA can be safely used when confronted to a lesion of the lower fourth ventricle.

Step-by-Step Guide on How to Make a 2-Dimensional Operative Neurosurgical Video: Microsurgical Resection of a Right Lateral Ventricle Subependymoma by an Anterior Interhemispheric Transcallosal Approach

BACKGROUND

Digital video recordings are increasingly used across various medical and surgical disciplines with advances in computer hardware and software technologies. The creation of high-quality surgical video footage requires a basic understanding of key technical considerations, together with creativity and sound aesthetic judgment. Online operative videos have become a core resource within neurosurgical education.

OBJECTIVE

To provide a step-by-step description for making operative videos using a video from a real case as an example.

METHODS

We recorded an operative video of the microsurgical resection of a right lateral ventricle subependymoma performed by an anterior interhemispheric transcallosal approach. The patient consented to surgical resection of the subependymoma and to publication of this operative video. With the video, we explain the step-by-step process the authors used for developing the raw video into a publishable surgical video.

RESULTS

The patient depicted in our video tolerated the surgery well and made a complete recovery. The final video produced from the surgery illustrated elements that Operative Neurosurgery, Neurosurgery, and other journals require in surgical videos.

CONCLUSION

Although more than 1200 peer-reviewed (PubMed) neurosurgical operative videos have been published so far, there has not been a single publication that describes the step-by-step process of producing an operative video. To the best of our knowledge, this is the first published detailed description of editing of an educational operative video in neurosurgery and the first video case report of a microsurgical resection of subependymoma of the lateral ventricle in the peer-reviewed English literature.

Imaging characteristics of 4th ventricle subependymoma

PURPOSE

Subependymomas located within the 4th ventricle are rare, and the literature describing imaging characteristics is sparse. Here, we describe the clinical and radiological characteristics of 29 patients with 4th ventricle subependymoma.

METHODS

This is a retrospective multi-center study performed after Institutional Review Board (IRB) approval. Patients diagnosed with suspected 4th ventricle subependymoma were identified. A review of clinical, radiology, and pathology reports along with magnetic resonance imaging (MRI) images was performed.

RESULTS

Twenty-nine patients, including 6 females, were identified. Eighteen patients underwent surgery with histopathological confirmation of subependymoma. The median age at diagnosis was 52 years. Median tumor volume for the operative cohort was 9.87 cm³, while for the non-operative cohort, it was 0.96 cm³. Thirteen patients in the operative group exhibited symptoms at diagnosis. For the total cohort, the majority of subependymomas (n = 22) were isointense on T1, hyperintense (n = 22) on T2, and enhanced (n = 24). All tumors were located just below the body of the 4th ventricle, terminating near the level of the obex. Fourteen cases demonstrated extension of tumor into foramen of Magendie or Luschka.

CONCLUSION

To the best of our knowledge, this is the largest collection of 4th ventricular subependymomas with imaging findings reported to date. All patients in this cohort had tumors originating between the bottom of the body of the 4th ventricle and the obex. This uniform and specific site of origin aids with imaging diagnosis and may infer possible theories of origin.

Molecular Classification and Therapeutic Targets in Ependymoma

Ependymoma is a biologically diverse tumor wherein molecular classification has superseded traditional histological grading based on its superior ability to characterize behavior, prognosis, and possible targeted therapies. The current, updated molecular classification of ependymoma consists of ten distinct subgroups spread evenly among the spinal, infratentorial, and supratentorial compartments, each with its own distinct clinical and molecular characteristics. In this review, the history, histopathology, standard of care, prognosis, oncogenic drivers, and hypothesized molecular targets for all subgroups of ependymoma are explored. This review emphasizes that despite the varied behavior of the ependymoma subgroups, it remains clear that research must be performed to further elucidate molecular targets for these tumors. Although not all ependymoma subgroups are oncologically aggressive, development of targeted therapies is essential, particularly for cases where surgical resection is not an option without causing significant morbidity. The development of molecular therapies must rely on building upon our current understanding of ependymoma oncogenesis, as well as cultivating transfer of knowledge based on malignancies with similar genomic alterations.

Large Subependymoma Inferior to the Cerebellopontine Angle With Significant Obstructive Hydrocephalus: A Case Report on an Extremely Rare Tumor

Subependymomas are rare yet benign tumors that are commonly found within the ventricular system. We describe the case of a 51-year-old male presenting with hydrocephalus and progressive headaches found to have a right cerebellopontine angle (CPA) lesion encasing multiple blood vessels and cranial nerves (CN). The lesion was resected subtotally via a retrosigmoid approach and was found to be a subependymoma. CPA subependymomas are extremely rare lesions. The neuroimaging and histopathological findings as well as a comprehensive literature review of similar cases are discussed.

Tumor characteristics and surgical outcomes of intracranial subependymomas: a systematic review and meta-analysis

OBJECTIVE

The tumor characteristics and surgical outcomes of intracranial subependymomas are poorly defined. In this study the authors aimed to provide a comprehensive review of all clinical, pathological, radiological, and surgical aspects of this important neoplasm to inform future management strategies.

METHODS

A systematic review and meta-analysis of MEDLINE, EMBASE, Cochrane, and Google Scholar databases adherent to PRISMA guidelines was conducted.

RESULTS

Of the 1145 articles initially retrieved, 24 studies encompassing 890 cases were included. The authors identified 3 retrospective cohort studies and 21 case series, but no controlled trials. Mean age at presentation was 46.7 ± 18.1 years with a male predominance (70.2%). Common sites of tumor origin were the lateral ventricle (44.5%) and fourth ventricle (43.1%). Cumulative postoperative mortality and morbidity rates were 3.4% and 24.3% respectively. Meta-analysis revealed that male sex (HR 3.15, 95% CI 1.39-7.14, p = 0.006) was associated with poorer 5-year overall mortality rates. All-cause mortality rates were similar when performing subgroup meta-analyses for age (HR 0.50, 95% CI 0.03-7.36, p = 0.61), smaller subependymoma size (HR 1.51, 95% CI 0.78-2.92, p = 0.22), gross-total resection (HR 0.65, 95% CI 0.35-1.23, p = 0.18), and receipt of postoperative radiation therapy (HR 0.88, 95% CI 0.27-2.88, p = 0.84). Postoperative Karnofsky Performance Index scores improved by a mean difference of 1.62 ± 12.14 points (p = 0.42). The pooled overall 5-year survival rate was 89.2%, while the cumulative recurrence rate was 1.3% over a median follow-up ranging from 15.3 to 120.0 months. The pure subependymoma histopathological subtype was most prevalent (85.6%), followed by the mixed subependymoma-ependymoma tumor variant (13.7%).

CONCLUSIONS

Surgical extirpation without postoperative radiotherapy results in excellent postoperative survival and functional outcomes in the treatment of intracranial subependymomas. Aggressive tumor behavior should prompt histological reevaluation for a mixed subependymoma-ependymoma subtype. Further high-quality controlled trials are still required to investigate this rare tumor.

Myxoid glioneuronal tumour - report of three cases of a new tumour in a typical location and review of literature

Formerly called dysembryoplastic neuroepithelial tumour (DNET) of the septum pellucidum, myxoid glioneuronal tumour (MGT) was recently recognized as a distinct entity. We report three cases of presumed MGT with typical location and image features.

Intraparenchymal subependymoma: Case report and literature review

Background:

Intracranial subependymomas are rare slow-growing benign tumors typically located in the ventricular system, accounting for 0.07–0.7% of all intracranial neoplasms. Intraparenchymal subependymoma is extremely rare lesions, imposing a challenging diagnosis and management.

Case Description:

We describe a case of a supratentorial intraparenchymal mass on left occipital lobe in a 26-year-old woman with progressive headache and visual impairment. Differential diagnosis mainly included gliomas, neuronal-glial tumors, ependymoma, and subependymoma. Complete surgical resection was performed and histopathology analysis confirmed diagnosis of subependymoma. Despite its benign behavior the Ki67/MIB-1 labeling index assessed by immunohistochemistry was 5%. After 1 year of follow-up she was free of tumor recurrence.

Conclusion:

Intraparenchymal subependymoma is extremely rare tumors and literature review showed only 11 cases reported. In general, they are misdiagnosed as other tumors, so careful attention on clinical and radiological features must be taken when looking at a tumor close to the ventricular system, even though it does not have any obvious direct connection to it. Despite its benign nature, total removal must be attempted given that there are reports of recurrence, especially in partially removed tumors with high proliferation index. The role of adjuvant therapy is still limited and new treatment options are being developed as our knowledge on biological and molecular characteristics advances.

A rare case of intraparenchymal subependymoma in a child

Subependymoma is a slow-growing, exophytic, intraventricular glial neoplasm that commonly arises in the ventricular system. However, a report found that the frequency of intracerebral subependymoma was 0.4% in 1000 routine autopsies. To the best of our knowledge, only seven cases of intracerebral subependymoma have been reported. We report a rare case of intracerebral subependymoma in a child. An 11-year-old girl with generalized tonic-clonic seizures visited the emergency room and had an intraparenchymal tumor on the left frontal lobe on magnetic resonance imaging (MRI). Craniotomy with gross total removal was performed without any perioperative morbidities. The tumor was finally histopathologically diagnosed as a subependymoma.

Intracranial ependymomas: The role of advanced neuroimaging in diagnosis and management

Intracranial ependymomas represent a rare subgroup of glial tumours, showing a wide variety of imaging characteristics, often representing a challenging diagnosis for neuroradiologists. Here, we review the most recent scientific Literature on intracranial ependymomas, highlighting the most characteristic computed tomography and magnetic resonance imaging features of these neoplasms, along with epidemiologic data, recent classification aspects, clinical presentation and conventional therapeutic strategies. In addition, we report an illustrative case of an 18-year-old girl presenting with an intracranial supratentorial, anaplastic ependymoma, with the aim of contributing to the existing knowledge and comprehension of this rare tumour.

Intraventricular neuroepithelial tumors: surgical outcome, technical considerations and review of literature

Background

Intraventricular neuroepithelial tumors (IVT) are rare lesions and comprise different pathological entities such as ependymomas, subependymomas and central neurocytomas. The treatment of choice is neurosurgical resection, which can be challenging due to their intraventricular location. Different surgical approaches to the ventricles are described. Here we report a large series of IVTs, its postoperative outcome at a single tertiary center and discuss suitable surgical approaches.

Methods

We performed a retrospective chart review at a single tertiary neurosurgical center between 03/2009–05/2019. We included patients that underwent resection of an IVT emphasizing on surgical approach, extent of resection, clinical outcome and postoperative complications.

Results

Forty five IVTs were resected from 03/2009 to 05/2019, 13 ependymomas, 21 subependymomas, 10 central neurocytomas and one glioependymal cyst. Median age was 52,5 years with 55.6% (25) male and 44.4% (20) female patients. Gross total resection was achieved in 93.3% (42/45). 84.6% (11/13) of ependymomas, 100% (12/21) of subependymomas, 90% (9/10) of central neurocytomas and one glioependymal cyst were completely removed. Postoperative rate of new neurological deficits was 26.6% (12/45). Postoperative new permanent cranial nerve deficits occurred in one case with 4th ventricle subependymoma and one in 4th ventricle ependymoma. Postoperative KPSS was 90% (IR 80–100). 31.1% of the patients improved in KPSS, 48.9% remained unchanged and 20% declined. Postoperative adverse events rate was 20.0%. Surgery-related mortality was 2.2%. The rate of shunt/cisternostomy-dependent hydrocephalus was 13.3% (6/45). 15.4% of resected ependymomas underwent adjuvant radiotherapy. Mean follow-up was 26,9 (±30.1) months.

Conclusion

Our surgical findings emphasize satisfactory complete resection throughout all entities. Surgical treatment can remain feasible, if institutional experience is given. Satisfying long-term survival and cure is possible by complete removal. Gross total resection should always be performed under function-remaining aspects due to mostly benign or slow growing nature of IVTs. Further data is needed to evaluate standard of care and alternative therapy options in rare cases of tumor recurrence or in case of patient collective not suitable for operative resection.

Microsurgical Resection of the IV Ventricle Subependymoma: 2-Dimensional Operative Video

In this video, we demonstrate microsurgical resection of IV ventricle subependymoma. To the best of our knowledge, this is the first video case report of a microsurgical resection of subependymoma of the IV ventricle in the peer-reviewed English literature.

Subependymomas are benign central nervous system tumors, typically arising in ventricular spaces, mostly in the IV and lateral ventricles.^1-3 They are isointense on T1 and hyperintense on T2-weighted magnetic resonance imaging (MRI) with minimal or no enhancement.⁴ Microsurgery remains the mainstay treatment. Complete tumor resection is possible and curative with excellent prognosis.^1,5-7 Although the clinical course appears benign, the inability to diagnose them radiographically with certainty and the possibility of an alternative malignant lesion support a low threshold for early and safe resection.⁸

A 39-yr-old man presented with severe headache and balance problems. Pre- and postcontrast neuroaxis MRI revealed a centrally located IV ventricle lesion without hydrocephalus. The aim of the surgery was complete tumor resection. Surgery was performed in the prone position by the senior author (KIA) with intraoperative neurophysiology monitoring. A small suboccipital craniotomy and C1 posterior arch removal was done. After opening the dura and arachnoid membrane, the tumor was identified and meticulously dissected from the adjacent posterior inferior cerebellar artery and the floor of the fourth ventricle and from brain stem white matter at the tumor-neural tissue interface to avoid brainstem interference. Histological analysis revealed subependymoma (World Health Organization Grade I). Postoperative pre- and postcontrast MRI revealed complete resection. Headache and balance problems completely resolved; the patient was neurologically intact.

The patient provided written consent and permission to publish his image.

Short-term outcome following surgery for rare brain tumor entities in adults: a Swedish nation-wide registry-based study and comparison with SEER database

Objective

To investigate outcomes after surgery for rare brain tumors using the Swedish Brain Tumor Registry (SBTR).

Methods

This is a nationwide study of patient in the SBTR, validated in the Surveillance, Epidemiology, and End Results (SEER) registries. We included all adults diagnosed 2009–2015 with a rare brain tumor entity (n = 216), defined as ependymoma (EP, n = 64), subependymoma (SUBEP, n = 21), ganglioglioma (GGL, n = 54), pilocytic astrocytoma (PA, n = 56) and primitive neuroectodermal tumor (PNET, n = 21). We analyzed symptomatology, tumor characteristics and outcomes.

Results

Mean age was 38.3 ± 17.2 years in GGL, 36.2 ± 16.9 in PA, 37.0 ± 19.1 in PNET, 51.7 ± 16.3 in EP and 49.8 ± 14.3 in SUBEP. The most common symptom was focal deficit (39.6–71.4%), and this symptom was most common in GGL patients with 64.2% of GGL presenting with seizures. Most patients had no or little restriction in activity before surgery (Performance Status 0–1), although up to 15.0% of PNET patients had a performance status of 4. Gross total resection was achieved in most (> 50%) tumor categories. Incidence of new deficits was 11.1–34.4%. In terms of postoperative complications, 0–4.8% had a hematoma of any kind, 1.9–15.6% an infection, 0–7.8% a venous thromboembolism and 3.7–10.9% experienced a complication requiring reoperation. There were 3 deaths within 30-days of surgery, and a 1-year mortality of 0–14.3%.

Conclusion

We have provided benchmarks for the current symptomatology, tumor characteristics and outcomes after surgery for rare brain tumors as collected by the SBTR and validated our results in an independent registry. These results may aid in clinical decision making and advising patients.

Subependymoma of the Conus Medullaris with Cystic Formation: Case Report and a Literature Review

BACKGROUND

Subependymoma in the spinal cord is very rare and usually occurs in the cervical cord. We report an exceptional case of subependymoma that occurred at the conus medullaris with cystic formation. This article reviews the literature on subependymoma in the conus medullaris; discusses its clinical manifestations, imaging findings, and differential diagnoses; and offers an opinion about the cystic formation of the subependymoma.

CASE DESCRIPTION

A 69-year-old woman experienced progressive limb weakness with a somatosensory abnormality for 3 months. Preoperative magnetic resonance imaging showed a cystic intramedullary lesion at the conus medullaris with a well-defined margin. A preliminary diagnosis of epidermoid cyst was made based on the imaging findings. During the operation, cystic formation of the tumor was found, and the tumor was completely removed. Pathology showed an uneven proliferation of glial cells, consistent with subependymal morphology, and the tumor was confirmed as subependymoma.

CONCLUSIONS

We present an extremely rare case of cystic formation in subependymoma at the conus medullaris. Subependymoma should be included in the differential diagnosis of intramedullary cystic lesions. The breakdown of the blood-brain barrier and excessive extravasation may be potential mechanisms of cystic formation.

Minimizing cortical disturbance to access ventricular subependymoma - A novel approach utilizing spinal minimally invasive tubular retractor system

Background:

Subependymomas are rare benign tumors found primarily in the lateral and fourth ventricles. Patients become symptomatic when the tumor obstructs cerebrospinal fluid pathways. We present a novel minimally invasive technique for lateral ventricular subependymoma resection.

Case Description:

A 57-year-old male presented after a period of progressive ataxia, right upper extremity tremor, and syncopal events. Emergent non-contrast computed tomography of the brain demonstrated a lobulated mass in the left lateral ventricle causing moderate-to-severe obstructive hydrocephalus. Emergent ventriculostomy was placed as a temporizing measure. Subsequent magnetic resonance imaging (MRI) illustrated a large benign appearing mass causing obstruction of the left foramen of Monroe. A small craniotomy was performed utilizing previous ventriculostomy twist hole. The left lateral ventricle was accessed through sequential dilation of ventriculostomy tract using a minimally invasive spine surgery tubular system. Tumor was resected en bloc under microscopic assistance. The patient had an excellent outcome with return to baseline mental status and was discharged from the hospital postoperative day 1. Follow-up MRI demonstrated gross total resection of the mass and decreasing lateral ventricle hydrocephalus with minimal cortical disturbance.

Conclusion:

A minimally invasive tubular system approach to ventricular tumors can be utilized to minimize cortical resection and brain retraction. Minimally invasive surgery also has the potential to decrease the length of stay and enhance postoperative recovery.

Subependymoma and dysembryoplastic neuroepithelial collision tumor in the foramen of Monro: case report

Intracranial collision tumors have rarely been reported in the literature and generally include at least 1 malignant tumor component. Subependymoma with dysembryoplastic neuroepithelial tumor (DNET) is an as-yet unreported combination. Both components are uncommon tumors, and presentation in the foramen of Monro is even more unusual. A 16-year-old male patient with a past medical history significant for asthma presented with a 3-month history of headaches and radiographic evidence of mild obstructive hydrocephalus secondary to a nonenhancing ventricular lesion at the foramen of Monro. He underwent endoscopic biopsy and resection. Pathological analysis revealed distinct components of subependymoma and DNET. At the 1-year follow-up, the patient was doing well without regrowth of tumor. The authors describe a case of intracranial collision tumor demonstrating 2 grade I components: a novel combination of subependymoma and DNET.

Unusual Exophytic Appearance of Spinal Cord Subependymoma

BACKGROUND

Subependymomas are rare in the spinal cord. They are typically expansile, intramedullary spinal cord masses, eccentrically located with minimal gadolinium enhancement.

CASE DESCRIPTION

We present a case of subependymoma originating from the cervical cord with an unusual exophytic appearance. Hallmarks of subependymoma and treatment are reviewed.

CONCLUSIONS

This is the first case, to our knowledge, where imaging revealed a mass appearing to be completely extramedullary with a primary exophytic component. Therefore, subependymomas should remain on the differential for masses in the spinal cord that appear extramedullary and exophytic.

Subependymoma involving multiple spinal cord levels: A clinicopathological case series with chromosomal microarray analysis

Subependymomas of the spinal cord are rare, do not often involve multiple levels, and very rarely recur. Here, we present a series of spinal cord subependymomas with a detailed description of the clinical, radiological and pathological features, and characterization by chromosomal microarray analysis. Briefly, the four patients included two men and two women, between the ages of 22 and 48 years. The most common presenting symptoms were neck and arm pain with upper extremity weakness. By imaging, the tumors were found to involve multiple spinal levels, including cervical/ cervico-thoracic (three patients) and thoracic (one patient), were all eccentric, and had minimal to no post-contrast enhancement. Two patients underwent gross total resection, one had a sub-total resection, and one underwent biopsy alone with a decompressive laminectomy. Follow up ranged from 6 months to 22 years. One patient (case 4) had recurrence 15 years following gross total resection and chromosomal microarray analysis revealed deletions on the long arm of chromosome 6. Our limited series suggests that spinal cord subependymomas can rarely recur, even following gross total resection, suggesting a possible role for long-term surveillance for these rare tumors.

A Case of Rapidly-Progressing Cervical Spine Subependymoma with Atypical Features

This was a study of the case of a 60-year-old woman who presented with a six-month history of headache and numbness radiating to the right arm. MRI revealed a fusiform intramedullary spinal tumor spanning C2 to C5 at the hospital where she first presented. As her right upper limb weakness had presented gradually, she visited our hospital after one and a half years. Neurological examination revealed muscle weakness in the right deltoid, but no sensory disturbance. The patient underwent a C2-C6 total laminectomy and posterior midline myelotomy from the posterior median fissure of the spinal cord. The intraoperative histological diagnosis was glioma. Pathological findings in low magnification demonstrated clusters of small uniform nuclei embedded in a dense and fibrillary matrix in hematoxylin-eosin staining (H.E.). On immunohistochemical staining, the tumor cells were weakly positive for glial fibrillary acidic protein (GFAP), but negative for the epithelial membrane antigen (EMA). The histopathological findings were consistent with the diagnosis of a subependymoma. However, the MIB-1 labeling index was of moderately high level up to approximately 8%. In this case, we performed total resection because the tumor had rapidly increased in size and was of atypical form in histological findings. It should be minded that some of subependymomas have a possibility of rapidly increasing in size with progressing neurological deficits.

Surgical management and long-term outcome of intracranial subependymoma

BACKGROUND

Intracranial subependymomas account for 0.2-0.7% of central nervous system tumours and are classified as World Health Organization (WHO) grade 1 tumours. They are typically located within the ventricular system and are detected incidentally or with symptoms of hydrocephalus. Due to paucity of studies exploring this tumour type, the objective was to determine the medium- to long-term outcome of intracranial subependymoma treated by surgical resection.

METHODS

Retrospective case note review of adults with intracranial WHO grade 1 subependymoma diagnosed between 1990 and 2015 at the Walton Centre NHS Foundation Trust was undertaken. Tumour location, extent of resection (defined as gross total resection (GTR), sub-total resection (STR) or biopsy) and the WHO performance status at presentation and through follow-up were recorded.

RESULTS

Thirteen patients (7 males; 6 females) with a mean age of 47.6 years (range 33-58 years) and a median follow-up of 46 months (range 25-220 months) were studied. Eight patients had symptomatic tumours (headache, visual disturbance); five had incidental finding. Tumours were most commonly located in the fourth ventricle (n = 8). The performance status scores at diagnosis were 0 (n = 8) and 1 (n = 5). The early post-operative performance status scores at 6 months were 0 (n = 5) and 1 (n = 8) and at last follow-up were 0 (n = 11) and 1 (n = 2). There was no evidence of tumour re-growth following GTR or STR. The commonest complication was hydrocephalus (n = 3).

CONCLUSION

Subependymoma are indolent tumours. No patients exhibited a worsening of performance status at medium- to long-term follow-up and there were no tumour recurrence suggesting a shorter follow-up time may be sufficient. Surgical resection is indicated for symptomatic tumours or those without a clear imaging diagnosis. Incidental intraventricular subependymoma can be managed conservatively through MRI surveillance.

A symptomatic large subependymoma with neuroradiological features mimicking a high-grade glioma: A case report

A subependymoma is a benign primary brain tumor classified as a World Health Organization grade I tumor; it is asymptomatic in most cases. We present the case of a 66-year-old Japanese man with a complaint of recurrent vomiting that led to the discovery of a large mass with hemorrhage, peritumoral edema, and a midline shift in the posterior horn of the right lateral ventricle. The patient was pathologically diagnosed with subependymoma after undergoing total tumor resection; a year after the surgery, he was free from tumor recurrence. Although symptomatic subependymomas are rare, they tend to show hemorrhage with peritumoral edema on neuroradiological tests and tend to be confused with high-grade brain tumors. In the present case, we highlight the importance of the appropriate diagnosis for subependymomas showing neuroradiological features that mimic high-grade gliomas. This diagnosis will help in providing suitable treatment for subependymomas.

Surgical outcomes of spinal cord and cauda equina ependymoma: Postoperative motor status and recurrence for each WHO grade in a multicenter study

BACKGROUND

The goals of the study are to analyze postoperative outcomes and recurrence in cases of spinal cord and cauda equina ependymoma in each World Health Organization (WHO) Grade, and to examine the influence of extent of surgical removal on prognosis. Spinal ependymoma has a relatively high frequency among intramedullary spinal cord tumors. The tumor is classified in WHO guidelines as grades I, II, and III, but few studies have examined postoperative prognosis based on these grades.

METHODS

The records of 80 patients undergoing surgery for spinal cord and cauda equina ependymoma were examined in a multicenter study using a retrospective database. Neurological motor status, pathological type, extent of resection, and tumor recurrence were evaluated.

RESULTS

The histopathological types were grade I in 23 cases (myxopapillary: 21, subependymoma: 2), grade II in 52 cases, and grade III in 5 cases (including all anaplastic cases). Total resection was performed in 60 cases (83%), and eight cases had recurrence, including 2 in WHO grade I, 2 in grade II, and 4 in grade III. The 5-year recurrence-free survival rates were 90%, 91%, and 20% in grades I, II and III, respectively. Adjuvant radiotherapy for the local site was performed in 8 cases, including 3 in grade I and 5 in grade III; however, 4 of the 5 grade III cases (80%) had recurrence after radiotherapy. Among 59 patients with normal ambulation or independence without external assistance (McCormick Grade I or II), 53 (90%) maintained the same mobility after surgery. In cases that underwent total resection, the recurrence rate was significantly lower (p < 0.01). A good preoperative motor status also resulted in significantly better postoperative recovery of motor status (p < 0.05).

CONCLUSIONS

Total resection of spinal cord and cauda equina ependymoma leads to postoperative motor recovery and may reduce tumor recurrence. Therefore, early surgery for this tumor is recommended before aggravation of paralysis.

Recent Advances in the Classification and Treatment of Ependymomas

OPINION STATEMENT

Ependymomas are a subgroup of ependymal glia-derived neoplasms that affect children as well as adults. Arising within any CNS compartment, symptoms at presentation can range from acute onset due to increased intracranial pressure to insidious myelopathy. The overall survival (OS) outcomes in adult patients across the subgroups is heterogeneous with subependymoma having an excellent prognosis often even in the absence of any treatment, whereas supratentorial ependymomas tend to be higher grade in nature and may have an OS of 5 years despite gross total resection and adjuvant radiation. The rarity of ependymal tumors, together still only representing 1.8% of all primary CNS tumors, has been a long-standing challenge in defining optimal treatment guidelines via prospective randomized trials. Retrospective studies have supported maximal safe resection, ideally gross total resection, as the optimal treatment with adjuvant radiation therapy proffering additional tumor control. The evidence for efficacy of chemotherapy and targeted agents in adult ependymomas is minimal. Recent investigations of the molecular, genetic, and DNA methylation profiles of ependymal tumors across all age groups and CNS compartments have identified distinct oncogenic gene products as well as nine molecular subgroups correlating with similar outcomes. The 2016 World Health Organization of Tumors of the Central Nervous System update addresses some of these findings, although their clinical significance has not yet been fully validated. There are inconsistent survival outcomes in retrospective studies for ependymomas graded as II versus III, bringing into question the validity of histologic grading which is subject to high interobserver variability in part due to inconsistent application of mitotic count parameters.

Subependymomas Are Low-Grade Heterogeneous Glial Neoplasms Defined by Subventricular Zone Lineage Markers

OBJECTIVE

Subependymomas are infrequent, low-grade gliomas associated with the ventricular system and the spinal cord. Little is known about the origin and natural history of these slow-growing lesions.

METHODS

We identified all patients with pathologically proven subependymomas presenting to our institution between 1998 and 2016. We retrospectively reviewed clinical, radiographic, histologic, and surgical outcomes data in all patients who underwent surgical resection. Immunohistochemical analyses for cell lineage markers were performed.

RESULTS

A total of 31 patients with pathologically proven subependymomas were identified. Of these, 7 asymptomatic lesions were discovered at autopsy and 24 symptomatic cases were treated surgically. There were 15 (48%) lateral ventricle tumors, 11 (35%) fourth ventricular tumors, and 5 (17%) spinal tumors. Symptomatic intracranial lesions most commonly presented with headaches and balance and gait abnormalities. Subependymomas had no distinguishing radiographic features that provided definitive preoperative diagnosis. At last follow-up, no patient treated surgically experienced recurrence. Immunohistochemical analyses demonstrated a diffusely GFAP-positive glial neoplasm with mixed populations of cells that were variably positive for Olig2, NHERF1, Sox2, and CD44. The Ki67 proliferation index was generally low (<1% in many of the tumors).

CONCLUSIONS

Subependymomas demonstrate mixed populations of cells expressing glial lineage markers as well as putative stem cell markers, suggesting these tumors may arise from multipotent glial progenitors that reside in the subventricular zone. Definitive diagnosis requires surgical sampling. Although the clinical course of subependymomas appears benign, the inability to radiographically diagnose these lesions, and the possibility of an alternative malignant lesion support a low threshold for early and safe maximal resection.

MR Spectroscopy to Distinguish between Supratentorial Intraventricular Subependymoma and Central Neurocytoma

PURPOSE

The purpose of this study was to discriminate supratentorial intraventricular subependymoma (SIS) from central neurocytoma (CNC) using magnetic resonance spectroscopy (MRS).

METHODS

Single-voxel proton MRS using a 1.5T or 3T MR scanner from five SISs, five CNCs, and normal controls were evaluated. They were examined using a point-resolved spectroscopy. Automatically calculated ratios comparing choline (Cho), N-acetylaspartate (NAA), myoinositol (MI), and/or glycine (Gly) to creatine (Cr) were determined. Evaluation of Cr to unsuppressed water (USW) was also performed. Mann-Whitney U test was carried out to test the significance of differences in the metabolite ratios. Detectability of lactate (Lac) and alanine (Ala) was evaluated.

RESULTS

Although a statistically significant difference (P < 0.0001) was observed in Cho/Cr among SIS, control spectra, and CNC, no statistical difference was noted between SIS and control spectra (P = 0.11). Statistically significant differences were observed in NAA/Cr between SIS and CNC (P = 0.04) or control spectra (P < 0.0001). A statistically significant difference was observed in MI and/or Gly to Cr between SIS and control spectra (P = 0.03), and CNC and control spectra (P < 0.0006). There were no statistical differences between SIS and CNC for MI and/or Gly to Cr (P = 0.32). Significant statistical differences were found between SIS and control spectra (P < 0.0053), control spectra and CNC (P < 0.0016), and SIS and CNC (P < 0.0083) for Cr to USW. Lac inverted doublets were confirmed in two SISs. Triplets of Lac and Ala were detected in four spectra of CNC.

CONCLUSION

The present study showed that MRS can be useful in discriminating SIS from CNC.