Contemporary Management of Pediatric Brainstem Tumors.

Brain tumors are the second most common malignancy in childhood. Around 15-20% of pediatric brain tumors occur in the brainstem. The most common type of brainstem tumor are diffuse tumors in the ventral pons, whereas focal tumors tend to arise from the midbrain, medulla, and dorsal pons. Glioma is the most common pathological entity. Contemporary management consists of surgery, radiotherapy, chemotherapy, and other adjuvant treatment. Surgical options range from biopsy to radical excision. Biopsy can be performed for diagnostic and prognostic purposes, or in the setting of clinical trials, mainly for diffuse intrinsic pontine gliomas. For focal tumors, surgeons need to carefully balance clinical outcomes against possible neurological sequelae in order to achieve maximal safe resection. Radiotherapy is essential for control of high-grade tumors and may be applied to residual or recurrent low-grade tumors. Proton therapy may provide similar efficacy and less neurotoxicity in comparison to conventional photon therapy. Oncological treatment continues to evolve from conventional chemotherapy to targeted therapy, immunotherapy, and other novel treatment methods and holds great potential as adjuvant therapy for pediatric brainstem tumors.

Bibliometric analysis of emerging trends and research foci in brainstem tumor field over 30 years (1992-2023).

PURPOSE: Over the past several decades, numerous articles have been published on brainstem tumors. However, there has been limited bibliometric analysis in this field. Therefore, we conducted a bibliometric analysis to elucidate the evolution and current status of brainstem tumor research. METHODS: We retrieved 5525 studies published in English between 1992 and 2023 from the Web of Science Core Collection database. We employed bibliometric tools and VOSviewer to conduct the analysis. RESULTS: We included a total of 5525 publications for further analysis. The annual publications have exhibited steady growth over time. The United States accounted for the highest number of publications and total citations. Among individual researchers, Liwei Zhang had the highest number of publications, while Cynthia Hawkins and Chris Jones shared the most citations, closely followed by Eric Bouffet in this field. The study titled "Diffuse brainstem glioma in children: critical review of clinical trials" stood out as the most cited work in this field. Keyword analysis revealed that immune therapy and epigenetic research are the focal points of this field. CONCLUSIONS: Our bibliometric analysis underscores the enduring significance of brainstem tumors in the realm of neuro-oncology research. The field's hotspots have transitioned from surgery and radiochemotherapy to investigating epigenetic mechanisms and immune therapy.

Role of surgery in the treatment of pediatric low-grade glioma with various degrees of brain stem involvement.

OBJECTIVE: Posterior fossa pediatric low-grade glioma involving the brainstem and cerebellar peduncles (BS-pLGG) are a subgroup with higher risks at surgery. We retrospectively analyzed the role of surgery in the interdisciplinary armamentarium of treatment options in our institutional series of BS-pLGG with various degrees of brainstem involvement. MATERIAL AND METHODS: We analyzed data of 52 children with BS-pLGG after surgical intervention for clinical/molecular characteristics, neurological outcome, factors influencing recurrence/progression pattern, and tumor volumetric analysis of exclusively surgically treated patients to calculate tumor growth velocity (TGV). Tumors were stratified according to primary tumor origin in four groups: (1) cerebellar peduncle, (2) 4th ventricle, (3) pons, (4) medulla oblongata. RESULTS: The mean FU was 6.44 years. Overall survival was 98%. The mean PFS was 34.07 months. Two patients had biopsies only. Fifty-two percent of patients underwent remission or remained in stable disease (SD) after initial surgery. Patients with progression underwent further 23 resections, 15 chemotherapies, 4 targeted treatments, and 2 proton radiations. TGV decreased after the 2nd surgery compared to TGV after the 1st surgery (p < 0.05). The resection rates were significantly higher in Groups 1 and 2 and lowest in medulla oblongata tumors (Group 4) (p < 0.05). More extended resections were achieved in tumors with KIAA1549::BRAF fusion (p = 0.021), which mostly occurred in favorable locations (Groups 1 and 2). Thirty-one patients showed postoperatively new neurological deficits. A total of 27/31 improved within 12 months. At the end of FU, 6% had moderate deficits, 52% had mild deficits not affecting activities, and 36% had none. Fifty percent of patients were free of disease or showed remission, 38% were in SD, and 10% showed progression. CONCLUSION: The first surgical intervention in BS-pLGG can control disease alone in overall 50% of cases, with rates differing greatly according to location (Groups 1 > 2 > 3 > 4), with acceptable low morbidity. The second look surgery is warranted except in medullary tumors. With multimodality treatments almost 90% of patients can obtain remission or stable disease after > 5 years of follow-up. An integrated multimodal and multidisciplinary approach aiming at minimal safe residual disease, combining surgery, chemo-, targeted therapy, and, as an exception, radiation therapy, is mandatory.

Roles and outcomes of stereotactic biopsy for adult patients with brainstem lesion.

PURPOSE: This study aimed to assess the benefit-risk ratio by determining diagnostic yield and safety of brainstem biopsies in adult patients. The secondary objectives were (i) to compare brainstem biopsy safety and postbiopsy patients' outcomes and survival with those of patients biopsied for a brain or cerebellar lesion, and (ii) to assess the impact of brainstem biopsy on final diagnosis and further therapeutic management. METHODS: Among 1784 stereotactic biopsies performed in adult patients at a tertiary center between April 2009 and October 2020, we retrospectively examined 50 consecutive brainstem biopsies. We compared variables regarding diagnostic yield, safety and post-biopsy outcomes between brainstem biopsy patients and brain/cerebellum biopsy patients. RESULTS: Brainstem biopsy led to a diagnosis in 86% of patients (94.6% in patients with suspected tumor). Lesion contrast enhancement on imaging was the sole predictor of obtaining a diagnosis. Rates of symptomatic complications and mortality were significantly higher in brainstem biopsy patients compared to brain/cerebellum biopsy patients (20% vs 0%; p < 0.001 and 6% vs 0%; p = 0.01, respectively). Transfrontal trajectory and prebiopsy swallowing disorders were predictors of brainstem biopsy-related symptomatic complications. Brainstem biopsy findings led to diagnostic change in 22% of patients. CONCLUSIONS: Stereotactic biopsy in adult patients with brainstem lesion has a high diagnostic yield. Although stereotactic brainstem biopsy is associated with more functional and fatal complications than biopsies targeting the brain/cerebellum, its safety profile appears acceptable. Thus, the benefit-risk ratio of stereotactic biopsy in patients with brainstem lesion is favorable but should nevertheless be carefully weighted on a case-by-case basis.

Surgical management of sporadic hemangioblastomas located in the posterior fossa of brain.

PURPOSE: Hemangioblastomas (HBs) are highly vascular tumors, constituting 2%-3% of central nervous system (CNS) tumors. Surgery is a treatment option for HBs. The purpose of this study was to evaluate the demographic, clinical, and radiological findings of patients with HBs who were operated on via microsurgical technique at our clinic and to determine the findings specific to HBs and evaluate their pathological findings and confirmation. METHODS: We evaluated age, gender, initial complaints and duration of 100 patients (50 female and 50 male patients), presence of cranial nerve deficits, magnetic resonance imaging, data (localization, presence of hydrocephalus, tumor size, enhancement pattern, and cystic and solid component features), resection rates, pathological findings (grade, Ki-67 ratio, and staining results), recurrence, special conditions of patients, and the final status of patients in this study. RESULTS: Mean age was 39.08 ± 14.77 years and 66.7% of the patients presented with cerebellar findings. Five of the cases were located in the brainstem, five were located in the cerebellopontine angle, and two were in the cerebellar cortex. In all patients, gross total resection was performed using arteriovenous malformation repair. CONCLUSIONS: Surgical intervention of small and cystic tumors can be performed safely with en bloc resection along with preoperative detailed imaging, improved microsurgical techniques, and an extensive understanding of anatomical and vascular structures. On the contrary, patients with a brainstem invasion and solid structure present surgical difficulties due to arteriovenous malformation-like vascularizations; therefore, gross total resection is the optimal treatment in HBs.

Culture methods of diffuse intrinsic pontine glioma cells determine response to targeted therapies.

Diffuse intrinsic pontine glioma (DIPG) is an aggressive type of brainstem cancer occurring mainly in children, for which there currently is no effective therapy. Current efforts to develop novel therapeutics for this tumor make use of primary cultures of DIPG cells, maintained either as adherent monolayer in serum containing medium, or as neurospheres in serum-free medium. In this manuscript, we demonstrate that the response of DIPG cells to targeted therapies in vitro is mainly determined by the culture conditions. We show that particular culture conditions induce the activation of different receptor tyrosine kinases and signal transduction pathways, as well as major changes in gene expression profiles of DIPG cells in culture. These differences correlate strongly with the observed discrepancies in response to targeted therapies of DIPG cells cultured as either adherent monolayers or neurospheres. With this research, we provide an argument for the concurrent use of both culture conditions to avoid false positive and false negative results due to the chosen method.

The incidence of brainstem primitive neuroectodermal tumors of childhood based on SEER data.

PURPOSE: Incidence of BS primitive neuroectodermal tumors (BS-PNET) in children is not reported to date. Our main objectives were to estimate the incidence and report the outcome of BS-PNET in children. METHODS: Data were collected using the Surveillance Epidemiology and End Results cancer registry. RESULTS: From 1973 to 2013, we identified 83 pediatric patients (aged 0-21 years). Patients were divided into two age groups (0-3 years and 4-21 years). Median overall survival was 53 months. Patients in the older age group had a significant survival advantage (P < 0.001), as did those who received three modalities of therapy (surgery, chemotherapy, and radiation therapy) (P < 0.001) and patients with gross or subtotal tumor resection (P < 0.001). CONCLUSIONS: This study presents the first estimate of incidence and the largest cohort of pediatric BS-PNETs to date. A high index of suspicion of BS-PNET in similar cases is crucial for diagnosis, treatment, and outcome.

Discrepant longitudinal volumetric and metabolic evolution of diffuse intrinsic Pontine gliomas during treatment: implications for current response assessment strategies.

INTRODUCTION: Based on clinical observations, we hypothesized that in infiltrative high-grade brainstem neoplasms, such as diffuse intrinsic pontine glioma (DIPG), longitudinal metabolic evaluation of the tumor by magnetic resonance spectroscopy (MRS) may be more accurate than volumetric data for monitoring the tumor's biological evolution during standard treatment. METHODS: We evaluated longitudinal MRS data and corresponding tumor volumes of 31 children with DIPG. We statistically analyzed correlations between tumor volume and ratios of Cho/NAA, Cho/Cr, and NAA/Cr at key time points during the course of the disease through the end of the progression-free survival period. RESULTS: By the end of RT, tumor volume had significantly decreased from the baseline (P < .0001) and remained decreased through the last available follow-up magnetic resonance imaging study (P = .007632). However, the metabolic profile of the tumor tissue (Cho/Cr, NAA/Cr, and Cho/NAA ratios) did not change significantly over time. CONCLUSION: Our data show that longitudinal tumor volume and metabolic profile changes are dissociated in patients with DIPG during progression-free survival. Volume changes, therefore, may not accurately reflect treatment-related changes in tumor burden. This study adds to the existing body of evidence that the value of conventional MRI metrics, including volumetric data, needs to be reevaluated critically and, in infiltrative tumors in particular, may not be useful as study end-points in clinical trials. We submit that advanced quantitative MRI data, including robust, MRS-based metabolic ratios and diffusion and perfusion metrics, may be better surrogate markers of key end-points in clinical trials.

Giant duodenal ulcers after neurosurgery for brainstem tumors that required reoperation for gastric disconnection: a report of two cases.

BACKGROUND: Despite the efficacy of pharmacotherapy for gastrointestinal ulcers, severe cases of bleeding or perforation due to gastrointestinal ulcers still occur. Giant duodenal ulcer perforation is an uncommon but difficult-to-manage pathology with a high mortality rate. We report two cases of giant duodenal ulcer perforation after neurosurgery for brainstem tumors that needed reoperation for gastric disconnection because of postoperative leakage and bleeding. CASE PRESENTATION: Both cases had undergone neurosurgery for brainstem tumors, and the patients were in a shock state for several days with peritonitis due to giant duodenal perforation. In Case 1, antrectomy with Billroth II reconstruction was performed. However, reoperation for gastric disconnection was needed because of major leakage of gastrojejunostomy and jejunojejunostomy. In Case 2, an omental patch, cholecystectomy, and insertion of a bile drainage tube from the cystic duct were performed for the giant duodenal ulcer, but leakage and bleeding from the ulcer edge required reoperation for gastric disconnection. CONCLUSIONS: Brainstem tumors in these cases might have been related to duodenal ulcer perforation with late diagnosis that progressed to severe sepsis. For giant duodenal ulcer perforation with poor general condition, simple closure including omental patch or antrectomy with reconstruction is hazardous. Antrectomy with gastric disconnection, meaning gastrostomy, duodenostomy, feeding jejunostomy and cholecystectomy, is recommended.

Perioperative problems in patients with brainstem tumors and their influence on patient outcome.

BACKGROUND AND AIMS: Patients with brainstem tumors have many associated systemic abnormalities and are prone to develop perioperative complications. We studied the problems associated with brainstem tumors and their influence on the postoperative neurological outcome. MATERIAL AND METHODS: Retrospective review of records of patients who underwent surgery for brainstem tumors over a period of 8 years was done. Preoperative variables, perioperative complications and neurological outcome as assessed by Glasgow Outcome Scale at the time of hospital discharge were noted. Association between perioperative factors and the unfavorable neurological outcome was evaluated. RESULTS: Data of 70 patients were retrieved, 7 patients were excluded from the study because of incomplete data and data analysis was carried out for 63 patients. We found that lower cranial nerve palsies (32%) and hydrocephalus (43%) were common preoperatively. Various intraoperative problems encountered were hemodynamic instability (56%), major blood loss requiring blood transfusion (40%) and venous air embolism (11%), and postoperative problems were meningitis (51%), hypokalemia (38%), chest infection (21%), seizure (11%), deterioration of Glasgow Coma Scale (GCS, 11%), hyponatremia (8%), hydrocephalus (6%), respiratory distress (3%) and operatives site hematoma (3%). Fifty-six (89%) patients had favorable outcome at hospital discharge whereas, 7 (11%) had an unfavorable outcome. There was no association between pre- and intra-operative factors and the neurological outcome. Deterioration of GCS, chest infection, and the need for reintubation and tracheostomy were associated with unfavorable neurological outcome. CONCLUSION: Patients of brainstem tumors are at increased risk of perioperative complications. Some of the postoperative complications were associated with unfavorable neurological outcome.

Histopathological, Demographic, and Clinical Signatures of Medulla Oblongata Germ Cell Tumors: A Case Report With the Review of Literature.

The medulla oblongata is one of the rarest sites of occurrence for germ cell tumors (GCTs) of the central nervous system. As there is scant data regarding epidemiology, clinical presentations, optimal intervention, and long-term prognosis, we aimed to delineate the features of this rare entity by presenting our representative case and performing a quantitative review of the literature. A 24-year-old woman presented to our department with vertigo and swallowing difficulties. Magnetic resonance imaging revealed a homogenously enhanced exophytic lesion arising from the medulla oblongata and extending to the fourth ventricle. Surgical resection was performed and a histological diagnosis of pure germinoma was made. The patient underwent chemotherapy and whole-ventricular irradiation. No recurrence has been experienced for 4 months after the surgery. According to the literature, the prognosis of GCTs at the medulla oblongata seems no worse than those at typical sites. Striking features including occurrence at an older age, female preponderance, and a predominance of germinoma were noteworthy. The pattern of local recurrence suggests extensive radiation coverage is not a prerequisite. Special attention is needed for cardiac and respiratory functions as the main factors eliciting mortality.

A Comparison of the Safety, Efficacy, and Accuracy of Frame-Based versus Remebot Robot-Assisted Stereotactic Systems for Biopsy of Brainstem Tumors.

BACKGROUND: Brainstem tumors are rare and extremely heterogeneous and present significant challenges in surgical treatment. Thus, biopsies often set the foundation for the diagnosis of brainstem tumors. Multimodal, image-guided, robot-assisted frameless stereotactic biopsies are increasingly popular in neurosurgery centers. This study aimed to compare the safety, efficacy, and duration of the Remebot robot-assisted (Remebot) frameless brainstem tumor biopsy versus those of frame-based stereotactic biopsy. METHOD: A retrospective analysis of 33 patients with brainstem tumors who underwent stereotactic brainstem biopsies in the department of neurosurgery from January 2016 to January 2021 was conducted. The patients were divided into two groups: the Remebot group (n = 22) and the frame-based group (n = 11). The clinical characteristics, trajectory strategy, duration of procedure, diagnostic yielding, histopathological diagnosis, and postoperative complications were retrospectively analyzed and compared between the groups. RESULTS: More pediatric patients performed Remebot frameless brainstem tumor biopsy than frame-based biopsy, with a mean age of 17.3 ± 18.7 vs. 32.8 ± 17.1 (p = 0.027). The diagnostic yield had no significant difference in the two groups, with the diagnostic yield of frame-based biopsy and Remebot frameless brain biopsy being 90.9% and 95.5%, respectively. The time of the total process was 124.5 min for the frame-based biopsy and 84.7 min for the Remebot frameless brain biopsy (p < 0.001). There were no significant differences with respect to the occurrence of complication or the duration of the operation between the two groups. CONCLUSION: Remebot frameless stereotactic brainstem biopsy is as safe and efficacious as frame-based stereotactic biopsy. However, Remebot frameless biopsy can reduce the total duration of the procedure and has better application in young pediatric patients. Remebot frameless stereotactic biopsies can be a better option towards the safe and efficient treatment of brainstem tumors.

Neuroanatomy of Cerebellar Mutism Syndrome: The Role of Lesion Location.

Approximately 25% of pediatric patients who undergo cerebellar tumor resection develop cerebellar mutism syndrome (CMS). Our group recently showed that damage to the cerebellar deep nuclei and superior cerebellar peduncles, which we refer to as the cerebellar outflow pathway, is associated with increased risk of CMS. Here, we tested whether these findings replicate in an independent cohort. We evaluated the relationship between lesion location and the development of CMS in an observational study of 56 pediatric patients who underwent cerebellar tumor resection. We hypothesized that individuals that developed CMS after surgery (CMS+), relative to those that did not (CMS-) would have lesions that preferentially intersected with: 1) the cerebellar outflow pathway, and 2) a previously generated 'lesion-symptom map' of CMS. Analyses were conducted in accordance with pre-registered hypotheses and analytic methods (https://osf.io/r8yjv/). We found supporting evidence for both hypotheses. Compared with CMS- patients, CMS + patients (n = 10) had lesions with greater overlap with the cerebellar outflow pathway (Cohen's d = .73, p = .05), and the CMS lesion-symptom map (Cohen's d = 1.1, p = .004). These results strengthen the association of lesion location with risk of developing CMS and demonstrate generalizability across cohorts. These findings may help to inform the optimal surgical approach to pediatric cerebellar tumors.

Two Pediatric Patients with Acute Acquired Comitant Esotropia as the First Symptom of Brainstem Tumor: A Case Report.

Introduction: Acute acquired comitant esotropia (AACE) is an acquired strabismus with uncrossed sudden-onset diplopia due to esodeviation, comitant esotropia without accommodation factor, or paretic eye movement. The diagnosis of AACE entails differentiation from incomitant esotropia caused by abnormalities in the central nervous system. We present 2 pediatric patients with AACE as the first symptom of brainstem tumor. Case Presentation: The 2 patients were aware of their diplopia and had no other neurological abnormalities. There were no special findings in the anterior segment, ocular media, or fundus. Esotropia with a difference of no more than 10Δ between distant and near fixations was observed. Eye movements were normal, and Hess red-green test under prism neutralization did not reveal abduction restriction. The presumed cause of AACE in both patients was excessive use of digital displays, and brain magnetic resonance imaging (MRI) was performed to confirm the absence of neurological abnormality. Using MRI, a definitive diagnosis of AACE was made based on comitant esotropia associated with diffuse median glioma and medullary pilocytic astrocytoma without abducens nerve palsy. Conclusion: Although the incidence of AACE caused by brainstem tumors may be low, it is necessary to perform head imaging to confirm etiology. Furthermore, Hess red-green test under prism neutralization is considered important for the differentiation of abducens nerve palsy.

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.

Compassionate Treatment of Brainstem Tumors with Boron Neutron Capture Therapy: A Case Series.

Brainstem tumors are heterogenous and cancerous glioma tumors arising from the midbrain, pons, and the medulla that are relatively common in children, accounting for 10% to 20% of all pediatric brain tumors. However, the prognosis of aggressive brainstem gliomas remains extremely poor despite aggressive treatment with chemotherapy and radiotherapy. That means there are many life-threatening patients who have exhausted all available treatment options and are beginning to face end-of-life stage. Therefore, the unique properties of highly selective heavy particle irradiation with boron neutron capture therapy (BNCT) may be well suited to prolong the lives of patients with end-stage brainstem gliomas. Herein, we report a case series of life-threatening patients with end-stage brainstem glioma who eligible for Emergency and Compassionate Use, in whom we performed a scheduled two fractions of salvage BNCT strategy with low treatment dosage each time. No patients experienced acute or late adverse events related to BNCT. There were 3 patients who relapsed after two fractionated BNCT treatment, characterized by younger age, lower T/N ratio, and receiving lower treatment dose. Therefore, two fractionated low-dose BNCT may be a promising treatment for end-stage brainstem tumors. For younger patients with low T/N ratios, more fractionated low-dose BNCT should be considered.

Diffuse Intrinsic Pontine Glioma : Clinical Features, Molecular Genetics, and Novel Targeted Therapeutics.

Diffuse intrinsic pontine glioma (DIPG) is a deadly paediatric brain cancer. Transient response to radiation, ineffective chemotherapeutic agents and aggressive biology result in rapid progression of symptoms and a dismal prognosis. Increased availability of tumour tissue has enabled the identification of histone gene aberrations, genetic driver mutations and methylation changes, which have resulted in molecular and phenotypic subgrouping. However, many of the underlying mechanisms of DIPG oncogenesis remain unexplained. It is hoped that more representative in vitro and preclinical models-using both xenografted material and genetically engineered mice-will enable the development of novel chemotherapeutic agents and strategies for targeted drug delivery. This review provides a clinical overview of DIPG, the barriers to progress in developing effective treatment, updates on drug development and preclinical models, and an introduction to new technologies aimed at enhancing drug delivery.

Lessons to Be Remembered from a Dural Arteriovenous Fistula Mimicking Medulla and High Cervical Cord Glioma.

The radiological signs of intracranial dural arteriovenous fistulas (ICDAVFs) are heterogenous. While it is commonly accepted that hyper intense T2 wedge magnetic resonance imaging of the brainstem and cervical cord mainly concern gliomas, it is so far uncommon and probably unknown that ICDAVFs can imitate similar radiological pattern, especially with gadolinium contrast enhancement and cord enlargement. Thus the angiography is poorly documented in the diagnostic workup. We report the unusual history of ICDAVFs, revealed by clinical and radiological features that mimicked a medulla or cervical spinal cord glioma. This observation provides information on the management of atypical lesions mimicking medulla or cervical cord glioma and arguments for a careful radiological study. Looking for dilated veins around the brainstem and the cord is mandatory in the workup of a supposed infiltrating brainstem or spinal cord lesion, in order to rule out an ICDAVF. Even if the hyperintense T2 images associated with contrast enhancement is in favor of a brainstem or spinal cord glioma, additional cerebral angiography should be mandatory. Moreover, this clinical case highlights the need for a multidisciplinary approach including neuroradiologist, oncologist and neurosurgeon.

Intra- and Extramedullary Dumbbell-Shaped Schwannoma of the Medulla Oblongata: A Case Report and Review of the Literature.

BACKGROUND: Brainstem intramedullary schwannomas (ISs) are extremely rare. Various theories have been suggested to explain its origin. It was first speculated that ISs arise from the region where the nerve roots lose their sheaths on penetrating the pia mater. Later, it was further predicted that ISs would contain both intra- and extramedullary parts and would be shaped like a dumbbell. However, no cases reported previously can support this assumption adequately. CASE DESCRIPTION: A 40-year-old woman presented with constant cervical pain, accompanied by progressive weakness of upper extremities and glove distribution numbness. Magnetic resonance imaging of the brain revealed a rare intra- and extramedullary dumbbell-shaped lesion of the medulla oblongata, which was partially removed via a midline suboccipital craniectomy. Histologic and immunohistochemical examinations confirmed the diagnosis of schwannoma. Routine imaging performed 20 months after the initial resection revealed a regrowth of the intramedullary part, which was subsequently partially removed through a far-lateral approach, with symptoms alleviated. At 2-year follow-up, there continued to be no radiologic or clinical evidence of regrowth. CONCLUSIONS: To date and to our knowledge, there are only 16 reported cases of brainstem ISs, none of which contained both intra- and extramedullary components. We believe this is the first report of dumbbell schwannoma of the medulla oblongata with adequate radiologic evidence. The relevant literature is reviewed, and an assumption has been proposed that dumbbell or surfacing ISs arising near entry zones of sensory nerves, mixed cranial nerves, or ventral root may originate from the aberrant Schwann cells.