In recent decades, trans-cerebellomedullary fissure (trans-CMF) approaches have gained prominence in fourth ventricle surgery and are largely based on cadaveric anatomical studies of normally sized ventricles. In clinical practice, however, the fourth ventricle is often dilated and distorted by tumor growth. Recent endoscopic in vivo anatomical studies depicting the internal surfaces of both normal and enlarged fourth ventricles have prompted a reassessment of traditional schematic representations of trans-CMF approaches. This refinement does not introduce new surgical strategies but aims to provide neurosurgeons with a realistic in vivo perspective of the ventricular roof prior to its incision across different ventricular sizes. Very selected panoramic endoscopic views of the inner roof of twelve cases of both hydrocephalic dilated and normal fourth ventricles were reviewed and analyzed. The anatomical landmarks were identified, and the schematic cutlines of telovelar procedures were redesigned according to the classical diagrams by Matsushima. In this way, realistic models of roof dissections viewed from inside were obtained, indicating the safest and less safe tracks of the telovelar approach. This study has enabled the anatomical representation of the internal surface of the roof of very dilated fourth ventricles, creating a more realistic model that better aligns with the clinical realities of fourth ventricles dilated and deformed by tumors. By replicating the classic trans-CMF dissections on these internal roof images, the study provides a more comprehensive and reliable anatomical understanding of the approach.

Cerebellopontine Angle (CPA) tumours are uncommon intracranial neoplasms that can present significant anaesthetic challenges, particularly in pregnant patients. The physiological, hormonal, and anatomical changes of pregnancy can mask neurological symptoms, delay diagnosis, and complicate both surgical and anaesthetic management. The authors report a rare case of a 22-year-old primigravida at 14 weeks of gestation who presented with progressive blurring of vision and left-sided tinnitus. Magnetic Resonance Imaging (MRI) revealed a large left CPA lesion compressing the fourth ventricle. She had a history of Ventriculoperitoneal (VP) shunt placement for hydrocephalus two weeks prior. The patient was subsequently planned for an elective left retromastoid suboccipital craniotomy. The procedure was performed under Total Intravenous Anaesthesia (TIVA) using propofol and dexmedetomidine, with continuous neurophysiological monitoring to preserve cranial nerve function. Muscle relaxants were avoided following intubation to facilitate Electromyographic (EMG) monitoring. Haemodynamic stability and foetal heart rate were maintained throughout the eight-hour procedure. The patient was electively ventilated overnight, extubated on the first Postoperative Day (POD) without neurological deficits, and postoperative imaging confirmed complete tumour excision. She later delivered a healthy male infant at 36 weeks via elective caesarean section. The present case highlights the successful perioperative management of a large CPA tumour during early pregnancy, where the timing of surgery, meticulous use of TIVA without muscle relaxants, and continuous foetal and cranial nerve monitoring ensured favourable maternal and foetal outcomes.

The autonomic nervous system (ANS) coordinates the body's response to stress. Proinflammatory cytokines [e.g., tumor necrosis factor-alpha (TNFα)], released in response to different stressors, may influence underlying pathophysiology involving autonomic dysfunction. The present study evaluated the impact of peripheral TNFα on cellular activation in brain stem nuclei associated with autonomic function, including the dorsal vagal complex (DVC) and the ventral lateral medulla (VLM). Mice received a single intraperitoneal injection of TNFα and were processed 2 h later to identify immunoreactive c-Fos in brain stem nuclei as a measure of cellular activity. The number of c-Fos-immunoreactive cells increased after TNFα challenge within the DVC and VLM. Cells immunoreactive for c-Fos were concentrated lateral to the area postrema (AP), a circumventricular organ medial to the subdivision of the caudal portion of the nucleus of the solitary tract (cNTS) within the DVC. To examine the role of microglia in mediating cellular responses to peripheral TNFα, minocycline was administered into the fourth ventricle to decrease microglial function. Minocycline treatment reduced ionized calcium binding adapter molecule 1 (IBA-1) immunoreactivity in the AP and cNTS. When animals were challenged with TNFα after receiving minocycline, fewer c-Fos-positive cells were induced in the DVC and selectively in the rostral VLM. These findings highlight the spatial selectivity of cells in the brain stem to increased peripheral proinflammatory signaling, as well as the impact of resident microglia on autonomic circuitry responses.NEW & NOTEWORTHY This study investigates how peripheral tumor necrosis factor-alpha (TNFα) affects neuronal activity in autonomic nuclei of the brain stem and how microglia contribute to this response. Peripheral TNFα increased neuronal activation (c-Fos expression) in the dorsal vagal complex (DVC) and ventrolateral medulla (VLM), particularly near the area postrema. Inhibiting microglia with intracerebroventricular minocycline reduced both microglial markers and TNFα-induced neuronal activity, suggesting that microglia play a key role in modulating cytokine-driven autonomic signaling in the brain stem.

The neurodevelopmental outcome of 'Cystic' malformations of the posterior fossa with marked opening of the fourth ventricle, such as Dandy Walker malformation (DWM) and large Blake's pouch cyst (BPC), is a major issue. This study aimed to refine relevant MRI criteria for distinguishing DWM from BPC and identify prognostic factors. Inclusion criteria were prenatal retrocerebellar fluid space diameter >10mm, marked opening of the fourth ventricle with a tegmento-vermian angle (TVA)>40°, and postnatal follow-up > 2years. 27 patients were classified as follows: 6 DWM characterized by an overall upward orientation of the tentorium, an open tegmento-tentorial angle (TTA>78) and a high TVA (median 132°); 15 BPC with a normal downward orientation of the proximal part of the tentorium (TTA<68°) and distal upward displacement (median TVA 74°); 3 PHACE syndromes (Posteriorfossa abnormalities, Haemangioma, Arterial cerebrovascular anomalies, Cardiac defects, Eye anomalies) and 3 unclassified. Four prognostic factors were identified, (i) diagnosis: DWM (two deaths, three learning disabilities and one typical development (TD)) versus BPC (five learning disabilities [4/5 with associated malformation or genetic defects] and 10 TD); (ii) associated versus isolated (36% vs. 87% TD); (iii) obstructive ventriculomegaly versus no hydraulic complications (20% vs. 91% TD); and (iv) the foetal TVA value and clinical outcome (correlation coefficient=0.561, p=0.006).

The goal of this study was to systematically analyze tumor subgroup, location, and volume in relationship to extent of resection (EOR) through a retrospective approach and examine the role for second-look surgery with a single-institution case series. Retrospective data review of pathologically confirmed medulloblastoma patients under the age of 21 who underwent surgery at the Mayo Clinic Rochester. There were 45 patients who met the inclusion criteria. All subgroups were represented, and those without subgroup data were classified as unknown with histopathologic confirmed grade IV medulloblastoma. The most common location of tumors was the fourth ventricle, though this varied by subgroup. The foramen of Lushka was the most invaded structure. Tumor size and volume were classified with respect to EOR and subgroup and there was no statistically signifcant difference noted. There were 5 non-WNT non-SHH subgroup patients who underwent second look surgery. EOR and the location of residual tumor varied, but GTR was achieved in all cases. When indicated, second look surgery is safe and offers an opportunity to achieve GTR. The EOR and role of second look surgery remain controversial, and larger multicenter studies will be needed.

To apply the Magnetization Transfer Indirect Spin Labeling (MISL) MRI technique for quantifying tissue-CSF water exchange in the human brain, and to investigate its utility in (1) evaluating tissue-CSF water exchange within perivascular spaces (PVS), and (2) characterizing altered water exchange dynamics in pathologic conditions. MISL was implemented on a 3 T MRI using off-resonance magnetization transfer to label parenchymal water. The resulting exchange with CSF was captured via long-TE 3D-TSE readout to suppress parenchymal signals. CSF-region-specific quantification was achieved by atlas-based segmentation. Studies were conducted in healthy subjects across age groups and in patient with metastatic brain tumor. MISL revealed widespread and regionally heterogeneous tissue-CSF exchange, with the strongest signals observed in the PVS and areas adjacent to the choroid plexus. MISL signals were typically 2%-3% in the ventricles and subarachnoid space, and reached 3% in the cerebellar regions, suggesting tissue-to-CSF flow (TCF) in the range of 100-300 mL/100 mL/min. The high MISL signals observed in the PVS (∼8.4%) indicated active tissue-CSF water exchange, providing functional information of the PVS that conventional T2w imaging cannot capture. Significant age-dependent declines in TCF were observed across most brain regions, except for the third and fourth ventricles. In the tumor patient, MISL revealed elevated water exchange, even where no overt FLAIR hyperintensity was present. MISL enables robust, non-invasive mapping of tissue-CSF exchange with high sensitivity and spatial resolution. MISL provides a unique window into tissue-CSF exchange within PVS, which may reflect glymphatic function.

Fully automated volumetry of ventricular subregions on computed tomography using object detection and semantic segmentation

Rosette-forming glioneuronal tumors (RGNT) are rare and novel World Health Organization grade I neoplasms that typically arise in the fourth ventricle and progress slowly. Surgical resection is the standard treatment. However, owing to their adherence to critical structures, complete resection is often not possible. The role of stereotactic radiosurgery (SRS) in the management of RGNT remains inconclusive. We present a case of tissue-confirmed RGNT successfully treated with SRS.A 24-year-old woman presented with diplopia and dysequilibrium and was subsequently diagnosed with a fourth ventricular tumor. Subtotal resection was performed at another hospital, and a tissue-based diagnosis of RGNT was made. After a multidisciplinary discussion and following the patient's willingness, single-session SRS was prescribed at a marginal dose of 12Gy. During the subsequent 66-month follow-up period, radiologic regression of the tumor with corresponding resolution of symptoms was noted. She remained neurologically intact at her last official visit.The treatment paradigm for residual RGNT remains elusive due to its scarcity and varied presentation. We have presented our preliminary experience with a residual RGNT that was managed with SRS, attaining long-term freedom from tumor progression. SRS may be a safe, effective, and durable treatment modality for patients with RGNT.

This study aimed to evaluate the choroid plexus volume in patients with spontaneous intracranial hypotension (SIH), including the lateral, third, and fourth ventricles, and explore its potential relationship with clinical characteristics. SIH is caused by cerebrospinal fluid (CSF) leaks. The choroid plexus is predominantly responsible for CSF production and has been implicated in altered CSF dynamics in various neurological conditions. This retrospective case control study included 25 patients with SIH who were diagnosed between 2022 and 2024 from a single tertiary center. In addition, 25 age- and sex-matched healthy controls were included. Choroid plexus volumes were manually segmented from 3D contrast-enhanced magnetization-prepared rapid acquisition gradient echo MRI sequences using 3D Slicer. The total intracranial volume was also calculated. Clinical data, including the Bern score and Headache Impact Test-6 score, were collected from patients with SIH. Group differences in choroid plexus volumes were assessed using a generalized linear mixed model for the lateral ventricles and multivariable linear regression for the third and fourth ventricles, adjusting for age, sex, body mass index, and total intracranial volume. Associations with clinical variables were evaluated using univariable linear regression. After adjusting for covariates, the choroid plexus volume in the lateral ventricles was significantly higher in patients with SIH compared to that in healthy controls (unstandardized regression coefficient = 201.81 mm3, p = 0.016). However, no significant differences were observed in the choroid plexus volumes of the third (p = 0.617) and fourth ventricles (p = 0.314). Additionally, choroid plexus volume was not associated with disease duration (p = 0.292), Bern score (p = 0.580), and Headache Impact Test-6 score (p = 0.539) in patients with SIH. The lateral ventricular choroid plexus is enlarged in patients with SIH, which may represent a compensatory response to CSF hypovolemia.

Choroid plexus papilloma is a rare, benign neuroepithelial tumour arising from the choroid plexus of the brain. It is reported to be more common in the lateral ventricles among paediatric populations and in the fourth ventricle in adults. These tumours are known to cause hydrocephalus, resulting in increased intracranial pressure, which in turn leads to symptoms such as headaches, nausea, and vomiting. Pathologically, choroid plexus papilloma is noted as well-circumscribed, cauliflower-like masses macroscopically. The tissues of the choroid plexus papilloma exhibit a papillary, finger-like architecture comprised of singular cuboidal-columnar epithelial cells with very low mitotic activity and mild nuclear pleomorphism. This is case of a 50-year-old male, presented with headache and was diagnosed with choroid plexus papilloma. The patient was successfully managed by surgical excision. The novelty of imaging in choroid plexus papilloma lies in the multimodal approach, where Magnetic Resonance Imaging (MRI) offers superior soft-tissue detail, Computed Tomography (CT) detects calcifications, and ultrasound enables early diagnosis in neonates.

Background: Mature teratomas of the central nervous system are rare congenital germ cell tumours, accounting for &lt;0.5% of all intracranial neoplasms. Spontaneous rupture with dissemination of fatty material into the ventricles and subarachnoid spaces is uncommon, particularly from the fourth ventricle, and may precipitate aseptic meningitis, complicating diagnosis and management. Case: We report a 10-year-old girl with progressively worsening headaches, recurrent vomiting, and new-onset generalised tonic–clonic seizures. Neurological examination showed mild truncal ataxia without focal motor deficits. Cranial computed tomography (CT) demonstrated a heterogeneous fourth ventricular mass with fat–fluid levels and fat droplets layering the ventricular system and basal cisterns. Intervention: The patient underwent telovelar microsurgical gross total resection (GTR). The procedure was uneventful, and early postoperative contrast-enhanced CT confirmed complete excision with patent cerebrospinal fluid pathways. No adjuvant chemotherapy or radiotherapy was given, as histopathology confirmed a mature teratoma. Outcome: The postoperative course was uncomplicated. At 3- and 6-month follow-up, the child remained neurologically intact and free of headaches, seizures, and other symptoms, with no radiological evidence of residual or recurrent tumour. Long-term follow-up with serial clinical and imaging assessments is planned for at least three years to monitor for recurrence or delayed complications. Conclusion: Telovelar gross total resection alone may achieve excellent outcomes in ruptured fourth ventricular mature teratomas. This case, to our knowledge the first report of spontaneous rupture of such a lesion from a rural African neurosurgical centre, underscores the growing capacity for complex neurosurgical care in resource-limited settings.

Background: Accurate evaluation of posterior fossa structures is critical for distinguishing brainstem from cerebellar and fourth ventricular lesions. This study aimed to establish normative values for the ratio between the distance from the dorsum sellae to the roof of the fourth ventricle (DS–V4) and the distance from the dorsum sellae to the torcula (DS–T) in an African population, and to evaluate its diagnostic utility. Methods: In this cross-sectional study, 420 individuals underwent cranial MRI. Distances from the dorsum sellae to the roof of the fourth ventricle (DS–V4) and to the torcula (DS–T) were measured on midsagittal T1-weighted images, and the DS–V4/DS–T ratio was calculated. Results were compared with existing literature to assess differences in these ratios relative to non-African cohorts. Results: Mean DS–V4/DS–T ratios were 0.568 (95% CI, 0.543–0.594) in males and 0.570 (95% CI, 0.561–0.579) in females, with no significant sex difference. Age-related trends reflected expected cranial growth patterns. Ratios in this West African cohort appeared slightly higher than values reported in some European series. Conclusion: A higher DS–V4/DS–T ratio may suggest brainstem or clival lesions, whereas a lower ratio may indicate cerebellar or posterior fossa lesions. The DS–V4/DS–T ratio represents a practical diagnostic marker for posterior fossa assessment and may be particularly valuable in low-resource settings where access to advanced imaging is limited.

Dandy-Walker malformation is a rare congenital anomaly of the posterior fossa of the skull and cerebellum. The pathology includes hypoplasia or agenesis of the vermis of the cerebellum, cystically dilated fourth ventricle, and an enlarged posterior fossa of the skull. This anomaly of the cerebellum can lead to a wide spectrum of clinical presentations ranging from mild developmental delay to severe hydrocephalus, seizures, and fatality. It is usually diagnosed prenatally using anomaly scans. A detailed study of morphological and microscopic findings is necessary for a better understanding of the etiopathogenesis of this anomaly. Autopsy is considered the gold standard for confirmation of findings associated with this anomaly. It can also help to explore other associated anomalies which can further help in genetic studies and patient counseling. Herein, we present an autopsy report of a 20-week-old male fetus with Dandy-Walker malformation diagnosed prenatally and sent for autopsy with informed consent after medical termination of pregnancy. Gross and microscopic findings were studied and compared with those of previous studies done in the past.

Posterior fossa decompression is the main surgical treatment for Chiari malformation type I (CM-I). The authors present findings on patient presentation, surgical methods, and postoperative complications from a large cohort of pediatric patients with the aim of utilizing this institutional experience to guide evidence-based management of pediatric CM-I. A departmental operative database was queried for patients who underwent a posterior fossa decompression for CM-I between 1992 and 2021. The charts of identified patients were reviewed. Data regarding demographics, presentation, operative details, and complications were collected. A total of 510 patients were identified. The mean patient age was 10.2 ± 5.2 years, and 57% of patients were female. The most common presenting clinical symptoms or associated signs were exertional suboccipital headaches (65%), syringomyelia (55%), and scoliosis (18%). The mean cerebellar tonsillar descent was 14.2 ± 6.4 mm below the foramen magnum. At surgery, 20% of the patients with a preoperative syrinx had documented arachnoid veils obstructing the outflow tract of the fourth ventricle. Operatively, 99% of patients underwent cervical laminectomy; of these laminectomies, 89% were C1 only. Ninety-seven percent of all patients underwent suboccipital craniectomy with expansile duraplasty (PFDD), while 3% underwent bone-only decompression (PFD). Eighty-seven percent of the patients with PFDD received tonsillopexy and/or tonsillar resection. The median postoperative hospital stay was 2 days for PFD patients and 3 days for PFDD patients (p < 0.01). Postoperative complications developed in 12% of cases, with CSF leakage (5%) and aseptic meningitis (4%) being most common. CSF leakage and aseptic meningitis were also the most common reasons for early readmission after surgery. There were no intraoperative or postoperative deaths. The authors demonstrate an institutional preference for PFDD and tonsillopexy. Exertional suboccipital pain and syringomyelia were the most common indications for surgery. Complications tended to be more common with PFDD. There was a significant difference in postoperative length of stay between patients who underwent PFD (median 2 days) versus PFDD (median 3 days). CSF leakage and aseptic meningitis were the most common reasons for readmission.

Objective: To analyze age- and gender-related differences in the length and width of the fourth ventricle using MRI in healthy adults in two different age groups. Methodology: This cross-sectional study was conducted in the Department of Anatomy and Radiology of Jinnah Postgraduate Medical Centre, Karachi, from November 2019 to December 2021. The study was carried out on 206 healthy subjects. divided into two age groups: Group A (20–40 years) and Group B (41-60 years). Both groups included male and female participants with no clinical symptoms or metallic implants. Images were acquired using a thin-slice (1 mm) 3D brain MRI protocol on a 1.5-Tesla scanner (T1-weighted, T2-weighted, and FLAIR sequences). Fourth-ventricle dimensions were measured on axial images using MicroDicom: length was measured craniocaudally at the midline (roof-to-floor), and width was measured transversely at the level of the lateral recesses. Results: The fourth ventricle was slightly larger in males than in females in both age groups. In Group A (20–40 years), males had a mean length of 14.3 ± 1.16 and width of 13.6 ± 1.36, compared to females (length 13.8 ± 0.91, width 12.9 ± 1.35; p = 0.007). In Group B (41–60 years), males were slightly larger (length 14.7 ± 1.19, width 13.9 ± 1.19) than females (length 14.5 ± 1.02, width 13.6 ± 1.21), without statistical significance. Age-related comparison showed a significant increase in females’ length (p = 0.001) and width (p = 0.005), while males showed no significant change (all values in mm). Conclusion: The study provides MRI-based normative reference values for fourth-ventricle dimensions in healthy Pakistani adults, demonstrating modest gender differences and age-related enlargement, particularly in females. These population-specific measurements serve as an important baseline for distinguishing normal anatomical variation from pathological ventricular dilation in clinical practice.

Hindbrain herniation is part of Chiari II deformation and serves as an inclusion criterion for prenatal open neural tube defect (ONTD) repair. Its assessment on fetal MRI remains challenging, due to limited spatial resolution, fetal motion and difficulty obtaining a true mid-sagittal plane. We aimed to evaluate the reproducibility of the Hindbrain herniation severity classification, based on repeated consensus readings by two evaluators. We retrospectively reviewed fetuses who underwent prenatal ONTD repair at a single center (2011-2024), with pre- and 6week post-operative T2-weighted fetal brain MRI scans. Hindbrain herniation was graded as: 0 = normal; 1 = effacement of the 4th ventricle and/or cisterna magna without Hindbrain herniation; 2 = Hindbrain herniation above the C1 posterior arch; 3 = Hindbrain herniation bellow C1 posterior arch. Two experienced fetal imaging specialists independently assessed all scans, resolved discrepancies by consensus, and repeated the evaluation two months later, blinded to initial grading. Reproducibility was assessed with weighted Cohen's Kappa overall and separately for pre- and post-operative scans. 121 fetuses were included. Postoperative MRI was available in 113 (93.4%). Overall reproducibility was excellent (κ = 0.87). Agreement was lower for pre-operative (κ = 0.57) than post-operative (κ = 0.74) scans (p < 0.01). Hindbrain herniation grading on fetal MRI shows excellent overall reliability. The moderate agreement in preoperative scans reflects the difficulty of assessing Hindbrain herniation before prenatal repair and highlights the need for more standardized imaging criteria, when accurate assessment is necessary for surgical eligibility and parental counseling.

Rosette-forming glioneuronal tumors (RGNTs) are rare, World Health Organization grade 1 tumors that typically arise around the fourth ventricle. However, cerebral hemisphere RGNTs have recently been reported, with some exhibiting clinical features resembling low-grade epilepsy-associated tumor (LEAT). We report a case of multifocal RGNT in a patient with drug-refractory epilepsy. A 14-year-old woman was incidentally found to have multifocal brain tumor involving the left temporal lobe and bilateral thalamus, she developed drug-resistant epilepsy ten years later and underwent surgery. Partial tumor resection and anterior temporal lobectomy were performed. Histopathology revealed a glioneuronal tumor with oligodendroglia-like cells, neurocytic rosette, and perivascular pseudorosette, exhibiting an infiltrative growth pattern extending into the white matter. Genetic analysis revealed Fibroblast Growth Factor Receptor 1 mutation. The methylation profile analysis matched the low-grade glioneuronal tumor class but did not yield to any subclass category. Finally, the tumor was diagnosed as RGNT-like low-grade glioneuronal tumor with dysembryoplastic neuroepithelial tumor (DNT) features. Cases presenting with a LEAT-like clinical course and exhibiting histopathological features of RGNT are often difficult to definitively distinguish from DNT based on histological and genetic findings. Epilepsy-associated RGNT may harbor genetic profiles distinct from those of prototypical RGNTs, highlighting the need for further investigation.

Dandy Walker malformation (DWM) is a complex malformation involving the posterior fossa and cerebellum. Aim of this study represents chronic disorder DWM, is a rare condition with an estimated incidence of 1 in 350,000 live births in the united state. Hydrocephaly, a common finding, is seen in approximately 80% of cases. DWM is present in 4% to 12% of cases of hydrocephaly in infants. DWS is more frequent cerebral malformation where hypoplasia and upward rotation of the vermis cerebelli, occipital encephalocele a cystic enlargement of fourth ventricle and in total enlarged posterior fossa. LAMB1 mutations are linked to lissencephaly 5 a severe neurodevelopmental defects and congenital brain defects. In Whole-exome sequencing we identified two likely compound heterozygous variants of LAMB1 gene that are c.5225-8_5230del location intron 33-exon 34 and c.1364G&gt;A; (p. Cys455Tyr) location exon 11, both classified as VUS but predicted to be detrimental. The phenotype overlaps with known LAMB1-related malformations, suggesting a potential pathogenic association. This case emphasizes the utility of prenatal WES and expands the clinical spectrum of LAMB1 variants. It this report a fetus with severe posterior fossa malformations, including cerebellar vermis hypoplasia, enlarged cisterna magna, and a small occipital encephalocele detected on prenatal ultrasound.

The choice of surgical technique for decompression of the cervicomedullary junction remains controversial. The authors report their experience with using subpial tonsillectomy for Chiari malformation with and without associated syringohydromyelia. Children from two institutions who underwent the subpial tonsillar resection technique for decompression of the craniocervical junction from 2014 to 2024 were included. Demographic information, relevant presurgical symptoms, surgical history, perioperative radiographic characteristics, postoperative outcomes, complications, reoperations, and 90-day readmissions were collected. Two outcomes were assessed at last follow-up: 1) status of presenting symptom(s); and 2) radiographic status of syringohydromyelia or isolated presyrinx edema, if present preoperatively. A total of 109 patients were identified with a mean age of 10.8 years. Seventy-eight (71.6%) of these patients presented with headaches, and 23 (21.1%) had medullary or lower cranial nerve dysfunction. Radiographically, 86 (78.9%) patients had Chiari type 1 and 23 (21.1%) had Chiari type 1.5. The mean (range) preoperative cerebellar tonsillar herniation was 14.0 (4.5-40) mm, and 49 (45%) patients had syringohydromyelia or presyrinx edema. The mean operative time was 152 minutes, and the mean length of stay was 3.49 days. Fourteen patients were readmitted within 90 days of surgery, 9 within the first 30 days, and 5 after 30 days. Of these 14 readmissions, 8 (57%) were for reasons attributable to the index operation. Over a mean follow-up of 3.70 years, headaches resolved or improved in 68 of 78 (87.2%) patients, and 18 of 23 (78.3%) patients with brainstem or lower cranial nerve dysfunction demonstrated improvement. Of the patients with syringohydromyelia who had follow-up (n = 45), 39 (86.7%) had complete resolution of their syringohydromyelia (n = 16) or > 50% reduction in diameter of the syrinx (n = 23). One patient was deemed a treatment failure, eventually needing a syringopleural shunt. Subpial tonsillar resection for Chiari malformations is a safe and effective method to maximally decompress the craniocervical junction and immediately reestablish pulsatile cerebrospinal fluid flow out of the fourth ventricle. Most patients will experience improvement or resolution of their associated symptoms and significant reduction (> 50% diameter reduction) or resolution of their syringohydromyelia.

Introduction. Burkitt lymphoma is an aggressive B-cell lymphoma characterized by pathomorphological, immunophenotypic, and cytogenetic features that are the main criteria for its diagnosis. Burkitt lymphoma with isolated involvement of the central nervous system (CNS) is an extremely rare nosological form of primary lymphoma of the central nervous system. The small number of observations in the literature does not allow us to fully determine the main clinical, radiological and age-related features of this lymphoma, as well as standardize the treatment tactics for patients with primary Burkitt lymphoma of the central nervous system. Aim: to present a clinical case of a patient with primary Burkitt lymphoma of the CNS with damage to the right hemisphere of the cerebellum and brainstem with compression of the cavity of the fourth ventricle. Main findings . The diagnosis was established based on the basis of pathomorphological and immunohistochemical examination of the removed neoplasm of the fourth ventricle and was confirmed by in situ fluorescence hybridization using the DNA probe MYC gene break apart detection dual-color probe, which revealed a classical translocation involving the MYC/8q24 gene. The patient underwent 4 courses of chemotherapy under the LB-M-04 program, at the end of which a regression of the neoplasm was achieved.