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Summary The integration of the growth of the brain and the cranial base suggests that each system may influence the other, notably during the first three years of life, although this influence has never been proven to be exclusive. The aim of our work was to analyse the dynamics of normal growth on the one hand, and the development and ontogenetic allometry of the cranial base in the infant on the other hand. Material and method A total of 32 infants (17 males/15 femeles) having been included in the unexpected infant death french protocol were analyzed. Three-dimensional reconstructions of the cranial base were performed from CT scans. The technique combined manual segmentation of regions of interest, contour extraction and surface reconstruction. Nineteen landmarks were positioned on each of the bone surfaces. Results No correlation was observed between sex assigned at birth and shape, weight, crown-heel length, or head circumference. Principal component analysis showed that 85.5% of the variance observed on the first component was secondary to growth. After Procrustes superimposition, 25% of the shape variance observed was explained by the first principal component. It showed anteroposterior lengthening of the cranial base. In addition, the height, width and length of the posterior fossa increased and the relative position of the basion was displaced inferiorly and anteriorly with flexion of the sphenoid angle. Negative allometry was also observed. Conclusion Our study, carried out in a rigorously selected population of infants, presents a fundamental approach to ontogeny through study of shape, growth and ontogenetic allometry.

Objective To analyze radiological characteristics, treatment strategy, and treatment outcomes of posterior fossa giant solid hemangioblastomas (GSHBs; ≥ 4 cm in maximum diameter). Methods We performed a retrospective study on 13 consecutive patients (9 male and 4 female patients [mean age 57.5 ± 13.3 years; range 24-76 years]) with GSHB who underwent surgical resection at a single institution between 2002 and 2018. The median follow-up was 33 months (range 12-120 months). For each patient, neuroimaging findings, operative record, and treatment outcome were reviewed. Results Seven tumors (53.8%) were located within cerebellar hemispheres, 4 (30.8%) in proximity to the brainstem, 1 (7.7%) within the cerebellar vermis, and 1 (7.7%) in the cerebellopontine angle. The mean maximum diameter was 4.8 ± 0.8 cm (range 4.0-6.7 cm). Gross total resection was achieved in 11 patients (84.6%), and near-total resection (NTR) in 2 patients (15.4%). Surgical complications occurred in 5 patients (38.5%); persistent neurological deficits occurred in 2 patients (15.4%). Estimated progression-free survival rates after surgery were 92.3%, 80.8%, and 80.8% at 1, 5, and 10 years, respectively, while the estimated 1-, 5- and 10-year overall survival rates were 100%, 90% and 90%, respectively. Conclusions GSHBs are surgically challenging. The current study shows that favorable outcome can be achieved for GSHBs in the cerebellar hemispheres and vermis. For those involving the brainstem, planned NTR or STR in a piecemeal fashion can be attempted if en bloc resection is judged to be infeasible, and further intervention can be considered as needed.

Posterior reversible encephalopathy syndrome (PRES) has traditionally been described as a reversible leukoencephalopathy with a distinct pattern of posteriorly distributed vasogenic oedema involving the subcortical regions of parietal and occipital lobes. PRES commonly occurs in the setting of hypertensive emergencies, pre-eclampsia/eclampsia, impaired renal function, and immunosuppressive therapy. The various clinical presentations of PRES include encephalopathy, seizures, headache, visual, and focal neurological deficits. As knowledge of this entity grows, the range of clinical, and radiological features is seen to be much broader than originally described. The brain oedema may not always be posteriorly distributed and the syndrome may not be uniformly reversible. Of special note are some uncommon imaging features (unilateral cerebral involvement, and isolated posterior fossa involvement) and also some uncommon complications (haemorrhage, cytotoxic oedema, and vasoconstriction). These red herrings may lead to potential diagnostic challenges and pitfalls especially for trainee radiologists, who often read these scans in an emergency setting. Early and accurate diagnosis is crucial for prompt optimum management, thereby avoiding residual morbidity. This review article focusses on the atypical radiological features of PRES in adults with extensive case-based imaging examples. A brief description of the pathophysiology, clinical, and classic radiological features of PRES has also been included. A tabulated summary of potential mimics with diagnostic pearls is provided to highlight pertinent take home points and to serve as an easy guide for day-to-day clinical practice.

Laser interstitial thermal therapy (LITT) is a minimally invasive neurosurgical technique that has been demonstrated to successfully ablate intracranial tumors. While LITT for supratentorial lesions can often be straightforward, ablation of infratentorial lesions can be difficult with current targeting technologies and instrumentation. The anatomical difficulty of targeting posterior fossa masses can be further complicated in patients who have had a prior craniectomy or other procedure that removed the bone that is required to set the surgical trajectory. This article describes use of a three-dimensional (3D)–printed customized surgical implant to improve and enable targeting of posterior fossa lesions using LITT, particularly in the setting of prior craniectomy. A 3D-printed implant was customized for a patient with a history of metastatic lung cancer and prior posterior fossa craniectomy who presented for treatment of a progressively enlarging contrast-enhancing lesion in the right cerebellar hemisphere. The device included a built-in bolt trajectory for LITT ablation. The temporary implant was successfully fabricated for use with laser ablation of a right cerebellar mass. Three potential trajectories for the LITT bolt were incorporated into the temporary implant, but only the primary trajectory was utilized. Laser ablation was performed with the implant and a SideFire laser probe. Customized 3D-printed implants can enable the use of LITT for patients who would not otherwise be candidates.

Rosai–Dorfman disease is a non–Langherans cell histiocytosis typically revealed by a lymphadenopathy. Central nervous system involvement is rare, exceptionally isolated, and usually consists of dural masses mimicking meningioma. Very few reports have described non-dural-based lesions, especially with an intra-ventricular development. We report hereby the case of a Rosai–Dorfman disease in a 30-year-old man presenting as an isolated mass arising from the right cerebellar peduncle and protruding into the fourth ventricle. We provide the results of the MRI examination with a special focus on advanced MRI features. As the diagnosis relies on pathological examination, we also detail the results of the analysis that followed the surgical resection of the mass including the immunohistochemical profile. This report highlights the necessity to consider Rosai–Dorfman disease as a potential diagnosis in case of an infra–tentorial mass and/or intra-ventricular mass.

Background The best surgical treatment for adult Chiari malformation type 1 remains widely debated. Objective This study aimed to assess the efficacy of posterior fossa decompression and duraplasty with arachnoid preservation compared with arachnoid dissection for the treatment of adult Chiari malformation type 1. Methods Two reviewers (M.O.-G. and M.A.) performed a PubMed, MEDLINE, and Embase literature search using the following terms: (“Chiari” OR “Chiari 1”) AND (“duraplasty” OR “arachnoid preservation” OR “arachnoid spar∗” OR “posterior fossa surgery” OR “posterior fossa decompression” OR “foramen magnum decompression”). Studies assessing the efficacy of posterior fossa decompression with duraplasty for the treatment of patients aged >18 years with Chiari malformation type 1 were included. Case reports with Results Of 195 studies identified, 24 were included for meta-analysis. In the 1006 participants, there was no difference in postoperative clinical or radiologic improvement between the 2 techniques. Patients who underwent posterior fossa decompression with duraplasty and arachnoid dissection had a greater prevalence of total complications (0.20, 95% confidence interval [CI], 0.13–0.29 vs. 0.09, 95% CI, 0.05–0.14; Q = 6.47; P = 0.01) and cerebrospinal fluid–related complications (0.15, 95% CI, 0.10–0.22 vs. 0.05, 95% CI, 0.02–0.12; Q = 4.88; P = 0.03) compared with arachnoid preservation. Furthermore, the prevalence of reoperation in the arachnoid dissection group was 25 times greater than in the arachnoid preservation group (0.08, 95% CI, 0.06–0.10 vs. 0.003, 95% CI, 0.00–0.02; Q = 10.73; P > 0.001). Conclusions Posterior fossa decompression and duraplasty with arachnoid preservation is a beneficial technique to treat Chiari malformation type 1 and reduces the risk of complications, particularly cerebrospinal fluid–related complications and the rate of reoperation.

Surgery is the definitive treatment option for symptomatic Chiari malformation I (CMI), but there is no clear consensus as to the preferred surgical method. This study aimed to quantitatively assess and compare the effect and safety of dura splitting decompression (DSD) and posterior fossa decompression with duraplasty (PFDD) in treating patients with CMI.A literature search of EMBASE, MEDLINE, PubMed, Cochrane Library, and Web of Science databases was conducted. References from January 1990 to September 2020 were retrieved. We only included papers containing original data, comparing the use of DSD and PFDD in CMI patients.Overall, 11 relevant studies were identified, wherein 443 patients treated for CMI by DSD were compared with 261 patients treated by PFDD. No difference was observed between PFDD and PFD in terms of clinical improvement (P = 0.69), syringomyelia improvement (P = 0.90), or reoperation (P = 0.22). DSD was associated with shorter operation durations (P = 0.0007), shorter length of stay (P = 0.0007), and shorter overall postoperative complications (P0.0001) (especially cerebrospinal fluid [CSF] leak [P = 0.005], meningitis [P = 0.002], and pseudomeningocele [P = 0.002]), as compared with PFDD.This study confirmed that dura splitting decompression has clinical and syringomyelia improvement outcomes comparable to posterior fossa decompression with duraplasty. Compared with PFDD, DSD not only significantly shortened the operation time and length of stay, but also significantly reduced the overall complication rate, especially those related to incidence of CSF-related complications. More evidence from advanced multicenter studies are needed to require to validate the findings.

Background Tension pneumoventricle (TPV) is a subtype of tension pneumocephalus in which the air is trapped inside the ventricles through a one-way osteodural defect, causing an increase in intracranial pressure. TPV secondary to cutaneous-ventricular fistula has been reported only twice in the literature. Case Description Herein, we report the third case in a 53-year-old woman who developed TPV with decreased level of consciousness after removal of a posterior fossa meningioma while she was on external ventricular drainage. There was no identifiable bony defect on neuroimaging. The drain was changed urgently, and the fistula located at the drain tunneling site was sealed. Conclusions This case report highlights the importance of suspecting and treating cutaneous-ventricular fistulas in TPV urgently in patients without skull base defects or those who showed no improvements with external ventricular drainage.

Background Considering that primary watertight dural closure is not always possible following posterior fossa surgery, several methods of dural reconstruction were proposed to reduce the risk of cerebrospinal fluid (CSF) leakage. This study aimed to evaluate the efficacy of collagen matrix inlay graft compared with other techniques in a propensity score–matched cohort. Methods Between 2000 and 2019, 176 consecutive patients who underwent posterior fossa surgery were enrolled. Of these, 103 patients underwent dural reconstruction with collagen matrix inlay graft (inlay group). After propensity score matching, 67 pairs were derived. The primary outcome was the development of CSF leakage. Pseudomeningocele and surgical site infection were also investigated. Results Median follow-up period was 53.9 months. None of the patients in the inlay group had CSF leakage; however, leakage was evident in 5 patients (6.8%) who underwent dural reconstruction without a collagen matrix inlay graft (no-inlay group; P = 0.011). Pseudomeningocele was noted in 1 (1.4%) patient in the no-inlay group, while surgical site infection was noted in 3 (3.0%) patients in the inlay group and 4 (5.5%) patients in the no-inlay group. None of the surgical site infections were related to the use of the inlay graft. After propensity score matching, CSF leakage was still prevalent in the no-inlay group (P = 0.042). Conclusions Dural reconstruction using a collagen matrix inlay graft efficiently reduces CSF leakage after posterior fossa surgery and does not increase the risk of postoperative infection and inflammation. It seems to be a feasible option for dural reconstruction.

OBJECTIVE Posterior fossa ependymoma (PF-EPN) was categorized into PF-EPN-A and PF-EPN-B subgroups based on the DNA methylation profiling. PF-EPN-A was reported to have poorer prognosis compared with PF-EPN-B. In this study, we particularly evaluated preoperative imaging to distinguish PF-EPN-A from PF-EPN-B. METHODS Sixteen cases of PF-EPN were treated in our institution from 1999 to 2018. The patients were divided into PF-EPN-A and PF-EPN-B groups based on H3K27me3 immunostaining positivity. We evaluated progression-free survival, overall survival, as well as preoperative magnetic resonance imaging and computed tomography scan images in both groups. Based on T1WI and Gd-T1WI magnetic resonance images, the tumor contrast rate was determined from dividing the volume of gadolinium enhanced tumor by the overall tumor volume. RESULTS Nine cases (4 male, 5 female) were grouped as PF-EPN-A, and 7 (4 male, 3 female) as PF-EPN-B. The median age of PF-EPN-A and PF-EPN-B were 4 and 43 years old, respectively. In the PF-EPN-A group, the progression-free survival median value was 32.6 months, and the overall survival median was 96.9 months. In contrast, PFS in PF-EPN-B did not reach a median value (P < 0.05) and all the patients were alive (P < 0.05) at the end of the study. With imaging, tumor contrast rate in PF-EPN-B was more than 50% and significantly different from PF-EPN-A (P = 0.0294). Calcification was mainly observed in PF-EPN-A, whereas cystic formation was only seen in PF-EPN-B. CONCLUSIONS Contrast rate less than 50%, based on the magnetic resonance images, was characteristic in the PF-EPN-A group. Comparatively, cystic component and absence of calcification were more characteristic in the PF-EPN-B group.

Pleomorphic xanthoastrocytoma (PXA) is a rare glioma usually occurring in children and young adults. It is a benign World Health Organization (WHO) grade II tumor that accounts for

Background Tissue diagnosis for lesions in the posterior fossa, such as the brainstem, cerebellar peduncle, and cerebellum, is an important determinant of the next treatment option. Herein, we present our 10-year experience with magnetic resonance imaging (MRI)–guided frame–based stereotactic biopsy for 39 patients with posterior fossa lesions, the largest case series in this matter. Methods We performed a retrospective cross-sectional study on all patients with posterior fossa lesion admitted to 2 referral centers between 2006 and 2016. We used Leksell Frame G for stereotactic biopsy of all patients. MRI systems of both hospitals were 1.5 T. Results We performed analysis on the 39 cases (21 men and 18 women). Age of the patients ranged between 9 and 73 years (mean, 35.4 ± 15.7 years). Localization success rate was 100%. For 38 patients (97.4%), tissue sample size was enough for tissue diagnosis. For 1 case, it was insufficient and nondiagnostic. In this series, we had no surgery-related complications. Conclusions We present the largest reported series of MRI-guided frame-based stereotactic biopsy of the posterior fossa lesions via a transcerebellar route. We prefer oblique positioning of the frame on the skull and use a transcerebellar route to reduce surgical complications and achieve a greater localization success rate.

Background Infratentorial multinodular lesions resembling multinodular and vacuolating neuronal tumor of the cerebrum (MVNT) have been indicated in literature with 2 different names reflecting alternative perspectives: multinodular and vacuolating posterior fossa lesions of unknown significance (MV-PLUS), suggesting that these lesions may belong to a new entity, and MVNT of the brain, assuming that they actually correspond to infratentorial MVNT. Because of the limited number of cases reported and the absence of histopathologic data, it is unclear which denomination should be used. Cases Description Two patients, a 41-year-old man (case 1) suffering headache and a 44-year-old man (case 2) with vertigo, underwent magnetic resonance imaging (MRI) examination. MRI showed, in both cases, multinodular lesions involving the vermis, broadly extending to the superior part of the right cerebellar hemisphere in case 1, and involving the superior paravermian part of the left cerebellar hemisphere in case 2. The follow-up period was 3 years in case 1 and 14 years in case 2. Conclusions Infratentorial lesions show nodules with cystic or cyst-like signal intensity on MRI, a feature infrequently reported in supratentorial MVNT, and may involve the cortex. No variations were noted during a prolonged follow-up supporting the benign behavior of these lesions.

Schwannomas of the glossopharyngeal nerve are extremely rare tumors of the posterior fossa. In a 100-year review, a total of 42 cases were found between 1908-2008. The most common clinical data are associated with its location, the most common being cochlear vestibule symptoms and symptoms of glossopharyngeal nerve function. its diagnosis has now been facilitated by the use of magnetic resonance, however, it is very complicated to define preoperatively if the tumor originates from the ix, x or xi NC. We present the case of a 42-year-old patient with a syndrome of angulopentocerebellar syndrome, posterior torn (jugular) hole syndrome + anterior condyle (Collet-Sicard). The treatment used was surgical with transcondylar lateral extreme approach, with monitoring of cranial nerves and trans-operative evoked potentials.

Background The portion of the occipital condyle that is safe to remove remains controversial in the transcondylar approach. We aimed to correlate the gain in exposure with incremental removal of the occipital condyle to determine if there is a point where further drilling yields diminishing gains. Methods Virtual reality rendering of the skull was generated from 25 subjects with no posterior fossa pathology. A suboccipital far lateral craniotomy was done in virtual reality space, stopping at the posterior edge of the occipital condyle. Angular measurements of surgical corridor were taken at this point and after removal of 25% and 50% of the condyle. Two surgical targets were used: at the anterior midline of the foramen magnum and the vertebrobasilar junction. Results Progressive removal of the occipital condyle increased exposure to both targets in a linear fashion. For the midline of the foramen magnum, the working angle increased from 12° to 18° for quarter condylectomy and then to 25° for half condylectomy. The corridor to the vertebrobasilar junction was much tighter, and the angle increased from 5.5° to 9° for quarter condylectomy and then to 12° for half condylectomy. The gain in exposure for the low target was greater than for the high target (P Conclusions Progressive removal of the occipital condyle yielded a linear increase in exposure without an ideal point beyond which the drilling was futile. However, the impact of condylectomy was greater for our low target compared with our high target.

Ependymomas are neuroepithelial tumors that differentiate along the ependymal cell lineage, a lining of the ventricles of the brain and the central canal of the spinal cord. They are rare in adults, but account for around 9% of brain tumors in children, where they usually have an aggressive course. Efficient stratification could lead to improved care but remains a challenge even in the genomic era. Recent studies proposed a multivariate classification system based on tumor location, age, and broad genomic findings like global patterns of methylation and copy number variants (CNVs). This system shows improved prognostic utility, but is relatively impractical in the routine clinical setting because it necessitates multiple diagnostic tests. We analyzed 13 intracranial grade II and III ependymoma specimens on a DNA microarray to identify discrete CNVs that could support the existing classification. The loss of chr22 and the gain of 5p15.31 were common throughout our cohort (6 and 11 cases, respectively). Other CNVs correlated well with the previously proposed classification system. For example, gains of chr20 were unique to PF-EPN-B tumors of the posterior fossa and may differentiate them from PF-EPN-A. Given the ease of detecting CNVs using multiple, clinically validated methods, these CNVs should be further studied to confirm their diagnostic and prognostic utility, for incorporation into clinical testing algorithms.

In a breakthrough study in a recent issue of Cell, Michealraj et al. (2020) demonstrate that posterior fossa A ependymoma, a lethal pediatric brain tumor with a silent genome, is dependent upon metabolic changes associated with hypoxia that drive the tumor's characteristic epigenetic dysregulation.

Background Postoperative hemorrhage is a serious complication of intracranial surgery. Epidural hematomas (EDHs) are one of the common forms of bleeding after surgery, with ≤12% of patients requiring re-exploration. However, distant or remote site EDHs have been rare, in particular, those in a supratentorial location after infratentorial surgery. Case Description We report an unusual complication of surgery for fourth ventricular outlet obstruction. A young male patient developed multiple sequential supratentorial EDHs after posterior fossa surgery. He required 2 re-explorations after the primary surgery for evacuation of the EDHs within 24 hours. In the available data, we found only 28 such reported cases previously. Only 2 additional cases have been reported to have sequential EDHs after surgery. Various theories have been postulated, ranging from sudden intracranial pressure decompression, pin site hematoma, and shunt site bleeding due to dural stripping. None has been proven to definitively explain the complication. Conclusions We wished to highlight this unusual complication of posterior fossa surgery, with an emphasis on rapid computed tomography scanning of the brain for patients in the early postoperative period with any neurological deterioration. Early radiological detection and timely intervention can be lifesaving.

Neuro-otologists rely on the expertise and judgment of a skilled neuroradiologist to identify radiographic abnormalities in the complicated regional anatomy of the temporal bone and middle and posterior fossa, and more importantly, to alert the surgeon to potential operative pitfalls. This article highlights some of the common otologic surgical procedures that stress this important dynamic. The surgical perspective on quick and effective clinical decision-making pearls to keep in mind during a thorough radiographic analysis of the ear and lateral skull base is presented.

Background: The etiology of Chiari I malformation (CMI) has not been fully elucidated. Therefore, we performed a genetic study of a Turkish family in which 3 sisters had a diagnosis of CMI with or without syringomyelia. Methods: In a family with 7 children, 4 daughters complained of occipital headaches. In 2 of these daughters, CMI had been diagnosed during their 30s, and CMI plus syrinx had been diagnosed in the other daughter in her 40s. Cranial magnetic resonance imaging of the fourth daughter who had developed headaches during her 30s showed normal findings. Because the other siblings in the family were asymptomatic, radiological examinations were not performed. The family had a history of distant consanguineous marriage between parents. Additionally, the father had died, and the mother was asymptomatic, with radiologically normal findings. Array comparative genome hybridization studies were performed for 12 persons from 3 generations of this family. Results: None of the 12 cases examined harbored copy number variations. Conclusions: This family with 3 sisters having CMI suggested a possible autosomal recessive single-gene etiology. Cases of familial CMI are unusual but important to study because they could reveal the specific genes involved in posterior fossa/foramen magnum structure and function and provide insights into the cause of sporadic cases. © 2018 Elsevier Inc.

Introduction The term pneumocephalus refers to the existence of air in any intracranial compartment. Its presence in the follows of a supratentorial craniotomy is very common, and it usually represents a benign complication as it is very rarely responsible for clinical manifestations. Case presentation We report the case of a 24 years-old man, who underwent posterior fossa surgery in prone position for resection of a vermian tumor. Postoperative, the patient presented a tonic-clonic generalized seizure associated to high levels of arterial pressure and decerebration. Control CT scan showed an important pneumocephalus. On the posterior fossa, the air was responsible for a compression of the brainstem, without any other postoperative complications. Following 12 h of conservative management, a brain MRI showed a total regression of the pneumocephalus. 3 days later, the patient presented a favorable outcome as he was extubated without any major impairments. Discussion Transformation of pneumocephalus into tension pneumocephalus responsible for clinical inadvertance is rare. This complication is mainly related to surgeries performed in sitting position. The occurrence of compressive pneumocephalus after a posterior fossa craniotomy performed in a prone position is seldom. Conclusions Through this case, we discuss pathophysiology and therapeutic approaches for tension pneumocephalus following posterior fossa performed in prone position., Highlights • Pneumocephalus may be source for major postoperative inadvertance • Tension pneumocephalus was reported in supratentorial surgeries. Posterior fossa craniotomies may also lead to this inadvertence. • Rigorous peroperative prevention of pneumocephalus should be considered in order to minimize complications.

Objective Posterior fossa tumor surgery is associated with a significant risk of complications, and the complications are typically more frequent compared with similar supratentorial surgeries. This study aimed to evaluate 1) the extent of resection and neurologic outcomes and 2) perioperative complications with use of minimally invasive approaches for intra-axial posterior fossa tumors from our case series. Methods All consecutive patients who underwent nonbiopsy surgery of a posterior fossa tumor using tubular retractors and exoscopic visualization from January 2016 to May 2018 were prospectively identified and included. Results During the reviewed period, 15 patients underwent resection of an intra-axial posterior fossa tumor. Eight (53%) patients were men, and the median age was 63.0 years (interquartile range: 45.0–67.5 years). The tumor was located in the cerebellar hemisphere in 11 (73%) cases, vermis in 3 (20%) cases, and middle cerebellar peduncle in 1 (7%) case. The median preoperative and postoperative lesion volumes were 21.6 cm3 (interquartile range: 10.1–33.0 cm3) and 0 cm3 (interquartile range: 0–1.2 cm3), respectively. The percent resection was 100% (92%-100%). Following surgery, 12 (80%) patients had improved and 3 (20%) patients had stable Karnofsky performance scale scores, whereas no patients had a decline in Karnofsky performance scale score postoperatively. No patients incurred other postoperative regional or medical complications. Conclusions We demonstrated the possible efficacy of a minimally invasive approach with the use of tubular retractors and exoscopic visualization for resecting posterior fossa intra-axial tumors with relatively high efficacy and low morbidity.

With advances in fetal imaging, prenatal diagnosis of posterior fossa anomalies has been greatly improved. Based on the anatomical approach proposed by Guibaud and Desportes in 2006, the main anomalies depicted according to the algorithm includes: (1) increased "fluid-filled" space of the posterior fossa, (2) abnormal biometry of the cerebellum, and (3) abnormal cerebellar anatomy. In this review, the spectrum of PF anomalies is covered in an attempt to update this approach in the light of both our experience, more than a decade since this algorithm was published, and the latest data in the literature.

Background A ruptured vertebral artery dissecting aneurysm (VADA) with a high clinical grade (Hunt and Hess grade 5) has a devastating prognosis. Because of the high rebleeding rate and location, rapid mortality can occur in patients owing to brainstem compression. Adjuvant decompression of the posterior fossa after securing the aneurysm may improve the outcomes of these patients. Methods Between January 2011 and December 2016, 22 patients who presented with Hunt and Hess grade 5 ruptured VADA underwent endovascular treatment. Patients were divided into 2 groups: group 1 (n = 12) received conventional endovascular treatment of VADA and external ventricular drainage, and group 2 (n = 10) received external ventricular drainage and suboccipital craniectomy for posterior fossa decompression after rapid endovascular trapping of VADA. Results In group 2, the survival rate and good clinical outcome rate (modified Rankin scale score ≤2) were 80% and 60%, respectively, which were favorable to the corresponding rates in group 1 (66.67% and 16.67%). Moreover, 80% of patients (8/10) in group 2 regained consciousness compared with 50% of patients in group 1. Conclusions Adjuvant decompression of the posterior fossa can improve outcomes in patients with Hunt and Hess grade V ruptured VADA.

Background Acute subdural hematomas are frequently seen in brain trauma−injured patients. However, spontaneous subdural hematomas are uncommon, especially those localized in the posterior fossa, where fewer than 10 case reports have been described in the medical literature. Case Description We describe a patient who suddenly had a headache and progressed rapidly to coma and signs of brainstem compression. She was diagnosed with posterior fossa subdural hematoma after image examinations that were endorsed by surgical findings. A posterior fossa craniectomy was performed and was associated with blood drainage. Conclusions The patient had a great outcome, with no neurologic deficits at hospital discharge and the 1-year follow-up.

We report our initial experience using Minimally-Invasive Surgery (MIS) technique for Posterior Fossa Decompression (PFD) in Adult Chiari 1 Malformation (C1M) patients. Five subjects who were treated with MIS PFD at our center and followed up over a 5-year period. Another nine subjects who were treated with Open PFD and follow up over the same period were used for comparison. This study suggests that there are little differences in efficacy and safety between MIS and Open PFD. Larger series and prospective randomized trials comparing the two methods would provide higher-quality evidence and clarify the role of either technique in the treatment of C1M.

Brain metastases (BMs) have a major impact on life expectancy and quality of life for many breast cancer patients. Knowledge about treatment patterns and outcomes is limited.We analysed clinical data of 1712 patients diagnosed with BMs from breast cancer between January 2000 and December 2016 at 80 institutions.Median age at diagnosis of BMs was 56 years (22-90 years). About 47.8% (n = 732) of patients had HER2-positive, 21.4% (n = 328) had triple-negative and 30.8% (n = 471) had hormone receptor (HR)-positive, HER2-negative (luminal-like) primary tumours. The proportion of patients with HER2-positive BMs decreased comparing the years 2000-2009 with 2010-2015 (51%-44%), whereas the percentage of patients with luminal-like tumours increased (28%-34%; p = 0.0331). Patients with BMs in the posterior fossa were more often HER2 positive (n = 169/314, 53.8%) than those diagnosed with triple-negative (n = 65/314, 20.7%) or luminal-like primary breast cancer (n = 80/314, 25.5%), (p 0.0001). Median overall survival (OS) time after development of BMs for the overall cohort was 7.4 months (95% confidence interval [CI]: 6.7-8.0 months). One-year survival rate was 37.7% (95% CI: 35.2-40.1). Patients with HER2-positive tumours had the longest median OS of 11.6 months (95% CI: 10.0-13.4) compared with 5.9 months (95% CI: 5.0-7.2) for patients with luminal-like and 4.6 months (95% CI: 3.9-5.4) for patients with triple-negative tumours. Patients with HER2-positive tumours who received anti-HER2 treatment had longer median OS than those without (17.1 months versus 7.2 months, p 0.0001).Prognosis of patients after developing BMs varies significantly according to the subtype. The outcome in this cohort is similarly poor in triple-negative and HR-positive/HER2-negative patients. Our results underline the high medical need for improvement of treatment and prevention strategies for BMs in breast cancer patients.

Background There is no consensus concerning the management of adult patients with posterior fossa metastasis–associated obstructive hydrocephalus, especially regarding surgical procedures. A literature review was performed to assess the surgical strategy in the management of patients with metastatic brain tumor. Methods A literature search was conducted of PubMed in November 2017 to identify all studies concerning brain metastases and obstructive hydrocephalus in English. All studies (except case reports and pediatric studies) between December 1953 and November 2017 that were about posterior fossa metastasis–associated obstructive hydrocephalus in adult patients were eligible. Eligible studies were classified by level of evidence. We assessed epidemiology, clinical and imaging findings, neurosurgical management, and prognosis of adult patients with posterior fossa metastasis–associated obstructive hydrocephalus. We suggest some practical considerations and a management decision tree on behalf of the Neuro-oncology Club of the French Society of Neurosurgery, with evidence-based analysis. Results Direct surgical resection could be considered for patients with asymptomatic obstructive hydrocephalus, and endoscopic third ventriculostomy seems to be a reasonable procedure for patients with symptomatic obstructive hydrocephalus. A ventriculoperitoneal or atrial shunt seems to be a valid alternative when patients have a history of central nervous system infection or ventricular hemorrhage, leptomeningeal carcinomatosis, or unfavorable anatomy for an endoscopic third ventriculostomy to be performed. Conclusions The Neuro-oncology Club of the French Society of Neurosurgery suggests a prospective assessment of these neurosurgical procedures to compare their safety and efficacy.

Rosette-forming glioneuronal tumor of the fourth ventricle is a primary central nervous system tumor introduced in the group of glioneuronal tumors in the WHO classification of 2007. Initially it was described around the fourth ventricle, but recently have been published cases in different locations. We present 2cases of this rare tumor, both surgically treated. The first in a 41 year old man with typical symptoms of posterior fossa injury. The second in an 18 year old woman, with incidental finding of posterior fossa injury that was also surgically treated. We present pre- and post-surgical magnetic resonance images, histological pictures of this tumor and we make a review of the literature.

Cranial ultrasonography is a reliable and readily available tool for neonatal brain imaging. It has become indispensable in the care of neonates as it helps to detect common congenital and acquired brain abnormalities. The use of modern ultrasound scan machines with the appropriate choice of probes, settings and acoustic windows has improved the diagnostic value of the cranial ultrasound in experienced hands. The standard acoustic window for imaging is the anterior fontanelle which is suitable for viewing the supratentorial structures. However, supplementary acoustic windows can be used for better visualisation of brain stem and posterior fossa structures. Doppler studies help to assess flow velocities in major vessels. Though cranial ultrasound has numerous advantages, it has some limitations. This article reviews the practical aspects of performing cranial ultrasound in a neonate.

Background Hypertrophic olivary degeneration (HOD) occurs because of posterior fossa or brainstem lesions that disrupt the dentato-rubro-olivary tract, well known as the Guillain-Mollaret triangle. Clinical and radiologic hallmarks of this condition are palatal myoclonus and T2 hyperintensity of the inferior olivary complex on magnetic resonance imaging (MRI), respectively. Because symptomatic HOD can complicate the recovery of patients with posterior fossa or brainstem lesions, the purpose of this study is to evaluate clinical and imaging findings of patients with HOD. Methods Sixteen patients (8 female and 8 male) with a mean age of 40.7 years, (range, 5–83 years) years were included in this study based on clinical symptoms and MRI findings. Results We reviewed the clinical and imaging findings in 16 cases of HOD at our institution. Seven patients (43.7%) had posterior fossa tumors, 6 patients (37.5%) had cavernoma, 2 patients (12.5%) sustained traumatic brain injury, and only 1 patient (6.2%) had cerebellar infarction. Posterior fossa surgery was performed in 13 (81.2%) of these patients. HOD was detected a mean of 7.2 months (range, 0.5–18 months) after surgery or primary neurologic insult. Unilateral HOD was observed in 10 patients (62.5%), while bilateral HOD was observed in only 6 patients (37.5%). Seven patients (43.7%) were asymptomatic for HOD, whereas 5 patients (31.2%) had symptoms attributable to HOD. Two patients died because of primary tumors, although mean follow-up after detection of HOD on MRI was 52.2 months (range, 1–120 months) in the remaining 14 patients. In these cases, no change in clinical symptoms or imaging findings was detected during follow-up. Conclusions In this series, posterior fossa tumors and cavernomas were the most common causes of HOD. Although most of the patients with HOD remained asymptomatic, HOD complicated the course of recovery in almost one quarter of the patients included in this study. Neurosurgeons should be aware of HOD, which has characteristic clinical and imaging findings. In addition, HOD can complicate the recovery of patients with disruption to the dentato-rubro-olivary tract.

Medulloblastoma is the most common posterior fossa tumor of childhood typically within the fourth ventricle. However, extra-axial medulloblastoma in posterior fossa is an uncommon diagnosis. We report a case in a 33-month-old male who presented with repeated complaints of abdominal pain, intermittent emesis, and diarrhea, and diagnosed with right cerebellar extra-axial medulloblastoma, which was surgically resected. Majority of the reported extra-axial medulloblastoma in posterior fossa in the United States are located in the cerebellopontine angle. However, to the best of our knowledge, our case is the first to document medulloblastoma occurring exclusively in the cerebellar hemispheric extra-axial space rather than the cerebellopontine angle. Although the diagnosis can present as a radiological dilemma, a systematic multimodality imaging approach can aid in narrowing the differential diagnosis and timely management. In this case report, we will discuss the imaging characteristics, differential diagnosis, and management strategies, alongside a brief review of the world literature of extra-axial medulloblastoma. Keywords: Medulloblastoma, Pediatric neoplasm, Posterior fossa tumors, Extra-axial

A 4-year-old girl presented repeatedly with a complicated occipital mass, which was erroneously treated as a pyogenic granuloma. Imaging performed before a planned surgical resection detected an underlying intraoccipital dermoid with a sinus tract to the skin surface and extension into the posterior fossa. This case highlights the value of high-resolution computed tomography imaging for depiction of anatomic details and the value of magnetic resonance imaging for differential diagnosis and surgical management. A comprehensive literature review of intraosseous dermoid cyst and detailed discussion of the differential diagnoses are provided.

The diagnosis of ischemic stroke in Posterior Fossa (PF) using conventional Computed Tomography (CT) is limited. Meanwhile, the identification of PF slices in CT is a very complicated task due to their varying structures for each slices. Traditionally, the identification of PF slices by the radiologist is based on the PF structure that present in the CT images. This procedure can introduce misidentification issue and time consuming. In this paper, a method for automated classification of PF slices in CT brain images is investigated to sort the slice that contains PF for further study of ischemic stroke detection. This framework employs 11 features of Gray Level Co-Occurrence Matrix (GLCM). All the obtained features have been passed through Artificial Neural Network (ANN) classifier using Multilayer Perceptron (MLP) architecture. The experimental results show that, the combination of GLCM with ANN is promising to be applied in the classification of PF slices as they can provide 93%, 92.5% and 94.2% of precision, recall, and accuracy average rate respectively with average processing time of 0.36 seconds per slices.

Highlights • Brain metastases are rare forms of manifestations of gastro-intestinal stromal tumors. • Brain metastases of gastro-intestinal stromal tumors are usually supra-tentorial. Infra-tentorial localizations are very rare. • The treatment is based on surgery and radiotherapy. Chemotherapy has only limited interest., Introduction Intracranial metastases of gastro intestinal tumors are very rare. To the best of our knowledge only few cases were reported on the literature. Case description We describe the case of 66-year-old male that presented with headache and vomiting. Physical examination found a kinetic cerebellar syndrome. Brain CT scan and MRI showed a right cerebellar tumor. Sub-occipital craniotomy was performed and the tumor was completely resected. Surgical outcomes were marked by the occurrence of an abdominal pain two days after brain surgery. Peritonitis was diagnosed and the patient underwent surgery. Per-operatively, a hemorrhagic tumor perforating the intestines was found and resected. Pathologic examination of the cerebral tumor's resection piece and the intestinal resection piece concluded to a metastasis of a stromal gastro-intestinal tumor. Discussion Gastro-intestinal stromal tumors are frequent neoplasms, but intracranial metastases of these neoplasms are extremely rare. Abdominal symptomatology frequently reveals the pathology. However, extra digestive symptoms may in rare cases disclose intestinal tumors. Intracranial metastases of gastro-intestinal stromal tumors are generally solitary mainly supratentorial. Infratentorial metastases are very uncommon. Management of gastro-intestinal stromal tumors is based on surgical removal of the tumor. Adjuvant treatment consisting on chemotherapy and radiotherapy is subject of debate. Conclusions Gastro-intestinal stromal tumors are frequent neoplasms with a high metastasizing potential on liver and peritoneum. Brain metastases are extremely rare and the prognosis is worse when they are present. Surgery remains the main treatment for the primitive and the secondary lesions.

Background: Arteriovenous malformations (AVMs) of the superior vermis are extremely rare. Although they have a higher rate of hemorrhagic presentations than supratentorial AVMs, the surgical approaches for AVMs at this location remain controversial. Case description: We report the case of a 73-year-old man with a hemorrhagic superior vermian AVM that was treated with surgical resection through the occipital transtentorial approach (OTA). This approach, with a direct perpendicular view of the whole lesion, enabled us to control the feeding arteries safely and to finally accomplish a total resection. Conclusions: The OTA is an elegant approach for the resection of superior vermian AVMs. Detailed assessment of angiographic features is mandatory in selecting an effective and safe surgical approach for posterior fossa AVMs depending on their location. Keywords: Arteriovenous malformation, Occipital transtentorial, Posterior fossa, Superior vermian, Surgical approach

Chiari malformations have long been considered sporadic conditions, without a heritable etiology. However, there have been a number of case reports identifying familial aggregation and clustering of Chiari malformation type 1, suggesting a genetic basis. The authors report a 53 years old mother and 32 years old daughter duo, who presented with symptomatic Chiari malformation type 1 suggesting familial transmission. A literature review was conducted and familial Chiari malformation type 1 has been increasingly reported, however, genetic data are still under investigation. Clinicians need to be aware of familial Chiari malformation type 1 that could help in early identification and intervention for family members at risk, allowing for improved patient outcome.

The discovery of the important role of cerebrospinal fluid (CSF) drainage of cerebral metabolite waste, known as the glymphatic system, has changed our view of brain waste clearance. We recently performed experiments to evaluate the glymphatic system in non-human primates (NHP). Here, we report the case of an NHP with iatrogenic CSF leakage. In this animal, solute transport through the brain, assessed by gadolinium injection in the CSF, was severely impaired by iatrogenic pseudomeningocele. This observation raises an important question: does brain surgery, and particularly posterior fossa surgery, lead to chronic impairment of parenchymal CSF circulation and solute transport?

Objective The effective treatment of posterior fossa ependymomas is surgery followed by radio-chemotherapy. Our aim is to evaluate the effects of sex, age, methylation subgrouping, extent of resection, radiation treatment (RT), MIB-1 index, grade, ATRX and H3K27M mutations on prognosis in pediatric patients with posterior fossa ependymoma (PFE). Methodology This is a retrospective study. Forty-two children with PFE who had surgery in our institution between 1996 and 2018 were included. Formalin-fixed paraffin-embedded tumor samples were evaluated for H3K27me3 immunostaining, MIB-1 index, WHO grades, ATRX and H3K27M mutations.Samples with global H3K27me3 reduction were grouped as posterior fossa ependymoma group A (PFA), whereas tumor samples with H3K27me3 nuclear immunopositivity were grouped as posterior fossa ependymoma group B (PFB). Results Mean age of patients was 4.4 years (range 0.71-14.51). Thirty-one patients (73.8%) were PFA, whereas 11 patients (26.2%) were PFB. WHO grades of PFAs were statistically higher in comparison to WHO grades of PFBs. There are no significant differences between PFAs and PFBs in terms of resection rates, disease recurrence and survival parameters.Patients with total surgical excisions had significantly better PFS and OS rates. Conclusion Extent of surgical excision is the most important prognostic indicator in PFEs. Prognostic effect of methylation subgrouping may be minimized with more aggressive surgical strategy in PFAs.

Posterior fossa cystic lesions display a diagnostic challenge as the apparent simplistic image portrays a vast array of pathological entities. We hereby present the case of mature cystic teratoma of the posterior fossa with atypical radiological appearance, in a previously healthy 6-month old male, presenting with increased head circumferences, non-communicating hydrocephalus. The lesion underwent en bloc resection, and the infant was discharged home a week later with no neurological deficits. Follow-up MRI did not demonstrate any evidence of recurrence or residual tumor.

Background: Shared indications about the best management of intra-axial thalamic (IAT) and posterior fossa (PF) pediatric tumors are still lacking. The aim of this study was to analyze neurosurgical outcome in these tumors and to investigate factors associated with postoperative worsening. Methods: A retrospective single-center study on IAT and PF pediatric tumor patients treated surgically over a 7-year period was conducted. The Lansky Scale (LS) was used to assess patients’ functional status. Surgical complexity was graded with the Milan Complexity Scale (MCS). The following analyses were performed: a longitudinal analysis of the preoperative, discharge, and 3 months’ follow-up (FU) LS, a comparison between improved/unchanged and worsened patients, and an analysis of the predictive value of single MCS items. Results: 37 cases were collected: 20 PF and 17 thalamic. Mean MCS score was 6 ± 1.7. Mean preoperative, discharge and FU LS were 80.8, 74.6 and 80.3 respectively. Surgical mortality was 0%.The longitudinal analysis showed a neurological worsening at discharge compared to preoperative status (p = 0.011) and an improvement at FU compared to discharge (p

Obstetric protocols dictate that the fetal cerebellum should always be assessed during sonograms during pregnancy. For various reasons, including technical limitations or inconclusive sonographic findings, suspicion of cerebellar abnormalities is one of the most common indications for prenatal magnetic resonance imaging (MRI). Although sonography is the imaging technique of choice to assess the cerebellum, MRI shows the anatomy of the posterior fossa and abnormalities in the development of the fetal cerebellum in greater detail and thus enables a more accurate prenatal diagnosis. We describe and illustrate the normal anatomy of the fetal cerebellum on MRI as well as the different diseases that can affect its development. Moreover, we review the most appropriate terminology to define developmental abnormalities, their differential diagnoses, and the role of MRI in the prenatal evaluation of the posterior fossa.

Obstetric protocols dictate that the fetal cerebellum should always be assessed during sonograms during pregnancy. For various reasons, including technical limitations or inconclusive sonographic findings, suspicion of cerebellar abnormalities is one of the most common indications for prenatal magnetic resonance imaging (MRI). Although sonography is the imaging technique of choice to assess the cerebellum, MRI shows the anatomy of the posterior fossa and abnormalities in the development of the fetal cerebellum in greater detail and thus enables a more accurate prenatal diagnosis. We describe and illustrate the normal anatomy of the fetal cerebellum on MRI as well as the different diseases that can affect its development. Moreover, we review the most appropriate terminology to define developmental abnormalities, their differential diagnoses, and the role of MRI in the prenatal evaluation of the posterior fossa.

Purpose Posterior fossa epidural hematomas (PFEDH) are uncommon in children but usually require timely surgical intervention due to the risk of life-threatening brainstem compression. We attempt to make the surgical procedure less invasive by treating selected pediatric patients with trephination mini-craniectomy. Methods We retrospectively reviewed the clinical courses, radiological findings, surgical procedures, and prognoses of the pediatric patients who were treated in our departments for traumatic PFEDH from January 2010 to January 2015. Results During this period, a total of 17 patients were surgically treated for PFEDH and 7 were managed with trephination mini-craniectomy for hematoma evacuation. The outcomes were good in all 7 patients as evaluated with Glasgow Outcome Score. There was no mortality in this series. The on average 30-month clinical follow-up showed that patients experienced satisfactory recoveries without complications. Conclusion Our results suggest that trephination mini-craniectomy is a safe surgical technique for selected PFEDH patients with moderate hematoma volume and stabilized neurological functions. However, standard craniectomy is recommend when there are rapid deteriorations in patients' neurological functions or the hematomas are large and exerted severe mass effects.

Background Chiari III malformation is an extremely rare congenital anomaly. At present, its primary and associated pathognomonic factors remain poorly understood. The authors report a case of a male neonate born with an occipital encephalocoele with herniation of posterior fossa contents associated with bilateral postaxial polydactyly. Case Description The patient is a dichorionic, diamniotic twin conceived via assisted reproductive methods; his twin sister has no congenital anomaly. Neurosurgical management included successful repair of the encephalocoele and subsequent cerebrospinal fluid diversion via a ventriculoperitoneal shunt. Conclusions Owing to the uniqueness of this patient's presentation, the concurrent diagnoses of Chiari III malformation and polydactyly are discussed in concordance with updated literature.

Introduction Cerebellar liponeurocytoma is a rare tumor of the central nervous system occurring mainly in the posterior fossa, which shows neuronal and variable astrocytic differentiation, along with foci of lipomatous differentiation. Case presentation Herein, we describe a 50-year-old female patient who presented to the hospital complaining of headache, tinnitus, and vertigo with positive cerebellar signs. MRI revealed a left cerebellar tumor. After tumor resection, histological examination and immunohistochemistry were done and the diagnosis of cerebellar liponeurocytoma was confirmed. Discussion Liponeurocytoma may be mistaken as a medulloblastoma with lipidized cells or a lipomatous ependymoma. Histopathological examination, reinforced by immunohistochemistry and electron microscopy, are required to distinguish between these entities. The rarity of this tumor and paucity of pertinent information regarding its biological potential and natural history have resulted in the application of various treatment modalities. Conclusion Liponeurocytoma is a rare benign tumor with cerebellum is the typical site for it. Although surgery is the treatment of choice; however, postoperative radiotherapy may have a role in case of incomplete tumor resection or recurrence., Highlights • Cerebellar liponeurocytoma is a rare benign tumor that mainly occurs in the posterior fossa. • Surgery is the first line in management. • Postoperative radiotherapy has a role in case of incomplete tumor resection or recurrence.

Ultrasound and magnetic resonance imaging are the two imaging modalities used in the assessment of the fetus. Ultrasound is the primary imaging modality, whereas magnetic resonance is used in cases of diagnostic uncertainty. Both techniques have advantages and disadvantages and therefore they are complementary. Standard axial ultrasound views of the posterior fossa are used for routine scanning for fetal anomalies, with additional orthogonal views directly and indirectly obtainable using three-dimensional ultrasound techniques. Magnetic resonance imaging allows not only direct orthogonal imaging planes, but also tissue characterization, for example to search for blood breakdown products. We review the nomenclature of several posterior fossa anomalies using standardized criteria, and we review cerebellar abnormalities based on an etiologic classification.