Post-operative meningeal thickening seen on magnetic resonance imaging

Posterior fossa tumors are relatively common in children, and the meningeal dissemination of these tumors is well established in the literature. Although leptomeningeal dissemination is more common in high-grade tumors, even low-grade tumors can generate meningeal metastases. In this case report, we would like to discuss the importance of leptomeningeal dissemination assessment of posterior fossa tumors in children, in the preoperative period, through the entire neuroaxis magnetic resonance imaging (MRI). This is important since transient meningeal thickening is very common in the postoperative periods of neurosurgical patients, and can be found for up to 5 or 6 years after surgery, causing these patients to undergo prolonged follow-ups and repeated MRIs and lumbar punctures.

NI-11 Usefulness of the magnetic resonance imaging arterial spin labeling method for diagnosing posterior fossa hemangioblastoma

Purpose: It is sometimes challenging to diagnose hemangioblastoma by MRI when the tumor is a solid mass in the posterior fossa. We therefore evaluated perfusion images and diffusion-weighted images to diagnose hemangioblastoma in order to obtain the most useful quantitative features. Methods: Thirty-one posterior fossa tumors whose pathological diagnosis was confirmed by surgery were included in groups A (12 hemangioblastomas) and B (non-hemangioblastoma 19 cases: metastatic tumor 6 cases, pilocytic astrocytoma 3 cases, malignant lymphoma 3 cases, glioblastoma 2 cases, medulloblastoma 2 cases, and other 3 cases). All cases were imaged by 3.0-Tesla MRI, with the apparent diffusion coefficient (ADC) on diffusion-weighted imaging as the parameter, arterial spin labeling (ASL) as the relative value from the CBF map to the region of interest (ROI) in the contralateral hemisphere as perfusion image, dynamic susceptibility contrast (DSC) as rCBF, rCBV, corrected CBV, and K2. The ROI was set to match the contrast-enhanced part, and the two groups were compared and examined. Results: The relative ASL value of group A and the corrected CBV in DSC were significantly higher than group B (p<0.001). In contrast, the ADC showed no marked difference between the two groups. In the distinction between the two groups, the receiver operating characteristic (ROC) analysis showed that the area under the curve (AUC) of the relative ASL value was significantly higher than the other parameters (AUC 0.995, cut-off value 2.34, sensitivity 100%, specificity 99.5%). Discussion/Conclusion: The non-contrast ASL method was extremely useful for diagnosing hemangioblastoma in posterior fossa tumors. The ASL method has been reported helpful for the follow-up of residual tumors or recurrence after surgery. Contrast-enhanced DSC is not always essential for diagnosing posterior fossa hemangioblastoma. It should be noted that measuring the ROI by ASL is difficult when the size of the mural nodule is small.

Ventriculoperitoneal Shunt versus Endoscopic Third Ventriculostomy in the treatment of Obstructive Hydrocephalus in Pediatric Midline Posterior Fossa tumors

Background Treatment of secondary hydrocephalus due to posterior fossa tumors in these children is still a matter of controversy, although preoperative ventriculo-peritoneal shunt (VP shunt) insertion before tumor excision is widely accepted among neurosurgeons but many attempts are rising to minimize permanent VP shunt insertion and associated complications and introducing third endoscopic ventriculostomy (ETV) as one of the options of 2ry hydrocephalus. Objectives Comparing the post-operative clinical success with resolution of the manifestations and post-operative complications between endoscopic third ventriculostomy and ventriculoperitoneal shunt as different modes of CSF diversion in children with 2ry hydrocephalus due to midline posterior fossa tumors. Methods The following electronic databases were searched from June 2009 to june2019: PubMed, Google scholar search engine. Cochrane database of systematic reviews, EMBASE and science Direct, using the keywords ―hydrocephalus; posterior fossa tumors; pediatrics; ventriculoperitoneal shunt; endoscopic third ventriculostomy‖. Studies were eligible if they contain the target keywords in title or abstract, addressing the Pediatric age group with 2ry hydrocephalus due to de novo posterior fossa tumor manifested by signs of increase the intra cranial tension including persistent headache and vomiting, blurred vision, 6th nerve palsy, papilledema in fundus examination, acute DCL and 2ry hydrocephalus confirmed by brain imaging. Exclusion criteria included studies including age group below 1yr or above 18 yr, or patients with recurrent post fossa tumors and operated before or patients presented by failed previously attempt of CSF diversion. Results: A total of 1255 citations were screened for eligibility,6 studies were included in our systematic review discussing, comparing and evaluating the durability of ETV versus VP shunt in treatment the 2ry hydrocephalusdue to pediatric posterior fossa tumor.. Overall study population reached 474 patients. the overall clinical findings at presentation and postoperative outcomes regarding the clinical findings improvement, radiological improvement and postoperative complications between ETV and VP shunt are compared and showing that ETV should be considered as an alternative procedure to VP shunt in controlling severe hydrocephalus related to posterior fossa tumors to relieve symptoms quickly during the preoperative period when patients should wait for their definite tumor excision. Conclusion The shorter duration of surgery, the lower incidence of morbidity, the absence of mortality, the lower incidence of procedure failure of endoscopic third ventriculostomy as compared to ventriculoperitoneal shunt, and the significant advantage of not becoming shunt dependent make endoscopic third ventriculostomy to be recommended as the first choice in the treatment of pediatric patients with marked obstructive hydrocephalus due to posterior fossa tumors. It is a preliminary, simple, safe, effective, physiological, minimally invasive procedure for the relief of elevated intracranial pressure before direct tumor removal.

Permanent Cerebrospinal Fluid Diversion in Adults With Posterior Fossa Tumors: Incidence and Predictors

BACKGROUND Posterior fossa tumors (PFTs) can cause hydrocephalus. Hydrocephalus can persist despite resection of PFTs in a subset of patients requiring permanent cerebrospinal fluid (CSF) diversion. Characteristics of this patient subset are not well defined. OBJECTIVE To define preoperative and postoperative variables that predict the need for postoperative CSF diversion in adult patients with PFTs. METHODS We surveyed the CNS (Central Nervous System) Tumor Outcomes Registry at Emory (CTORE) for patients who underwent PFT resection at 3 tertiary-care centers between 2006 and 2019. Demographic, radiographic, perioperative, and dispositional data were analyzed using univariate and multivariate models. RESULTS We included 617 patients undergoing PFT resection for intra-axial (57%) or extra-axial (43%) lesions. Gross total resection was achieved in 62% of resections. Approximately 13% of patients required permanent CSF diversion/shunting. Only 31.5% of patients who required pre- or intraop external ventricular drain (EVD) placement needed permanent CSF diversion. On logistic regression, size, transependymal flow, use of perioperative EVD, postoperative intraventricular hemorrhage (IVH), and surgical complications were predictors of permanent CSF diversion. Preoperative tumor size was only independent predictor of postoperative shunting in patients with subtotal resection. In patients with intra-axial tumors, transependymal flow (P = .014), postoperative IVH (P = .001), surgical complications (P = .013), and extent of resection (P = .03) predicted need for shunting. In extra-axial tumors, surgical complications were the major predictor (P = .022). CONCLUSION Our study demonstrates that presence of preoperative hydrocephalus in patients with PFT does not necessarily entail the need for permanent CSF diversion. We report the major predictive factors for needing permanent CSF diversion.

A validation study of the modified Canadian Preoperative Prediction Rule for Hydrocephalus in children with posterior fossa tumors

OBJECTIVE Perioperative management of hydrocephalus in children with posterior fossa tumors (PFTs) remains challenging. The modified Canadian Preoperative Prediction Rule for Hydrocephalus (mCPPRH) has been previously described as a useful tool in predicting which children are at higher risk for permanent hydrocephalus following PFT resection and can be used in guiding treatment. The aim of this study was to externally validate this predictive model. METHODS A retrospective review of the children treated in a single unit was conducted, recording all of the mCPPRH parameters (age, preoperative radiological diagnosis, presence of moderate/severe hydrocephalus, transependymal edema, and metastatic disease at the time of diagnosis), the need for a CSF diversion procedure at 6 months, time to surgery, and management of hydrocephalus. A receiver operating characteristic (ROC) curve was plotted using the mCPPRH, age, Evans index (EI), and frontooccipital horn ratio (FOHR), and an area under the curve (AUC) was calculated. A point-biserial correlation was run to determine the relationship between time to surgery, the insertion of an external ventricular drain (EVD), or initial EVD clamping and the development of postoperative persistent hydrocephalus. RESULTS From a total of 75 patients (mean age 6.99 years, 62.7% male) who were included in the study, 8 (10.7%) required permanent CSF diversion following PFT resection. The AUC of the ROC curve was 0.618 for the mCPPRH (p = 0.18, SE 0.088, 95% CI 0.446–0.791), 0.633 for age (p = 0.26, SE 0.119, 95% CI 0.4–0.867), 0.604 for the EI (p = 0.34, SE 0.11, 95% CI 0.389–0.818), and 0.663 for the FOHR (p = 0.17, SE 0.121, 95% CI 0.427–0.9). A significant positive correlation between EVD insertion (r = 0.239, p = 0.03) and insertion of a ventriculoperitoneal shunt was found. A negative correlation between the postoperative clamping of the EVD (r = −0.158, p = 0.4) and the time to PFT surgery (r = −0.06, p = 0.6) did not reach statistical significance. CONCLUSIONS The implementation of the mCPPRH score failed to reliably predict which children would require permanent CSF diversion following PFT resection when applied to this cohort. Clinical judgment remains the mainstay of choosing the perioperative treatment of hydrocephalus.