Post-operative diffusion weighted imaging as a predictor of posterior fossa syndrome permanence in paediatric medulloblastoma.

PURPOSE: Posterior fossa syndrome (PFS) is a serious complication faced by neurosurgeons and their patients, especially in paediatric medulloblastoma patients. The uncertain aetiology of PFS, myriad of cited risk factors and therapeutic challenges make this phenomenon an elusive entity. The primary objective of this study was to identify associative factors related to the development of PFS in medulloblastoma patient post-tumour resection. METHODS: This is a retrospective study based at a single institution. Patient data and all related information were collected from the hospital records, in accordance to a list of possible risk factors associated with PFS. These included pre-operative tumour volume, hydrocephalus, age, gender, extent of resection, metastasis, ventriculoperitoneal shunt insertion, post-operative meningitis and radiological changes in MRI. Additional variables included molecular and histological subtypes of each patient's medulloblastoma tumour. Statistical analysis was employed to determine evidence of each variable's significance in PFS permanence. RESULTS: A total of 19 patients with appropriately complete data was identified. Initial univariate analysis did not show any statistical significance. However, multivariate analysis for MRI-specific changes reported bilateral DWI restricted diffusion changes involving both right and left sides of the surgical cavity was of statistical significance for PFS permanence. CONCLUSION: The authors performed a clinical study that evaluated possible risk factors for permanent PFS in paediatric medulloblastoma patients. Analysis of collated results found that post-operative DWI restriction in bilateral regions within the surgical cavity demonstrated statistical significance as a predictor of PFS permanence-a novel finding in the current literature.

Disseminated extracranial metastatic meningioma.

Meningiomas are usually low-grade, solitary lesions that rarely metastasize. In this group of central nervous system tumours, the higher grade subtypes are notorious for resistance to conventional chemo-radiation therapies. Recent studies have shown efficacy in the use of bevacizumab in patients with recurrent and, or progressive anaplastic meningioma. The authors report a case of a young patient with recurrent anaplastic meningioma who despite being treated with bevacizumab, progressed with disease dissemination to multiple extracranial sites. Although the majority of meningiomas are amendable to treatment, the higher grade subtypes remain therapeutically challenging. The unexpected resistance to anti-angiogenic therapy in this patient adds another layer of complexity to an elusive subset of a supposedly benign disease. This patient report reflects the need for in-depth studies, molecular characterization and overall, better disease understanding in order to improve prognosis for affected patients.