Although it is true that posterior fossa tumours are much more common in children than in adults the distribution does vary with age:
0 to 3 years of age: supratentorial > infratentorial
4 to 10 years of age: infratentorial > supratentorial
10 to early adult hood: infratentorial = supratentorial
adults: supratentorial > infratentorial
Overall 50-55% of all brain tumours in children are found in the posterior fossa.
Cerebellar metastases (most common)
Cerebellar astrocytomas and medulloblastomas are rare in the posterior fossa of adults (<1% all tumours) An important space occupying lesion (the most common in fact) to remember is that of a stroke, which when subacute can mimic a tumour.
This retrospective study was conducted under approval of the institutional review board. In the hospital information system, 27 patients with posterior fossa intra-axial tumor between January 2009 and June 2015 were enrolled and grouped as the following 7 entities: low grade glioma (LGG) 6, anaplastic astrocytoma (AA) 2, glioblastoma (GBM) 3, medulloblastoma (MB) 3, hemangioblastoma (HB) 6, metastatic tumor (Mets) 3, and malignant lymphoma (ML) 4. Tl and FDG uptakes were measured at the tumors and control areas, and several indexes were derived. Using indexes selected by the stepwise method, discriminant analysis was conducted with leave-one-out cross-validation.The predicted accuracy for tumor classification was 70.4% at initial analysis and 55.6% at cross-validation to differentiate 7 tumor entities. HB, LGG, and ML were well-discriminated, but AA was located next to LGG. GBM, MB, and Mets largely overlapped and could not be well distinguished even applying multiple discriminant analysis. Correct classification in the original and cross-validation analyses was 44.4% and 33.3% for Tl-SPECT and 55.6% and 48.1% for FDG-PET 1).
Quarante et al report 2 new pediatric cases of posterior reversible encephalopathy syndrome (PRES) that developed after surgical resection of a posterior fossa tumor. Appropriate management includes supportive measures, antihypertensive agents, and antiepileptic drugs, if needed. Full recovery is the most likely outcome in line with previous articles 2).
Clinical data of 36 patients with posterior fossa lesions who accepted neuroendoscopy assisted microneurosurgery (NEAM group) in the department of neurosurgery of the First Affiliated Hospital of Chongqing Medical University, from January 2014 to December 2016, were retrospectively enrolled. A total of 113 cases diagnosed with the same lesions and accepted conventional microneurosurgery (non-NEAM group) in the same period were analyzed as control group. The total tumor resection rate, postoperative leakage of cerebrospinal fluid, intracranial infection, operating time and the recovery of facial nerve function were compared between the two groups. Results: Ninety-three patients with acoustic neuroma were analyzed, which were divided into non-NEAM group 78 cases (removed posterior lip of internal auditory canal in different degrees) and NEAM group 15 cases (not removed posterior lip of internal auditory canal). The total tumor resection rate and postoperative facial nerve function had no significant statistical differences between two groups. The operating time of NEAM group was longer than that of non-NEAM group (P=0.048, P<0.05), but the rate of leakage of cerebrospinal fluid and intracranial infection did not increase. Twenty-seven cases were diagnosed with cerebellopontine angle cholesteatoma. These cases were divided into two groups, 17 cases in non-NEAM group and 10 cases in NEAM group. NEAM group have higher total tumor resection rate (P=0.014, P<0.05), better short-term postoperative facial nerve function (P=0.039, P<0.05), and longer operating time (P=0.015, P<0.05), compared with non-NEAM group. No significant statistical differences were observed on long-term postoperative facial nerve function and postoperative complications. Of the 16 cases diagnosed tentorial meningioma, 10 cases were in non-NEAM group and 6 cases in NEAM group. Six cases in non-NEAM group and 4 cases in NEAM group were total removal. For the mean operating time, non-NEAM group was (6.6±1.0) hours and NEAM group was (7.1±0.7) hours. Thirteen cases were with fourth ventricular cholesteatoma, which all were totally resected, and 8 cases were in non-NEAM group and 5 cases in NEAM group. For non-NEAM group, 5 cases dissected cerebellar vermis and the mean operating time is (6.0±0.7) hours. However, NEAM group all did not dissect cerebellar vermis and the mean operating time is (6.4±0.4) hours. Conclusions: Neuroendoscopy assisted microneurosurgery for cranial fossa lesions was benefit to totally resect tumor and reduce unnecessary injury. It needed longer operating time, but not increase postoperative intracranial infection 3).