When is the radiology report of a posterior fossa containing cyst/cystic-like CSF collection of clinical or surgical significance?

Abstract

Abstract OBJECTIVE: The nomenclature characterizing posterior fossa (PF) CSF collections in radiological reports can be quite variable leading to uncertainty about the subsequent clinical course that may result in multiple follow-up imaging studies that might not be needed and occasionally to operative intervention not warranted. The important factor is the CSF collection’s mass effect on adjacent structures, the presence of hydrocephalus, and the likelihood of the CSF collection increasing in size over time. METHODS: We respectively reviewed the imaging database at Children’s Hospital Los Angeles to identify all radiological reports from 2000 to 2015 indicating the presence of a CSF collection in the PF that were characterized as containing a cyst, being cystic, or an abnormal CSF collection. RESULTS: 332 reports in 65 patients were analyzed. 47 (72%) did not undergo PF surgery for a reported extra-ventricular PF CSF collection, of which 11 were reported as exerting mass effect. 18 (28%) patients did undergo PF surgery of whom 14 had both hydrocephalus and brainstem displacement, 2 had brainstem displacement but no hydrocephalus, and 2 had neither brainstem displacement nor hydrocephalus who in retrospect did not benefit from PF surgery. CONCLUSIONS: The terminology in radiology reports is highly variable, inconsistent, and does not correlate well with clinical management or the need for PF surgery. Significant brainstem displacement in the presence of extra-ventricular PF CSF collection is highly correlated with the need for PF surgery. After 5 years of age, the instance of a PF CSF collection increasing to become symptomatic appears remote.