Defining the Normal Range of Cerebrospinal Fluid Opening Pressure in Adults: A Systematic Review

It has been theorized that the visual changes observed in the astronaut population described by the Spaceflight Associated Neuro-ocular Syndrome (SANS) are related to elevated intracranial pressure (ICP). To better understand the mechanism of SANS and provide adequate prevention, treatment, and countermeasures for this population, direct measurement of ICP via lumbar puncture has been suggested. However, the normal range of cerebrospinal fluid opening pressure (CSFOP) is first needed to interpret values obtained via lumbar puncture in the astronaut population. Many clinical guidelines utilize an upper limit of normal CSFOP of 20 cmH2O, but clinical and research experience suggests many normal individuals may have CSFOP above this cutoff. The aim of this study was to provide a description of the normal CSFOP range in adults via a qualitative systematic review of the literature. The PubMed (MEDLINE) database was searched including records published through June of 2018. Reference lists from eligible articles were manually reviewed and physicians in relevant fields contacted to ensure a comprehensive search. The primary outcome was the mean CSFOP with standard deviation where reported. An additional 9 items were abstracted by a single reviewer including range of CSFOP. Overall, 164 records were identified for screening, with 12 studies remaining after inclusion and exclusion criteria were applied. Data were abstracted by the author and presented in table format. Mean CSFOP ranged from 12.98 to 18.8 cmH2O where reported. Of the 12 studies included, six (50%) reported subjects with a CSFOP that exceeded 20 cmH2O. Five (42%) studies recruited healthy volunteer subjects only, and six (50%) included subjects undergoing diagnostic LP who did not have a diagnosis that is thought to affect ICP. Studies involving only healthy volunteers generally had a smaller sample size, limiting information available on the range of CSFOP in healthy, asymptomatic individuals. Future work will involve a quantitative meta-analysis of identified records in order to provide a clear definition of CSFOP for comparison to the astronaut population.