Cerebrospinal Fluid Biomarkers As Predictors of Shunt Response in Idiopathic Normal Pressure Hydrocephalus: A Systematic Review

ABSTRACTBackground:The widely accepted treatment for idiopathic normal-pressure hydrocephalus (iNPH) is a cerebrospinal fluid (CSF) diversion shunt procedure, to which approximately 80% of patients will respond. The purpose of this systematic review was to identify which CSF biomarkers have been investigated in predicting shunt responsiveness in iNPH patients, and to analyze the level of evidence for each.Methods:To find all relevant articles, a comprehensive search of Medline, Embase, and PsycINFO was conducted.Results:The literature search identified 344 unique citations, of which 13 studies satisfied the inclusion criteria and were analyzed in our review. These 13 studies reported on 37 unique biomarkers.Conclusions:The available studies suggest that there is evidence for the utility of CSF biomarkers in predicting shunt responsiveness in iNPH patients, though none have been shown to predict shunt response with both high sensitivity and specificity. We found that there is no available evidence for the use of Aβ38, Aβ40, Aβ43, APL1β25, APL1β27, APL1β28, sAPP, aAPPα, sAPPβ, TNF-α, MCP-1, sCD40L, sulfatide, MBP, L-PGDS, cystatin C, transthyretin, TGF-β2, or YKL-40 in predicting shunt response. There is minimal evidence for the use of TGF-β1, TBR-II, homocysteine, and interleukins (particularly IL-1β, IL-6, and IL-10). However, the available evidence suggests that these biomarkers warrant further investigation. Aβ42, tau, p-tau, NFL, and LRG have the greatest amount of evidence for their predictive value in determining shunt responsiveness in iNPH patients. Future research should be guided by, but not limited to, these biomarkers.