Smith JH, et al. - Researchers appraised associations between post-dural puncture headache (PDPH) and opening pressure (OP), closing pressure (CP), and volume of cerebrospinal fluid (V) removed via conducting a systematic literature review. In addition, they evaluated pressure-volume index (PVI) as a novel risk factor for PDPH via undertaking a case-control study. They used ICHD-3 criteria to perform this retrospective, case-control study with 1:1 matching. Searching Cochrane Database of Systematic Reviews, Ovid EMBASE, OVID MEDLINE, Scopus, and Web of Science yielded 22 references, evaluating V (n = 14), OP (n = 11), and/or CP (n = 4). Outcomes yielded no reliable evidence for an association of PDPH with OP or CP. They suggest a possible association of PDPH to V in cases of high-volume removal and dependence of PDPH on the timing of outcome assessment.