The effect of whole body position on lumbar cerebrospinal fluid opening pressure

Abstract We compared cerebrospinal fluid (CSF) opening pressure measurements in the lumbar subarachnoid space between the flexed position (F-OP) and relaxed position (R-OP) in recumbent patients. We devised an equation for using F-OP to determine the existence of raised intracranial pressure (ICP). Patients (n = 83) underwent lumbar puncture while in the flexed lateral decubitus position and then were moved to the relaxed position. F-OP and R-OP were measured with a water manometer. R-OP > 180 mmH2O plus relevant clinical signs were taken as indicators of raised intracranial pressure. Mean pressures for F-OP and R-OP were 178.54 and 160.52 mmH2O respectively, p 180, raised ICP could be significantly over diagnosed. The authors recommend an equation [R-OP(calculated, mmH2O) = 0.885 × F-OP(measured, mmH2O)] or using 200 mmH2O as the threshold for increased ICP with flexed posture.