CLINICAL ARTICLE - BRAIN TUMORS Effect of postural changes on ICP in healthy and ill subjects Morten Andresen & Amer Hadi & Lonnie G. Petersen & Marianne Juhler Received: 4 September 2014 /Accepted: 1 October 2014 /Published online: 14 October 2014 # Springer-Verlag Wien 2014 Abstract Background Reference values and physiological measure- ments of intracranial pressure (ICP) are primarily reported in the supine position, while reports of ICP in the vertical posi- tion are surprisingly rare considering that humans maintain the vertical position for the majority of the day. In order to distinguish normal human physiology from disease entities such as idiopathic intracranial hypertension and normal pres- sure hydrocephalus, we investigated ICP in different body postures in both normal and ill subjects. Methods Thirty-one patients were included: four normal pa- tients following complete removal of a solitary clearly demar- cated small brain tumour and fitted with a telemetric ICP monitoring device for long-term ICP monitoring; 27 patients requiring invasive ICP monitoring as a part of their diagnostic work-up or monitoring of shunt treatment effect. ICP was recorded in the following body positions: upright standing, sitting in a chair, supine and right lateral lumbar puncture position. Results Linear regression of median ICP based on patient posture, group, and purpose of monitoring presented a signif- icant model (p <0.001), but could not distinguish between patient groups (p =0.88). Regression of differences in median ICP between body postures and supine ICP as the baseline, presented a highly significant model (p <0.001) and adjusted R 2 =0.86. Both body posture (p <0.001) and patient group (p <0.001) were highly significant factors. Conclusions Differences in ICP between body postures en- abled us to distinguish the normal group from patient groups. Normal patients appear able to more tightly regulate ICP when switching body postures. Keywords ICP monitoring . Intracranial pressure . Hydrocephalus . Postural changes . Idiopathic intracranial hypertension Introduction Humans maintain the upright vertical position for the majority of each day. Considering this, it is curious (perhaps even questionable) that diagnostic and clinical investigations of intracranial pressure (ICP) are usually carried out with the patient in the supine position. In recent years attention has been directed towards moni- toring ICP under circumstances, which are as close to the patient’ s daily life as possible. We have shown excellent technical quality and clinical value of ICP data obtained from home-monitoring, with the patient carrying out his regular daily routines and activities [2]. However, in order to take full advantage of these data, we need reliable reference material for ICP in different body postures, for different disease enti- ties, and—most importantly—a normal group for comparison. Based on reference values in a model of normal ICP obtained from a group of patients without any suspicion of cerebrospinal fluid (CSF) dynamic disturbances, but with maintained telemetric invasive ICP monitoring following re- moval of a solitary clearly demarcated small brain tumour [1], our objective in this study was to investigate if: Conference presentations Preliminary results were presented in abstract form at the 15th International Symposium on Intracranial Pressure, in Singapore, November 2013 M. Andresen (*) : A. Hadi : M. Juhler Clinic of Neurosurgery, Copenhagen University Hospital, Blegdamsvej 9, 2100 Copenhagen E, Denmark e-mail: andresen@gmail.com L. G. Petersen Department of Biomedical Sciences, The Panum Institute, University of Copenhagen, Copenhagen, Denmark Acta Neurochir (2015) 157:109–113 DOI 10.1007/s00701-014-2250-2