Cerebrospinal fluid pressure in adults

BACKGROUND:: Lumbar puncture (LP) is a widely-used investigative procedure. It allows relatively non-invasive measurement of intracranial pressure (ICP) which may have a significant impact on diagnosis and/or patient management. Over the years there has been considerable discussion about various aspects of the procedure, including what constitutes a normal opening pressure, what factors might influence this, and how LP is best performed. EVIDENCE ACQUISITION:: A review of the literature was carried out by searching PubMed and Medline, scanning relevant medical journals for recent publications, and carrying out secondary referencing and contacting other clinicians, where appropriate. RESULTS:: The normal range of ICP measured by LP in adults in a typical clinical setting should now be regarded as 6 to 25 cmH2O (95% confidence intervals), with a population mean of about 18 cmH2O. There is, however, considerable variability: some normal individuals have pressures of 30 cmH2O (or, occasionally, even higher) meaning that pressure measurements must be interpreted in the clinical context. CONCLUSIONS:: This article aims to provide the practicing neuro-ophthalmologist with up-to-date information about the ways in which various factors can influence pressure measurements obtained at LP.