Population-based evaluation of the variability of lumbar puncture opening pressures

Abstract

Purpose : An elevated opening pressure (OP) on lumbar puncture (LP) is important in making a diagnosis of idiopathic intracranial hypertension (IIH). However, there is variability in OPs and there are many patients that are incorrectly diagnosed with IIH based on a single elevated OP, which can be falsely elevated with Valsalva and other factors. The goal of this study was to evaluate the variability of LP opening pressures in a community-based population of patients using the Mayo Clinic Study of Aging (MCSA) and evaluate for factors that contribute to the variability.

Methods : The CSF was obtained from a subset of MCSA participants aged 32 to 95 years who underwent LP in the lateral decubitus position between November 1, 2007, and October 1, 2017, as part of routine data collection for the MCSA, a longitudinal, population-based study of residents of Olmsted County, MN. Opening pressures were recorded along with variables that could possibly influence OP or variability, including age, body mass index (BMI), needle gauge, and also headache and anxiety, and depression, which could possibly increase the risk of Valsalva during the LP. To understand the relationships and variability amongst OP, repeated mixed measure models were fit on the natural log of OP and collected characteristics. Additionally, the variability of OP measurements was compared with Bland-Altman Plots, coefficient of variation (CV), and coefficient of repeatability (CR).

Results : A total of 1087 LPs (57% male) were obtained with recorded OPs in 839 among 642 participants. The average age was 72.7 (SD 10.7) with a mean BMI of 28.4 (SD 5.12). The median OP was 150 mm H2O (range 56 to 360). Increasing age was associated with lower OP (p<0.001), while increasing BMI was associated with higher OP (p<0.001). Opening pressures did not vary significantly with gender, needle gauge, headache, anxiety, or depression. Opening pressure was elevated ≥200 mmH2O in 117 (18%) participants, who were younger (mean: 63.7, SD: 9.6, p<0.001) and had higher BMI (mean: 31.5, SD: 4.3, p<0.001). Only 15 (2.3%) had an OP ≥250. Among the 160 participants with at least 2 LPs, the CV was 13.6 and CR was 68.2. 14% (n=23) had an OP difference ≥50mm H2O between serial LPs.

Conclusions : LP opening pressures can vary significantly among normal individuals. Higher opening pressures were associated with a higher BMI and younger age.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.