Variability of Consecutive Lumbar Puncture Opening Pressures

BACKGROUND: Lumbar puncture (LP) opening pressures (OPs) are known to fluctuate based on diurnal, environmental, and pathologic conditions. Despite their dynamic nature, single OPs are often deemed sufficient for diagnosis of elevated intracranial pressures (ICPs) in nonspecialists' hands. The purpose of this study was to determine the variability of consecutive LP OPs at a large referral center to determine the potential range of variability for a given LP OP. METHODS: In this retrospective cohort study, medical records of all patients seen at Mayo Clinic, Rochester, MN, from January 1, 2001, through June 1, 2016, were screened for ≥2 LP OPs within 30 days of each other. Patients with pathologic conditions known to influence ICP were excluded. RESULTS: There were 148 eligible patients (39.2% female) with mean age of 63.5 ± 15.5 years and mean body mass index (BMI) 28.0 ± 6.0. The LPs were a mean of 10 ± 9 days apart. Mean OP for the first and second LP was 149 ± 51 mm H2O and 148 ± 48 mm H2O (P = 0.78), respectively, with a mean difference of 1 mm H2O, providing an overall coefficient of repeatability (CR) of 86.4 between consecutive LPs. There was a significant correlation between initial OP and BMI (r = 0.39, P < 0.001). OP >200 mm H2O had a significantly higher CR of 111.4, compared to OP <200 mm H2O, with CR 74.6 (P = 0.006). CRs were also higher for patients with diagnoses of headache (P = 0.002) or anxiety (P = 0.03). CONCLUSIONS: Higher initial LP OP, headache, and anxiety were associated with greater variability on subsequent LPs. OPs that are not consistent with the patients' clinical signs and symptoms should therefore be interpreted with caution.