From the Guidelines
Normal opening pressure during a lumbar puncture typically ranges between 10 to 20 cmH2O (or 70-180 mmH2O) when measured with the patient lying in the lateral recumbent position. This is based on the most recent and highest quality study available, which emphasizes the importance of accurate measurement of lumbar puncture opening pressure in the diagnosis and management of various neurological conditions 1. The study highlights that the lumboperitoneal (LP) opening pressure should be measured in the lateral decubitus position, and that values above 20-25 cmH2O are generally considered elevated and may indicate conditions such as idiopathic intracranial hypertension, meningitis, subarachnoid hemorrhage, or brain tumors.
Some key points to consider when measuring lumbar puncture opening pressure include:
- Patient positioning: The patient should be lying in the lateral recumbent position with legs extended.
- Relaxation: The patient should be relaxed, as anxiety can transiently increase pressure.
- Measurement technique: The pressure should be recorded before removing any CSF for analysis, using a manometer attached to the lumbar puncture needle after CSF flow is established.
- Factors that can affect measurements: Obesity, recent straining or coughing, and other factors can affect lumbar puncture opening pressure measurements.
It's worth noting that the normal range for lumbar puncture opening pressure is not universally agreed upon, and different studies may report slightly different ranges. However, the range of 10 to 20 cmH2O (or 70-180 mmH2O) is widely accepted and supported by recent and high-quality evidence 1. In contrast, an older study from 2000 mentions a normal baseline opening pressure of less than 200 mm H2O, but this is not as relevant or reliable as the more recent study 1.
From the Research
Normal Opening Pressure for Lumbar Puncture
The normal opening pressure for a lumbar puncture (LP) can vary, but several studies provide guidance on this topic.
- A study published in the Journal of neuro-ophthalmology in 2014 2 suggests that the normal range of intracranial pressure (ICP) measured by LP in adults is 6 to 25 cmH2O, with a population mean of about 18 cmH2O.
- Another study published in The American journal of emergency medicine in 2024 3 defines elevated intracranial pressure as a cerebrospinal fluid (CSF) opening pressure greater than 25 cmH2O.
- A population-based study published in Frontiers in neurology in 2019 4 found that the mean opening pressure was 155.4 mmH2O, with a 95% reference interval of 82-242 mmH2O.
- A study published in the Journal of the neurological sciences in 2021 5 aimed to detect cases with raised or normal CSF opening pressure, but does not provide a specific normal range for opening pressure.
- A study published in the South African medical journal in 2018 6 compared the use of an intravenous giving set (IVGS) with a spinal manometer for measuring CSF opening pressure, and found that the IVGS consistently underestimated the CSF opening pressure, with an upper limit of normal CSF opening pressure of 19 cmH2O on the IVGS equivalent to 25 cmH2O on the manometer.
Factors Influencing Opening Pressure
Several factors can influence the opening pressure measured during a lumbar puncture, including:
- Age: increasing age is associated with lower opening pressure 4
- Body mass index (BMI): increasing BMI is associated with higher opening pressure 4
- Obstructive sleep apnea (OSA): presence of OSA is associated with higher opening pressure 4
- Patient position: patient position can affect the measurement of CSF opening pressure 3