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Content is anchored to trusted sources where available, but Compass has not yet been clinically reviewed. It provides general information rather than medical advice.

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Tests and measurements

Lumbar puncture

Taking a small sample of the fluid around the spinal cord using a needle in the lower back.

What it means

Local anaesthetic first, then a fine needle between the bones of the lower back collects a few millilitres of the fluid that surrounds the brain and spinal cord. It is used to look for other conditions, and increasingly to measure markers used in research.

Why you might hear it

  • It may be part of the tests done while reaching a diagnosis.
  • It is how neurofilament levels are usually measured.

People who may help

Where Compass goes into this

About this explanation

These are plain explanations of words you may come across, not advice about your own situation. Where a word matters to a decision, the question pages go into it properly, and your own team is the place to take it.