Have you ever performed a lumbar puncture (LP) in a patient, only to have them return the next day for new debilitating headaches? It’s worse when sitting up, and much improved when laying down. You hate adding more problems for the patient, put you are certain that s/he now has a post-LP headache.
What causes a post-LP headache?
It’s a headache after a LP, presumably because of a persistent CSF leak from the puncture site.
How can you minimize the risk of a post-LP headache?
There are several techniques you can used, as summaried in a 2006 JAMA article:
1. Use an atraumatic, blunt needle.
- The standard LP needle has a cutting edge. A non-cutting needle requires a small scalpel nick in the patient’s skin before inserting the blunt needle.
- The incidence of post-LP headaches MAY be decreased (OR 4.6, range 0.19-1.07), because it doesn’t actually cut any dural or arachnoid fibers.
- Balance this with the fact that 3 studies show a trend towards an increased number of attempts required with the atraumatic needle. Personally, I don’t use a blunt needle.
2. Use a smaller gauge LP needle.
- A smaller gauge (26 gauge vs 22 gauge) needle yields fewer post-LP headaches with an absolute risk reduction of 26%.
- Next time, look at what size LP needle comes in your LP kit. Consider using a smaller gauge.
3. Reinsert the stylet in the needle prior to needle removal
- This causes fewer post-LP headaches with absolute risk reduction of 11%.
- The theory is than arachnoid strand may flow into the needle during CSF collection. Removing the needle without the stylet may “pull” the strand through the dura, causing a persistent CSF leak.
Straus SE, Thorpe KE, Holroyd-Leduc J. How Do I Perform a Lumbar Puncture and Analyze the Results to Diagnose Bacterial Meningitis? JAMA. 2006;296:2012-22.