Bevel Orientation During Lumbar Puncture
When performing a lumbar puncture with a cutting needle, orient the bevel parallel to the long axis of the spine (perpendicular to the dural fibers running transversely) to reduce the risk of post-dural puncture headache. 1
Rationale for Bevel Orientation
The UK Joint Specialist Societies guideline explicitly recommends orientation of the bevel in a transverse plane (perpendicular to the longitudinal axis) as a practice associated with reduced risk of post-LP headache. 1 This means the bevel should be parallel to the patient's spine, which allows the needle to spread rather than cut the longitudinally-oriented dural fibers. 2
A meta-analysis demonstrated that inserting a cutting needle with the bevel oriented parallel/longitudinal to the spine resulted in significantly lower incidence of post-dural puncture headache compared to perpendicular/transverse orientation (10.9% versus 25.8%; odds ratio = 0.29). 2 This represents a nearly 60% reduction in headache risk. 2
Important Caveat About Needle Type
This bevel orientation is probably less important if you are using an atraumatic (pencil-point) needle, which should be your first choice. 1 The 2023 consensus guidelines recommend that if using a cutting needle, insertion with the bevel parallel to the long axis of the spine is preferred (evidence grade B, moderate certainty). 1
Practical Implementation
- Position the bevel: Face the bevel toward the patient's side (parallel to the spine) when inserting the needle 3, 4
- Additional technique: Replace the stylet before withdrawing the needle to further reduce headache risk 1
- Consider rotating: Some evidence suggests rotating the needle 90 degrees before withdrawal may help 3
Hierarchy of Prevention Strategies
The most effective strategy is using atraumatic (pencil-point) needles rather than cutting needles, which dramatically reduces post-dural puncture headache regardless of bevel orientation. 1, 5 When atraumatic needles are unavailable and you must use a cutting needle, proper bevel orientation becomes your most important technical consideration. 1, 2