Lumbar Puncture Procedure

Positioning is Key

• Preferred position is LAO, particularly if fluoro unit is stationary
• Patient's right leg is bent
• Back is obliqued towards the operator

Use metallic device and marker to approximate skin entry site with fluoroscopy.
Tight collimation can be helpful to reduce parallax and beam exposure to operator's hands.

Typical Access Levels are L2-L3 and L3-L4

• Shorter distance from skin to thecal sac
• Thecal sac can narrow close to sacrum
• Preferable to prep skin with betadine
• Anesthetize skin and subcutaneous tissue with lidocaine using 25-g needle

Standard Needle is 3.5" 22 g Spinal Needle

• Evidence suggests that atraumatic needle tip may reduce post-dural puncture headache (aka: spinal headache)
• Atraumatic needles: Whitacre, Sprotte, Gertie Marx, and others
• Often need longer needles for larger patients

Advance Needle via Paramedian Approach into Thecal Sac

• Should feel loss of resistance as needle penetrates thecal sac
• Attempt to orient bevel of needle parallel to longitudinal fibers of the interspinous ligaments

Remove inner stylet and evaluate for CSF flow
• Helpful to have a goose neck lamp for improved visualization of CSF
• Connect connection tubing with 3 way stopcock on back
• Ideally, CSF should flow freely into tubing. If slow flow, many options for troubleshooting
• Rotate bevel of needle - will try bevel cranial and caudal first followed by both lateral positions
• Elevate head of bed to increase CSF flow - careful to not dislodge needle, can be difficult in obese patients
• Gentle aspiration with 10 ml syringe can be safe when used cautiously

If obtaining opening pressure, microbore connection tubing can be helpful
• Need connection tubing to bring 3-way stopcock to expected location of heart
• Usually cumbersome to reposition patient in decubitus position after intrathecal access is obtained
• Normal opening pressure 10-24 cm H2O

Volume of CSF to Obtain

• Depends on tests being requested
• Many places obtain 3 cc in first 3 tubes and 5 cc in the 4th tube
• High-volume lumbar puncture for idiopathic intracranial hypertension: removing >30 ml of CSF. Often times opening and closing pressure is requested. Helpful to use 20-g spinal needle for increased CSF flow.
• After CSF removed, replace stylet and remove needle.

Recommendations to Reduce Post-Procedural Complications

• Smaller gauge needle - can use 25g
• Minimize number of lumbar puncture procedure attempts
• Passive removal of CSF
• Safe to collect up to 30 mL of CSF
• Bedrest not shown to reduce post lumbar puncture complaints