Lumbar Puncture (Spinal Tap)

A lumbar puncture (LP), also called a spinal tap, involves inserting a needle into the lower back to measure the pressure of cerebrospinal fluid (CSF) and collect a sample for testing. It's essential for diagnosing conditions like IIH and ruling out infections.

Why It's Done

• Measure opening pressure for IIH or papilledema
• Rule out infection (meningitis)
• Diagnose inflammatory conditions (MS, NMO)
• Therapeutic—removing fluid can temporarily lower pressure

What to Expect

Before the Procedure

• Brain imaging (CT or MRI) usually done first
• Review medications—may need to hold blood thinners
• You may be positioned sitting up or lying on side

During the Procedure

• Lower back cleaned and numbed with local anesthetic
• Needle inserted between vertebrae
• Opening pressure measured
• Fluid collected (feels like pressure, not pain)
• Needle removed, bandage applied
• Takes about 30 minutes

After the Procedure

• Lie flat for 30-60 minutes
• Stay well hydrated
• Avoid strenuous activity for 24 hours
• Monitor for headache

Post-LP Headache

What It Is

• Headache worse when upright, better lying flat
• Can occur 1-5 days after procedure
• Due to CSF leak at puncture site

Prevention and Treatment

• Stay hydrated
• Caffeine (coffee, cola)
• Lie flat
• Blood patch if severe/persistent

Results

Opening Pressure

• Normal: 10-25 cm H2O
• Elevated in IIH: usually >25 cm H2O (>28 in obese patients)

CSF Analysis

• Cell count, protein, glucose
• Special tests for infection, antibodies