Lumbar Puncture
Anatomy
“Some Spanish Students Ingest Lime-Flavored Drinks And Sip”
S: Skin
S: Subcutaneous tissue (superficial&deep fascia)
S: Supraspinous ligament
I: Interspinous ligament
L: Ligamentum flavum
F: (Epi)Fural space → remember this is the epidural space
D: Dura mater
A: Arachnoid mater
S: Subarachnoid space
Landmarks
-“Pop” = ligamentum flavum
-CSF after dura + arachnoid
Before LP
- Do neuroimaging (CT/MRI) before LP
>Neuroimaging/LP should not delay therapy
Needle types
-Atraumatic (pencil-point): Whitacre, Autocan, Eldor, Greene→ Lower PDPH
-Cutting needle: Quincke→ Higher PDPH risk
-Epidural needles: Tuohy, Crawford→ Do NOT enter subarachnoid space intentionally
Contraindications
Absolute
-⬆️ICP 2/2 mass
-VZV at lumbar site
-Coagulopathy (Plat < 50K, INR > 1.5, PTT > 45s)
-Suspect epidural abscess
Relative
-IC mass without inc ICP
-Coagulopathy that can be reversed (give Plat)
Regarding anti-thrombotics/ thromboprophylaxis
-Non-urgent vs urgent LPs
Interesting
- Clopidogrel→ no correlation P2Y12 & LP safety, still time should be used
Technique
①Position
-Lateral decubitus→ OP
>Shoulder & hips stacked/parallel (avoid spinal rotation)
>Fetal position (nurse assistance, pillow btw knees)
-Seated→ no OP
>If OP is mandatory: seated and change to lat decubitus
②Landmarks
-Both post sup iliac crests→ L4-L5 region (Tuffier's line)
>Avoid above L3-L4
-Insert needle in midline, about 1 cm below supe spinous process
③Troubleshooting
"Bone depth helps determine what structure is blocking the needle"
-Bone at 1–2 cm→ Wrong level
-Bone at 2–4 cm→ Wrong side (off midline)
-Bone at 6–8 cm→ Almost there
-No bone + no CSF→ Missed the midline
-Radicular pain→ Too lateral
-Bloody tap→ Vein or traumatic puncture
-New/worsening lower-extremity weakness
-Saddle anesthesia
-Urinary retention
-Bowel or bladder incontinence
-Persistent/ worsening pain after needle removal
-Progressive neurological deficits