Lumbar puncture

Contraindications

1. Infection at LP site
2. Platelet count <20K
   1. Platelet counts >50K are safe for LP
3. INR >1.5
4. Heparin administration in past 24hr
5. Hemophilia, von Willebrand disease, other coagulopathies
6. Trauma to lumbar vertebrae

Procedure

1. Sterile prep L3-L4 and L4-L5 interspaces
2. Positioning
   1. Pt on side: able to measure opening pressure
   2. Pt sitting: helpful for difficult habitus, but must move pt to measure opening pressure
3. Needle selection
   1. 3.5 in atraumatic 22ga needle is ideal
   2. Needle >20ga almost doubles incidence of post-LP headache
4. Anesthetize both superficial skin as well as along intended path of LP needle
5. Insert needle with bevel facing the ceiling (if pt is on side)
6. Opening pressure should be measured with pt on side with legs extended
7. Collect 1mL in each tube

CT Head before LP

See CT Before Lumbar Puncture

Normal Values

Parameter	Preterm Infant	Term Neonate	Child
Celll Count (WBC)	9 (0-25) >30 suggests meningitis	8 (0-22) >30 suggests meningitis	0-7, >10 in child >1mo suggests meningitis
PMN (%)	57	61	0
Glucose	52 (24-63)	52 (34-119)	40-80
Protein	115 (65-150)	90 (20-170)	5-40
RBC	0	0	0

Subarachnoid Hemorrhage vs Bloody Tap

1. Xanthrochromia
   1. Suggestive of hemorrhage
2. RBC
   1. <50 suggestive of bloody tap
   2. >600 suggestive of SAH
   3. 50-600 = gray zone
3. Opening pressure
   1. Increased opening presure suggestive of SAH

Meningitis

Bacterial

1. Appearance Cloudy or purulent
2. Glucose (mg/dl) <40 or <40% serum
3. Protein (mg/dl) >100-500
4. Cell Count 100-100,000 (>5)
5. Differential >80% PMN
6. Pressure (cm H2O) Usually Inc

Fungal

1. Appearance Clear or cloudy
2. Glucose (mg/dl) 20-40
3. Protein (mg/dl) 25-500
4. Cell Count 25-1000
5. Differential mono & lymph
6. Pressure (cm H2O) N or I
7. India ink 50% sensitivity
8. LA assay for crypto antigen 80%.

Aseptic/Viral

1. Appearance Clear
2. Glucose (mg/dl) N or D
3. Protein (mg/dl) 50-200
4. Cell Count WBC 10-100
5. Differential Inc mono & PMN early, then lymph.
6. Pressure (cm H2O) N or I

TB

1. Appearance Cloudy
2. Glucose (mg/dl) <40
3. Protein (mg/dl) 100-2000
4. Cell Count 50-500
5. Differential Most lymph, some PMN
6. Pressure (cm H2O) Usually Incr

HSV

1. Appearance Bloody or xantho
2. Glucose (mg/dl) N or D
3. Protein (mg/dl) 50-100
4. Cell Count 20-500
5. Differential Mostly lymph
6. Pressure (cm H2O) N or Incr

Neoplasm

1. Appearance Clear or xantho
2. Glucose (mg/dl) 40-80
3. Protein (mg/dl) 50-1000
4. Cell Count <100
5. Differential Mostly lymph
6. Pressure (cm H2O) Usually Incr

Guillain-Barre

1. Appearance Clear or cloudy
2. Glucose (mg/dl) Normal
3. Protein (mg/dl) slight Inc
4. Cell Count <100
5. Differential Mostly lymph
6. Pressure (cm H2O) Normal

Complications

1. See Post-Lumbar Puncture Headache

Source

• Emergency Radiology: Case Studies Schwartz
• Hasbun, R. et al, (Yale), NEJM, Dec 13, 2001.