Lumbar Puncture

1. See Also
   1. Cerebrospinal Fluid
2. Precautions
   1. Obtain CT Head before Lumbar Puncture if significant risk factors for CNS mass
      1. Do not delay empiric antibiotics for CT Head if Bacterial Meningitis suspected (do obtain Blood Cultures before antibiotics)
   2. Indications for CT Head before Lumbar Puncture
      1. CSF Shunt
      2. Hydrocephalus
      3. Trauma
      4. Space occupying lesion
      5. Recent neurosurgery
      6. Papilledema
      7. Focal neurologic deficit
      8. New onset Seizures
      9. Significantly Altered Level of Consciousness
3. Contraindications
   1. Local infection at Lumbar Puncture site
   2. Cerebral mass lesion (risk of herniation)
      1. Large brain abscess
      2. Brain Tumor (especially posterior fossa)
      3. Subdural Hematoma
      4. Intracranial Hemorrhage
   3. Papilledema
   4. Uncorrected Bleeding Disorder
      1. Severe Thrombocytopenia
4. Indications
   1. Suspected CNS Infection
      1. Meningitis
      2. Encephalitis
   2. Evaluate for Hemorrhagic CVA (Subarachnoid Hemorrhage)
      1. Hemorrhage suspected despite negative Head CT
      2. Head CT not available
   3. Diagnostic Chemistry Evaluation
      1. CSF Gamma Globulin (Multiple Sclerosis)
   4. CSF Dynamics
      1. Spinal block diagnosis (Queckenstedt test)
      2. Normal Pressure Hydrocephalus evaluation
         1. Katzman infusion
         2. Radionucleotide cisternography
   5. CSF Cytology
      1. Carcinomatous Meningitis
      2. Lymphomatous Meningitis
   6. Therapeutic Lumbar Puncture
      1. Methotrexate infusion (CNS Leukemia)
      2. Amphotericin B infusion (fungal Meningitis)
      3. Removal of fluid to decrease Intracranial Pressure
         1. Pseudotumor Cerebri
         2. Headache associated with Subarachnoid Hemorrhage
5. Complications
   1. Spinal Headache
   2. Unexpected rise in Intracranial Pressure
   3. Worsening of spinal block
6. Equipment: Needle types
   1. Standard spinal needle
      1. Easier to obtain successful spinal tap
   2. Atraumatic or blunt spinal needle
      1. Smaller tapered needle with blunt tip
      2. Significantly lower Spinal HeadacheIncidence
   3. References
      1. Thomas (2000) BMJ 321:986-90
7. Technique
   1. Patient positioning
      1. Lateral decubitus position
         1. Fetal Position
         2. Back at right angles to bed
      2. Sitting position
         1. Leaning forward, holding a pillow
   2. Location
      1. Mark midline spinous process between iliac crests
      2. Corresponds with L3-L4 or L4-L5 interspace
   3. Spinal needle insertion
      1. Use 20 to 22 gauge spinal needle
      2. Insert needle bevel parallel to long axis of spine
      3. Keep needle parallel with bed
      4. Angle needle toward Umbilicus
      5. Insert needle until pop is felt or CSF fluid flows
         1. Coughing or Valsalva maneuver increases flow
   4. Mis-directed Needle hits bone
      1. Withdraw needle to skin level and redirect
   5. Adjuncts to difficult Lumbar Puncture
      1. Fluoroscopy
8. Standard CSF Orders
   1. Tube 1
      1. Gram Stain
      2. Culture and sensitivity
   2. Tube 2
      1. CSF Glucose
      2. CSF Protein
   3. Tube 3
      1. CSF Cell Count with Differential
   4. Tube 4
      1. CSF Latex Agglutination (Antigens)