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Lumbar Puncture

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Topic updated on 05/17/17 8:53pm

Overview
  • LPPurpose
    • withdrawal of cerebrospinal fluid (CSF) from lumbar cistern
    • it is an important diagnostic tool for evaluating a variety of CNS disorders including
      • bacterial, fungal, mycobacterial, and viral CNS infections
      • subarachnoid hemorrhage
      • CNS malignancies
      • demyelinating diseases
      • Guillain-Barré syndrome.
  • Location
    • performed with patient lying on side with back and hips flexed
    • flexion of vertebral column facilitates needle insertion by spreading apart vertebral laminae and spinous processes
    • in adult, needle can be safely inserted in midline between spinous processes L3/L4 or L4/L5.
      • recall the spinal cord extends to L1/L2 in adults and L3 in neonates.
    • needle "pops" through ligamentum flavum, punctures dura and arachnoid, and enters lumbar cistern.
    • plane that transects highest points of iliac crest passes through L4 spinous process and serves as important landmark in lumbar puncture
    • in newborn, needle is inserted in midline between spinous processes L4/L5
  • Order of structures penetrated
    • skin/superficial fascia
    • ligaments
      • supraspinous, interspinous, ligamentum flavum
    • epidural space
    • dura mater
    • subdural space
    • arachnoid mater
    • subarachonoid space - where CSF is contained
    • **note: pia is NOT pierced
      • recall pia lies directly on the nerve bundles of the actual spinal cord
  • CSF from the lumbar puncture is analyzed for:
    • color
    • cell type, morphology, and count
    • protein count
    • glucose level
Cerebrospinal Fluid Analysis
Test Normal Bacterial Viral Fungal/TB
Opening pressure
  • ≤ 20 cm H
    2
    O
  • normal or slightly ↑
Color
  • Clear
  • Cloudy
  • Clear
  • Cloudy
Cell count
  • 0-5 cells/µL
  • ↑ (PMN)
  • ↑ (Lymphocytes)
  • ↑ (Lymphocytes)
Protein
  • < 45 mg/dL
  • Slighty ↑
CSF:Serum glucose
  • > 0.6
  • Normal


  RATE CONTENT
4.0
AVERAGE 4.0 of 7 RATINGS

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