Technique

The technique for obtaining cerebrospinal fluid is as follows:

• position the patient:
  • if right-handed, move the patient to the edge of the bed on their left side
  • there should be maximal flexion of the thoracolumbar spine; a pillow is placed between the knees of the patient to prevent torsion of the spine
    
    
• the interspace to be used for the lumbar puncture:
  • the adult spinal cord ends at the level of L1-2
  • the plane of the iliac spine runs through L3-4; L3-4 or L4-5 space can be used
    
    
• technique of lumbar puncture:
  • put gloves on
  • put a drape on top of the patient
  • clean the area e.g. with betadine
  • anaesthetise the skin and subcutaneous tissues with lignocaine at the chosen site
  • place the spinal needle in the interspace with the bevel uppermost and advance it towards the umbilicus keeping it parallel to the ground
  • when advancing the needle consider:
    • there is an increase in resistance as the needle pierces the tough ligamentum flavum and a marked reduction of resistance as the needle passes through
    • when through the ligamentum flavum, the dura is very close (1-2 mm away) and the needle should be advanced carefully and the stylet withdrawn after each step
    • when the dura is pierced there should be a free flow of cerebrospinal fluid
  • measure the opening pressure with a manometer