Whitacre

• Solid conical pencil point ('atraumatic') tip 1
• Rectangular lateral aperture just proximal to tip 1

Quincke

• Diamond-shaped 'cutting' bevel 1
• Opening at the tip 1

• Separates the longitudinal fibres of the dura without cutting them, causing less trauma 1
• Reduces CSF leakage and hence PDPH rates 1
• Generates a more convincing ‘click’ on breaching the dura 1

• Lumbar puncture should be performed below the L2/3 interspace 1:
  • In adults, the solid spinal cord ends at L1 (ranges from T11 to upper L3)
  • At this level the conus medullaris continues distally as the cauda equina
  • Puncture above this level risks damaging the cord
• The L4/5 or L3/4 interspace is usually used
• The L4 spinous process can be estimated using Tuffier's line:
  • An imaginary line drawn between the iliac crests 1
  • Significant anatomical variation exists between patients
• Alternative anatomic landmarks include:
  • The tip of the scapula in line with T7 spinous process 1
  • The tip of the 10th rib in line with L1 spinous process 1

• Spinal cord ends at the conus medullaris
• Level of conus traditionally considered to be lower in infants and children than adults - studies suggest median level is similar
• Level of the conus medullaris varies significantly between individual patients:

• Keep drugs in different sized syringes1
• Only draw up what you need1
• Check drugs with a second person1
• Discard unnecessary or used drugs1
• Use and remove skin preparation solutions before opening the needle1