CT before lumbar puncture

LP without CT is likely safe if:

• History
  • Age < 60
  • Not immunocompromised
  • No history of CNS disease
  • No seizure within 1 week of presentation
• Physical Exam
  • No ALOC
    • Ability to answer two consecutive questions successfully
    • Ability to follow two consecutive commands successfully
  • Normal neurologic exam

If none of the above, chance of normal ct is 97%; none of the patients herniated

CT findings that prohibit LP:

• Midline shift
  • Unequal pressures between the 3 cerebral compartments (left/right supretentorial compartments, posterior fossa)
  • Intracerebral masses not causing midline shift
• Obstructive Hydrocephalus
  • Enlargement of ventricles prox to lesions and normal ventricles distal (especially 4th ventricle)
• Basilar cisterns compressed
  • Lateral/3rd ventricles may be small due to diffuse cerebral edema or enlarged due to obstr. hydroceph. +/- shift
• Posterior fossa mass
  • Displacement/compression of 4th ventricle

See Also

• Lumbar Puncture

References

Authors

Ross Donaldson