Template:CT before LP

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LP without CT is likely safe if:^[1]

History
- Age < 60
- Not immunocompromised
- No history of CNS disease
- No seizure within 1 week of presentation
Physical Exam
- No altered level of consciousness
  - 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:^[2]

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

↑ Computed Tomography of the Head before Lumbar Puncture in Adults with Suspected Meningitis. NEJM 2001; 345; 1727-33
↑ Emergency Radiology: Case Studies Schwartz

[1] Computed Tomography of the Head before Lumbar Puncture in Adults with Suspected Meningitis. NEJM 2001; 345; 1727-33

[2] Emergency Radiology: Case Studies Schwartz

[1]

[2]