CT before lumbar puncture
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
- No altered level of consciousness
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