CT Before LP and LP in Patients With CNS Disease

There have been studies looking at decision rules to selectively image patients with clinical features associated with abnormalities found on CT. One study published in 1999 by Gopal et al. found altered mental status, focal neurologic abnormality, and papaladema could serve as a screening tool. If none of these criteria were present, the negative likelihood ratio was 0.1. Clinical suspicion provided the same negative likelihood ratio with a much higher positive likelihood ratio of over 18. A delay in antibiotics can increase the risk of mortality by about 30% per hour in patients with meningitis.