Diagnostic Yield of Combined Lumbar Puncture and Brain MRI in Critically Ill Patients With Unexplained Acute Encephalopathy: A Retrospective Cohort Study.

Unlabelled: Critically ill patients frequently experience acute encephalopathy, often colloquially termed "altered mental status" (AMS); however, there are no consensus guidelines or criteria about performing lumbar puncture (LP) and advanced neuroimaging in medical ICU patients with unexplained encephalopathy.

Objectives: We sought to characterize the yield of combined LP and brain MRI (bMRI) in such patients as determined by both the frequency of abnormal results and the therapeutic efficacy of these investigations, that is, how often results changed management.

Design Setting And Participants: Retrospective cohort study of medical ICU patients admitted to a tertiary academic center between 2012 and 2018 who had documented diagnoses of "AMS" and/or synonymous terms, no clear etiology of encephalopathy, and had undergone both LP and bMRI.