ABSTRACT
Infectious meningitis and encephalitis are often life-threatening illnesses, though prompt workup and targeted treatment can greatly reduce morbidity and mortality. Although presentation of central nervous system infection can sometimes be subtle, this issue focuses on evidence-based strategies for identifying combinations of signs and symptoms to narrow the diagnosis. Identifying meningitis versus encephalitis; bacterial versus viral, fungal, or iatrogenic causes; and providing prompt empiric antimicrobials and appropriate diagnostic testing are key to management. Cerebrospinal fluid testing findings are outlined to help determine a potential cause for symptoms, along with blood and serum testing options. International society guidelines and evidence regarding the need for computed tomography prior to lumbar puncture are presented, which can help reduce unnecessary imaging. Disposition criteria are expanded to help determine whether a patient can go home, or the level of hospital care that will be required for those admitted.