Diagnostic approach and update on encephalitis.

PURPOSE OF REVIEW: The present article gives an update and outlines the fundamental principles of clinical reasoning and a diagnostic approach to a patient suspected to have acute encephalitis. RECENT FINDINGS: Encephalitis remains to be associated with significant mortality and neurological morbidity. Unfortunately, the etiologic diagnosis remains elusive for the majority of the patients with encephalitis preventing targeted therapies. Clinicians could utilize clues such as duration of symptoms, exposure history, cerebrospinal fluid profile, neuroimaging findings and locations, and entertain certain opportunistic infections in immunosuppressed individuals. A comprehensive diagnostic for the most common viral and autoimmune etiologies should be systematically done and prompt empiric antiviral therapy should be started. Evaluation and therapy for autoimmune etiologies should be done for patients with a negative viral work up. Brain biopsy and metagenomic sequencing should be considered for patients with unknown etiologies that are clinically worsening. SUMMARY: Encephalitis remains with unacceptable mortality and morbidity with the most common etiologies being idiopathic. A comprehensive diagnostic work up and prompt antiviral and autoimmune therapies are of paramount importance to improve the outcomes of this devastating disease.