Long-term Outcomes of Acute Aseptic Encephalitis In Adults - a Single Center Study

BACKGROUND: Encephalitis is a heterogeneous syndrome associated with significant mortality and neurophysiological sequelae. The etiology is identified in only 20–50% of cases, and long-term outcomes of survivors are underinvestigated, especially in patients with unknown etiology. The aim of this study was to describe long-term outcomes of patients with aseptic encephalitis of various etiologies. METHODS: The study population consisted of a retrospectively identified cohort of consecutive adult patients diagnosed with viral and etiologically undiagnosed encephalitis during a 24-month period (2014-2015) at the University Hospital for Infectious Diseases Zagreb, Croatia. Clinical, laboratory data and short-term outcomes were collected from medical records, and long-term outcomes were assessed by telephone interviews and quantified through modified Rankin scores (mRS). RESULTS: A total of 90 patients were identified (57.7% female; 51.5 ± 17.4 years). Viral etiology was identified in 20 (22.2%) patients: herpes simplex virus (HSV-1, 8.9%), varicella-zoster virus (VZV, 6.7%), Tick-borne encephalitis (TBE, 4.4%) and enteroviruses (2.2%). Postinfectious meningoencephalitis was suspected in 14 (15.6%) patients, and 56 (62.2%) had unknown etiology. Elevated CSF WBC was present in 77 patients (mean of 169.3 ± 279.4/mm3) and all but 6 had elevated CSF proteins (1.23 ± 0.88 g/L). Convulsions occurred more frequently in HSV-1 (37.5%) and in unknown etiology group (15.7%). GOS<3 was noted in 50% of HSV, 33% of VZV, 25% of TBE and 24% of unknown group patients during hospitalization. Mechanical ventilation was necessary in 17.1% of patients with unknown and 23.5% with viral etiology for the mean duration of 1.8 ± 6.7 and 3.2 ± 6.3 days, respectively. The mean length of stay was 23.2 ± 18.5 days. In-hospital mortality was 7.8%. Among 64 survivors who were available for follow-up interviews (mean follow-up of 28.6 ± 6.8 months), 73.1% with unknown and 90.9% with viral etiology had favorable outcomes (mRS 0–1); 4 (6.25%) had moderate (mRS 3) and 3 (4.6%) had severe neuropsychological deficits (mRS 4-5). CONCLUSION: Although the etiology of aseptic encephalitis is often unknown, long-term outcomes are favorable in the majority of patients. DISCLOSURES: All authors: No reported disclosures.