Autoimmune Encephalitis in the ICU: Analysis of Phenotypes, Serologic Findings, and Outcomes

To report the clinical and laboratory characteristics, clinical courses, and outcomes of Mayo Clinic, Rochester, MN, ICU-managed autoimmune encephalitis patients (January 1st 2003-December 31st 2012).

Based on medical record review, twenty-five patients were assigned to Group 1 (had ≥1 of classic autoimmune encephalitis-specific IgGs, n = 13) or Group 2 (had ≥3 other characteristics supporting autoimmunity, n = 12).

Median admission age was 47 years (range 22-88); 17 were women. Initial symptoms included ≥1 of subacute confusion or cognitive decline, 13; seizures, 12; craniocervical pain, 5; and personality change, 4. Thirteen Group 1 patients were seropositive for ≥1 of VGKC-complex-IgG (6; including Lgi1-IgG in 2), NMDA-R-IgG (4), AMPA-R-IgG (1), ANNA-1 (1), Ma1/Ma2 antibody (1), and PCA-1 (1). Twelve Group 2 patients had ≥3 other findings supportive of an autoimmune diagnosis (median 4; range 3-5): ≥1 other antibody type detected, 9; an inflammatory CSF, 8; ≥1 coexisting autoimmune disease, 7; an immunotherapy response, 7; limbic encephalitic MRI changes, 5; a paraneoplastic cause, 4; and diagnostic neuropathological findings, 2. Among 11 patients ICU-managed for ≥4 days, neurological improvements were attributable to corticosteroids (5/7 treated), plasmapheresis (3/7), or rituximab (1/3). At last follow-up, 10 patients had died. Of the remaining 15 patients, 6 (24%) had mild or no disability, 3 (12%) had moderate cognitive problems, and 6 (24%) had dementia (1 was bed bound). Median modified Rankin score at last follow-up was 3 (range 0-6).

Good outcomes may occur in ICU-managed autoimmune encephalitis patients. Clinical and testing characteristics are diverse. Comprehensive diagnostics should be pursued to facilitate timely treatment.