Background The spectrum of autoimmune encephalitis (AIE) is evolving due to heterogeneity of clinical syndromes associated with autoantibodies. While majority of patients present within 3 months, little is known about chronic presentations of AIE. This study aims to characterise the neurobehavioural profile and assess the long-term outcomes of patients with chronic presentations of AIE. Methods Patients with serum or cerebrospinal fluid AIE antibody positivity were included in the study. We reviewed their clinical, cognitive, imaging and treatment characteristics as well as their long-term outcomes. Addenbrooke’s Cognitive Examination-III and Clinical Dementia Rating score were used to evaluate global cognition and the severity of dementia, respectively. Results Of 306 patients diagnosed with dementia in a cognitive disorders’ clinic, 28 had chronic presentations of AIE. The mean age of 28 patients was 55 years (range: 50–60), and mean duration of illness was 12 months (range: 3–84). Of the 28 patients, 9 (32%) were positive for leucine-rich glioma inactivated 1 antibody, 7 (25%) anti-thyroid peroxidase, 5 (18%) N-Methyl D-Aspartate receptor, 5 (18%) glutamic acid decarboxylase 65 and 2 (7%) had contactin-associated protein antibodies. Memory, language and behavioural disturbances with prominent neuropsychiatric symptoms were characteristic clinical manifestations. The course was chronic progressive, relapsing and rapidly progressive in 18 (64%), 8 (28%) and 2 (7%) patients, respectively. On immunomodulator therapy, the majority (21/28) improved, while 7/28 patients remained unchanged or experienced an exacerbation of symptoms. Conclusions Chronic presentations of AIE are less known, and often misdiagnosed due to insidious progressive course and resemble degenerative dementias. A high index of suspicion in patients with chronic atypical cognitive syndromes and a low threshold for antibody testing will allow for prompt diagnosis, appropriate immunotherapy and improvement in clinical outcome.
Arshad et al. (Thu,) studied this question.