Clinical efficacy of plasma exchange in patients with autoimmune encephalitis

OBJECTIVE: To determine the clinical and antibody response after therapeutic plasma exchange (TPE) in patients with severe refractory antibody‐associated autoimmune encephalitis (AE). METHODS: This single‐center prospective cohort included all patients consecutively admitted to our hospital because of severe refractory AE over the period from July 2014 to June 2019. All patients received immunotherapy (steroids, intravenous immunoglobulin (IVIG), and/or TPE). The primary outcome was evaluated at 1‐ and 2‐month postenrollment, and the long‐term outcome was followed up at 6 and 12 months. AE antibody titers in the cerebrospinal fluid and plasma were evaluated before and after TPE/IVIG. RESULTS: This study enrolled 57 patients with severe refractory AE, including anti‐NMDA receptor encephalitis (n = 51), anti‐GABAb receptor encephalitis (n = 3), anti‐LGI 1 encephalitis (n = 2), and anti‐AMPA receptor encephalitis (n = 1). Of all 57 patients, 33 patients received TPE for a total of 193 procedures, and 24 patients with contraindications or refusal of TPE were in the non‐TPE group. Compared with the non‐TPE group, the TPE group exhibited greater clinical improvement: 21 (37%) versus 8 (14%) after 1 month (P = 0.03) and 31 (54%) versus 16 (28%) after 2 months (P = 0.01), respectively. Complications and adverse events associated with TPE occurred in 91 procedures (47%) without serious adverse events associated with the use of TPE. INTERPRETATION: TPE might be an effective rescue therapy associated with rapid functional improvement in patients with severe steroid/IVIG refractory antibody‐associated AE from this nonrandomized control trial.