Prolonged Corticosteroids Without Maintenance Immunotherapy for Treatment of Anti-LGI1 Encephalitis: Analysis of Outcomes and Relapse Rate

OBJECTIVES: To analyze outcomes and relapse rate of patients with anti-LGI1 encephalitis referred to the London Health Sciences Centre Autoimmune Neurology Clinic, where prolonged (≥3 months) corticosteroids without steroid-sparing maintenance immunotherapy are the typical treatment approach. METHODS: Retrospective chart review. RESULTS: Eighteen patients with anti-LGI1 encephalitis were identified. The median age at symptom onset was 65 years (interquartile range [IQR]: 62–70 years), and 13 (72%) were men. All patients received corticosteroids, with a median treatment duration of 6.3 months (IQR: 3.8–9.6 months). Other first-line immunotherapies used included IV immunoglobulin (n = 11, 61%) and plasma exchange (n = 2, 11%). Three patients referred for refractory disease received rituximab as second-line immunotherapy. No other steroid-sparing maintenance immunotherapies for anti-LGI1 encephalitis were prescribed. At last follow-up, 16/18 (89%) achieved seizure freedom, and 16/18 (89%) had a favorable modified Rankin Scale score. Among 9 patients who had ≥2 years of follow-up from symptom onset, there was disease relapse in 3 (33%), 2 of whom had been referred for refractory disease. DISCUSSION: Among our patients with anti-LGI1 encephalitis who typically received prolonged corticosteroids without steroid-sparing maintenance immunotherapy, outcomes were generally favorable, and relapses were uncommon outside of refractory disease. Further investigation is needed to clarify the optimal corticosteroid regimen and role of steroid-sparing maintenance immunotherapy in anti-LGI1 encephalitis.