Proportion and spectrum of movement disorders in adolescent and adult patients of autoimmune encephalitis of non-neoplastic aetiology.

We aimed to study the proportion of patients with movement disorders in seropositive autoimmune encephalitis of non-neoplastic aetiology and also to describe the spectrum of movement disorders in them. We prospectively screened 362 patients of age >12 years with encephalitis of unknown aetiology for a panel of antibodies for autoimmune encephalitis. Demographic and clinical characteristics with focus on the movement disorders were recorded. We also evaluated the differences in the spectrum of movement disorder based on various age groups and antibody positivity. Patients were treated with immune modulating drugs and were followed up for 6 months. Out of the 41 patients, 21 (51.2%) patients presented with movement disorder as a part of their clinical presentation. The commonest movement disorder encountered in our cohort was orofaciolingual dyskinesia (OFLD) 57.1% followed by tremor (38.1%), choreoathetosis (33.3%), paroxysmal dyskinesia (23.8%) stereotypies (14.3%), bradykinesia (13.1%), followed by dystonia (13.1%), catatonia (4.7%), neuromyotonia (4.7%) ballism (4.7%), ataxia (4.7%) and stiff person phenotype (4.7%). The hyperkinetic movement disorders were more commonly seen compared to hypokinetic disorders. All patients received immunomodulatory therapy. On follow, 17 (80.1%) patients had good response with total remission of the movement disorder. Four patients did not have total remission but significant improvement in the symptoms after 6 months of follow up. Our study shows that >50% of patients with antibody positive autoimmune encephalitis have movement disorder as a part of their clinical feature. Timely institution of immunotherapy leads to good outcome in majority of patients.