Phenotypic spectrum, etiology and outcomes of infection-related movement disorders: An observational cohort study.

BACKGROUND: Infection-related movement disorders (IRMD) constitute nearly one-fifth of secondary movement disorders, with higher prevalence in endemic regions. Timely recognition is critical, as many are treatable or preventable yet they often mimic primary movement disorders, leading to diagnostic delays.

METHODS: We conducted an observational prospective cohort study at the Movement Disorders Clinic of a tertiary-care centre in India (May 2024-July 2025). All consecutive patients fulfilling the 2024 International Parkinson and Movement Disorder Society consensus criteria for IRMD were included. Clinical, radiological, laboratory, therapeutic, and outcome data were systematically analysed and classified using the MDS six-axis framework.

RESULTS: Of 1102 patients screened, 100 (9.1 %) fulfilled criteria for IRMD (median age 22 years; male: female = 7:3). A preceding infection was identifiable in 80 %, most often viral (64 %) or mycobacterial (18 %). The most frequent etiologies were SSPE (40 %), TB-related (18 %), and JCV-related (12 %). Hyperkinetic disorders predominated (51 %), particularly myoclonus and dystonia, followed by ataxia (22 %). Associated features included cognitive/behavioral symptoms (34 %) and seizures (22 %). Infection-directed therapy was administered in 91 %, with symptomatic management in 59 %. Outcomes were monophasic with improvement in 35 %, static in 15 %, progressive in 17 %, and relapsing in 5 %; mortality was 16 %, largely among SSPE.

DISCUSSION: IRMD constitute a substantial proportion of movement disorders in India, with a predilection for younger patients. SSPE and tuberculosis emerged as leading etiologies. Strengthening vaccination programs and early recognition are pivotal to improving outcomes. Collaborative multicentric studies are essential to refine diagnostic and therapeutic strategies in this understudied domain.