Movement disorders in multiple sclerosis and neuromyelitis optica: A clinical marker of neurological disability.

INTRODUCTION: Movement disorders are not rare in demyelinating diseases but there are few studies comparing their frequency between multiple sclerosis and neuromyelitis optica spectrum disorder. Our aim was to determine the frequency and the related features of movement disorders in a cohort of patients with multiple sclerosis and neuromyelitis optica spectrum disorder. METHODS: It is a cross-sectional study of patients with multiple sclerosis and neuromyelitis optica spectrum disorder. Patients were evaluated by a movement disorder specialist. Data from a personal interview and neurological examination were collected. Fahn-Tolosa-Marin tremor rating scale was used for tremor evaluation. Health-related quality of life was assessed using EuroQol instrument. RESULTS: Two hundred fifty-three patients were included (mean [SD] age, 40 [12] years; 74.3% female; median [IQR] EDSS score 2.5 [1.0-6.0]); 26% presented with movement disorders. Paroxysmal dystonia (n = 32) and tremor (n = 27) were the most common movement disorders. Patients with multiple sclerosis and low Expanded Disability Status Scale score (below 4.0) have fewer movement disorders than patients with neuromyelitis optica spectrum disorder. The diagnosis of neuromyelitis optica spectrum disorder was strongly associated with paroxysmal dystonia (OR = 22.07, 95% CI = 2.56-189.78; p = 0.005). Patients with multiple sclerosis and patients without movement disorders have a slightly better quality of life. CONCLUSIONS: Paroxysmal dystonia was the most common movement disorder in demyelinating diseases and strongly associated with neuromyelitis optica spectrum disorder.