Introduction: Movement disorders are a dominant clinical feature of NMDAR encephalitis1. They are also observed in a group of patients with autoimmune basal ganglia (BG) encephalitis that have recently been shown to be associated with antibodies to the Dopamine-2 receptor2. We aimed to explore the movement disorder phenomenology in these entities.

Methods: Videos of 31 patients with NMDAR encephalitis (n=10), basal ganglia encephalitis (n=12) and Sydenham’s chorea (controls, n=9) (SC) were rated by 4 movement disorder neurologists. The raters were blinded to the diagnoses. Movement disorder phenomenology was rated as primary movement disorder, other movement disorders and any additional comments were recorded. A moderator ensured blinding and consensus with use of standard terminology.

Results: Patients with SC had chorea (n=9), dystonia (n=2) and ballism (n=1). Patients with NMDAR encephalitis had stereotypy (n=7), dystonia (n=5), chorea (n=4), tonic or clonic perseveration (n=4), pouting (n=2), akinesia (n=1), tremor (n=1) and ballism (n=1). BG encephalitis patients had dystonia (n=7), akinesia (n=5), tremor (n=4) and chorea (n=3).

Conclusion: The spectrum of movement disorders in NMDAR encephalitis is wide but dominated by stereotyped movements and dystonia. BG encephalitis can be differentiated by the dominant akinesia that accompanies dystonia and sometimes chorea and tremor. Clinical differentiation of the disorders can aid diagnostic workup and management.