RBD Associated with Paraneoplastic Neurological Syndromes and Autoimmune Disorders

Abstract

REM sleep behavior disorder (RBD) has been described in the setting of some paraneoplastic neurological disorders and autoimmune diseases. Reports include small case series and single reports suggesting that the association is not strong or that it has been underestimated because physicians paid little attention to RBD features when patients presented with acute or subacute disabling neurological symptoms (e.g., mental confusion, seizures, paralysis, ataxia) linked to the underlying condition. RBD confirmed by polysomnography has been described in the paraneoplastic syndromes anti-Ma2 encephalitis and cerebellar degeneration and in the limbic encephalitis associated with LGI1 antibodies. In most of the cases reported, RBD symptoms were not prominent, but the associations reflect that the brain stem (damaged in the anti-Ma2 encephalitis), limbic system (the amygdala is impaired in the anti-LGI1 limbic encephalitis), and the cerebellum (severe Purkinje cell loss in paraneoplastic cerebellar degeneration) play a role in the pathogenesis of RBD. Some patients with Morvan syndrome present with agrypnia excitata, a form of status dissociatus. RBD is present in some autoimmune diseases including narcolepsy (probably due to lack of hypocretin input to the brain stem nuclei that regulate REM sleep) and multiple sclerosis (when plaques are located in the pontine tegmentum). REM sleep without atonia has been described in the acute phase of Guillain-Barre syndrome in some patients. RBD is very common in the anti-IgLON5 disease (a condition of probable autoimmune origin linked to neuronal antibodies and tau deposits in the brain, with a strong HLA link) in association with purposeful behaviors in NREM sleep, disorganized sleep architecture, laryngeal stridor, and obstructive apnea.