REM sleep behavior disorder and narcoleptic features in anti-Ma2-associated encephalitis

Abstract

A 69-year-old man with anti-Ma2 paraneoplastic encephalitis presented with subacute onset of severe hypersomnia, memory loss, parkinsonism, and gaze palsy. A brain magnetic resonance imaging study showed bilateral damage in the dorsolateral midbrain, amygdala, and paramedian thalami. Videopolysomnography disclosed rapid eye movement (REM) sleep behavior disorder, and a Multiple Sleep Latency Test showed a mean sleep latency of 7 minutes and 4 sleep-onset REM periods. The level of hypocretin-1 in the cerebrospinal fluid was low (49 pg/mL). This observation illustrates that REM sleep behavior disorder and narcoleptic features are 2 REM-sleep abnormalities that (1) may share the same autoimmune-mediated origin affecting the brainstem, limbic, and diencephalic structures and (2) may occur in the setting of the paraneoplastic anti-Ma2-associated encephalitis.

Figure 1

Axial FLAIR brain magnetic resonance imaging study (MRI) shows bilateral hyperintensities in the amygdala (white arrows) and dorsolateral midbrain (grey arrow) (A), and polysomnography demonstrates characteristic features of rapid eye movement (REM) sleep behavior disorder (sustained tonic electromyogram (EMG) activity in the chin and excessive phasic EMG activity in the lower limbs channels during REM sleep) (B). LOC refers to left electrooculogram; ROC, right electrooculogram; Al, left ear; A2, right ear; C3, left central electroencephalogram (EEG); C4, right central EEG; Ol, left occipital EEG; 02, right occipital EEG; Chin, chin surface EMG; L Bic, left biceps surface EMG; R Bic, right biceps surface EMG; LAT, left anterior tibilais surface EMG; RAT, right anterior tibilais surface EMG; Nasal, nasal airflow; Thor, thoracic breathing effort; EKG, electrocardiogram.