Hypersomnia as the prominent symptom of anti-Ma2 associated encephalitis

Abstract

Objective To investigate the characteristics and mechanisms of sleep disorders in anti-Ma2 associated encephalitis. Methods Report a case of anti-Ma2 associated encephalitis with excessive sleepiness as the initial and prominent symptom who was diagnosed in our hospital. The characteristics of this case were studied from several aspects such as clinical, imaging, polysomnography and cerebrospinal fluid, etc. Results This case was characterized mainly by the symptom of lethargy, together with memory loss, mental and behavior disorder and walking instability. MRI examination indicated the damage of limbic system, hypothalamus and upper brainstem. The polysomnography showed narcolepsy-like symptoms and rapid eye movement sleep behavior disorder. In addition, the level of hypocretin from cerebrospinal fluid remained normal (186 pg/ml), the anti-Ma2 antibodies in blood and cerebrospinal fluid showed positive, and the lymphoma was identified by colon histopathology. As a result, this case was diagnosed as lymphoma with anti-Ma2 associated encephalitis. Conclusions The sleep disorders in anti-Ma2 associated encephalitis manifest a variety of forms including excessive sleepiness, narcolepsy-like symptoms and rapid eye movement sleep behavior disorder, which are associated with the structural damage in hypothalamus, brainstem and limbic system. Further, the incidence of such narcolepsy symptoms might involve other neurotransmitter systems other than hypocretin. Key words: Limbic encephalitis; Autoantibodies; Disorders of excessive somnolence; Sleep disorders; Antigens, neoplasm; Nerve tissue proteins