Narcolepsy secondary to anti-Ma2 encephalitis: two case reports.

Recent studies suggest that sleep disorders are present in two-thirds of patients with autoimmune encephalitis. In anti-Ma2 encephalitis, hypersomnia appears to be frequent. However, only few cases of type 1 narcolepsy have been reported to date with anti-Ma2 encephalitis. We report 2 new cases of patients with narcolepsy secondary to anti-Ma2 encephalitis. Patient 1, a 68-year-old man, had narcolepsy type 1, including sleep attacks, cataplexy, abnormal Multiple Sleep Latency Tests and hypocretin-1 deficiency (< 50 ng/L) in the cerebrospinal fluid (CSF), associated with a cerebellar syndrome. Anti-Ma2 antibodies were present in the serum and CSF and antivoltage-gated potassium channel antibodies in the serum. He benefited from a treatment with pitolisant. Patient 2, a 42-year-old man, had narcolepsy type 2, including hypersomnolence, no cataplexy, intermediate CSF levels of hypocretin-1 (138 ng/L), abnormal Multiple Sleep Latency Tests, and a limbic encephalitis presentation. Anti-Ma2 antibodies were present in the serum and CSF, and anti-Ma1 antibodies were in the CSF. For both, repeated polysomnographies were necessary to establish the precise diagnosis of central hypersomnia, emphasizing the importance of carrying out sleep investigations in a tertiary neurology center with sleep medicine expertise in patients with anti-Ma2 encephalitis. CITATION: Brunet de Courssou J-B, Testard P, Sallansonnet-Froment M, et al. Narcolepsy secondary to anti-Ma2 encephalitis: two case reports. J Clin Sleep Med. 2023;19(4):837-841.