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.

Central pontine and extra-pontine myelinolysis: a complication of lithium toxicity in a pregnant woman.

Osmotic demyelinating syndromes consisting of central pontine and extra-pontine demyelination are very uncommon disorders characterized by non-inflammatory lesions involving the pons and sometimes spreading to other areas. Rapid changes in serum sodium concentration are usually regarded as the main pathophysiological mechanism. We report herein the case of a 23-year-old woman in the 24th week of pregnancy, who demonstrated both central pontine and extra-pontine demyelination occurring at the time of a recently introduced treatment with lithium. The disorder was related to the rapid correction of pregnancy-related hyponatremia, as a consequence of lithium-induced diabetes insipidus. Hence, lithium toxicity is a rare cause of osmotic demyelinating syndromes and appears to correlate with disturbances in sodium homeostasia.