Anti-Ma2-Associated Encephalitis Presenting as Hypersomnia

Anti-Ma2-associated encephalitis is one of the paraneoplastic neurological syndromes. It has been shown to be associated with various neoplasms, mainly testicular, lung, and breast cancers. Most patients with anti-Ma2-associated encephalitis present limbic-diencephalic-brainstem dysfunctions such as seizure, mood disorder, excessive daytime sleepiness, and ophthalmoparesis. Some patients develop symptoms indicating the multifocal involvement of the limbic system, diencephalon, or brainstem. However, there are few case studies of anti-Ma2-associated encephalitis presenting as isolated hypersomnia. We report a case of anti-Ma2-associated encephalitis presenting as hypersomnia.