Anti–ma2-associated Encephalitis Is an Autoim- Mune Paraneoplastic Disorder Usually Associ- Ated with Testicular Cancer. Patients Present

767 ANTI–MA2-ASSOCIATED ENCEPHALITIS IS AN AUTOIMMUNE PARANEOPLASTIC DISORDER USUALLY ASSOCIATED WITH TESTICULAR CANCER. PATIENTS PRESENT with symptoms of brainstem, limbic, and hypothalamic impairment, such as eye movement abnormalities, memory loss, and endocrine dysfunction.1 In addition, some patients may develop narcoleptic features such as hypersomnia and cataplexy due to hypocretin-1 deficiency, indicating the occurrence of a rapid eye movement (REM) sleep dysregulation of hypothalamic origin.1-5 REM sleep behavior disorder (RBD) is a REM-sleep parasomnia characterized by increased muscle activity associated with vigorous dream-enacting behaviors during REM sleep which is caused by brainstem and limbic system impairment.6,7 Abnormalities of REM-sleep control such as REM-sleep intrusion into wakefulness and persistence of muscle tone during REM sleep have not been well characterized or described in subjects with anti–Ma2-associated encephalitis. Herein, we report a patient with anti–Ma2associated encephalitis who developed both RBD and clinical, electrophysiologic, and biologic narcoleptic features. This case illustrates that RBD and narcolepsy are 2 REM-sleep disturbances that may share a common autoimmune-mediated origin associated with brainstem, limbic system, and hypothalamic damage.