Sudden Onset Of Sleep Due To Bilateral Hypothalamic Lesions In Neuromyelitis Optica Spectrum Disorder Positive For Aquaporin 4 Antibody (AQP4) (P5.298)

OBJECTIVE:To describe a patient with neuromyelitis optica spectrum disorders (NMOSD) who presented with sudden onset of sleep (SOOS) as the initial manifestation. BACKGROUND: It is now known that NMOSD patients may develop excessive sleepiness due to hypothalamic lesions. However, there is no report of SOOS in this disorder. DESIGN/METHODS:Single case report. RESULTS:A 41-year-old Japanese woman was admitted to our hospital because of a 3-month history of SOOS. During this time, she was involved in two car accidents because she suddenly fell asleep while driving. She did not feel sleepiness beforehand at each event. In another occasion, she fell asleep holding the chopsticks while eating. She also felt slight sleepiness in working time but she did not take a nap. Neurological examinations revealed no definite abnormalities. Cerebrospinal fluid protein was 20 mg/dl and cell count was 7/mm3. FLAIR images of brain MRI showed high-intensity areas in the bilateral hypothalamic regions. AQP4 antibody was positive in the serum. We diagnosed her as NMOSD and treated her by intravenous methylprednisolone for 3 days. After the treatment, SOOS completely disappeared in a few weeks. CONCLUSIONS:SOOS is a well-known serious side effect of non-ergot dopamine agonists, antiparkinsonian agents. Excessive daytime sleepiness and hypersomnia has been reported as a frequent symptom of NMOSD patients with hypothalamic lesions. However, there has been no report of SOOS in NMOSD patients. SOOS is a serious condition that may lead to critical car accidents, just as has occurred for the present patient, because of the lack of heralding sleepiness, and should be strictly discriminated from simple hypersomnia. It is imperative for physicians to recognize SOOS as a possible symptom of NMOSD.