Narcolepsy as an initial manifestation of neuromyelitis optica with antiaquaporin-4 antibody

Abstract

JO N 3139 brospinal fluid (CSF) hypocretin level is useful for a diagnosis of narcolepsy [3]. The symptoms of narcolepsy are also known to occur secondary to hypothalamic lesions of various neurological conditions, such as brain tumors [6] and multiple sclerosis (MS) [2, 9]. Neuromyelitis optica (NMO) is a demyelinating disease typically manifesting transverse myelitis and bilateral optic neuritis. Anti-aquaporin-4 (AQP4) antibody was discovered as a disease-specific autoantibody in NMO patients [5]. Recently, brain lesions of NMO have been identified by many investigators and it has been reported that the lesions are generally observed in the hypothalamic region [7, 10]. In this paper, we report a case of NMO with anti-AQP4 antibody, whose initial manifestation was narcolepsy and marked decrease of CSF hypocretin level. A 35-year-old woman was referred for evaluation of excessive daytime sleepiness. On examination, apart from excessive daytime sleepiness, no neurological deficit was detected. She had no episode of cataplexy. A MRI scan showed a nonenhancing T2 lesion in the hypothalamus (Fig. 1 A). CSF study showed a slight degree of pleocytosis (12/mm3) and a normal protein level (23 mg/dl). The CSF hypocretin-1 level was markedly decreased (91 pg/ml; normal 200–350 pg/ml). She had narcolepsy-associated HLA haplotypes such as DR2 [3], but the DNA haplotypes were not typical for this disease (DRB1*1502, DQB1*0301, and DQB1*0601). Her sleep pattern was evaluated by nocturnal polysomnography (PSG) and multiple sleep latency test (MSLT). Her sleep latency was less than 10 min with SOREMP and total sleep time was 9.5 hours in PSG. The mean sleep latency by MSLT (4 naps) was 6 min with 4 SOREMPs. She was diagnosed as having narcolepsy due to Toru Baba Ichiro Nakashima Takashi Kanbayashi Masatoshi Konno Toshiyuki Takahashi Kazuo Fujihara Tatsuro Misu Atsushi Takeda Yusei Shiga Hiromasa Ogawa Yasuto Itoyama