Background. Neuromyelitis optica (NMO) is a severely disabling autoimmune disorder of the CNS, which mainly affects the optic nerves and spinal cord. However, recent studies have shown that extra-opticospinal are more common in NMO than previously thought. Objective. To investigate olfactory function (OF) in patients with neuromyelitis optica (NMO) versus healthy controls (HC). Methods. Psychophysical testing of the orthonasal OF was performed using the Threshold-Discrimination-Identification test (TDI), measuring different qualities of olfaction, in 10 unselected NMO patients and 10？HC. Results. Five of 10？NMO patients (50%) showed hyposmia, while all 10？HC were normosmic. Moreover, NMO patients had significantly lower mean TDI-scores compared to HC, based on a poorer performance in both the Discrimination and the Identification subtests. Conclusions. Our results suggest that hyposmia might be part of the expanding clinical spectrum of NMO. 1. Introduction Neuromyelitis optica (NMO, Devic’s syndrome) is an autoimmune central nervous system disorder that predominantly affects the optic nerves and the spinal cord [1, 2]. Impaired olfaction is increasingly recognized in neurodegenerative diseases such as Parkinson’s and Alzheimer’s diseases and has been reported in patients with multiple sclerosis (MS) [3, 4]. As the clinical presentation of NMO may extend beyond relapses of optic neuritis and myelitis [2, 5], we here investigated whether olfactory function (OF) is altered in NMO. 2. Patients and Methods This pilot study was performed from July 2011 to October 2012. Ten patients with NMO according to the 2006 diagnostic criteria [1] were prospectively recruited from the Charité outpatient clinics. Aquaporin-4 antibodies were tested using a commercially available cell-based assay employing recombinant human target antigen (EUROIMMUN, Luebeck, Germany) [6]. A healthy control group (HC) of 10 individuals closely matched for gender and age (±3 years) was recruited among the hospital staff. Exclusion criteria for both groups were olfactory disorders (postinfectious, posttraumatic, and sinunasal), infections of the upper respiratory tract, tumours treated with radiation or chemotherapy, allergies, major depression, and Parkinson’s or Alzheimer’s disease. All study participants declared to be nonsmokers. Patients taking drugs that could cause olfactory dysfunction as for example amitriptyline and D-penicillamine were excluded from the study. Furthermore, patients receiving corticosteroid treatment during the testing period were excluded because corticosteroids
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