Background. - Area postrema syndrome (APS) is recognized as a core feature in neuromyelitis optica (NMO) diagnosis. Isolated APS can occur at NMO onset and frequently results in a delay of diagnosis, along with devastating secondary neurologic deficits. To date, few studies have characterized APS-onset neuromyelitis optica spectrum disorder (APSO-NMOSD). Objective. - We aimed to describe the clinical and radiologic features of patients with APSO-NMOSD who are initially misdiagnosed in a cohort of patients from Zhengzhou, China. Materials and methods. - We identified 15 patients who presented with APS as an initial manifestation, based on the 2015 international consensus diagnostic criteria for NMOSD, and reviewed their demographic, clinical, laboratory, and magnetic resonance imaging (MRI) data. Result. - Fifteen patients (3 men, 12 women) aged 14-50 years old were included in our study. All patients presented with APS that included intractable nausea, vomiting, or hiccups (INVH) as the initial manifestation; many experienced a delay in diagnosis. Serum AQP4 was positive in eleven patients and myelin oligodendrocyte glycoprotein (MOG) in one patient. All patients had a linear medullary lesion or a linear medulla-spinal lesion on sagittal MRI. An "inverted V sign'' on axial medulla oblongata images, representing a lesion involving the area postrema, was noted in seven patients in this study. Conclusions. - APS can occur as a sole and initial manifestation of NMOSD, often leading to misdiagnosis in the early process of disease. Identifying patients with an "inverted V'' sign and a linear medullary lesion upon MRI examination can help to quickly identify APS patients and avoid further diagnostic delays. (C) 2020 Elsevier Masson SAS. All rights reserved.