Aquaporin-4 autoantibody: a neurogenic cause of anorexia and weight loss.

Neuromyelitis optica (NMO) is a severe inflammatory demyelinating disease often associated with a highly specific autoantibody, aquaporin-4 antibody. Although the classic syndrome involves the optic nerves and spinal cord, aquaporin-4 antibody has been important in defining the true spectrum of NMO, which now includes brain lesions in areas of high aquaporin-4 expression. Brainstem involvement, specifically area postrema involvement in the medulla, has been associated with intractable vomiting in some patients with NMO. We describe a 14-year-old female with positive aquaporin-4 antibody whose clinical course was dominated by severe anorexia with associated weight loss (from 68-41kg; body mass index 25.2-15.6). Magnetic resonance imaging showed lesions in the medulla, pons, and thalami. Although she had asymptomatic radiological longitudinally extensive transverse myelitis, she never had symptoms or signs referable to the spinal cord or the optic nerves. We propose that anorexia and weight loss should be considered part of the NMO spectrum, probably related to area postrema involvement.