A 12-year-old girl sought care for subacute onset of cramping back pain, along with paresthesias in her lower limbs up to the waistline, both hands, upper back, and chest, followed by rapidly progressive (over a few hours) painful vision loss affecting initially the right eye with subsequent involvement of the left eye. She underwent neuroophthalmologic evaluation and was diagnosed with bilateral optic neuritis. A positive Lhermitte sign was also present.
The patient was tested for aquaporin-4-immunoglobulin G autoantibodies, which were positive in both serum and cerebrospinal fluid.
A diagnosis of aquaporin-4-immunoglobulin G–positive neuromyelitis optica was made.
The patient was treated with rituximab (anti-CD20 monoclonal antibody) and became episode-free, with no further accumulation of disability.
The discovery of aquaporin-4-immunoglobulin G in 2004 has permitted the distinction of neuromyelitis optica spectrum disorder from other inflammatory central nervous system disorders. Aquaporin-4-immunoglobulin G represents a highly specific biomarker for neuromyelitis optica (almost 100% using molecular-based techniques), with sensitivity of approximately 80%. According to the most recent diagnostic criteria published in 2015, a diagnosis of neuromyelitis optica spectrum disorder can also be made for patients who are aquaporin-4-immunoglobulin G seronegative by any testing method, regardless of assay sensitivity, provided that more stringent clinical and radiologic requirements are met. Serial testing is recommended for these patients because late seroconversion has been described up to 4 years after the first episode.
Evidence of Müller Glial Dysfunction in Patients with Aquaporin-4 Immunoglobulin G–Positive Neuromyelitis Optica Spectrum Disorder
