Characteristic brain magnetic resonance imaging abnormalities in central nervous system aquaporin-4 autoimmunity

Although neuromyelitis optica has been traditionally regarded as a disease without brain involvement, brain abnormalities are not uncommon in patients with neuromyelitis optica-related disorders.

We aimed to characterize the brain magnetic resonance imaging (MRI) abnormalities in neuromyelitis optica spectrum disorder patients who are seropositive for anti-aquaporin-4 autoantibody (AQP4 Ab). Of 236 consecutive patients with inflammatory demyelinating central nervous system diseases, we retrospectively analyzed MRI characteristics of 78 patients who were seropositive for AQP4 Ab.

For an average observational period of 6.3 years, 62 patients (79%) had brain lesions on MRI. Twenty-four patients (31%) had brain MRI abnormalities at the onset of disease, and 35 (45%) had symptomatic brain involvement. Characteristic brain MRI abnormalities were classified into five categories: (1) lesions involving corticospinal tracts (e.g. posterior limb of internal capsule and cerebral peduncle (44%); (2) extensive hemispheric lesions likely due to vasogenic edema (29%); (3) periependymal lesions surrounding aqueduct and the third and fourth ventricles (22%); (4) periependymal lesions surrounding lateral ventricles (40%); and (5) medullary lesions, often contiguous with cervical lesions (31%). Fifty-four patients (69%) showed at least one kind of brain abnormality among the five characteristic MRI lesions. Ten patients showed gadolinium-enhancing lesions, which were characterized by multiple patchy enhancing patterns with blurred margins.

In central nervous system AQP4 autoimmunity, brain MRI abnormalities were more common than is generally appreciated and were characterized by their unique localization and configuration.