Neuromyelitis optica spectrum disorder mimicking cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy with symmetrical lesions in the temporal poles and external capsules on MRI.

Symmetrical lesions in the temporal poles and external capsules on brain MRI are known as radiological markers of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL); however, similar imaging findings have also been reported in neuromyelitis optica spectrum disorder (NMOSD), and this study investigated the frequency of such findings. The study included 55 NMOSD patients who met the 2015 international NMO diagnosis panel (IPND) criteria and were positive for aquaporin-4 antibodies (AQP4-Ab). Images were evaluated based on the consensus of two neuroradiologists, and brain lesions were detected in 33 patients, of whom 2 (6%) had symmetrical lesions in both the temporal poles and external capsules, and 1 (3%) had symmetrical lesions confined to the external capsules. Therefore, when symmetrical lesions in the temporal poles and external capsules are observed on MRI, NMOSD should be considered in the differential diagnosis.