Brain Abnormalities in Neuromyelitis Optica Spectrum Disorder

Figure 2

Characteristic brain abnormalities in neuromyelitis optica spectrum disorder (NMOSD) patients on T2-weighted or fluid-attenuated inversion recovery (FLAIR) MRI. (A) Periependymal lesions surrounding the third ventricle and cerebral aqueduct. These lesions can be unilateral (a) or bilateral (b) and sometime accompany with the periependymal lesions surrounding the lateral ventricles (c). They often involve the thalamus and hypothalamus (d, e). (B) Brainstem lesions adjacent to the fourth ventricle. The dorsal part of brainstem adjacent to the fourth ventricle is commonly involved (a–c). They can be edematous and form extensive lesions involving the cerebellar peduncle (d). These lesions are often contiguous with cervical lesions (e). (C) Periependymal lesions surrounding the lateral ventricles. Unlike the lesions in multiple sclerosis, NMOSD lesions are located immediately next to the lateral ventricle, following the ependymal lining in a disseminated pattern and are often edematous and heterogeneous (a). Sometimes the callosal lesions involve the entire thickness of the corpus callosum, including the splenium-like “arch bridge” (b–d). These lesions often extend into the cerebral hemisphere, forming an extensive and confluent white matter lesion (e). (D) Lesions involving the posterior limb of internal capsule and cerebral peduncle of midbrain unilaterally (a, c) or bilaterally (b, d, and e). In coronal images (e), these lesions are contiguous and longitudinally extensive following the corticospinal tracts and appear to be synonymous with a longitudinally extensive cord lesion following the descending tract. (E) Extensive and confluent hemispheric white matter lesions. They can be tumefactive (a, b) or spindle-like (c). Some lesions look like “spilled ink” along the white matter tracts. Usually they show high signal intensities on diffusion-weighted images (DWIs) (d) and an increase in apparent diffusion coefficient (ADC) values (e, paired with d), suggesting vasogenic edema. (F) Cerebral cortex involvement (a–d) and leptomeningeal enhancement (e, paired with d).