Background: Aquaporin-4 (AQP4) is densely expressed in the ependymal region and leptomeninges, and it is susceptible to pathological responses triggered by antibodies from blood and cerebral spinal fluid (CSF). Therefore, enhancement of these regions may be related to neuromyelitis optica spectrum disorder (NMOSD).
Methods: MRI from a consecutive cohort of 84 subjects (NMOSD=47, multiple sclerosis [MS]=37) with AQP4 antibodies in serum and CSF were analyzed retrospectively.
Results: The brain was normal in five of the 47 patients with NMOSD and none of the MS patients showed a normal brain. Twelve patients in each group had parenchymal enhancing lesions. Of these, white matter enhancement was more frequently found in MS patients than in NMOSD patients (12/12 vs 4/12, p=0.001). "Cloud-like" enhancement was found in three NMOSD patients (3/12) and in one MS patient. Nine of the 12 NMOSD patients showed "pencil-thin" ependymal enhancement, whereas one of the 12 MS patients showed ependymal enhancement (p=0.003). Enhancement along the lateral ventricle was more frequently found in NMOSD patients than in MS patients (p=0.027), whereas enhancing lesions around the fourth ventricle tended to be more frequent in NMOSD patients than MS patients (p=0.097). Leptomeningeal enhancement around the brainstem was found in six (12.8%) NMOSD patients and in no MS patients (p=0.032).
Conclusion: Enhancement of the leptomeninges and ventricular ependymal region more frequently occurs in NMOSD patients than in MS patients. This may be considered as characteristic clue in the diagnosis of NMOSD.
Keywords: Aquaporin; Enhancement; Multiple sclerosis; Neuromyelitis optica.
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