NINJA; Normal-appearing Imaging-associated, Neuroimmunologically Justified, Autoimmune Encephalomyelitis (P5.383)

Objective: To examine cases with a clinical course, signs, and symptoms mimicking multiple sclerosis (MS), but without abnormalities on conventional magnetic resonance imaging (MRI). Background: The widely used 2010 McDonald criteria allow diagnosis of MS in cases without abnormalities on conventional brain and spinal cord MRI. Nevertheless, such patients have generally been excluded from MS cohort studies, under the assumption that negative MRI findings could never coexist with demyelination. Design/Methods: Among 550 people with a tentative diagnosis of MS or neuromyelitis optica spectrum disorder (NMOSD), we selected patients, who met the 2010 McDonald diagnosis criteria for MS, but did not show abnormal findings on conventional brain and spinal cord MRI. After evaluating their clinical data, we analyzed fractional anisotropy (FA) values in the brain white matter on diffusion tensor MR images and the frequencies of B cell subsets in the peripheral blood in the corresponding cases as compared to healthy subjects. Results: Eleven patients (age: 41.1 ± 8.0 years, nine females and two males) met the selection criteria. They were functionally disabled, with an expanded disability status scale of 6.1 ± 1.6. Cerebrospinal fluid oligoclonal bands were negative in all cases. Intravenous methylprednisolone and plasmapheresis were found to be efficacious, whereas there was no evidence for efficacy of interferon-s. Diffusion tensor MRI analysis revealed extensive white matter abnormalities characterized by significantly decreased FA values. The frequency of plasmablasts in the peripheral blood was significantly increased in these patients, similar to NMOSD. Conclusions: The neurological disabilities in these patients could be ascribed to white matter damage, as revealed by advanced MRI analysis, whereas efficacy of plasmapheresis and B cell abnormalities in the patients suggested an autoimmune-mediated pathogenesis. We provisionally name this treatable condition, which is clearly distinct from MS, “Normal-appearing Imaging-associated, Neuroimmunologically Justified, Autoimmune Encephalomyelitis” (NINJA). Disclosure: Dr. Takewaki has nothing to disclose. Dr. Lin has nothing to disclose. Dr. Sato has nothing to disclose. Dr. Ono has nothing to disclose. Dr. Nakamura has nothing to disclose. Dr. Araki has received compensation for serving on the Board of Directors of Chugai Pharmaceutical Co., Ltd.; Novartis Pharmaceuticals; Biogen Japan; Bayer Holding Ltd; Takeda Pharmaceuti-cal Co., Ltd. Dr. Okamoto has received research support from Takeda Pharmaceutical Co., Ltd. Dr. Takahashi has nothing to disclose. Dr. Kimura has nothing to disclose. Dr. Ota has nothing to disclose. Dr. Sato has nothing to disclose. Dr. Yamamura has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Biogen Japan, Chugai Pharmaceutical Co., Ltd. and Takeda Pharmaceutical Co., Ltd. Dr. Yamamura has received compensation for serving on the Board of Directors of Mitsubishi Tanabe Pharma, Novartis, Nihon, Santen, Abbott Japan/Eisai, Biogen Japan, Dainippon Sumitomo, Bayer Holding, and Astellas Pharma Inc., and Takeda Pharmaceutical Co., Ltd. Dr. Yamamura has received research support from Ono, Chugai, Teva, Mitsubishi Tanabe Pharma, Asahi Kuraray Medical, and the Ministry of Health, Labor, and Welfare of Japan.