The Abnormal and Pathological Findings of the First Brain and Cervical Spine MRI of The Neuromyelitis Optica Spectrum Disorders Patients (ORP-01)

Background: Neuromyelitis optica spectrum disorder is a rare inflammatory disease of the central nervous system with an autoimmune nature. According to the 2015 NMOSD criteria, the presence of longitudinal extensive transverse myelitis (LETM) on MRI of the spinal cord is one of the main characteristic findings in NMOSD. It should be noted that LETM is neither specific nor sensitive. There are reports of atypical brain MRI findings in NMOSD, which are not included in the criteria.
Methods: This is an observational study on the 173 NMOSD cases (56 seropositive) who were registered in the NMOSD registration system in the Isfahan Kashani Hospital MS Center. The first MRI of brain and cervical spine were evaluated to find any abnormal and pathological findings.
Results: Our findings showed that just about 28.32% of cases had normal brain MRI at time of diagnosis. The brain stem structures, periepandymal area and corpus callosum were the most affected sites. 4 patients demonstrated tumefactive lesions at the time of diagnosis. In 21.96% of patients, we found typical plaques in nonspecific areas, which are not mentioned in the criteria, such as the periventricular zone.
In the first cervical MRI, LETM was obvious in 44.5% of patients (51.78% of seropositive). In 18.49% of participants, the LETM was observed in the MRI without any relative symptoms (23.21% in the seropositive group). In 31.78% of them, a non-LETM lesion (segmental or single plaques) would be seen. Some people with clinical manifestations of myelitis (3.46%) did not show any abnormalities in the cervical MRI. Despite of diagnostic criteria, which emphasizes the role of LETM, in conjunction with clinical myelitis, there are reports of non-LETM lesions in NMOSD patients. 
Conclusion: The cervical LETM can be asymptomatic at first. If high resolution MRI is done in such cases, it may show several continuous plaques rather than LETM. But a cervical MRI is recommended for all suspected patients even without major signs of myelitis, which may help in the early diagnosis. The abnormal lesion was found in the first brain MRI in 71.68% of patients.