Background: Optic neuritis (ON) is a common first demyelinating event in multiple sclerosis (MS), and one of absolute clinical events to diagnose neuromyelitis optica (NMO). However, it seemed not all ON attacks are clinically evident. Certain proportions of patients with clinical definite MS had visual evoked potential (VEP) abnormalities without clinical history of ON. We performed this study to evaluate the value of VEP to predict conversion of myelitis to recurrent demyelinating diseases such as MS, NMO, and recurrent myelitis. Methods: We reviewed Korean MS and NMO registry and selected patients’ records met following criteria; (1) patients who had myelitis as the first clinical event, (2) patients who performed VEP at time when they haven’t had any clinical ON. The results of VEP were compared between disease subgroups. Result: Seventy-seven patients with myelitis performed VEP without clinical history of ON. Of the 77 patients, 13 and 4 patients were converted to MS and NMO, respectively. Recurrent myelitis was developed in 29 patients including 22 patients with long segment lesion. Proportion of patients with abnormal VEP were significantly different in function of disease subgroups as 23.1% in MS, 75% in NMO, 15% in long segment recurrent myelitis, and 6.4 % in monophasic myelitis. No patients with short segment myelitis had abnormal VEP (p = 0.016). Conclusion: Patients with NMO had the most prevalent asymptomatic VEP abnormality, and followed by MS, recurrent myeltis with long segment lesion, monophasic myelitis, and recurrent myelitis with short segment lesion in sequence. VEP may be useful tool to predict prognosis in patients with myelitis.
Read More: Value of asymptomatic visual-evoked potential abnormality in patients with myelitis