* Brain MRI not meeting diagnostic criteria for multiple sclerosis
* NMO-IgG seropositive status
Criteria for multiple sclerosis:
* Two or more attacks; objective clinical evidence of two or more lesions, OR
* Two or more attacks; objective clinical evidence of one lesion, dissemination in space, demonstrated by: MRI or two or more MRI-detected lesions consistent with MS plus positive CSF or wait further clinical attack implicating a different site, OR
* One attack; objective clinical evidence of two or more lesions, dissemination in time, demonstrated by: MRI or second clinical attack, OR
* One attack; objective clinical evidence of one lesion (monosymptomatic presentation; clinically isolated syndrome), dissemination in space, demonstrated by: MRI or two or more MRI-detected lesions consistent with MS plus positive CSF and dissemination in time, demonstrated by: MRI or second clinical attack, OR
* Insidious neurological progression suggestive of MS, one year of disease progression (retrospectively or prospectively determined) and two of the following:
1. Positive brain MRI (nine T2 lesions or four or more T2 lesions with positive VEP)
