Early MRI in optic neuritis: the risk for disability.

BACKGROUND

MRI findings influence the risk of patients with optic neuritis (ON) developing clinically definite (CD) multiple sclerosis (MS) but their influence on future disability is less clear.

OBJECTIVE

To investigate in patients with ON the influence of lesion number, location and activity, and non-lesion MRI measures obtained on early scans on disability.

METHODS

A total of 106 of 143 prospectively recruited patients with ON had reached a scheduled 5-year follow-up, of whom 100 were evaluated clinically. Lesion number, location, and activity measures were analyzed at baseline (within 3 months of onset) and lesion activity measures were studied at 3-month follow-up. Brain atrophy, magnetization transfer ratio, and spectroscopy measures were also analyzed. Ordinal logistic regression assessed the association between early MRI findings and subsequent disability.

RESULTS

At median 6 years follow-up, 48% had converted to CDMS and 52% remained with clinically isolated syndrome (median Expanded Disability Status Scale 2 and 1). In the final models, both the presence and the number of spinal cord lesions at baseline (odds ratios [OR] 3.30, 1.94) and new T2 lesions at follow-up (OR 7.12, 2.06) were significant independent predictors of higher disability. Disability was also predicted by the presence at baseline of gadolinium-enhancing lesions (OR 2.78) and number of infratentorial lesions (OR 1.82). Only spinal cord lesions predicted disability in patients converting to CDMS.

CONCLUSION

Spinal cord, infratentorial, and gadolinium lesions within 3 months of optic neuritis onset and new T2 lesions after 3 months predicted disability after 6 years; only spinal cord lesions were predictive of disability in those developing clinically definite multiple sclerosis.