THE 5-YEAR RISK OF MS AFTER OPTIC NEURITIS - EXPERIENCE OF THE OPTIC NEURITIS TREATMENT TRIAL

The objective of our study was to assess the 5-year risk of and progno stic factors for the development of clinically definite multiple scler osis (CDMS) following optic neuritis. In a prospective cohort study de sign, 388 patients, who did not have probable or definite MS at study entry enrolled in the Optic Neuritis Treatment Trial between 1988 and 1991, and were followed for the development of CDMS. The 5-year cumula tive probability of CDMS nias 30% and did not differ by treatment grou p. Neurologic impairment in the patients who developed CDMS was genera lly mild. Brain MRI performed at study entry was a strong predictor of CDMS, with the 5-year risk of CDMS ranging from 16% in the 202 patien ts with no MRI lesions to 51% in the 89 patients with three or more MR I lesions. Independent of brain MRI, the presence of prior nonspecific neurologic symptoms was also predictive of the development of CDMS. L ack of pain, the presence of optic disk swelling, and mild visual acui ty loss were features of the optic neuritis associated with a low risk of CDMS among the 189 patients who had no brain MRI lesions and no hi story of neurologic symptoms or optic neuritis in the fellow eye. The 5-year risk of CDMS following optic neuritis is highly dependent an th e number of lesions present on brain MRI. However, even a normal brain MRI does not preclude the development of GDMS. In these patients with no brain MRI lesions, certain clinical features identify a subgroup w ith a particularly low 5-year risk of CDMS.