Progression of optic neuritis to multiple sclerosis: an 8-year follow-up study.

Objective: The relationship between acute monosymptomatic optic neuritis (AON) and subsequent multiple sclerosis (MS) is still doubtful. We investigated the risk of developing MS in patients from North Bavaria, who were suffering from AON.
Patients/methods: Twenty-nine patients with clinical evidence of AON were included in the study. Initial evaluation included brain resonance imaging (MRI) and a clinical neurological examination. Follow-up examinations were performed after 72-108 months (mean: 96 months) in 26 patients (three patients were lost to follow-up) and consisted of a second complete neurological examination. Diagnosis of MS was established according to the criteria of Poser CM, Paty DW, Scheinberg L. New diagnostic criteria for multiple sclerosis: guidelines for research protocols. Ann Neurol 1983:13:227-231.
Results: At follow-up, 14 of 26 patients (54%) had converted to clinically definite MS. Nine patients (64%) had developed MS within 2 years after the onset of AON.
Conclusion: We observed the development of MS in 54% of the 26 investigated AON patients. The exceptional feature of the present study was the relatively long follow-up period of 8 years.