THE DEVELOPMENT OF MULTIPLE-SCLEROSIS FOLLOWING AN ISOLATED EPISODE OF OPTIC NEURITIS - MAGNETIC-RESONANCE STUDY

BACKGROUND: An important controversy on the development of multiple sc lerosis (MS) after an isolated episode of optic neuritis (ON) exists. Magnetic resonance imaging (MRI) is the method of election in order to detect demyelinated lesions in MS. The current study was designed to determine the prevalence of brain abnormalities on MRI and to asses th e further development of MS after an isolated idiopathic ON in our pop ulation. PATIENTS AND METHODS: From 1991 to 1995, 60 patients with dec rease of visual acuity were studied, 35 (28 women, half age 31 +/- 10 years) completed criteria of idipathic ON. A brain MRI was performed i n ail patients after the diagnosis of idiopathic CIN and they subseque ntly were followed in the outpatient clinic from our center for a mean time of 29 +/- 16 months, 24 out of the 35 patients were treated with corticosteroids in different ways. RESULTS: it has been found 43% of the patients with idiopathic ON to have brain lesions by MRI, During t he follow-up 14% of the patients developed a clinically definite MS; a ll of them had a pathological brain MRI at the basal evaluation (p = 0 .009). None of the patients that were treated wth high-dose of intrave nously corticosteroids developed MS. CONCLUSIONS: The prevalence of si lent cerebral lesions in the MRI after an idiopathic ON is elevated in our population although further development of MS is lower possibly d ue to the short follow-up carried out. The presence of lesions Tn the MRI confers a high risk for developing MS after an idiopathic ON.