Correlation of magnetic resonance imaging and CSF findings in patients with acute monosymptomatic optic neuritis.

Acute monosymptomatic optic neuritis (AMON) may be the first indication of multiple sclerosis (MS), and this sign offers a special opportunity to study the very early clinical stages of MS. This prospective investigation compares results of CSF findings and magnetic resonance imaging (MRI) in a large, homogeneous and well-defined group of patients with AMON. Of 68 consecutively referred patients, 11 had clinically definite MS, another 5 refused a lumbar puncture, and 7 could not participate for various reasons. With the remaining 45 untreated patients, aged 12-52 (mean 31) years, with idiopathic AMON, we have studied interrelationships of CSF findings (leucocyte count, IgG-index and in 29 of the patients oligoclonal bands (OB)) and MRI. Lumbar puncture and MRI were performed within median 24 and 16 days of onset, respectively. In the CSF one or more abnormalities (in 17/45 = 38% pleocytosis, in 16/45 = 36% increased IgG-index, and in 20/29 = 69% OB) was found in a total of 23/29 = 79% of patients. MRI at 1.5 T (double SE and IR sequences) showed multiple cerebral lesions in 65% of patients. A significant relation was observed between results of MRI and leucocyte count (p < 0.05) and between results of MRI and IgG-index (p < 0.05), but not between results of MRI and OB (p > 0.20). Over a median observation period of 27 months, 13 patients developed clinically definite MS. All of these patients had lesions on MRI at onset, illustrating the prognostic importance of MRI findings. Results of CSF had until now no marked predictive value for developing clinically definite MS.