What is the role of MRI in the diagnosis of optic neuritis in multiple sclerosis (MS)?

Updated: Feb 25, 2016
  • Author: Pil (Peter) S Kang, MD; Chief Editor: James G Smirniotopoulos, MD  more...
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Answer

Answer

The real contribution of imaging in the setting of optic neuritis is made by imaging of the brain, not of the optic nerves themselves. This is due to the fact that the most valuable predictor for the development of subsequent MS is the presence of white matter abnormalities. Between 27% and 70% of patients (in various studies) with isolated optic neuritis show abnormal MRI brain findings, as defined by the presence of 2 or more white matter lesions on T2-weighted images.

In the Optic Neuritis Treatment Trial, the 5-year risk of developing MS was 16% in patients with normal brain MRI findings, 37% with 1-2 lesions, and 51% with 3 or more lesions. At 10 years, the only statistically significant difference was between no lesions (22% risk) and 1 or more lesions (56% risk). [16]

Bonhomme et al found that children with brain MRI abnormalities at the time of optic neuritis diagnosis had an increased risk for MS. The investigators studied the rate of conversion to MS after a diagnosis of optic neuritis in children (younger than 18y) who presented with optic neuritis between 1993 and 2004 at the Children's Hospital of Philadelphia.

In the study, Bonhomme and colleagues identified 29 children with idiopathic optic neuritis. Eleven of the 29 patients (38%) had white matter T2/FLAIR (fluid-attenuated inversion recovery) lesions in the brain (not including the optic nerves). Eighteen patients were followed for more than 24 months, and 3 of the 18 (17%) developed MS. All 3 patients who developed MS had an abnormal brain MRI scan at their initial presentation of optic neuritis. None of the patients who had normal MRI scans developed MS over an average follow-up period of 88.5 months. [1]

Swanton et al found that the presence and number of spinal cord lesions at baseline and of new T2 lesions at follow-up were significant independent predictors of higher disability. In their report, the investigators studied patients with optic neuritis to determine the influence of lesion number, location, and activity, as well as non-lesion MRI measures obtained on early scans. At 6-year follow-up, 48% of patients had converted to clinically definite MS, and 52% remained with clinically isolated syndrome. [17]

Disability was also predicted by the presence at baseline of gadolinium-enhancing lesions and the number of infratentorial lesions. Only spinal cord lesions predicted disability in patients converting to clinically definite MS.

The Optic Neuritis Treatment Trial found that there was a 50% cumulative probability of developing MS within 15 years after the onset of optic neuritis. The presence of lesions on a baseline, non–contrast-enhanced MRI of the brain was a significant factor in the occurrence of MS. The study also found that in patients with optic neuritis who had no lesions on baseline brain MRI, 25% developed MS during follow-up, while among patients with 1 or more lesions, 72% developed MS. [2]

In a study of 34 children with isolated optic neuritis, abnormal cranial MRI (cMRI) was found to be associated with an increase in the odds of MS development (odds ratio 20.57; 95% CI 2.16-196.10, P< 0.001). Positive oligoclonal bands in spinal fluid was also found to be associated with MS, but only cMRI remained statistically significant in multiple regressions. [18]


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