The value of neurophysiological and MRI assessment in demyelinating optic neuritis (DON).

PURPOSE

To study, by neurophysiological means, the possible involvement of the retina, in demyelinating optic neuritis (DON).

MATERIAL AND METHODS

Thirty-five patients fulfilling strict criteria of unilateral DON were investigated with a battery of neurophysiological tests and MRI within 3 weeks of the onset of their symptoms. Flash-ERG (F-ERG) in photopic conditions, Flash-VEPs and PR-VEPs were recorded. MRI of the brain and the optic nerve were performed.

RESULTS

The amplitude of b-wave of F-ERG in photopic conditions was statistically significantly lower in the affected eye (p < 0.001) compared to normal controls, whereas in the unaffected eye, it was also statistically significantly lower than normal controls (p < 0.01). All patients had statistically significant prolongation of P100 latency in PR-VEPs of the affected eye (p < 0.001) in comparison to normal controls. The P100 wave of the unaffected eye was also delayed (p < 0.01). In MRI, Gd-DTPA enhancement was observed in 7 symptomatic nerves with only minimal enhancement of the optic nerve between optic chiasm and optic canal, whereas 11 patients were presented with intracranial associated plaques. Five of the above patients had optic nerve enhancement and diffused demyelinating findings simultaneously.

CONCLUSION

These results are a neurophysiological indication of involvement of the retina in DON, probably of vascular origin.