Visual evoked blink reflex in optic neuritis.

The optically evoked blink reflex (BR) was recorded in 30 patients (20 females, 10 males) with primary acute optic neuritis (ON) unassociated with other CNS disorders. The reflex was studied in the acute stage between the 1st and 6th day after onset, during the 1st month following the acute stage once a week, and then 2 and 6 months later. In patients in whom a relapse occurred, the programme was restarted from the beginning. Control values were taken from prior investigations in 50 healthy subjects. In the acute stage differences in the amplitudes were present in 26 patients, but the latencies remained within normal limits. Six patients (20%) developed multiple sclerosis during the 5-year follow-up until December 1985. In these cases the optic BR showed increased latencies and decreased amplitudes. In patients without manifestation of multiple sclerosis the BR remained normal. In 7 patients cranial magnetic resonance imaging (MRI) was done. All patients with some abnormalities in the visual BR also had an abnormal MRI. The pattern-shift visual evoked potentials were abnormal in the acute stage of ON in 90%, and CSF abnormalities were found in 56.6%. In 4 patients (13%) the visual BR could not be evoked at all.