Visual evoked response in transient monocular visual loss

Application of pattern reversal visual evoked potentials (PVEPS) in transient monocular blindness (resp. amaurosis fugax)

We investigated 11 patients (63.1 +/- 10.9 y) after recovery (median: 3 days) from amaurosis fugax of 12.1 +/- 12.0 min duration with the method of pattern reversal visual evoked potentials (PVEPs) derived from Oz to Fz (Cz ground) after randomized monocular stimulation.

SELECTION CRITERIA

clear-cut cases with no hemispheric symptomatology, normal vision and normal cranial CT. The parameters were measured without knowing the affected eye and compared with age matched controls (n = 32). N80 latencies of the affected eyes were significantly prolonged (3.2 +/- 1.9 ms; p < .025) in comparison with the not affected eyes. The controls did not show such interocular difference. P100 latency behaved similarly but less prominently so (2.0 +/- 2.3 ms; p < .05; controls: p > .05). N80/P100 amplitude was reduced in 82% after stimulation of the affected side without reaching statistical significance. The 5 patients showing angiographically ipsilateral very tight stenosis of carotid artery (> 95%) behaved more prominently so in all 3 parameters. The findings indicate a damage of nerval tissue responsible for visual perception or a hemodynamic insufficiency under stimulus condition in affected eyes outlasting the clinical symptomatology for a certain period of time.