Application of Pattern Reversal Visual Evoked Potentials (PVEPS) in Transient Monocular Blindness (Resp. Amaurosis Fugax)

Abstract

We investigated 11 patients (63.1 |mP 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.

Key Words:

• VEP
• PVEP
• amaurosis fugax
• TMB