Visual Evoked Potentials in Symptomatic and Asymptomatic Carotid Artery Stenosis

Carotid artery stenosis is a major risk factor for ischemic stroke; however, functional impairment varies depending on the efficiency of collateral circulation. Visual Evoked Potentials (VEPs) provide a non-invasive means of assessing visual pathway integrity. Beyond the degree of anatomical stenosis, metabolic factors may also influence collateral function. This study aimed to evaluate the relationship between VEP responses, biochemical markers, and symptomatic status in patients with moderate to severe İnternal Carotid Artery (ICA) stenosis.

A total of 80 patients (40 symptomatic, 40 asymptomatic) with cervical ICA stenosis (50-70% or >70%) confirmed by CT angiography were prospectively enrolled. All patients underwent ophthalmological examination and pattern-reversal VEP testing. Abnormal VEP was defined as a P100 latency >110 ms, an interocular latency difference >10 ms, or an amplitude <5 μV. Laboratory parameters, including HDL and HbA1c, were also analyzed.

VEP latencies did not significantly differ between symptomatic and asymptomatic groups or between moderate and severe stenosis subgroups, indicating preserved visual pathway function. However, HDL levels were significantly higher in asymptomatic patients (p =0.033), while HbA1c levels were elevated in those with >70% stenosis (p =0.011). These findings suggest that metabolic status contributes to the preservation or impairment of collateral circulation, independent of stenosis severity.

Our results demonstrate that VEP latencies remained comparable across symptomatic and carotid stenosis subgroups, suggesting preserved visual pathway function despite carotid narrowing. In contrast, higher HDL in asymptomatic patients and elevated HbA1c in severe stenosis indicate a metabolic influence on collateral efficiency. These findings highlight that vascular risk factors and metabolic status may be as critical as anatomical stenosis in determining functional outcomes.

Cervical carotid stenosis severity alone does not predict functional compromise. Integrating VEP assessment with metabolic profiling-particularly HDL and HbA1c levels-may enhance risk stratification, offering a more comprehensive and individualized evaluation, especially in asymptomatic patients. This novel perspective links biochemical markers to electrophysiological integrity and collateral efficiency in ICA stenosis.