Visual suppression of vestibulo-ocular reflex in patients treated with carotid artery revascularization: A potential biomarker for cerebral perfusion

Background: Carotid endarterectomy (CEA) and carotid artery stenting (CAS) are common treatments for ischemic stroke prevention in patients with carotid artery stenosis. However, the beneficial effects of CEA/CAS for cerebral hypoperfusion due to carotid artery stenosis have yet to be fully established. As dizziness is a common symptom in patients with carotid artery stenosis, we aimed to evaluate the effects of CEA/CAS on cerebral function in patients with carotid artery stenosis, using equilibrium function tests. Methods: This prospective observational cohort study included 50 patients who had carotid artery stenosis and were scheduled to undergo CEA or CAS. Before CEA/CAS, we quantitatively evaluated the vestibulo-ocular reflex (VOR) and vestibular evoked myogenic potential (VEMP), as indicators of brainstem/inner ear functions related to balance, and visual suppression of VOR, as an indicator of cerebral control over the brainstem reflex related to balance. These were then compared with supratentorial cerebral blood flow (CBF). Changes in VOR, VEMP, visual suppression of VOR, CBF, and dizziness after CEA/CAS were also evaluated. Results: The visual suppression rates of VOR correlated with supratentorial CBFs before CEA/CAS (correlation coefficient = 0.47, p = 0.003). The visual suppression rates of VOR (p < 0.001) and supratentorial CBFs (p = 0.003) were improved by CEA/CAS, while VOR and VEMP did not change. Symptoms of dizziness improved after CEA/CAS. Conclusions: Our results suggest that visual suppression of the VOR may be a novel and practical marker for the beneficial effects of CEA/CAS on supratentorial cerebral function.