The Influence of Unilateral Vertebral Artery Occlusion on Brainstem and Inner Ear Blood Flow in Rat

Abstract

We investigated the influence of unilateral VA occlusion on blood regulation in the brainstem and the inner ear, using laser-Doppler flowmetry in rat. Chemical control was evaluated by blood flow response to CO, inhalation, and nutoregulation by that to induced hypotension. The results were as follows: i) Unilateral VA occlusion impairs chemical control and autoregulation of brainstem blood flow and affects autoregulation in the inner ear. ii) Unilateral VA occlusion damages the potential for blood flow regulation more strongly in the brainstem than in the inner ear. These results suggest that occlusive disease within the vertebro-basilar system leads to the impairment of blood flow regulation in both the brainstem and the inner ear more strongly in the brainstem—possibly contributing to symptoms such as vertigo and hearing disturbance. at least in certain groups of patients when hemodynamic factors such as systemic hypotension are added.

Key Words:

• chemical blood flow control
• autroregulation
• CO₂ inhalation
• induced hypotension
• laser-Doppler flowmetry