Bilateral asymmetry of the internal diameter of the vertebral arteries is common and is associated with congenital development. If the blood flow rate is normal, no treatment is needed, but if the flow rate is abnormal, it may result in an inadequate blood supply or the presence of other diseases. The vertebral arteries tend to develop asymmetrically on both sides of the body and can be detected on ultrasound, with the left side generally being thicker than the right. Although the diameter of both vertebral arteries is asymmetrical, if there is no obstruction of blood flow throughout the whole process, it has no effect on the blood supply to the brain, which is a normal physiological phenomenon and does not need to be dealt with. If one side is too narrow, or there are other diseases, it can be manifested as localized blood flow increase, which may affect the blood supply to the brain, and need to be treated with drugs or surgery. If the patient finds that the internal diameter of both vertebral arteries is asymmetrical during the examination, he/she can consult a neurologist.