Changes and implications of blood flow velocity of vertebral artery during extreme extension of head

Objective:To study the effects of extreme extension of head to the blood flow velocity of vertebral artery experimentally and clinically. Method: The instillative experiment in 10 cases of the fresh cervical spines was made. The blood flow velocity of vertebral artery with TCD in the 27 asymptomatic subjects with routine physical examination and 23 students were measured and recorded.Result: During extreme extension of head, the drops of the bilateral vertebral arteries reduced obviously in the instillative experiment. The blood flow velocity of bilateral vertebral arteries decreased when the arteries were provoked by extreme extension and extreme extension rotation of head.Pulsatility index of right vertebral arteries increased more than that of the left vertebral arteries in extreme extension and that of bilateral vertebral arteries in neutral position. Conclusion:Extreme extension is dangerous to the patients who have abnormal vertebral arteries when the extremely extensive manipulations are applied. Doctors should be very careful when rotating the head to the right side. Author′s address Institute of Clinical Anatomy and Biomechnics, the First Military Medical University,Guangzhou, 510515