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

Objective: To study the effects of extension and extension-rotation of the head on the blued flow velocity of the vertebral artery experimentally and clinically. Design: Randomized experimental clinical study. Setting: Institute of Clinical Anatomy and Biomechanics and the Department of Ultrasound, NanFang Hospital of the First Military Medical University, G uangzhou, China. Subjects: The fresh spines from T1-2 to the occipital bone were obtained fr om persons who died of acute brain death (n = 10). For the transcranial Dop pler measurement, 27 asymptomatic subjects with routine physical examinatio n results and 23 students from the above-mentioned university took part in the test. Interventions: The instillation experiment in the cadavers was made. Clinic al measurements of blood flow velocity in the vertebral artery in the subje cts and students were taken and recorded. Main Outcome Measures: Changes in the drop of the vertebral artery were mea sured by the instillation test in the experimental sample. The blood flow v elocity was measured with transcranial Doppler sonography during extension and extension-rotation of the head. Results: During one-sided rotation of the head with extension of the head, measurements in the contralateral vertebral artery and the bilateral verteb ral arteries were both reduced in the instillation experiment. The blood fl ow velocity in the bilateral vertebral arteries decreased during extension and extension-rotation of the head in the subjects and the students. The pu lsatility index in the right vertebral arteries increased more than that in the left in extreme extension and that in the bilateral vertebral arteries in neutral position. Conclusions: Extreme rotation and extension are dangerous to patients who h ave abnormal vertebral arteries when extreme rotatory and extension manipul ations are applied. Doctors should be very careful when rotating the patien t's head to the right side.