EFFECT OF VARIOUS HEAD AND NECK POSITIONS ON VERTEBRAL ARTERY BLOOD-FLOW

The purpose of this study was to assess blood flow velocity in the ver tebral arteries with duplex Doppler ultrasound during various position s of the head and neck. Vertebral artery morphology and blood flow vel ocity were assessed in a control group and in a group of subjects who displayed clinical signs and symptoms of vertebrobasilar insufficiency . The two groups did not differ in vertebral artery gross morphology a s assessed by ultrasound. The arteries were examined for vascular impe dance by calculating the ratio of peak systolic velocity to end diasto lic velocity (systolic/diastolic ratio). In the context of this study, a lower velocity ratio implied less resistance to vascular flow. Thes e velocity ratios were established during several positions of the hea d and neck, including a widely used provocational test manoeuvre for v ertebrobasilar insufficiency. No meaningful significant differences in mean velocity ratios were found between the two groups. None of the s ubjects had abnormal spectral flow patterns during the different testi ng positions.