Sonographic detection of haemodynamic changes in a case of vertebrobasilar insufficiency.

We present a diagnostically challenging case of vertebrobasilar insufficiency caused by head rotation. The patient was a 58-year-old man complaining of dizziness and faintness with head rotation to the left. Vertebral arteriography with the head turned to the left revealed mechanical compression of the right vertebral artery at the occipitoatlantal joints and an occluded left vertebral artery. Duplex sonography demonstrated disappearance of the end-diastolic flow signal in the right vertebral artery on head rotation, paralleling the appearance of symptoms. Decompression of the vertebral artery by transversectomy of the atlas and hemilaminectomy of the axis completely relieved the symptoms and the Doppler flow signal pattern of the vertebral artery returned to normal: End-diastolic flow in the right vertebral artery did not disappear even when the head was rotated to the left.