The evaluation of the vertebrobasilar system by transcranial Doppler ultrasound

Transcranial doppler ultrasound has not been well applied to vertebrobasilar system, because usual midline approach via foramen magnum cannot accurately record the Doppler signals from vertebral artery, and the anatomical variation of the system is not quite established. In this study, the probe of Doppler instrument was placed in the suboccipital area at the lateral two thirds between forman mugnum and mastoid process. This lateral approach was adopted on the ground that the mean angle of the vertebral arteries from midline plane was 31.3 degrees in seventeen human fixed brains. Trascranial Doppler recordings of eighty healthy adults by the combined midline and lateral approach revealed that mean flow velocity of the basilar arteries and vertebral arteries was 35.9±10.3cm/sec and 31.0±11.6cm/sec and mean plusatility index 0.92±0.14 and 0.96±0.18, respectively. The index was significantly higher in the eldery, while the velocity was not. Diagnostic Doppler signals were recorded in the twenty one cases with cerebrovascular disease of the system, such as arterial occlusive disorders, aneurysms, arterio-venous malformations, and colichoectasias.