Effectiveness of Doppler Image of the Vertebral Artery as an Anatomical Landmark for Identification of Ultrasound-Guided Target Level in Cervical Spine

STUDY DESIGN A prospective sonographic study. PURPOSE To verify the effectiveness of simultaneous application of two landmarks, Doppler image of the vertebral artery and shape of the transverse tubercle of the seventh cervical (C7) vertebra. OVERVIEW OF LITERATURE Counting upwards from the C7 vertebra which only has a posterior tubercle of the transverse process is a commonly used method for ultrasound-guided cervical nerve root block. However, each transverse process has a different shape. METHODS Sonograms of 20 volunteers were examined. At first, we identified the C7 transverse process based on the presence of the vertebral artery without the anterior tubercle. The C5 and C6 transverse processes were identified based on the presence of anterior tubercle without the vertebral artery. Subsequently, we placed needles on the C5, C6, and C7 transverse processes and the location and direction of needles were confirmed by fluoroscopy. RESULTS In the 120 segments, 93.3% of needles were placed correctly as desired; 97.5% of needles were placed on the 5C transverse process; 97.5% of needles were placed on the C6 transverse process; and 85.0% of needles were placed on the C7 transverse process, respectively. Both sides showed the same accuracy of 93.3%. CONCLUSIONS Simultaneous application of Doppler image of the vertebral artery and shape of the C7 transverse tubercle showed 93.3% accuracy in identifying the target cervical level. Therefore, Doppler image of the vertebral artery can be considered to be a useful landmark for ultrasound-guided cervical nerve root block.