Ultrasound-guided cervical selective nerve root block: a fluoroscopy-controlled feasibility study.

BACKGROUND AND OBJECTIVES Reports of intravascular injection during cervical transforaminal injections, even after confirmation by contrast fluoroscopy, have led some to question the procedure's safety. As ultrasound allows for visualization of soft tissues, nerves, and vessels, thus potentially improving precision and safety, we evaluated its feasibility in cervical nerve root injections. METHODS This is a prospective series of 10 patients who received cervical nerve root injections using ultrasound as the primary imaging tool, with fluoroscopic confirmation. Our radiologic target point was the posterior aspect of the intervertebral foramen just anterior to the superior articular process in the oblique view and at the midsagittal plane of the articular pillars in the anteroposterior (AP) view. RESULTS The needle was exactly at the target point in 5 patients in the oblique view and in 3 patients in the AP views. The needle was within 3 mm in all patients in the lateral oblique view and in 8 patients in the AP view. In the remaining 2 patients, the needle was within 5 mm from the radiologic target. In 4 patients, we were able to identify vessels at the anterior aspect of the foramen, whereas 2 patients had critical vessels at the posterior aspect of the foramen, and in 1 patient, this artery continued medially into the foramen, most likely forming or joining a segmental feeder artery. In both cases, the vessels might well have been in the pathway of a needle correctly positioned under fluoroscopic control. CONCLUSIONS Our case series shows the feasibility of using ultrasound imaging to guide selective cervical nerve root injections. It may facilitate identifying critical vessels at unexpected locations relative to the intervertebral foramen and avoiding injury to such vessels, which is the leading cause of the reported complications from cervical nerve root injections. A randomized controlled trial to compare the effectiveness and safety of ultrasound imaging against other imaging techniques seems warranted.