Ultrasound and chronic pain: Innovative approaches

Ultrasound (US) is an increasingly used imaging technique in interventional pain management. It allows the identification of soft tissues, vessels and nerves, without exposing patients and personnel to radiation. Imaging can be performed continuously and the fluid injected is visualized in a real time fashion. Possible applications are nerve blocks of the cervical and lumbar zygapophysial joints, stellate ganglion block, intercostal and paravertebral nerve blocks, inguinal nerve blocks, occipital nerve blocks, blocks of painful stump neuromas, caudal epidural injections and injections of trigger/tender points. Due to direct nerve visualization, US has a potential application for destructive procedures, such as cryoanalgesia, radiofrequency lesions or chemical neurolysis. Limitations are the poor resolution of narrow-gauge needles, the loss of resolution with increasing working depth and possible interference of echoes from overlying structures with the image of the target area. US opens new perspectives in interventional pain management. However, there is a need for more clinical trials investigating efficacy and safety of US-guided pain procedures. Until these studies are completed, US cannot replace fluoroscopy or computed tomography in most interventional pain procedures and remains the domain of well-trained and experienced physicians. The limited evidence supporting the clinical utility of nerve blocks remains a problem, irrespective of the imaging technique employed.