Ultrasound-guided thoracic paravertebral nerve block is utilized in a variety of clinical scenarios as a diagnostic, prognostic, and therapeutic maneuver as well as to provide surgical anesthesia for thoracic and upper abdominal surgeries. As a diagnostic tool, ultrasound-guided thoracic paravertebral block allows accurate placement of the needle tip within the thoracic paravertebral space when performing differential neural blockade on an anatomic basis in the evaluation of chest wall and intra-abdominal pain. As a prognostic tool, ultrasound-guided thoracic paravertebral block can be utilized as a prognostic indicator of the degree of motor and sensory impairment that the patient may experience if thoracic nerve roots are going to be destroyed in an effort to palliate intractable pain in patients too sick to undergo neurosurgical destructive procedures. In the acute pain setting, ultrasound-guided thoracic paravertebral block with local anesthetics may be used to palliate acute pain emergencies while waiting for pharmacologic, surgical, and/or antiblastic methods to become effective. This technique has great clinical utility in both children and adults when managing acute postoperative and posttrauma pain. Sympathetically mediated pain syndromes including the pain of acute herpes zoster of the thoracic dermatomes, intractable angina, phantom breast syndrome, and the pain of acute pancreatitis can also be effectively managed with local anesthetics and or steroids administered into the thoracic paravertebral space (Fig. 88.1). Pain of malignant origin of the chest wall, flank, and abdomen as well as spinal metastatic disease (especially from breast and prostate primary cancers) is also amenable to treatment with local anesthetics and/or steroids and neurolytic agents such as phenol administered into the thoracic paravertebral space.

The boundaries of the triangular-shaped thoracic paravertebral space are the parietal pleura anterolaterally, the superior costotransverse ligament posteriorly, and the vertebral elements including the posterolateral surface of the vertebral body, intervertebral disc, and the intervertebral foramen (Fig. 88.2). Exiting their respective intervertebral foramen and passing just below the transverse process are the thoracic paravertebral nerves. After exiting the intervertebral foramen, the thoracic paravertebral nerve gives off a recurrent branch that loops back through the foramen to provide innervation to the spinal ligaments, meninges, and its respective vertebra and can be an important contributor to spinal pain. The thoracic paravertebral nerve also provides fibers to the sympathetic nervous system and the thoracic sympathetic chain via the myelinated preganglionic fibers of the white rami communicantes as well as the unmyelinated postganglionic fibers of the
gray rami communicantes. The thoracic paravertebral nerve then divides into a posterior and an anterior primary division (see Fig. 88.2).The posterior division courses posteriorly and, along with its branches, provides innervation to the facet joints and the muscles and skin of the back. The larger, anterior division courses laterally to pass into the subcostal groove beneath the rib to become the respective intercostal nerves. The 12th thoracic nerve courses beneath the 12th rib and is called the subcostal nerve. The intercostal and subcostal nerves provide the innervation to the skin, muscles, ribs, and the parietal pleura and parietal peritoneum. Because blockade of the thoracic paravertebral nerve is performed at the point at which the nerve is beginning to give off its various branches, it is possible to block the anterior division and the posterior division as well as the recurrent and sympathetic components of each respective thoracic paravertebral nerve (see Fig. 88.2). Since the thoracic paravertebral space is not a closed space, drugs injected into this space not only block the paravertebral nerve at the level of needle placement, but if the volume of injectate is large enough, the injectate may spread to block adjacent thoracic paravertebral nerves as well as spread into the epidural space medially.