37 Paravertebral Block
Continuous Cervical Paravertebral Block
Perspective
As originally described, this block was painful because it required multiple injections and penetrated the often-tender paraspinal extensor muscles of the neck. Recently, a modification was described that avoids penetration of the extensor cervical muscles. This technique minimizes the pain associated with this approach to the brachial plexus by inserting the needle in the window between the levator scapulae and trapezius muscles at the level of the sixth cervical vertebra (Fig. 37-1).
Placement
Anatomy
The brachial plexus is situated between the anterior and middle scalene muscles (Fig. 37-2). The phrenic nerve is anterior to the anterior scalene muscle and lateral to the superior cervical plexus. The vertebral artery and vein are situated anterior to the pars intervertebralis (articular column of the vertebrae) and typically travel through the transverse foramen in the center of the transverse processes of the first to sixth cervical vertebrae. The vertebral artery lies anterior to the interarticular parts of the vertebrae, so there is minimal risk of arterial injury with a posterior needle approach.
Needle Puncture
Next, an insulated 17- or 18-gauge Tuohy needle is inserted at the apex of the “V” formed by the trapezius and levator scapulae muscles at the level of the sixth cervical vertebra (see Fig. 37-1). The negative lead of the nerve stimulator, set to a current of 1.5 to 3 mA, a frequency of 2 Hz, and a pulse width of 100 to 300 µsec, is attached to the needle. If the block is intended for the management of pain associated with shoulder surgery, the needle is advanced anteromedially and is angled approximately 30 degrees caudad, aiming toward the suprasternal notch or cricoid cartilage until the transverse process of C6 or the pars intervertebralis of C6 is encountered. If the block is intended for wrist or elbow surgery, the needle is directed toward C7. This block is readily performed with ultrasonographic guidance, which avoids bony contact. However, close proximity to the bone is necessary if a true root-level block is intended. If the needle is directed too far laterally, the procedure will become no different from a traditional interscalene block except that the needle approach is posterior and not lateral.