Selective Cervical Nerve Blocks
Chronic neck and shoulder pain as well as pain in the occiput may originate from the cervical zygapophyseal or facet joints (1,2,3). The sequential distention of normal facet joints with saline or contrast produces a segmentally distinctive pattern of pain distribution in the posterior occiput, neck, and shoulder of the injected side (4). Pain receptors in the synovium and capsule of the facets joints from C3 to C7-T1 are innervated by the medial branch of the dorsal ramus of the segmental spinal nerve. These nerves have a constant relationship to the mid-waist of the lateral cortex of the corresponding articular pillars (5), and are easily accessible to local anesthesia by needle placement under fluoroscopic or computed tomography (CT) guidance. Local anesthetic blocks into the facet joint or of the corresponding medial branch may afford complete relief of pain in the segment supplied by these joints, thus attributing this joint as the source of pain (1). The effect of local anesthetic applied to the medial branches has a similar validity to an intra-articular injection of local anesthesia (6).