Cervical Zygapophysial Joint Pain

Abstract

The role of the cervical zygapophysial joints as sources of chronic neck pain has attracted considerable attention and some controversy. Cervical zygapophysial joints are typical synovial joints and are innervated by the medial branches of the cervical dorsal rami. Stimulation of these joints in normal volunteers causes neck pain and pain referred to the head, shoulder girdle, and upper limb. Injuries to these joints, including tears of the joint capsule, intra-articular hemorrhage, bruising of the meniscoids, and fractures of the subchondral bone and articular pillars, have been found in postmortem studies. Diagnosis of such injuries in vivo has been a challenge because they defy resolution by conventional imaging. Local anesthetic blocks of the cervical medial branches are purported to be a reliable diagnostic test. In the past, their validity was disputed on the grounds that they could be nonspecific or confounded by placebo responses. Nevertheless, recent studies have shown that medial branch blocks are target-specific and that their reliability is increased by employing control blocks, either by using two local anesthetics with different durations of action (comparative blocks) or by adding an inactive placebo injection (placebo-controlled blocks). Based on controlled blocks, the prevalence of lower cervical zygapophysial joint pain is 49%, and among patients with chronic, dominant headache, the C2–3 zygapophysial joint is the single most common source of pain. Despite extensive study, no clinical features of cervical zygapophysial joint pain have been identified. Consequently, controlled local anesthetic blocks remain the only means of diagnosing the condition. There is no evidence to support the efficacy of any form of nonoperative treatment for cervical zygapophysial joint pain. Indeed, intra-articular steroids have been shown to be ineffective. Neurosurgery remains the only practical and validated treatment for this common condition.