Facet joint pain in chronic spinal pain: an evaluation of prevalence and false-positive rate of diagnostic blocks.

STUDY DESIGN A retrospective review. OBJECTIVES Evaluation of the prevalence of facet or zygapophysial joint pain in chronic spinal pain of cervical, thoracic, and lumbar origin by using controlled, comparative local anesthetic blocks and evaluation of false-positive rates of single blocks in the diagnosis of chronic spinal pain of facet joint origin. SUMMARY OF BACKGROUND DATA Facet or zygapophysial joints are clinically important sources of chronic cervical, thoracic, and lumbar spine pain. The previous studies have demonstrated the value and validity of controlled, comparative local anesthetic blocks in the diagnosis of facet joint pain, with a prevalence of 15% to 67% variable in lumbar, thoracic, and cervical regions. False-positive rates of single diagnostic blocks also varied from 17% to 63%. METHODS Five hundred consecutive patients receiving controlled, comparative local anesthetic blocks of medial branches for the diagnosis of facet or zygapophysial joint pain were included. Patients were investigated with diagnostic blocks using 0.5 mL of 1% lidocaine per nerve. Patients with lidocaine-positive results were further studied using 0.5 mL of 0.25% bupivacaine per nerve on a separate occasion. Medial branch blocks were performed with intermittent fluoroscopic visualization, at 2 levels to block a single joint. A positive response was considered as one with at least 80% pain relief from a block of at least 2 hours duration when lidocaine was used, and at least 3 hours or longer than the duration of relief with lidocaine when bupivacaine was used, and also the ability to perform prior painful movements. RESULTS A total of 438 patients met inclusion criteria. The prevalence of facet joint pain was 39% in the cervical spine [95% confidence interval (CI), 32%-45%]; 34% (95% CI, 22%-47%) in the thoracic pain; and 27% (95% CI, 22%-33%) in the lumbar spine. The false-positive rate with a single block in the cervical region was 45%, in the thoracic region was 42%, and in the lumbar region 45%. CONCLUSIONS This retrospective review once again confirmed the significant prevalence of facet joint pain in chronic spinal pain.