Background: Based on responses to controlled diagnostic blocks of cervical facet joints, the prevalence of cervical facet joint pain in chronic neck pain has been shown to range from 54% to 67%, with false-positive results of 27% to 63% with a single diagnostic block. Other confounding factors claimed to influence the diagnostic validity of cervical facet joint blocks include administration of anxiolytics and narcotics prior to or during the procedure.
Objective: To evaluate the effect of midazolam and fentanyl on the validity of diagnosis of cervical facet joint pain.
Study Design: Randomized, prospective, double-blind, placebo-controlled evaluation.
Methods : The study was undertaken in an interventional pain management practice. The design consisted of a placebo group receiving sodium chloride solution and two experimental groups receiving either midazolam or fentanyl. The patients included in the study were treated in the past and were presenting for repeat treatment after a significant period of symptom relief.
Outcome Measures: Outcomes were assessed at baseline and after the administration of 1 of the 3 solutions (Group I, sodium chloride solution; Group II, midazolam; or Group III, fentanyl). Outcome measures included numeric pain scale, proportion of pain relief, and ability to perform prior painful movements.
Results: Pain relief of > 80% was noted in 5% of the patients in Group I, 8% in Group II, and 8% in Group III. However, > 50% relief was noted in 8% of the patients in Group I, 13% in Group II, and 27% in Group III. Overall, 8% of the patients in Group I, 13% in Group II, and 27% in Group III were able to perform movements which were painful prior to injection.
Conclusion: The administration of sedation with midazolam or fentanyl is a confounding factor in the diagnosis of cervical facet joint pain in patients with chronic neck pain. However, if > 80% pain relief with ability to perform prior painful movements is used as the standard for evaluating the effect of controlled local anesthetic blocks, the diagnostic validity of cervical facet joint nerve blocks may be preserved.
Keywords: Chronic neck pain, cervical facet joint pain, controlled comparative local anesthetic blocks, false-positives, confounding factors, analgesia