Background: Zygapophysial or facet joint pain in patients suffering with chronic spinal pain without disc herniation or radiculopathy may be diagnosed with certainty by the use of controlled diagnostic blocks. But, in patients suffering with either lumbar or cervical facet joint pain, even this diagnostic approach may be confounded by false-positives when using a single diagnostic block. It may also be confounded by the administration of anxiolytics and narcotics prior to, or during, the controlled diagnostic facet joint blocks. The effect of sedation on the validity and potential differential results in patients suffering with combined cervical and lumbar facet joint pain has not been evaluated.
Objective: To assess the effects of midazolam and fentanyl on the diagnostic validity of facet joint blocks in patients suffering with both cervical and lumbar facet joint pain.
Study Design: Randomized, doubleblind, placebo-controlled study.
Methods: The design consisted of a placebo group receiving a sodium chloride solution and two experimental groups receiving either midazolam or fentanyl. Patients included in the study had been diagnosed with facet joint pain using controlled comparative local anesthetic blocks of the medial branches and L5 dorsal rami. They had been treated with lumbar and cervical facet joint nerve blocks and experienced good pain relief; and were presenting for repeat treatment after a period of symptom relief. The study was performed in an interventional pain management practice in the United States; a total of 60 patients participated with 20 patients randomly allocated into each group. Outcome measures included numeric pain scores, proportion of pain relief, and ability to perform prior painful movements.
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).
Results: Overall, 50% of the patients were relaxed or sedated in the placebo group, while 100% of the patients in the midazolam and fentanyl groups were relaxed or sedated. As many as 10% of the patients reported signifi cant relief (>=80%) with the ability to perform prior painful movements.
Conclusions: Perioperative administration of sodium chloride, midazolam, or fentanyl can confound results in the diagnosis of combined cervical and lumbar facet joint pain. False-positive results with placebo or sedation may be seen in a small proportion of patients.
Key Words: Spinal pain, facet joint pain, controlled comparative local anesthetic blocks, false-positives, confounding factors, analgesia