| Determination of the False Positive Rate of Uncontrolled Diagnostic Block for Lumbar Medial Branch of Dorsal Rami. |
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Jae Chol Shim, Dong Won Kim |
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Department of Anesthesiology, College of Medicine, Hanyang University. |
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| Abstract |
BACKGROUND
Patients without genuine zygapophysial joint pain exhibit a positive response to uncontrolled diagnostic blocks. We determined the false positive rate of single uncontrolled diagnostic zygapophysial joint block in patients with chronic back pain.
METHOD
Thirty-five patients with chronic lower back pain were studied prospectively. All patients underwent a series of medial branch of dorsal rami blocks with lidocaine and bupivacaine starting at the symptomatic level to a maximum of three levels or until the pain was abolished.
RESULTS
All patients proceeded with the injections. 16 patients (45%) had a definite or greater response to the initial lidocaine injection at one or more levels but only 5 (14%) had a 50% or greater response to a confirmatory injection of 0.5% bupivacaine. Using the confirmatory blocks as the criterion standard, the false positive rate of uncontrolled diagnostic blocks was 37% and the positive predictive value was only 31%.
CONCLUSION
Uncontrolled diagnostic blocks may be unreliable for the diagnosis of lumbar zygapophysial joint pain. |
| Key Words:
Nerve, nerve block, medial branch of dorsal rami block; Pain, low back pain, zygapophysial joint pain |
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