Korean J Anesthesiol.  1999 Nov;37(5):859-866. 10.4097/kjae.1999.37.5.859.

Determination of the False Positive Rate of Uncontrolled Diagnostic Block for Lumbar Medial Branch of Dorsal Rami

• Shim JC
• Kim DW

• KMID: 2239029
• DOI: http://doi.org/10.4097/kjae.1999.37.5.859

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.

Keyword

Nerve, nerve block, medial branch of dorsal rami block; Pain, low back pain, zygapophysial joint pain

MeSH Terms

Arthralgia
Back Pain
Bupivacaine
Diagnosis
Humans
Joints
Lidocaine
Low Back Pain
Prospective Studies
Bupivacaine
Lidocaine