Distribution of referred pain from the lumbar zygapophyseal joints and dorsal rami

Objective: The purpose of this study was to determine the distribution of referred pain from the lumbar zygapophyseal joints (L1/2 to L5/S1) and the medial branches of the lumbar dorsal rami (Th12 to L5) in a large number of patients with chronic low back pain. Setting: This study was conducted at the pain clinics of Kanto Teishin Hospital and Hannan Central Hospital from March 1994 to May 1996. Patients and Design: Chronic low back pain patients who underwent zygapophyseal joint injection or radiofrequency facet denervation were studied. Under fluoroscopic control, the joints from L1/2 to L5/S1 were stimulated by injection of contrast medium, and the lumbar medial branches of the dorsal rami from Th12 to L5 underwent electrical stimulation during radiofrequency facet denervation. Outcome Measures: If the injection or electrical stimulation reproduced the patient's usual pain, the distribution of induced pain was determined, and the sites of induced pain were divided into six areas. Results and Conclusions: A total of 71 joints and 91 medial branches were studied in 48 patients. The distribution of referred pain from the L1/2 to L5/S1 zygapophyseal joints, and the medial branches of the dorsal rami from L1 to L5 were similar for each level stimulated, and the overlap of referred pain between each level was considerable.