Disc stimulation and patterns of referred pain

Study Design. Prospective, with in-subjects, observational experimental design. Objectives. To determine the pattern of pain response to noxious stimulation of the intervertebral disc. Summary of Background Data. Experimental studies have demonstrated that noxious stimulation of interspinous ligaments, facet joints, and paravertebral muscles causes referred pain into the extremity, with the distal extent of radiation dependent on the intensity of stimulation. Analogous studies have not been performed on the lumbar intervertebral disc. Methods. A total of 25 consecutive patients meeting inclusion criteria completed a pain diagram before undergoing the intradiscal electrothermal annuloplasty procedure. The location, intensity, and familiarity of any pain provoked during disc heating were correlated with presenting symptoms and duration of heating. Results. During disc heating, 68% of patients reported exact reproduction of their presenting pain, in both pain quality and location, None of the patients experienced unfamiliar pain during the procedure. The pattern of pain reproduction was consistent; pain originated proximally and progressed distally as stimulus intensity increased. Conclusion. Noxious stimulation of the intervertebral disc may result in low back and referred extremity in patients presenting with these symptoms. The distal extent of pain produced depends on the intensity of stimulation. Disc stimulation may reproduce pain that extends to below the knee.