DEGREE OF DISC DISRUPTION AND LOWER-EXTREMITY PAIN

Study Design. Data were collected prospectively from patient-completed pain drawings, lumbar discographic pain responses, and computed tomog raphic-discographic images. Objectives. To determine if there were dif ferences in pain location or the type of pain associated with the seve rity of symptomatic disc disruption. Summary of Background Data. Lower extremity pain related to spinal pathology was for a long time attrib uted primarily to nerve root compression. However, this simple model c ould not explain all lower extremity pain. Other mechanisms such as bi ochemical agents have been implicated. Also, nerve endings have been f ound in the outer layers of the anulus. Such endings could be associat ed with pain referred from the disc into the lower extremities. Pain d rawings have been used in several studies to investigate various back pain origins and provide an easily administered method to document pai n location. Methods. Pain drawings were completed by 187 patients unde rgoing discography at the three lowest levels. The study group consist ed of 118 men and 69 women with an average age of 37.2 years (range, 1 8-62 years). Computed tomographic discograms were scored using the Dal las discogram description, which assigns separate scores for discs wit h disruption of outer anular fibers (Grade 2) and those with disruptio n of the outermost anular layers associated with deformation or hernia tion of the outer anular wall (Grade 3). The pain response provoked wi th each disc injection was recorded as pressure only or painless, pain dissimilar to clinical symptoms, similar to symptoms, or the extra re production of clinical pain. In this study, the similar and exact repr oduction responses were combined and considered to be ''symptomatic.'' The drawings were classified based on the presence or absence of pain in three regions: low back or buttocks, thigh, and leg. The drawings were also scored using the system described by Ransford, and those tha t were likely to be indicative of psychological problems were analyzed separately (N = 43). Results. There was no significant difference in the distal location of lower extremity pain among patients whose most severe symptomatic disc disruption was a Grade 2 compared with those w ith symptomatic Grade 3 disruption (62.2% vs. 61.7%; P > 0.75; chi-squ are). The figure was similar for patients with both symptomatic Grade 2 and 3 disruption (72.7%). However, patients With symptomatic Grade 2 disruption used significantly more symbols to describe their pain, an d in particular aching pain, than did those with symptomatic Grade 3 d isruption. Conclusions. These results indicate that disc disruption pa ssing into the outer layers of the anulus, but not resulting in deform ation of the outer anular wall, was as frequently associated with lowe r extremity pain as were discs with more severe disruption deforming t he outer anular wall; however, they were associated with a greater deg ree of aching pain. These findings support that lower extremity pain m ay be referred from the disc.