2000 Volvo Award Winner in Clinical Studies - Lumbar high-intensity zone and discography in subjects without low back problems

Study Design. A prospective observational study of patients with low back p ain and those without was performed. Objective. To investigate the prevalence and significance of a high-intensi ty zone in a group of patients asymptomatic for low back pain, but who had known risk factors for lumbar disc degeneration. This asymptomatic group wa s compared with a symptomatic group of patients with respect to the presenc e of anular high-intensity zone and the pain response with discography. Summary of Background Data. Some authors have estimated the prevalence of a high-intensity zone in a group of symptomatic patients to be 86%. They hav e reported a strong correlation between a high-intensity zone and positive discography in patients with low back pain. Other investigators have report ed evidence either supporting or discounting these findings. Methods. Patients with low back pain and those without underwent physical e xamination, psychometric testing, plain radiograph, magnetic resonance imag ing, and discography. The presence of a high-intensity zone, anular disrupt ion, and positive discographic pain then were compared between the two grou ps. There were strict inclusion criteria for both groups. A total of 109 di scs in 42 patients were evaluated in the symptomatic group and compared wit h 143 discs in 54 patients in the asymptomatic group. The presence of a hig h-intensity zone was determined by a standardized criteria on T2-weighted m agnetic resonance images. Psychometric testing also was administered to eac h patient before discography, Standard discography was performed on all the patients, and the pain response was recorded using a visual analog scale a ccording to the Walsh et al criteria. Results. The prevalence of a high-int ensity zone in the patient populations was 59% in the symptomatic group and 24% in the asymptomatic group. In the symptomatic group, 33 (30.2%) of 109 discs were found to have a high-intensity zone. In the asymptomatic group, 13 of 143 discs were found to have a high-intensity zone. In the symptomat ic group, 72.7% of the discs with a high-intensity zone were positive on di scography, whereas 38.2% of the discs without a high-intensity zone were po sitive. In the asymptomatic group, 69.2% of the discs with a high-intensity zone were positive on discography, whereas 10% of the discs without a high -intensity zone were positive. In the patients with normal psychometric tes ting, 50% of the discs with a high-intensity zone were positive on discogra phy, as compared with 100% positive discography results in patients with ab normal psychometric testing or chronic pain. Conclusions. The presence of a high-intensity zone-does not reliably indica te the presence of symptomatic internal disc disruption. Although higher in symptomaticpatients, the prevalence of a high-intensity:zone inasymptomati c individuals with degenerative disc disease (25%) is too high for meaningf ul clinical use. When injected during discography the same percentage of as ymptomatic and symptomatic discs with a high-intensity zone were shown to b e painful.