Analysis of the relationship between morphology of intervertebral disc and some correlated factors following discography in patients with chronic low back pain

OBJECTIVE: To evaluate the diagnostic effectiveness of discography in discogenic low back pain (LBP). METHODS: Ninety-six cases of chronic LBP with or without referred thigh pain were enrolled in this study. All these cases received CT scan following discography once conservative treatment for at least 6 months had failed. There were 42 men and 54 women, aged from 24 to 67 years (average 46.4). Discography was performed on 218 discs. The positive discs were classified morphologically according to the Dallas Discogram Description (DDD). RESULTS: (i) The 56 cases (58.3%) which were positive on discography were divided into two subgroups of age less or more than 50 years. Positive rates for the two subgroups were 33.3% and 66.7%, respectively; (ii) one hundred and twenty-two discs, of which 62 (50.8%) were positive on discography, showed morphologic abnormality, whereas all the discography positive discs showed morphologic abnormality. No complication related to discography was found in any case. CONCLUSION: (i) Compared with the younger patients, older LBP patients have a lower positive rate of discography despite the presence of more serious degenerative disc changes; (ii) outer layer disruption of the annulus fibrous correlates with positive discography; (iii) MRI intensity changes are not specific in diagnosing discogenic pain. Additional discography is needed to identify the painful disc; and (iv) the contrast volume injected into discs can be affected by a variety of factors which restrict its diagnostic value.