The Accuracy of Different Diagnostic Tools to Evaluate the Reason for a Noncompressive Pain Syndrome Associated with Degenerative Processes in Lumbar Spine

Abstract

Introduction During recent decades, different minimal invasive interventions focused on vertebral column degenerative diseases treatment were widely introduced in clinical practice. Being highly specific to the main pain source, all those methods require exact diagnostics; however certain difficulties could be experienced because of clinical tests and neurovisualization methods limitations to determine the cause of pain. While methods of neurovisualization were reported to achieve 96% sensitivity and 97% specificity in relation to the compressive pain syndromes, concerning all pain sources those characteristics were accounted for 96.7 and 53.9% respectively1,2, thereafter certain diagnostic difficulties are expected especially in cases of noncompressive pain syndromes. The objective of this study is to evaluate the accuracy of different diagnostic methods to detect the source of pain in case of noncompressive pain syndromes associated with degenerative diseases of lumbar spine. Materials and Methods This is a prospective nonrandomized study of 83 consecutive patients presenting low back pain (LBP) with or without sciatica. There was no evidence of nerve root compression in all cases according to the results of clinical examination and neurovisualization. All patients were given neurological examination, pain intensity and disability were assessed applying visual analogue scale (the result is VAS score) and Oswestry disability questionnaire (the result is Oswestry disability index - ODI). Magnetic resonance imaging (MRI) was applied in all cases. To confirm the discogenic origin of pain, a provocative discography was applied under the control of the fluoroscopy, the diagnostic criterion was the reproduction of concordant pain. To detect the contribution, facet joints in LBP-repeated diagnostic blocks with various anesthetics were applied under the guidance of the fluoroscopy. The accuracy of this diagnostic manipulation was studied using criterion 50 and 80% pain intensity relief (VAS score). Patients were treated with nucleoplasty when evidence of discogenic pain was supported by results of discography. Using ablation and coagulation mode six channels were created within the disc. Radiofrequency denervation was applied in cases of facet joints blocks positive results. The criterion of clinically significant treatment results was at least 50% VAS score decrease and 40% decrease in ODI score after intervention was applied. The conclusion concerning the sensitivity and specificity of different diagnostic tools was based on the ability to predict the clinically significant result applying minimal invasive intervention specific to the structure suspected to be the main source of pain. Results Concerning the ability to detect discogenic pain the estimated sensitivity and specificity of MRI were 93 and 56%. The analysis of discography application showed relatively high rate of false-positive results accounting up to 31%, the estimated sensitivity and specificity were 96 and 48%, respectively. As it goes for the accuracy to detect pain syndrome associated with facet joints degeneration, the sensitivity and specificity of MRI were relatively low, forming 50 and 64%, respectively. The sensitivity and specificity of facet joints blocks was 100 and 73%, respectively if 50% pain intensity decrease was used as the diagnostic criterion. Restriction of the criterion up to 80% pain intensity relief resulted in the specificity approximation up to 100% with the sensitivity loss down to 59%. Conclusion Apparently, the rational diagnostic algorithm in case of noncompressive pain syndromes differs from this applicable in cases with evident nerve root compression. Clinical evidence of noncompressive pain syndrome reflects the limited accuracy of neurovisualization methods to detect the source of pain thereafter it is obvious that it is necessary to apply invasive diagnostic methods in all cases. Diagnostic methods used to detect discogenic pain could be characterized by the disbalance of sensitivity and specificity which could result in hyper diagnostics of this pain source as a consequence of considerable rate of false-positive results. Concerning the ability to detect facet joints pain, MRI tomography showed considerable limitations resulting in a considerable rate of false-negative and false-positive results thereafter the evaluation of structural changes does not correspond to the probability of this pain source detection. Diagnostic facet joints blocks appears to be of the most acceptable sensitivity and specificity ratio, however like in all cases when diagnostic criterion is based on the results of numeric scores, the critical value for the diagnosis validation should be chosen in accordance to the main purpose. While it is rational to diminish the number of false-positive results studying the efficacy of different technologies, this approach could not be considered rational in daily practice because of the sensitivity loss, especially in case of minimal invasive interventions application. I confirm having declared any potential conflict of interest for all authors listed on this abstract Yes Disclosure of Interest None declared Almeida-Matos M, Santos-Gusmão M. Valor diagnostico da ressonância magnetica na avaliação da dor lombar. Rev. Salud Publica 2008;10:105–112 Janssen ME, Bertrand SL, Joe C, Levine MI. Lumbar herniated disk disease: comparison of MRI, myelography, and post-myelographic CT scan with surgical findings. Orthopedics 1994;17:121–127