Psychophysical Measurements During Lumbar Discography

Abstract

Prospective clinical data analysis. To determine if heart rate (HR) response correlates with positive discography results. Lumbar discography is a controversial tool for the diagnosis of discogenic low back pain. The subjective nature of discography can make data interpretation difficult, leading to false-positive and false-negative results. HR changes have been found in numerous studies to be a reliable and valid indicator of acute pain. To date, there is no study analyzing the HR response to discography-induced pain. The HR measurements were recorded immediately preceding and after contrast injection into the each disc, and statistically correlated with the provocation of concordant pain, nonconcordant pain, and nonpainful discs. Discography was performed in 26 subjects with low back pain. Among 75 discograms, 26 discs elicited concordant pain, 9 provoked nonconcordant pain, and 40 elicited no pain response. There was no significant change in HR during disc stimulation for negative [no pain response (P=0.19) and nonconcordant (P=0.26)] discograms, whereas positive discograms [concordant pain (numerical rating scale> or =6/10)] were associated with a statistically significant increase in HR (P=0.000002). Lumbar discography induces positive HR response only in positive discograms. Although there is no immediate practical application of these results, 2 implications may deserve future research: (a) correlation of HR response with surgical and intradiscal electrotherapy treatment outcomes; (b) evaluation of HR measurement in cases of false-positive results (concordant pain on discography but no HR response).