Discomanometria

J Korean Med Sci 2006; 21: 911-6 ISSN 1011-8934

Copyright � The Korean Academy of Medical Sciences

Diagnostic Relevance of Pressure-Controlled Discography
Discogenic pain is a leading cause of chronic low back pain. The authors investigated the efficacy of pressure-controlled discography to determine its role in clinical decision-making for the management of patients with discogenic pain.Pressure-controlled discography was performed in 21 patients (51 discs) with pain-provocation, followed by post-discography computerized tomography scans. Pain response was classified as positive response and negative response, and measured with visual analog scale scores. Discographic findings were graded by the modified Dallas discogram scale. Elastance, pain provocation on intradiscal pressure,pressure and volume of initial pain response, and pain response intensity were statistically analyzed. Elastance showed significant differences between Grade 0 and Grade 4 & 5. Decreased elastance with positive pain response group was a good indicator to imply that disc degeneration presumably is a pain generator. Results of pain response were well correlated with intradiscal pressure but notwith the amount of injected volume. Among 31 discs of Grade 4 and 5, 74% showed negative pain response and 26% showed positive response. It was concluded that pressure-controlled discography was useful to diagnose discogenic pain and excellent guide in decision-making for spinal operations.
Key Words : Low Back Pain; Intervertebral Disk; Injections, Spinal

Dong-Ah Shin, Hyoung-Ihl Kim, Jae-HyunJung, Dong-Gyu Shin, Jung-Ok Lee
Department of Neurosurgery, Presbyterian Medical Center, Jeonju, Korea

Received : 10 February 2006 Accepted : 29 March 2006

Address for correspondence
Hyoung-Ihl Kim, M.D. Department of Neurosurgery, Presbyterian Medical Center, 300 1-ga, Junghwasan-dong, Wansan-gu, Jeonju 560-750, Korea Tel : +82.63-230-8264, Fax : +82.63-285-9573 E-mail :hyoungihl@hotmail.com

INTRODUCTION
Since Mixter and Barr found that compression of the nerve root by disc herniation could be a major cause of low back pain (LBP) (1), many diagnostic approaches including myelography, epidurography, and discography had been extensively used to demonstrate the mechanical factors which might compress the nerve roots (2). Introduction of modern neuroimaging techniques which canvisualize the internal structures of the spine, however, replaced the old techniques rapidly because of its non-invasiveness and superior imaging quality. Especially, high resolution magnetic resonance imaging (MRI) or computerized tomography (CT) seems to be an efficient way to find the pain source in the patients suffering from LBP. Consequently, based on the imaging findings on MRI, most spinalsurgeons perform operations with high confidence (3, 4). Furthermore, MRI facilitates the decision making on spinal pain, hence encourage extensive use of spinal operation (5). On the other hand, analysis of spinal operations revealed that incidence of failure after spinal operation is not decreasing despite wide application of modern neuroimaging techniques (6, 7). Boos et al. investigatedabnormal findings of MRI in the patients with disc disease and asymptomatic volunteers (8). Surprisingly, MRI examination showed disc herniation (76%) and extrusion (13%) in volunteers, even though they did not have any evidence of back pain. It implies that
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MRI is an excellent method to show the structural abnormality in the spinal canal, yet it does not indicate the pain source (9-11).Therefore, surgical decisions solely based on imaging findings are likely to lead to failure in back surgery. Recent studies revealed that discogenic pain is caused not only by mechanical compression of disc herniation, but also by chemical factors which are irritating dorsal root ganglion and spinal root (12-14). Structural damage in the disc and disruption of annulus fibrosus release the chemical...