308 Manchikanti et al • Contributions of Various Structures in Chronic Low Back Pain Pain Physician Vol. 4, No. 4, 2001 Pain Physician, Volume 4, Number 4, pp 308-316 2001, American Society of Interventional Pain Physicians ® ISSN 1533-3159 Original Article 308 Evaluation of the Relative Contributions of Various Structures in Chronic Low Back Pain Laxmaiah Manchikanti, MD*, Vijay Singh, MD # , Vidyasagar Pampati, MSc**, Kim S. Damron, RN ## , Renee C. Barnhill, RN ## , Carla Beyer, RN ## , and Kim A. Cash, RT Ω From Pain Management Center of Paducah, Paducah, Ken- tucky. *Medical Director, **statistician, ## clinical coordi- nators, and Ω radiological technologist at the Pain Manage- ment Center of Paducah. # Medical Director of Pain Diag- nostic Associates. Address correspondence: Laxmaiah Manchikanti, MD, 2831 Lone Oak Road, Paducah, Ken- tucky 42003. E-mail: drm@asipp.org An attempt was made to determine the relative contribution of various structures to chronic low back pain, including facet joint(s), disc(s), and sacroiliac joint(s) in a prospec- tive evaluation. Precision diagnostic blocks, including disc injections, facet joint blocks, and sacroiliac joint injections, are frequently used. In contrast, selective nerve root blocks or transforaminal epidural injections are used occasionally to evaluate persistent or recurrent low back pain in patients without appropriate radiologic or neurophysiologic diagno- sis. One hundred and twenty patients with a chief complaint of low back pain were evaluated with precision diagnostic injec- tions, which included medial branch blocks, provocative dis- cography and sacroiliac joint injections. In 40% (95% CL, 31%, 49%), of the patients, facet joint pain was diagnosed; and in 26% (95% CL, 18%, 34%) of the patients discogenic pain was diagnosed; and 2% of the patients were diagnosed with sacroiliac joint pain. Keywords: Chronic low back pain, medial branch blocks, provocative discography, sacroiliac joint injections, transfo- raminal epidural injections, selective nerve root blocks Kuslich et al (1) identified ligaments, fascia, muscles, in- tervertebral discs, facet joints, and nerve root dura as tis- sues capable of transmitting pain in the low back. Bogduk (2) postulated that for any structure to be deemed a cause of back pain, it should have a nerve supply; should be capable of causing pain similar to that seen clinically, ide- ally in normal volunteers; should be susceptible to dis- eases or injuries that are known to be painful; and should have been shown to be a source of pain in patients, using diagnostic techniques of known reliability and validity. Schwarzer et al (3-8) in their pioneering work, attributed origins of chronic low back pain to intervertebral discs in 39% of patients, to facet joints in 15% to 40%, and to sac- roiliac joints in 30%. Bogduk (9) postulated that precision diagnostic injections could assist in arriving at a definite diagnosis in low back pain in approximately 70% to 80% of patients based on Schwarzer et al’s (3-8) studies. Tradi- tionally, clinical features and imaging or neurophysiologic studies do not permit the accurate diagnosis of causation of low back pain in 85% of patients in the absence of disc herniation and neurological deficit (3-12). Second genera- tion studies of precision diagnostic injections showed facet joint pain in 32% to 45% of patients (13-17), and sacroiliac joint mediated pain in 19% of the patients (18) with chronic low back pain. Diagnostic blockade of a structure with a nerve supply with ability to generate pain, can be performed to test the hypothesis that the target structure is a source of the patient’s pain (12). Thus, precision diagnostic injections are potentially powerful tools for diagnosis of chronic spi- nal pain. True positive responses are secured by perform- ing controlled blocks. Ideally, these should be in the form of placebo injections of normal saline; but logistical and/or ethical considerations prohibit the use of normal saline in conventional practice (12). Muscle pain, ligament pain, and trigger points have at- tracted greatest popularity in clinical practice (2). Yet they are supported by very little scientific evidence. In con- trast, facet joint pain, discogenic pain and sacroiliac joint pain have been studied with controlled diagnostic tech- niques, withstanding scientific scrutiny (2). The facet joints of the spine can be anesthetized by fluoroscopically guided injections of local anesthetic, either into the target joint or