Focused Issue of This Month Causes and Diagnostic Strategies for Chronic Low Back Pain Hyoung Ihl Kim, MDDongGyu Shin, MD Department of Neurosurgery, Presbyterian Medical Center Email : hyoungihl@hotmail.comsdh8262@hanmail.net J Korean Med Assoc 2007; 50(6): 482-493 Abstract Chronic low back pain (CLBP) has become more prominent with globally increasing life expectancy. Its cause is more attributable to degenerative changes than to traumatic lesions. Although the diagnosis of CLBP is recently on higher demand, lack of clinical features and non-informative imaging findings in patients with CLBP are challenging to clinicians to establish the diagnosis. Therefore, understanding of the new concept of pathogenesis, elimination of prejudice, and evidencebased diagnostic steps are required to resolve the question of pain source. Analysis of pain distribution patterns and careful history taking can be utilized as an initial guide to divide CLBP into somatic and radicular pain. Zygapophyseal joint pain and sacroiliac joint pain representing somatic pain can be further investigated using medial branch and sacroiliac joint blocks. However, comparative blocks are essential to decreased false positive rate. Infiltration of a small volume of local anesthetics can increase the specificity of the procedures. Discogenic pain stemming from internal disk derangement can be confirmed by pressurecontrolled discography. Automated discography is recommended to provide the constant rate of dye injection with obviating the fluctuation of intradiscal pressure. Evidence based concept and diagnostic procedures can provide more accurate and efficient methods to establish the diagnosis of CLBP. Keywords : Low back pain; Nerve block; Discography; Evidencebased medicine 482
Causes and Diagnostic Strategies for CLBP Table 1. Causes of spinal pain and their representative examples Causes Representing diseases or conditions Degenerative Intervertebral disk, Zjoint arthropathy, SI joint arthropathy Traumatic Fracture Congenital Lumbarization, diastomatomyelia Metabolic Senile osteoporosis, estrogen deficiency, chronic steroid use Inflammatory Systemic infection, ankylosing spondylitis Neoplastic Osteid osteoma, giant cell tumor, hemangioma, metastasis Vascular Abdominal aortic aneurysm Mechanical Obesity, poor posture, low mobility, chronic sedentary work Psychogenic Traumarelated compensation *zjoint: zygapophyseal joint, SI:sacroiliac 483
Kim HIShin DG Sympathetic trunk Sinuvertebral Nerve Dorsal Ramus Ventral Ramus L5 dorsal ramus IOL SLB SN Lateral Branch Medial Branch SIJ Figure 1. Schematic drawing of lumbar vertebral area demonstrating the nerves and their innervated structures. IOL: interosseous ligament, SLB: sacral lateral branch, SN: sacral nerve, SIJ: sacroiliac joint Figure 2. Schematic drawing of sacroiliac joint demonstrating the innervating nerves. 484
Causes and Diagnostic Strategies for CLBP Table 2. Differential diagnosis of somatic versus radicular pain Somatic Pain Radicular Pain Origin Muscles and ligaments DRG Neurological Sign No Numbness, Myotomal weakness, Lost reflex Distribution Diffuse Quasilinear Quality Deep aching Lancinating, *DRG: dorsal root ganglion 485
Kim HIShin DG Type A Type B1 Type B2 Type B3 Figure 3. Pain distribution patterns in lumbar zygapophyseal joint dysfunction. Type E (undetermined type) is not depicted here. 486
Causes and Diagnostic Strategies for CLBP Type A Type B Type C Type D Figure 4. Pain distribution patterns in sacroiliac joint dysfunction. Type E (undetermined type) is not depicted here. 487
Kim HIShin DG Type A Type B Figure 5. Pain distribution patterns of discogenic pain. 488
Causes and Diagnostic Strategies for CLBP Grade 0 Grade 1 Grade 2 Grade 3 Grade 4 Grade 5 Figure 6. Modified Dallas discogram classification. Note that disk degeneration is confined inside the disk in Grade 1, 2, and 3. Disk herniations are demonstrated in Grade 4 and 5. 489
Kim HIShin DG Figure 7. Computer screen of automated discography device demonstrating the increase of intradiscal pressure (A) with change of pain severity (B). 490
Causes and Diagnostic Strategies for CLBP Zjoint: zygapophyseal joint, Exam: examination, SI: sacroiliac, MBB: medial branch block, IOL: interosseous ligament Figure 8. Algorithm for the management of chronic low back pain. 491
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