BROUGHT TO YOU BY This Special Report is supported through a grant from NEWS FACULTY: Tong J. Gan, MD Vice Chair of Anesthesiology Duke UniversityAll rights Medical reserved. Reproduction in whole or in part without permission is prohibited. School Durham, NC Copyright © 2007 McMahon Publishing Group unless otherwise noted. John B. Leslie, MD Professor of Anesthesiology Mayo Clinic DECEMBER 2007 Phoenix, AZ Joseph V. Pergolizzi, MD Adjunct Assistant Professor of Medicine Department of Medicine Johns Hopkins University Nonsurgical School of Medicine Baltimore, MD Spinal Decompression To Treat Chronic DISCLAIMER: Low Back Pain This monograph is designed to be a summary of information. While it is detailed, it is not an exhaustive clinical review. Introduction studies of LBP published between 1966 and McMahon Publishing and the 1998, the prevalence of LBP ranged from 12% authors neither affirm nor deny In most industrialized countries, chronic to 33%, 1-year prevalence from 22% to 65%, the accuracy of the information low back pain (LBP) is recognized as a wide- and lifetime prevalence from 11% to 84%. contained herein. No liability spread condition.1 Until recently, conventional Approximately 25% of adults in the United will be assumed for the use of wisdom held that most episodes of acute LBP States report having experienced LBP in the this educational review, and the absence of typographical errors are benign and self-limited, with 80% to 90% past 3 months, and the proportion of physi- is not guaranteed. Readers are of attacks resolving in about 6 weeks and that cian visits attributed to back pain has 5 strongly urged to consult any 5% to 10% of patients who experience an changed little since the 1990s. relevant primary literature. episode of acute LBP go on to experience Copyright © 2007, McMahon chronic back pain. This expectation is now in Publishing, 545 West 45th doubt: It is currently recognized that acute Economic and Social Burden Street, New York, NY 10036. LBP tends to relapse, and many patients Printed in the USA. All rights experience recurring episodes, leading to a Of Low Back Pain reserved, including the right of chronic condition. Current evidence shows In the United States, LBP is the second reproduction, in whole or in part, in any form. that 25% to 60% of patients will experience most common reason for a visit to a physi- another episode of LBP at 1 year or longer cian, the fifth most common cause of ad- after the initial episode.2 mission to a hospital, and the third most Most episodes of acute LBP are resolved common indication for surgery.6 A minority of without recourse to medical care. If a patient patients with back pain account for the Distributed by receives medical care, pain and disability usu- majority of health care costs related to back McMahon Publishing ally resolve and the patient can return to work, pain, indicating that the potential cost of treat- typically within 1 month.3 However, in as many ing all patients with back pain is much higher as 1 in 3 patients, chronic LBP eventually than the actual cost.3,7 LBP is among the top develops that persists indefinitely and is dis- 10 reasons for visits to internists and the abling. Patients can experience constant pain most common and most expensive reason and become functionally impaired, with 1 in 5 for work disability in the United States.8 It is reporting substantial limitations to their activi- also a frequent cause of early retirement for ties.3,4 In a literature review of 30 population medical reasons. Prevalence and Burden of Low Back Pain 3 groups: a) those with nonspecific LBP; b) those with back A study of the national prevalence and correlates of low pain potentially associated with radiculopathy or spinal steno- back and neck pain among adults in the United States found sis (suggested by the presence of sciatica or pseudoclaudica- that in 2002, the 3-month prevalence of LBP was 34 million.9 tion); and c) those with back pain potentially associated with The annual prevalence of chronic LBP is currently between other spinal causes. These include the small number of 15% and 45%; the average age-related prevalence of persistent patients with serious or progressive neurologic deficits or LBP is approximately 15% in children, adolescents, and adults underlying conditions that require prompt evaluation (eg, and 27% in the elderly.2 In the United States, the financial and tumor, infection, cauda equina syndrome), as well as condi- social costs of LBP include impaired function, limited activity, tions such as ankylosing spondylitis and vertebral compres- Alland rights a reduced reserved. quality of life,Reproduction as well as disability, in underemploy- whole or in partsion fracture.without permission is prohibited. ment, reduced productivity, and direct medical costs. In the Mechanical low back or leg pain accounts for 97% of all United States in 1998, direct health care costs attributable to cases of LBP. The term mechanical refers to an anatomic or LBP were estimatedCopyright at $26.3 © billion, 2007 and McMahon indirect costs Publishingrelated functional Group abnormality unless otherwise without underlying noted. malignant, neoplas- to days lost from work were substantial.3 Among US workers tic, or inflammatory disease. Lumbar strain or sprain will be the aged 40 to 65 years, exacerbations of back pain and lost pro- final diagnosis in 70% of these cases. Other mechanical and ductivity cost employers up to $7.4 billion per year; workers spinal phenomena that can help guide appropriate therapies with chronic back pain accounted for 71.6% of this cost. Behind include degenerative disk disease, a herniated disk, spinal these statistics are many other workforce costs, such as the stenosis, osteoporotic compression fracture, and spondylolis- need for hiring and training replacement workers, the effect on thesis. The incidence of the various causes of LBP may vary co-workers’ productivity, and the loss of leisure time.2 substantially according to the demographic characteristics and In addition to the obvious discomfort, inconvenience, and referral patterns in any specific clinical practice. For example, societal costs of LBP, a recent cross-sectional study of the spinal stenosis and osteoporosis will be more common in geri- comorbid conditions related to back pain found that compared atric practices. with a normal reference population, patients with LBP had sig- Mechanical causes of LBP include injury to the lumbosacral nificantly more neck pain, upper back pain, foot pain during muscles and ligaments, facet joint or sacroiliac joint arthro- exercise, headache, migraine, sleep problems, heat sensa- pathy, and discogenic disease due to degenerative changes.16 tions, anxiety, and sadness or depression. This finding led the In patients with back and leg pain, a history typical of sciatica authors to conclude that patients with LBP experience what is indicates a herniated disk.17 More than 90% of symptomatic effectively a “syndrome,” with an effect beyond that of the iso- lumbar disk hernias occur at the L4-5 and L5-S1 levels. A lated spinal pain.10 Although research on back pain has focused examination that includes the straight leg raise test focused primarily on younger, working adults, there is clear evi- and a neurologic examination that includes an evaluation of the dence that back pain is 1 of the most frequent complaints in strength and reflexes of the knees, strength of the great toes, older people and a proximate cause of functional limitations dorsiflexion of the feet, plantar flexion of the feet, ankle reflex- and perceived difficulty in performing the activities of daily liv- es, and distribution of sensory symptoms should be conducted ing (ADLs). It is also a risk factor for future disability.2 to assess the presence and severity of nerve root dysfunction.3 Discogenic pain most commonly affects the lower back, but- tocks, and hips and is likely a result of internal disk degenera- Management of Low Back Pain tion. Disk degeneration is likely due to the injury and subsequent repair of the annulus fibrosus, where growth fac- Diagnosing low back pain tors, macrophages, and mast cells involved in the repair of the injured annulus fibrosus contribute to subsequent deteriora- There are wide variations in testing and diagnostic routines, in tion. Discogenic pain may be due to progressive annular break- addition to a multitude of potential treatment approaches and down and tearing that stimulate pain fibers in the outer professional uncertainly about the optimal approach to the man- one-third of the annulus.18 agement of LBP.11 More than 85% of patients who initially consult Disk degeneration has been documented in asymptomatic a primary care physician for back pain have nonspecific LBP, or groups of people ranging in age from 10 to 19 years, with 20% pain that cannot easily be attributed to a specific disease or of people in their teens demonstrating mild disk degeneration.19 spinal abnormality. Efforts to identify specific anatomic sources By 50 years of age, 10% of disks show degenerative pathology, of the pain in such patients are frequently unsuccessful.3 and by 70 years of age, 60% of vertebral disks are severely Intervertebral disks, facet joints, ligaments, fascia, muscles, degenerated. Disk degeneration alone is thought to be associ- and nerve root dura have all been identified as structures that ated with sciatica, disk herniation and prolapse, alteration of can cause pain in the low back. Only abnormalities of the facet disk