Low back pain- it may not seem like a big deal to some. What’s an occasional back ache? For many people, it is simply an annoyance. For others, it can be excruciating and disabling. Your spine is a column of bones (vertebrae) held together by muscles, tendons and ligaments, cushioned by shock-absorbing disks (read more about the composition of the spine here). A problem in any part of your spine can cause back pain, but for now I’d like to focus on the low back.
According to National Institute of Health (NIH) if you have lower back pain, you are not alone. About 80 percent of adults experience low back pain at some point in their lifetime. It is the most common cause of job-related disability and a leading contributor to missed work days. In a large survey, more than a quarter of adults reported experiencing low back pain during the past 3 months.
Men and women are equally affected by low back pain, which can range in intensity from a dull, constant ache to a sudden, sharp sensation that can be incapacitating. Pain can begin abruptly as a result of an accident, or by lifting something heavy. Or, it can develop slowly over time due to age-related changes of the spine. Sedentary lifestyles also can set the stage for low back pain, especially when a weekday routine of long hours sitting at the office is punctuated by a desire to suddenly exercise or clean up the garage on weekends.
Most low back pain is acute, or short term, and lasts a few days to a few weeks. It tends to be self-limiting and resolves on its own. The majority of acute low back pain is mechanical in nature, occurring as a result of strained muscles of the back. The vertebral column is supported by muscles and soft tissues, stress at any point can cause pain. A precise anatomical source of mechanical back pain is often difficult to identify. Sometimes, a specific trauma or strenuous activity may be the etiology, but the majority of the time a specific reason for the pain is not found. Fortunately, most people recover in a relatively short period of time with simple treatment.
Chronic back pain is defined as pain that continues for over 12 weeks. The CDC estimates about 20 percent of people affected by acute low back pain go on to develop chronic low back pain with persistent symptoms at one year. In 1990, a study ranking the most burdensome conditions in the U.S. in terms of mortality or poor health as a result of disease put low back pain in sixth place. By 2010, low back pain had jumped to third place.
What causes lower back pain?
The vast majority of low back pain is mechanical in nature. In many cases, low back pain is associated with spondylosis, a term that refers to the general degeneration of the spine, associated with normal wear and tear that occurs in the joints, discs, and bones of the spine as people get older. According to the National Institute of Health, some causes of low back pain include:
• Sprains and strains account for most acute back pain. Sprains are caused by overstretching or tearing of ligaments, and strains are tears in tendons or muscles. Both can occur from twisting or lifting something improperly, lifting something too heavy, or overstretching. Such movements may also trigger painful spasms in back muscles.
• Intervertebral disc degeneration is one of the most common mechanical causes of low back pain, and it occurs when the usually rubbery discs lose integrity as a normal process of aging. In a healthy back, intervertebral discs provide height and allow bending, flexion, and torsion of the lower back. As the discs deteriorate, they lose their cushioning or “shock absorbing” ability.
• Herniated or ruptured discs can occur when the intervertebral discs become compressed and bulge outward (herniation) or rupture, causing low back pain.
• Radiculopathy is a condition caused by compression, inflammation and/or injury to a spinal nerve root. Pressure on the nerve root results in pain, numbness, or a tingling sensation that travels or radiates to other areas of the body served by that nerve. Radiculopathy may occur when spinal stenosis or a herniated or ruptured disc compresses the nerve root. Sciatica is a specific form of radiculopathy caused by compression of the sciatic nerve- the large nerve that travels through the buttocks and extends down the back of the leg. This compression causes shock-like or burning low back pain combined with pain through the buttocks and down one leg, occasionally reaching the foot.
• Mechanical fractures and other injuries to the vertebral bodies as we discussed in the post on compression fractures.
• Spondylolisthesis is a condition in which a vertebra of the lower spine slips out of place, pinching the nerves exiting the spinal column.
• A traumatic injury, such as from playing sports, car accidents, or a fall can injure tendons, ligaments or muscle resulting in low back pain. Traumatic injury may also cause the spine to become overly compressed, which in turn can cause an intervertebral disc to rupture or herniate, exerting pressure on the exiting nerve root.
• Spinal stenosis is a narrowing of the spinal column where the spinal cord resides that can ultimately lead to impact on the cord. Foraminal stenosis is a narrowing or tightening of the opening in the vertebral bodies where the spinal nerves exit to the arms and legs.
• Skeletal irregularities such as scoliosis, or a curvature of the spine can stretch, irritate, or impact nerves. It can also strain joints, causing them to become worn or inflamed. Scoliosis also affects posture, which can lead to pain via muscle spasms and fatigue.
It’s also important to rule out other medical conditions that can present as back pain, such as kidney stones, an abdominal aortic aneurysm, endometriosis, or prostatitis. When back pain persists, talk to your healthcare provider. Next Friday, we’ll discuss risk factors for developing low back pain and how to keep your back healthy.
Image courtesy of belltownchiro.com