Up to 80 percent of adults will experience significant low back pain at some point during their lifetime, with the first episode usually occurring between the ages of 20 and 40. Although most people’s back pain resolves within a few days to weeks, nearly a third aren't fully recovered within six months, and many individuals have recurrent back pain within a year or two. Back strains, which involve injury to the muscles and other soft tissues surrounding your spine, are more likely to resolve than disc injuries.
Your spinal column consists of a series of stacked bony vertebrae, each of which is separated from its upper and lower neighbor by a circular cartilage disc. The outer rim of an intervertebral disc is tough and elastic, while the center is relatively soft. Your spinal cord courses down the back of your spinal column, encased in a tunnel formed by bony arches projecting from each vertebra. At the level of each vertebral body that is located from the base of your skull to the top of your tailbone, two nerve roots leave your spinal cord, travel through holes in the sides of your spinal column and branch outward to serve the various structures of your body.
Nerve Root Compression
When a disc is damaged as the result of injury or aging, its tough outer ring may tear, allowing the soft center portion to protrude outward. As a disc herniates in this fashion, it may compress the nerve root exiting your spinal column at the same level. Although any disc can herniate, most disc herniations occur in the lower spine where the nerves serving your legs originate. Thus, the most common symptom of disc herniation is sciatica, which is pain, numbness or other unusual sensations radiating from your lower back into your leg or foot. Sciatica due to a herniated disc often worsens when you are sitting.
While a herniated disc is a common cause of back pain and sciatica, there are times when a herniated disc does not cause symptoms. Herniated or bulging discs are often discovered when people have CTs or MRIs of their back for reasons other than back pain or sciatica.
Soft Tissue Injury
Your spinal column is surrounded and supported by a variety of muscles, tendons, ligaments and connective tissues. Back strains, which are caused by injury to one or more of these structures, usually result from lifting, reaching, bending or a similar sudden mechanical stress. Back strains typically cause pain across broad portions of your lower back. While the discomfort from a back strain may spread into your buttocks, it does not extend into the legs. Pain due to a back strain is usually worse with movement and gets better with rest.
Although the pain caused by a herniated disc may be distinguished from a back strain by its tendency to travel into your leg, not all herniated discs cause sciatica. Some merely cause central back pain, which can be mistaken for a strain. In addition, both a back strain and herniated disc may occur during the same event, such as a heavy lifting episode, so you could develop generalized back pain as well as sciatica. Furthermore, a number of conditions -- fractured vertebrae, spinal arthritis, infected discs or vertebrae, inflamed pelvic organs, cancer or shingles -- can mimic the pain caused by a back strain or herniated disc.
Any back pain that persists for more than a few days and prevents you from performing your daily activities warrants a medical evaluation. Severe back pain or back pain associated with fever or signs of neurologic compromise -- loss of bowel or bladder control or inability to lift your leg or foot, for example -- should prompt an immediate visit to your physician. The underlying cause of back pain can be difficult to identify, and a number of studies, including blood work, x-ray or MRI, may be required to diagnose your condition. The majority of patients with back pain -- even those with herniated discs -- get better without surgery, but you may need pain medications, muscle relaxers and physical therapy, which may help you regain full function.