My Back is Killing Me
Acute low back pain (ALB) is often defined as back pain lasting less than 2-3 months. It is one of the most common medical conditions. In fact, 50 % of people will experience an episode of back pain this year and 80% of us will have at least one episode in our lifetime that will result in days lost from work or other activities. The expense including medical costs and lost time from work is estimated at over $100 billion dollars per year. Unfortunately, our understanding of the causes of low back pain is less than perfect. This helps explain why there are a bewildering number of treatments for low back pain. This article will touch upon a few of the concepts concerning ALB.
The anatomy of the lower back is complex. The shape of the spine resembles an “S” shaped spring. It is made up of 24 separate bones called vertebrae that are stacked upon each other like blocks. These bones are separated by cushions or the discs. The disc has an outer ring of fibrous tissue and an inner core of soft gelatinous material. There are several layers of muscles and connective tissue in the lower back. These attach to the spine, pelvis, and to structures deep in our abdomen. Any of these structures can be injured, resulting in similar pain symptoms. This often makes precise diagnosis of back pain difficult.
A common cause of ALB is strain (overstretching) or sprain (tearing or damage) of the muscles and connective tissues in the back. This frequently follows strenuous activity. However, non-strenuous activity such as sitting for long periods can also result in back strain. This posture results in abnormal forces in the back and pelvis which can lead to abnormal mechanics and back muscle deconditioning. Our sedentary life style may be a leading factor in the high incidence of low back pain. Pain from a strain type injury is usually centered in the lower back. It generally does not extend into the legs and there should be no weakness or numbness in the legs. It is often described as a deep ache associated with stabbing pain from muscle spasm. There are frequently tender or “trigger points” that are painful to pressure. Treatments may include such things as application of cold or heat, avoiding prolonged periods of either sitting or standing, various anti-inflammatory medications and occasional medicines that help to relax the back muscles. In more severe cases, therapies offered by physical therapists, chiropractors and osteopathic doctors can be beneficial. A key point is that this type of back injury will heal on its own if given time.
Another type of ALB is often referred to as “sciatica”. This is back pain that is associated with pain radiating into the leg(s). There may also be numbness or weakness in the leg(s). “Sciatica” actually refers to the leg symptoms and has multiple causes. Sciatica results from irritation of the sciatic nerve or referred pain from tissues close to the sciatic nerve. This is a more serious condition that should always be evaluated by a health care professional. One cause of sciatica is a “slipped disc”. This condition can arise when the tissues in the outer ring of the disc weaken allowing the inner material of the disc to protrude outwards (a disc bulge), or there may be a complete tear in the outer ring allowing material to leak out from the disc. This is often referred to as a slipped disc, disc rupture, herniated disc or disc protrusion, all describing the same process. In this condition the disc and nerve become inflamed and swollen causing pain in the areas that the nerve travels. The lowest nerves in the back are most commonly affected, causing pain in the back of the leg and foot. In certain types of disc herniatons, multiple nerves can be affected resulting in larger areas of numbness, leg weakness and even loss of control of bladder or bowel function. These are serious signs that should be immediately evaluated by a health care professional. Therapies for disc pain are beyond the scope of this article. The good news is that most people with disc herniations will get better with time and will not require surgery for this condition.
Another relatively common cause of sciatica is “piriformis syndrome”. This is due to injury of the piriformis muscle which lies deep in the pelvis. Since the sciatic nerve travels near to this muscle, the nerve can be irritated when this muscle is injured. This results in localized tenderness in the buttock and sciatica. This tends to be more common in physically active individuals. Other causes of “sciatica” include irritation of the small joints in the spine (facet joints), arthritis of the spine, injury of the sacroiliac joints, the deep muscle of the abdomen or pelvis, hip joint arthritis, and injury to the sciatic nerve itself.
A frequently asked question is: “Do I need an X-ray for my back pain?” As ALB is generally a self limited process, X-rays or scans are frequently not necessary unless the pain is persistent and unresponsive to usual treatments or more serious symptoms are present. Besides added cost and unnecessary exposure to X-rays there are other concerns regarding these tests. One of these is misdiagnosis. It is known that approximately 50% of adults without back pain have disc bulges and that approximately 25% will have disc herniations. The concern is for the potential of treatments based upon findings on these studies that may not be related to back pain.
Key issues of acute low back pain include that it is a common, generally self limited condition requiring symptomatic treatment and minimal testing. An excellent source for more information is available at www.nlm.nih.gov/medlineplus/backpain.html.