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by Dr. David Borenstein M.D. Medically Reviewed by Dr. C.H. Weaver M.D. 6/2022

When your back hurts, you feel quite alone. You think that no one can understand the extent of your discomfort. However, low back pain is the second most common affliction of humankind; only the common cold affects more people. Back pain doesn’t discriminate, either. People of all ages, both sexes, and all walks of life are afflicted with this debilitating discomfort. Perhaps you are a computer operator who sits at a desk for hours at a time, or maybe you’re a farmer or construction worker who engages in heavy lifting every day. If you happen to be a pregnant woman, then you may have difficulty finding any comfortable position—standing or sitting or lying flat on your back.

If you lift, bend, reach, squat, twist, or turn—or even sneeze—you are at some risk for developing back pain. In addition, a variety of medical conditions can result in back pain. So, as you can see, all six or so billion of us are vulnerable to back pain. In fact, it is documented that almost 80 percent of the human population will experience back pain at some point in their lives.

Is it Mechanical or Medical?

Most low back pain results from mechanical disorders of the spine related to overuse, such as habitually poor posture, or injury or deformity of a portion of the spine, such as herniated disc. The other 10 to 15 percent of cases are medical, caused by systemic illnesses such as nerve damage from diabetes or fibromyalgia, and require a more complete evaluation. I refer to this form of back pain as medical low back pain.

Discomfort associated with specific causes of low back pain has reproducible characteristics. For instance, ruptured discs pressing on nerves cause pain that runs from the back to the lower leg and foot. The pain from muscle injuries in the back may spread across the low back but not lower than the buttock. Knowing where the pain initially starts and ends helps us make a good guess about the cause.

Mechanical disorders are caused by local problems in the bones, joints, tendons, ligaments, muscles, and nerves of the low back. Characteristically, being active or at rest has an effect on the intensity of the pain, either making it better or worse. The position of the spine also affects the degree of pain. If you have a disc herniation, you feel more pain when you sit, while people with spinal arthritis feel worse when standing. Most mechanical problems heal or improve with time, physical therapy, and medications. Only 1 to 2 percent of these mechanical difficulties call for surgical intervention, such as when they cause loss of bladder control or leg weakness.

Medical disorders cause symptoms throughout the body and are not limited to discomfort in the lumbar spine, and they don’t get better or worse with activity or rest. In addition, many organs such as the kidneys, bladder, gastrointestinal system, lymph nodes, and major blood vessels fit up against the lower back (see fig. 1.1). Diseases that affect these organs can cause back pain, with each organ system causing a certain kind of pain. When back pain originates in a structure other than the spine, the unique character of the pain can help doctors find the diseased organ system.

Medical disorders generally produce these “red flags”:

  • Fever and/or weight loss
  • Pain that is worse at night or when lying down
  • Prolonged morning stiffness lasting hours
  • Severe bone pain in the middle of the back
  • Pain associated with eating, urination, or the menstrual cycle
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If you have any of these symptoms, see your doctor to find out if a systemic illness is causing your low back pain.

And while trauma to your back is mechanical, there are times when it becomes an emergency. Direct trauma to the lumbar spine may cause pain in any location in the low back, lower leg, or anterior thigh. These traumas are frequently the result of automobile accidents or falls. If the trauma is severe, emergency surgery may be needed to stabilize the spine and remove pressure on the nerves. Fractures of vertebrae without nerve compression generally call for bracing and rest. Lesser traumas to muscles and ligaments may be treated with medications and physical therapy.

Mary is an example of how medical and mechanical causes of back pain can be confused. Mary loved to work in her garden; and although at sixty-five she had occasional aches and pains after a long day of weeding and pruning, her discomfort disappeared in a day or two. However, one day she tripped and fell backward, landing on her behind. The fall caused acute discomfort that she brushed off at the time, but over the following three weeks the pain in the middle of her back increased in intensity, making it increasingly difficult to work in her garden. When she came to see me, Mary still believed her pain was related to an injury sustained in her fall, but the location and persistence of her pain—in the middle of her back—was a red flag. Her X ray showed a fracture in one of her vertebrae, and blood tests revealed elevation of blood proteins, consistent with a diagnosis of multiple myeloma, a bone marrow cancer. Obviously, her condition called for immediate medical intervention, and she went on to receive a course of chemotherapy. Her back pain improved when the cancer was diagnosed and appropriately treated. While Mary’s case clearly falls into the small percentage of cases in which the pain is caused by a medical disorder, her condition calls attention to the importance of addressing pain that does not subside or pain that worsens over time.

Rare Psychological Causes

Psychological or mental illness is a relatively rare cause of acute low back pain. Depending on individual characteristics, psychologic illnesses cause or exacerbate pain through a variety of mechanisms. For example, in schizophrenic patients, hallucinations are a rare but real cause of pain.

The psychiatric disorder commonly associated with low back pain is a conversion reaction: a mechanism for transforming anxiety or other emotions into a physical dysfunction. The symptoms lessen anxiety and symbolize the underlying conflict. Sufferers may benefit from their situation and may not be overly concerned about the physical problem. An abnormal body function, like back pain, is readily recognized and acceptable, but the perception is that psychological problems are not so easily accepted.

Someone with conversion reactions may have severe pain of a burning or cutting quality. The pain is excruciating in intensity and without any recognizable anatomic boundaries. On examination, they have a marked response to minimal pressure on palpation. Their areas of tenderness do not correspond to the tender points of fibromyalgia. Laboratory test results are normal, and in these patients, complaints are resistant to all forms of therapy. Unfortunately, even when the reason for the conversion reaction is evident, these patients may not improve.

The International Association for the Study of Pain defines pain as “an unpleasant sensory and emotional experience which we primarily associate with tissue damage or describe in terms of such damage, or both.” The definition of pain has two parts. One part deals with tissue damage or the threat of damage, but to experience pain one must have an emotional response to that injury. Mental stress may elicit an emotional response that is experienced as pain.