Low back pain

Low back pain is a common musculoskeletal symptom that may be either acute orchronic. It may be caused by a variety of diseases and disorders that affectthe lumbar spine. Low back pain is often accompanied by sciatica, which is pain that involves the sciatic nerve and is felt in the lower back, the buttocks, and the backs of the thighs.

Low back pain is a symptom that affects 80% of the general United States population at some point in life with sufficient severity to cause absence from work. It is the second most common reason for visits to primary care doctors,and is estimated to cost the American economy $75 billion every year.

Low back pain may be experienced in several different ways:

  • Localized.In localized pain the patient will feel soreness or discomfort when the doctor palpates, or presses on, a specific surface area of the lower back.
  • Diffuse. Diffuse pain is spread over a larger area and comes from deep tissue layers.
  • Radicular. The pain is caused by irritation of a nerve root. Sciatica is an example of radicular pain.
  • Referred. The pain is perceived in the lower back but is caused by inflammation elsewhere--often in the kidneys or lower abdomen.

Acute pain in the lower back that does not extend to the leg is most commonlycaused by a sprain or muscle tear, usually occurring within 24 hours of heavy lifting or overuse of the back muscles. The pain is usually localized, andthere may be muscle spasms or soreness when the doctor touches the area. Thepatient usually feels better when resting.

Chronic low back pain has several different possible causes:

Mechanical reasons. Chronic strain on the muscles of the lower back may be caused by obesity; pregnancy; or job-related stooping, bending, or other stressful postures.

Malignancy. Low back pain at night that is not relieved by lying down may becaused by a tumor in the cauda equina (the roots of the spinal nerves controlling sensation in and movement of the legs), or a cancer that has spread to the spine from the prostate, breasts, or lungs. The risk factors for the spread of cancer to the lower back include a history of smoking, sudden weight loss, and age over 50.

Ankylosing spondylitis is a form of arthritis that causes chronic pain in thelower back. The pain is made worse by sitting or lying down and improves when the patient gets up. It is most commonly seen in males between 16 and 35. Ankylosing spondylitis is often confused with mechanical back pain in its early stages.

Disk herniation is a disorder in which a spinal disk begins to bulge outwardbetween the vertebrae. Herniated or ruptured disks are a common cause of chronic low back pain in adults.

Back pain that is out of proportion to a minor injury, or that is unusually prolonged, may be associated with a somatoform disorder or other psychiatric disturbance.

Low back pain that radiates down the leg usually indicates involvement of thesciatic nerve. The nerve can be pinched or irritated by herniated disks, tumors of the cauda equina, abscesses in the space between the spinal cord and its covering, spinal stenosis, and compression fractures. Some patients experience numbness or weakness of the legs as well as pain.

The diagnosis of low back pain can be complicated. Most cases are initially evaluated by primary care physicians rather than by specialists.

When beginning an initial workup of the patient's history, the doctor will ask the patient specific questions about the location of the pain, its characteristics, its onset, and the body positions or activities that make it betteror worse. If the doctor suspects that the pain is referred from other organs,he or she will ask about a history of diabetes, peptic ulcers, kidney stones, urinary tract infections, or heart murmurs.

During the physical examination, the doctor will examine the patient's back and hips to check for conditions that require surgery or emergency treatment.The examination includes several tests that involve moving the patient's legsin specific positions to test for nerve root irritation or disk herniation.The flexibility of the lumbar vertebrae may be measured to rule out ankylosing spondylitis.

Imaging studies are not usually performed on patients whose history and physical examination suggest routine muscle strain or overuse. X rays are orderedfor patients whose symptoms suggest cancer, infection, inflammation, pelvic or abdominal disease, or bone fractures. MRIs are usually ordered only for patients with certain types of masses or tumors.

It is important to know that the appearance of some abnormalities on imagingstudies of the lower back does not necessarily indicate that they cause the pain. Many patients have minor deformities that do not create symptoms. The doctor must compare the results of imaging studies very carefully with information from the patient's history and physical examination.

All forms of treatment of low back pain are aimed either at symptom relief orto prevent interference with the processes of healing. None of these methodsappear to speed up healing.

Acute back pain is treated with nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, muscle relaxants, or aspirin. Applications of heat or cold compresses are also helpful to most patients. If the patient has not experienced some improvement after several weeks of treatment, the doctor will reinvestigate the cause of the pain.

Patients with chronic back pain are treated with a combination of medications, physical therapy, and occupational or lifestyle modification. The medicationsgiven are usually NSAIDs, although patients with hypertension, kidney problems, or stomach ulcers should not take these drugs. Patients who take NSAIDsfor longer than six weeks should be monitored periodically for complications.

Physical therapy for chronic low back pain usually includes regular exercisefor fitness and flexibility, and massage or application of heat if necessary.Lifestyle modifications include giving up smoking, weight reduction (if necessary), and evaluation of the patient's occupation or other customary activities. Patients with herniated disks are treated surgically if the pain does not respond to medication.

Patients with chronic low back pain sometimes benefit from pain management techniques, including biofeedback, acupuncture, and chiropractic manipulation of the spine.

Psychotherapy is recommended for patients whose back pain is associated witha somatoform, anxiety, or depressive disorder.

Treatment of sciatica and other disorders that involve the legs may include NSAIDs. Patients with long-standing sciatica or spinal stenosis that do not respond to NSAIDs are treated surgically. Although some doctors use cortisone injections to relieve the pain, this form of treatment is still debated.

A thorough differential diagnosis is important before any treatment is considered. There are times when alternative therapies are the most beneficial, andother times when more invasive treatments are needed.

Chiropractic treats patients by manipulating or adjusting sections of the spine. It is one of the most popular forms of alternative treatment in the United States for relief of back pain caused by straining or lifting injuries. Some osteopathic physicians, physical therapists, and naturopathic physicians also use spinal manipulation to treat patients with low back pain.

Practitioners of traditional Chinese medicine treat low back pain with acupuncture, tui na (push-and-rub) massage, and the application of herbal poultices.

Herbal medicine can utilize a variety of antispasmodic herbs in combination to help relieve low back pain due to spasm. Lobelia (Lobelia inflata) and myrrh (Commiphora molmol) are two examples of antispasmodic herbs.

Homeopathic treatment for acute back pain consists of applications of Arnica oil to the sore area or oral doses of Arnica or Rhus toxicodendron. Bellis perennis is recommended for deep muscle injuries.Other remedies may be recommended based on the symptoms presented by the patient.

Massage and the numerous other body work techniques can be very effective intreating low back pain. Yoga, practiced regularly and done properly, can be most useful in preventing future episodes of low back pain.

The prognosis for most patients with acute low back pain is excellent. About80% of patients recover completely in 4-6 weeks. The prognosis for recovery from chronic pain depends on the underlying cause.

Low back pain due to muscle strain can be prevented by lifestyle choices, including regular physical exercise and weight control, avoiding smoking, and learning the proper techniques for lifting and moving heavy objects. Exercisesdesigned to strengthen the muscles of the lower back, and chairs or car seatswith lumbar supports are also recommended.

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