Low back pain can begin during very ordinary activity when lifting objects not particularly heavy, during a quick movement, reaching for something, or while sitting for longer periods of time in abnormal postures.Because disorders of the spine usually develop slowly and over a number of years, a person becomes progressively more vulnerable to injury and pain from a relatively minor event or slight body movement.

Low back pain is very common. At least 80% of all people suffer from it once or more during their lifetime. Although low back pain is a potentially disabling condition, it is not life threatening. In the majority of people, the pain usually subsides in a few weeks. Frequent causes of low back and leg pain are abnormal conditions of the muscles, joints, and bones of the spine (musculoskeletal disorders). These conditions include muscle strains, herniated discs, spinal stenosis, spondylosis, scoliosis, and isthmic and degenerative spondylolisthesis in the lumbar spine.

Sciatic nerve

Figure 1: Sciatic nerve, involved in the
painful condition of sciatica. Note
lumbar and sacral nerve roots

Sciatica is a condition defined as pain radiating down the leg and is named after the sciatic nerve, the major nerve in the pelvic region controlling lower extremity function. Compression of the sciatic nerve is most often caused by degenerative lumbar conditions such as herniated discs and spinal stenosis, as well as spondylolisthesis. Sciatica is also called lumbar radiculopathy because it is essentially a neurologic injury of a lumbar nerve, often leading to symptoms of pain, numbness, tingling, and weakness of the muscles in the lower extremities.
[see Figure 1 ].

Back pain may be described as acute, subacute, or chronic depending on how long symptoms have been present; acute low back pain has a duration of less than 4 weeks, subacute 4 to 12 weeks, and chronic more than 12 weeks.The duration of symptoms may impact on the diagnostic tests ordered and the type of treatment recommended.

General Symptoms of Low Back Pain

Patients who develop low back pain suddenly or have pain from trauma or a fall usually seek medical care promptly.However, the symptoms of low back pain related to musculoskeletal conditions may be limited to feelings of mild discomfort felt from time to time. Patients may not seek medical care until the pain and the condition have significantly worsened.

Symptoms that warrant immediate medical attention include low back pain following any type of injury, pain accompanied by fever, pain which disturbs sleep, and pain occurring at rest. An inability to control either bowel movements or urination as well as noticeable weakness in the legs is a potentially emergent condition and must be evaluated immediately (see cauda equina syndrome below).

Leg pain from nerve impingement (sciatica) can have a sudden onset or be intermittent and range from mild discomfort to severe chronic pain. Activities which may aggravate leg pain symptoms includes sitting, riding in a car, coughing, sneezing, straining, and any activity that tends to initiate low back pain.

Risk factors for developing chronic low back pain have been identified over numerous studies and include: poor physical fitness, heavy smoking, psychological distress and depressive symptoms, low job dissatisfaction, significant personal problems (e.g., alcohol, marital, financial), a previous history of lower back pain, and adversarial medico-legal proceedings.