It is estimated that 80% of American adults will experience some form of back pain in their lives. For most, this is a transient phenomenon associated with full recovery without significant medical attention. However, many people will have symptoms severe enough to require medical intervention.
Back pain is usually a symptom of disease or injury to the structural components of the back, but it can also be a sign of disease or injury in other parts of the body, sometimes described as referred pain. We can differentiate the cause of back pain based on the anatomic component involved.
Musculoskeletal pain refers to pain originating from the muscles and the skeletons around the spine. Examples of this kind of pain include most athletic injuries and such syndromes as fibromyalgia and myofascial pain.
Skeletal pain can be as a result of noninfectious inflammation of the spine (spondylitis), infections of the spine (osteomyelitis), fractures of the spine such as vertebral compression fractures and/or tumors of the skeletal system.
Back pain can also be generated by the discs. With age, spinal discs lose moisture and get thinner (spondylosis). This can result in herniation or bulging of the discs.
The discs can be the primary pain generator, but they can also cause pain by impinging on the spinal cord or nerve roots. Classic sciatica is an example of a nerve root impingement syndrome. Degeneration in the spinal discs and joints can combine to narrow the spinal canal, causing spinal stenosis, which typically results in pain or weakness down both legs with standing or walking.
Occasionally disc material can directly impinge on the spinal cord, causing a cauda equina syndrome, sometimes associated with loss of bladder control. This requires immediate medical attention.
As previously mentioned, referred pain occurs as a result of abnormalities outside the structural components of the back. Common causes include kidney stones and infections and bladder and pelvic infections, and intra-abdominal causes such as pancreatitis, gallstones or vascular aneurysms.