Back pain (also known as dorsalgia) is pain felt in the back that usually originates from the muscles, nerves, bones, joints or other structures in the spine.
The pain can often be divided into neck pain, upper back pain, lower back pain or tailbone pain. It may have a sudden onset or can be a chronic pain; it can be constant or intermittent, stay in one place or radiate to other areas. It may be a dull ache, or a sharp or piercing or burning sensation. The pain may radiate into the arm and hand), in the upper back, or in the low back, (and might radiate into the leg or foot), and may include symptoms other than pain, such as weakness, numbness or tingling.
Back Pain is one of humanity's most frequent complaints. In the U.S., acute low back pain (also called lumbago) is the fifth most common reason for physician visits. About nine out of ten adults experience back pain at some point in their life, and five out of ten working adults have back pain every year.
The spine is a complex interconnecting network of nerves, joints, muscles, tendons and ligaments, and all are capable of producing pain. Large nerves that originate in the spine and go to the legs and arms can make pain radiate to the extremities. Back pain can be divided anatomically: neck pain, upper back pain, lower back pain or tailbone pain.
By its duration: acute (less than 4 weeks), subacute (4 – 12 weeks), chronic (greater than 12 weeks). By its cause: musculoskeletal (MSK), infectious, cancer, etc.
Back pain is classified according to etiology in mechanical or nonspecific back pain and secondary back pain. Approximately 98% of back pain patients are diagnosed with nonspecific acute back pain which has no serious underlying pathology. However, secondary back pain which is caused by an underlying condition accounts for nearly 2% of the cases.
Underlying pathology in these cases may include metastatic cancer, spinal osteomyelitis and epidural abscess which account for 1% of the patients. Also, herniated disc is the most common neurologic impairment which is associated with this condition, from which 95% of disc herniations occur at the lowest two lumbar intervertebral levels.
Back pain can be a sign of a serious medical problem, although this is not most frequently the underlying cause:
- Typical warning signs of a potentially life-threatening problem are bowel and/or bladder incontinence or progressive weakness in the legs.
- Severe back pain (such as pain that is bad enough to interrupt sleep) that occurs with other signs of severe illness (e.g. fever, unexplained weight loss) may also indicate a serious underlying medical condition.
- Back pain that occurs after a trauma, such as a car accident or fall may indicate a bone fracture or other injury.
- Back pain in individuals with medical conditions that put them at high risk for a spinal fracture, such as osteoporosis or multiple myeloma, also warrants prompt medical attention.
- Back pain in individuals with a history of cancer (especially cancers known to spread to the spine like breast, lung and prostate cancer) should be evaluated to rule out metastatic disease of the spine.
Back pain does not usually require immediate medical intervention. The vast majority of episodes of back pain are self-limiting and non-progressive. Most back pain syndromes are due to inflammation, especially in the acute phase, which typically lasts for two weeks to three months.
A few observational studies suggest that two conditions to which back pain is often attributed, lumbar disc herniation and degenerative disc disease may not be more prevalent among those in pain than among the general population, and that the mechanisms by which these conditions might cause pain are not known. Other studies suggest that for as many as 85% of cases, no physiological cause can be shown.
A few studies suggest that psychosocial factors such as on-the-job stress and dysfunctional family relationships may correlate more closely with back pain than structural abnormalities revealed in x-rays and other medical imaging scans.
There are several potential sources and causes of back pain. However, the diagnosis of specific tissues of the spine as the cause of pain presents problems. This is because symptoms arising from different spinal tissues can feel very similar and is difficult to differentiate without the use of invasive diagnostic intervention procedures, such as local anesthetic blocks.
One potential source of back pain is skeletal muscle of the back. Potential causes of pain in muscle tissue include muscle strains (pulled muscles), muscle spasm, and muscle imbalances. However, imaging studies do not support the notion of muscle tissue damage in many back pain cases, and the neurophysiology of muscle spasm and muscle imbalances is not well understood.
Another potential source of low back pain is the synovial joints of the spine (e.g. zygapophysial joints/facet joints). These have been identified as the primary source of the pain in approximately one third of people with chronic low back pain, and in most people with neck pain following whiplash. However, the cause of zygapophysial joint pain is not fully understood.
Capsule tissue damage has been proposed in people with neck pain following whiplash. In people with spinal pain stemming from zygapophysial joints, one theory is that intra-articular tissue such as invaginations of their synovial membranes and fibro-adipose meniscoids (that usually act as a cushion to help the bones move over each other smoothly) may become displaced, pinched or trapped, and consequently give rise to nociception (pain).
There are several common other potential sources and causes of back pain: these include spinal disc herniation and degenerative disc disease or isthmic spondylolisthesis, osteoarthritis (degenerative joint disease) and lumbar spinal stenosis, trauma, cancer, infection, fractures, and inflammatory disease.
Radicular pain (sciatica) is distinguished from 'non-specific' back pain, and may be diagnosed without invasive diagnostic tests. New attention has been focused on non-discogenic back pain, where patients have normal or near-normal MRI and CT scans. One of the newer investigations looks into the role of the dorsal ramus in patients that have no radiographic abnormalities.
Not all treatments work for all conditions or for all individuals with the same condition, and many find that they need to try several treatment options to determine what works best for them. The present stage of the condition (acute or chronic) is also a determining factor in the choice of treatment. Only a minority of back pain patients (most estimates are 1% - 10%) require surgery.
Heat therapy is useful for back spasms or other conditions. A meta-analysis of studies by the Cochrane Collaboration concluded that heat therapy can reduce symptoms of acute and sub-acute low-back pain. Some patients find that moist heat works best (e.g. a hot bath or whirlpool) or continuous low-level heat (e.g. a heat wrap that stays warm for 4 to 6 hours). Cold compression therapy (e.g. ice or cold pack application) may be effective at relieving back pain in some cases.