Back pain is pain felt in the back. Episodes of back pain may be acute, sub-acute, or chronic depending on the duration. The pain may be characterized as a dull ache, shooting or piercing pain, or a burning sensation. The pain may radiate into the arms and hands as well as the legs or feet, and may include tingling, weakness or numbness in the legs and arms. The most common area of pain is the lower back, or lumbar area.

The pain may originate from the muscles, nerves, bones, joints or other structures in the spine. Internal structures such as the gallbladder and pancreas may also refer pain to the back.

Although back pain is common, it is rare for it to be permanently disabling. In most cases of disc herniations and stenosis, rest, injections or surgery have similar outcomes of general pain resolution after one year. In the United States, 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.[1] Low back pain causes 40% of missed days of work in the United States.[2] Additionally, it is the single leading cause of disability worldwide.[3]

Back pain may be classified by various methods to aid its diagnosis and management. The anatomic classification of back pain follows the segments of the spine: cervical, thoracic, lumbar or sacral.

The duration of back pain is considered in three categories, following the expected pattern of healing of connective tissue. Acute pain lasts up to 12 weeks, subacute pain refers to the second half of the acute period (6 to 12 weeks), and chronic pain is pain which persists beyond 12 weeks.[4]

The character of back pain indicates its likely tissue of origin. Nonspecific back pain is believed to be due from the soft tissues such as muscles, fascia, and ligaments.[5]Radicular pain with or without spinal stenosis indicates involvement of nervous tissue. Secondary back pain results from a known medical diagnosis such as infection or cancer.[6] Non specific pain indicates that the cause is not known precisely but is believed to be due from the soft tissues such as muscles, fascia, and ligaments.[5]

Back pain has several causes. Approximately 98 percent of back pain patients are diagnosed with nonspecific acute back pain in which no serious underlying pathology is identified.[7] Nearly 2 percent are comprised by metastatic cancers, while serious infections such as spinal osteomyelitis and epidural abscesses account for fewer than 1 percent. The most common cause of neurologic impairment including weakness or numbness results from a herniated disc. Nearly 95 percent of disc herniations occur at the lowest two lumbar intervertebral levels.[8]

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 from two weeks to three months.

Back pain can be a sign of a serious medical problem, although this is not most frequently the underlying cause:

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.[9][10][11][12] Other studies suggest that for as many as 85% of cases, no physiological cause can be shown.[13][14]

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.[15][16][17][18]

There are several potential sources and causes of back pain.[19] 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 it 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 lower 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.[19] 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.[20] The anterior ligaments of the intervertebral disc are extremely sensitive, and even the slightest injury can cause significant pain.[21]

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. See Posterior Rami Syndrome.

In most cases of low back pain medical consensus advises not seeking an exact diagnosis but instead beginning to treat the pain.[22] This assumes that there is no reason to expect that the person has an underlying problem.[22] In most cases, the pain goes away naturally after a few weeks.[22] Typically, people who do seek diagnosis through imaging are not likely to have a better outcome than those who wait for the condition to resolve.[22]

In cases in which the back pain has a persistent underlying cause, such as a specific disease or spinal abnormality, then it is necessary for the physician to differentiate the source of the pain and advise specific courses of treatment.

The management goals when treating back pain are to achieve maximal reduction in pain intensity as rapidly as possible, to restore the individual's ability to function in everyday activities, to help the patient cope with residual pain, to assess for side-effects of therapy, and to facilitate the patient's passage through the legal and socioeconomic impediments to recovery. For many, the goal is to keep the pain to a manageable level to progress with rehabilitation, which then can lead to long-term pain relief. Also, for some people the goal is to use non-surgical therapies to manage the pain and avoid major surgery, while for others surgery may be the quickest way to feel better.

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.

For back pain with sciatica, injecting the spine with steroids into the epidural space under X-ray guidance may improve pain and reduce the need for surgery.[34]

For sacroiliac joints radiofrequency neurotomy is of unclear benefit.[35]

Surgery may sometimes be appropriate for people with:

Surgery is usually the last resort in the treatment of back pain. It is usually only recommended if all other treatment options have been tried or in an emergency situation. A 2009 systematic review of back surgery studies found that, for certain diagnoses, surgery is moderately better than other common treatments, but the benefits of surgery often decline in the long term.[36]

The main procedures used in back pain surgery are discetomies, spinal fusions, laminectomies, removal of tumors, and vertebroplasties.

There are different types of surgical procedures that are used in treating various conditions causing back pain. Nerve decompression, fusion of body segments and deformity correction surgeries are examples. The first type of surgery is primarily performed in older patients who suffer from conditions causing nerve irritation or nerve damage. Fusion of bony segments is also referred to as a spinal fusion, and it is a procedure used to fuse together two or more bony fragments with the help of metalwork. The latter type of surgery is normally performed to correct congenital deformities or those that were caused by a traumatic fracture. In some cases, correction of deformities involves removing bony fragments or providing stability provision for the spine. Another procedure to repair common intervertebral disc lesions which may offer rapid recovery (just a few days) involves the simple removal of the fibrous nucleus of the affected intervertebral disc.[37] Various techniques, such as in the following paragraph, are described in the literature.

A discectomy is performed when the intervertebral disc have herniated or torn. It involves removing the protruding disc, either a portion of it or all of it, that is placing pressure on the nerve root.[38] The disc material which is putting pressure on the nerve is removed through a small incision that is made over that particular disc. The recovery period after this procedure does not last longer than 6 weeks. The type of procedure in which the bony fragments are removed through an endoscope is called percutaneous disc removal.

Microdiscetomies may be performed as a variation of standard discetomies in which a magnifier is used to provide the advantage of a smaller incision, thus a shorter recovery process.

Spinal fusions are performed in cases in which the patient has had the entire disc removed or when another condition has caused the vertebrae to become unstable. The procedure consists in uniting two or more vertebrae by using bone grafts and metalwork to provide more strength for the healing bone. Recovery after spinal fusion may take up to one year, depending greatly on the age of the patient, the reason why surgery has been performed and how many bony segments needed to be fused.

In cases of spinal stenosis or disc herniation, laminectomies can be performed to relieve the pressure on the nerves. During such a procedure, the surgeon enlarges the spinal canal by removing or trimming away the lamina which will provide more space for the nerves. The severity of the condition as well as the general health status of the patient are key factors in establishing the recovery time, which may be range from 8 weeks to 6 months.

Back surgery can be performed to prevent the growth of benign and malignant tumors. In the first case, surgery has the goal of relieving the pressure from the nerves which is caused by a benign growth, whereas in the latter the procedure is aimed to prevent the spread of cancer to other areas of the body. Recovery depends on the type of tumor that is being removed, the health status of the patient and the size of the tumor.

People with back pain lasting for 3 months or more are at risk of physical, psychological and social dysfunctions. Such individuals are likely to experience less pain and disability if they receive a multidisciplinary intervention. This typically involves a combination of physical, psychological and educational interventions delivered by a team of specialists with different skills. Such multidisciplinary treatment programs are often quite intensive and expensive. They are more appropriate for people with severe or complex problems.[43]

People who have chronic back pain may have limited range of motion and/or tenderness upon touch. If the pain continues to worsen, or certain red flags that might indicate a variety of serious conditions are present further testing may be recommended. These red flags include weakness, numbness or tingling, fever, weight loss or problems with bowel and/or bladder control.

About 50% of women experience low back pain during pregnancy.[52] Back pain in pregnancy may be severe enough to cause significant pain and disability and pre-dispose patients to back pain in a following pregnancy. No significant increased risk of back pain with pregnancy has been found with respect to maternal weight gain, exercise, work satisfaction, or pregnancy outcome factors such as birth weight, birth length, and Apgar scores.

Biomechanical factors of pregnancy that are shown to be associated with low back pain of pregnancy include abdominal sagittal and transverse diameter and the depth of lumbar lordosis. Typical factors aggravating the back pain of pregnancy include standing, sitting, forward bending, lifting, and walking. Back pain in pregnancy may also be characterized by pain radiating into the thigh and buttocks, night-time pain severe enough to wake the patient, pain that is increased during the night-time, or pain that is increased during the day-time.

The avoidance of high impact, weight-bearing activities and especially those that asymmetrically load the involved structures such as: extensive twisting with lifting, single-leg stance postures, stair climbing, and repetitive motions at or near the end-ranges of back or hip motion can ease the pain. Direct bending to the ground without bending the knee causes severe impact on the lower back in pregnancy and in normal individuals, which leads to strain, especially in the lumbo-sacral region that in turn strains the multifidus.

Back pain is regularly cited by national governments as having a major impact on productivity, through loss of workers on sick leave. Some national governments, notably Australia and the United Kingdom, have launched campaigns of public health awareness to help combat the problem, for example the Health and Safety Executive's Better Backs campaign. In the United States lower back pain's economic impact reveals that it is the number one reason for individuals under the age of 45 to limit their activity, second highest complaint seen in physician's offices, fifth most common requirement for hospitalization, and the third leading cause for surgery.

An evolutionary perspective has been used to try to explain why humans have back pain. Selective pressures often resulted in our evolution as a species. At times we are able to postulate the reason for these changes, and other times we cannot seem to arrive at a logical conclusion about the possible benefits of the tradeoff. In the case of back pain, researcher Aaron G. Filler believes the evolutionary changes seen in the human skeleton occurred to ensure the survival of the species. Of special mention here is our ability to walk upright. Walking upright meant that our hands were now free to carry heavy objects and the young across great distances.[53]

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