back pain back pain back pain is pain felt in the back. it may be classified as neck pain (cervical), middle back pain (thoracic), lower back pain (lumbar) or coccydynia (tailbone or sacral pain) based on the segment affected. the lumbar area is the most common area affected. an episode of back pain may be acute, subacute or chronic depending on the duration. the pain may be characterized as a dull ache, shooting or piercing pain or a burning sensation. discomfort can radiate to the arms and hands as well as the legs or feet, and may include numbness or weakness in the legs and arms. back paindifferent regions (curvatures) of the vertebral columnspecialtyorthopedics the majority of back pain is nonspecific and idiopathic. common underlying mechanisms include degenerative or traumatic changes to the discs and facet joints, which can then cause secondary pain in the muscles and nerves and referred pain to the bones, joints and extremities. diseases and inflammation of the gallbladder, pancreas, aorta and kidneys may also cause referred pain in the back. tumors of the vertebrae, neural tissues and adjacent structures can also manifest as back pain. back pain is common; approximately nine of ten adults experience it at some point in their lives, and five of ten working adults experience back pain each year. some estimate that as many of 95% of people will experience back pain at some point in their lifetime. it is the most common cause of chronic pain and is a major contributor to missed work and disability. for most individuals, back pain is self-limiting. most people with back pain do not experience chronic severe pain but rather persistent or intermittent pain that is mild or moderate. in most cases of herniated disks and stenosis, rest, injections or surgery have similar general pain-resolution outcomes on average after one year. in the united states, acute low back pain is the fifth most common reason for physician visits and causes 40% of missed work days. it is the single leading cause of disability worldwide. classification back pain is classified in terms of duration of symptoms. acute back pain lasts <6 weeks subacute back pain lasts between 6 and 12 weeks. chronic back pain lasts for greater than 12 weeks. causes there are many causes of back pain, including blood vessels, internal organs, infections, mechanical and autoimmune causes. approximately 90 percent of people with back pain are diagnosed with nonspecific, idiopathic acute pain with no identifiable underlying pathology. in approximately 10 percent of people, a cause can be identified through diagnostic imaging. fewer than two percent of cases are attributed to secondary factors, with metastatic cancers and serious infections, such as spinal osteomyelitis and epidural abscesses, accounting for approximately one percent. common causes cause % of people with back pain nonspecific 90% vertebral compression fracture 4% metastatic cancer 0.7% infection 0.01% cauda equina 0.04% nonspecific in as many as 90 percent of cases, no physiological causes or abnormalities on diagnostic tests can be found. nonspecific back pain can result from back strain or sprains, which can cause peripheral injury to muscle or ligaments. many patients cannot identify the events or activities that may have caused the strain. the pain can present acutely but in some cases can persist, leading to chronic pain. chronic back pain in people with otherwise normal scans can result from central sensitization, in which an initial injury causes a longer-lasting state of heightened sensitivity to pain. this persistent state maintains pain even after the initial injury has healed. treatment of sensitization may involve low doses of antidepressants and directed rehabilitation such as physical therapy. spinal disc disease spinal disc disease occurs when the nucleus pulposus, a gel-like material in the inner core of the vertebral disc, ruptures. rupturing of the nucleus pulposus can lead to compression of nerve roots. symptoms may be unilateral or bilateral, and correlate to the region of the spine affected. the most common region for spinal disk disease is at l4–l5 or l5–s1. the risk for lumbar disc disease is increased in overweight individuals because of the increased compressive force on the nucleus pulposus, and is twice as likely to occur in men. a 2002 study found that lifestyle factors such as night-shift work and lack of physical activity can also increase the risk of lumbar disc disease. lumbar disc herniation severe spinal-cord compression is considered a surgical emergency and requires decompression to preserve motor and sensory function. cauda equina syndrome involves severe compression of the cauda equina and presents initially with pain followed by motor and sensory. bladder incontinence is seen in later stages of cauda equina syndrome. degenerative disease spondylosis, or degenerative arthritis of the spine, occurs when the intervertebral disc undergoes degenerative changes, causing the disc to fail at cushioning the vertebrae. there is an association between intervertebral disc space narrowing and lumbar spine pain. the space between the vertebrae becomes more narrow, resulting in compression and irritation of the nerves. spondylolithesis is the anterior shift of one vertebra compared to the neighboring vertebra. it is associated with age-related degenerative changes as well as trauma and congenital anomalies. spinal stenosis can occur in cases of severe spondylosis, spondylotheisis and age-associated thickening of the ligamentum flavum. spinal stenosis involves narrowing of the spinal canal and typically presents in patients greater than 60 years of age. neurogenic claudication can occur in cases of severe lumbar spinal stenosis and presents with symptoms of pain in the lower back, buttock or leg that is worsened by standing and relieved by sitting. vertebral compression fractures occur in four percent of patients presenting with lower back pain. risk factors include age, female gender, history of osteoporosis, and chronic glucocorticoid use. fractures can occur as a result of trauma but in many cases can be asymptomatic. infection common infectious causes of back pain include osteomyelitis, septic discitis, paraspinal abscess and epidural abscess. infectious causes that lead to back pain involve various structures surrounding the spine. osteomyelitis is the bacterial infection of the bone. vertebral osteomyelitis is most commonly caused by staphylococci. risk factors include skin infection, urinary tract infection, iv catheter use, iv drug use, previous endocarditis and lung disease. spinal epidural abscess is commonly caused by severe infection with bacteremia. risk factors include recent administration of epidurals, iv drug use or recent infection. cancer spread of cancer to the bone or spinal cord can lead to back pain. bone is one of the most common sites of metastatic lesions. patients typically have a history of malignancy. common types of cancer that present with back pain include multiple myeloma, lymphoma, leukemia, spinal cord tumors, primary vertebral tumors and prostate cancer. back pain is present in 29% of patients with systemic cancer. unlike other causes of back pain that commonly affect the lumbar spine, the thoracic spine is most commonly affected. the pain can be associated with systemic symptoms such as weight loss, chills, fever, nausea and vomiting. unlike other causes of back pain, neoplasm-associated back pain is constant, dull, poorly localized and worsens with rest. metastasis to the bone also increases the risk of spinal-cord compression or vertebral fractures that require emergency surgical treatment. autoimmune back pain can be caused by the vertebrae compressing the intervertebral discs. inflammatory arthritides such as ankylosing spondylitis, psoriatic arthritis, rheumatoid arthritis and systemic lupus erythematosus can all cause varying levels of joint destruction. among the inflammatory arthritides, ankylosing spondylitis is most closely associated with back pain because of the inflammatory destruction of the bony components of the spine. ankylosing spondylitis is common in young men and presents with a range of possible symptoms such as uveitis, psoriasis and inflammatory bowel disease. referred pain back pain can also be referred from another source. referred pain occurs when pain is felt at a location different than the source of the pain. disease processes that can present with back pain include pancreatitis, kidney stones, severe urinary tract infections and abdominal aortic aneurysms. risk factors heavy lifting, obesity, sedentary lifestyle and lack of exercise can increase the risk of back pain. cigarette smokers are more likely to experience back pain than are nonsmokers. poor posture and weight gain in pregnancy are also risk factors for back pain. in general, fatigue can worsen pain. a few studies suggest that psychosocial factors such as work-related stress and dysfunctional family relationships may correlate more closely with back pain than do structural abnormalities revealed in x-rays and other medical imaging scans. while back pain physical effects can range from muscle aching to a shooting, burning, or stabbing sensation. it can radiate pain down the legs and have pain increased by bending, twisting, lifting, standing, or walking. while the physical effects of back pain are always at the forefront back pain also has other psychological effects. back pain has been linked to depression, anxiety, stress, and avoidance behaviors due to mentally not being able to cope with the physical pain. both acute and chronic back pain can be associated with psychological distress in the form of anxiety (worries, stress) or depression (sadness, discouragement). psychological distress is a common reaction to the suffering aspects of acute back pain, even when symptoms are short-term and not medically serious. diagnosis diagnostic work-up for acute back pain. initial assessment of back pain consists of a history and physical examination. important characterizing features of back pain include location, duration, severity, history of prior back pain and possible trauma. other important components of the patient history include age, physical trauma, prior history of cancer, fever, weight loss, urinary incontinence, progressive weakness or expanding sensory changes, which can indicate a medically urgent condition. physical examination of the back should assess for posture and deformities. pain elicited by palpating certain structures may be helpful in localizing the affected area. a neurologic exam is needed to assess for changes in gait, sensation and motor function. determining if there are radicular symptoms, such as pain, numbness or weakness that radiate down limbs, is important for differentiating between central and peripheral causes of back pain. the straight leg test is a maneuver used to determine the presence of lumbosacral radiculopathy, which occurs when there is irritation in the nerve root that causes neurologic symptoms such as numbness and tingling. non-radicular back pain is most commonly caused by injury to the spinal muscles or ligaments, degenerative spinal disease or a herniated disc. disc herniation and foraminal stenosis are the most common causes of radiculopathy. imaging of the spine and laboratory tests is not recommended during the acute phase. this assumes that there is no reason to expect that the patient has an underlying problem. in most cases, the pain subsides naturally after several weeks. people who seek diagnosis through imaging are typically less likely to receive a better outcome than are those who wait for the condition to resolve. imaging magnetic resonance imaging (mri) is the preferred modality for the evaluation of back pain and visualization of bone, soft tissue, nerves and ligaments. x-rays are a less costly initial option offered to patients with a low clinical suspicion of infection or malignancy, and they are combined with laboratory studies for interpretation. imaging is not needed for the majority of patients with back pain. in cases of acute back pain, mri is recommended for those with major risk factors or clinical suspicion of cancer, spinal infection or severe progressive neurological deficits. for patients with subacute to chronic back pain, mri is recommended if minor risk factors exist for cancer, ankylosing spondylitis or vertebral compression fracture, or if significant trauma or symptomatic spinal stenosis is present. early imaging studies during the acute phase do not improve care or prognosis. imaging findings are not correlated with severity or outcome. laboratory studies laboratory studies are employed when there are suspicions of autoimmune causes, infection or malignancy. laboratory testing may include white blood cell (wbc) count, erythrocyte sedimentation rate (esr), and c-reactive protein (crp). elevated esr could indicate infection, malignancy, chronic disease, inflammation, trauma or tissue ischemia. elevated crp levels are associated with infection. ct scan of the spine, showing calcification of the longitudinal posterior ligament. red flags imaging is not typically needed in the initial diagnosis or treatment of back pain. however, if there are certain "red flag" symptoms present, plain radiographs (x-ray), ct scan or magnetic resonance