Most people suffer from back pain at some time in their lives. In many cases, no exact diagnosis is made because the pain gets better with rest and because analgesic drugs (painkillers) are used before any tests, such as X-rays, are carried out. In such cases, doctors may use the term “nonspecific back pain” to describe the condition.
Nonspecific back pain is one of the largest single causes of working days lost through illness in the UK. The people most likely to suffer from back pain are those whose jobs involve a lot of heavy lifting and carrying or those who spend long periods sitting in one position or bending awkwardly. Overweight people are also more prone to back pain – their backs carry a heavier load and they tend to have weaker abdominal muscles, which usually help to provide support to the back.
Nonspecific back pain is thought to be caused by a mechanical disorder affecting one or more structures in the back. This may be a ligament strain, a muscle tear, damage to a spinal facet joint, or disc prolapse (slipped disc). In addition to pain from a damaged structure, spasm of surrounding muscles will cause pain and tenderness over a wider area. This can result in temporary scoliosis (an abnormal sideways curvature of the spine).
Abnormalities of a facet joint and prolapse of an intervertebral disc can both cause sciatica (pain in the buttock and down the back of the leg into the foot). This condition is the result of pressure on a sciatic nerve root as it leaves the spinal cord. Coughing, sneezing, or straining will increase the pain. Pressure on the sciatic nerve can also cause a pins-and-needles sensation in that leg as well as weakness in muscles that are activated by the nerve. Rarely, pain may radiate down the femoral nerve at the front of the thigh.
Osteoarthritis in the joints of the spine can cause persistent back pain.
Ankylosing spondylitis (an inflammatory disorder in which arthritis affects the spine) causes back pain and stiffness with loss of back mobility.
Coccydynia (pain and tenderness at the base of the spine) may occur after a fall in which the coccyx has struck the ground, during pregnancy, or spontaneously for unknown reasons.
Fibrositis is an imprecise term that is sometimes used to describe pain and tenderness in muscles, which may affect the back. Fibrositis is often worse in cold and damp weather and is occasionally associated with feeling generally unwell. Unlike other causes of back pain, fibrositis is not accompanied by muscle spasm or restriction of back movement. It often improves when treated with nonsteroidal anti-inflammatory drugs.
Pyelonephritis (kidney infection) can cause back pain as well as pain and tenderness in the loin, fever, chills, and pain when passing urine.
Cancer in the spine can cause persistent back pain that disturbs sleep and is not relieved by rest.
People with back pain and sciatica are usually advised to remain as mobile as possible. Sleeping on a firm mattress and taking analgesic drugs can help to relieve pain. However, if pain persists, is very severe, or is associated with weakness in a leg or bladder control problems, immediate medical advice should be sought.
Examination of the back may show tenderness in specific areas or loss of back mobility.
Weakness or loss of sensation in the legs implies pressure on a nerve root, which needs prompt investigation.
X-rays of the spine may reveal narrowing between the intervertebral discs; osteoarthritis; osteoporosis; ankylosing spondylitis; compression fracture; stress fracture; bone cancer; or spondylolisthesis (displacement of vertebrae). X-rays will not reveal ligament, muscle, facet joint, or disc damage.
To detect pressure on a nerve root (due to disc prolapse, for example), myelography, CT scanning,or MRI is performed.
If a specific cause is found for the back pain, treatment will be for that cause. Research has shown that acute nonspecific back pain is best treated by early return to normal activity, helped by analgesic drugs. Bed rest should not be continued for more than two days.
Chronic nonspecific back pain is often more difficult to treat. Treatment may include use of aspirin and related drugs, nonsteroidal anti-inflammatory drugs, muscle-relaxant drugs, acupuncture, or spinal injection. Exercise, spinal manipulation, or wearing a surgical corset may also be helpful; and spinal surgery may sometimes be necessary.
Low back pain in more detail - technical
Over 70% of people in industrialized countries suffer from low back pain at some time, and it is one of the leading reasons for visits to physicians. Risk factors include heavy physical work, smoking, stress, depression, and job dissatisfaction. In more than 90% of cases the exact anatomical source of back pain cannot be determined, and the preferred diagnostic label is ‘nonspecific low back pain’.
‘Red flags’ is the term used for the presence on history of any of the following: age over 50, fever, weight loss, significant trauma, previous history of neoplasia, use of corticosteroids, drug or alcohol abuse, neurological symptoms and signs, night pain, morning stiffness, and the persistence of pain after 1 month of conservative therapy. Such red flags suggest the possibility of serious disorders, e.g. neoplasia, infection, or inflammatory spinal disease.
Investigation and management: investigation should be restricted to patients with red flags, with MRI the best imaging modality for the diagnosis of lumbar disorders. In the absence of red flags, patients with acute low back pain should be reassured and encouraged to remain active: simple analgesics, nonsteroidal anti-inflammatory drugs (NSAIDs), muscle relaxants, and spinal manipulation may help for pain relief.
The early recognition of psychosocial risk factors, or ‘yellow flags’, is important to identify patients who are at higher risk of progressing towards chronic low back pain. Cognitive behavioural therapy, supervised exercise therapy, brief educational interventions, multidisciplinary treatment, and short courses of manipulation/mobilization can each be recommended in patients with nonspecific chronic low back pain, but the condition is often refractory.
Low back pain is one of the commonest symptoms and was the fifth leading reason for all visits to doctors’ surgeries in the United States of America in 1990. Between 60 and 80% of adults suffer from at least one episode of back pain during their lifetime. Acute back pain is usually self-limiting, and most sufferers do not seek medical advice. Of those who do, more than 90% are back to work within 2 months, independent of the treatment received, including those in whom the acute episode results from a work-related injury for which compensation might be available. The 5 to 10% of patients who remain disabled after this time are a difficult therapeutic challenge, owing to the influence of psychological and social factors on the continuation of pain. These few patients are responsible for more than 75% of the total costs of low back pain to society, estimated to be between 1 and 2% of the gross national product in most industrialized countries.
Significant risk factors for the occurrence of back pain include older age, heavy labour (in particular jobs requiring lifting in an awkward position), lower education and income, smoking, high birth rate (in males), and obesity. Twin studies suggest that genetic factors have an important influence on the lifetime prevalence of back pain, with heritability ranging from 52 to 68%. Long-distance driving and whole-body vibration such as experienced by truck drivers are well-known risk factors for disc herniation. Previous episodes of back pain are strong predictors of recurrence. A number of psychosocial risk factors, or so-called ‘yellow flags’, predict poor outcomes. These include beliefs that back pain is harmful or potentially severely disabling, resulting in fear/avoidance behaviour and reduced activity levels, excessive reliance on aids and appliances, depressed mood, withdrawal from social interaction, and job dissatisfaction.
Many structures of the back, including the muscles, ligaments, discs, bones and zygapophyseal and sacroiliac joints are innervated and can therefore be a source of pain. However, in more than 90% of patients presenting with low back pain it is extremely difficult—if not impossible—to identify precisely the anatomical source of the pain on the basis of history and physical examination. These patients should be diagnosed as suffering from ‘nonspecific low back pain’. A host of clinical entities such as muscle strain, degenerative disc disease, facet syndrome, myofascial pain syndrome, segmental instability, minor intervertebral displacement, iliolumbar syndrome, piriformis syndrome, etc. have been described within this broad category based on the localization of pain and tenderness, reproduction of symptoms by specific manoeuvres, radiological features, or pathophysiological hypotheses. Unfortunately, the signs and manoeuvres described for each of these clinical syndromes lack sensitivity and specificity and are not reproducible, even by experienced clinicians. Moreover, the claim that any of these entities is responsible for the pain in a given patient can very rarely be validated. For example, it is hazardous to ascribe pain to degenerative disc disease or zygapophyseal joint osteoarthritis when it has been shown that individuals with similar radiological changes can be completely asymptomatic. The only way to determine if the discs or zygapophyseal or sacroiliac joints are the source of pain in a given patient is through injection studies done under stringent, controlled conditions (see below).
Clinical approach to the diagnosis of low back pain
In evaluating a patient presenting with low back pain, the physician should not try to differentiate between the various elusive entities responsible for nonspecific back pain, but rather should focus on determining if the patient needs emergency surgery, has sciatica with signs of nerve root compression, or has an underlying medical cause of back pain (infectious, inflammatory, metabolic, tumoural or visceral) (Table 1).
Is this a surgical emergency?
Cauda equina syndrome and an expanding vascular aneurysm are two extremely rare but important conditions to recognize, because both are surgical emergencies. In the first instance, the patient will usually present with low back and/or buttock pain, associated with bilateral sciatica, neurological symptoms in the lower extremities, and urinary and/or bowel incontinence. Physical examination may show bilateral weakness, sensory losses, saddle anaesthesia, decreased reflexes in the legs, and decreased rectal tone. Diagnostic procedures (MRI, CT, or myelogram) should be performed on an emergency basis if bowel and bladder control are to be preserved. Central disc herniation is the most common cause of the syndrome, followed by tumours and epidural abscesses.
An aortic aneurysm can be responsible for a dull, gnawing back pain due to direct compression of the aneurysm on the lumbar vertebrae. They are typically seen in elderly patients, especially white men, and physical examination may reveal a pulsating abdominal mass and decreased pulses in the legs. Diagnosis is most important because rupture or dissection of the aneurysm is often fatal, the patient presenting with sudden, excruciating, tearing abdominal or back pain radiating to the groin, buttocks, or thighs along with haemodynamic compromise (hypotension, tachycardia, and shock). Up to 30% of ruptured aneurysms are initially misdiagnosed. Preventive surgery (before rupture or dissection) is the optimal treatment.
|Table 1 Causes of back pain|
|Surgical emergencies||Cauda equina syndrome (disc, tumour mass, abscess)|
|Aortic aneurysm (ruptured, dissected)|
|Sciatica with neurological signs||Ruptured intervertebral disc|
|Spinal stenosis (the neurological examination is often normal)|
|Spinal cord tumours (extradural, intradural–extramedullary/intramedullary)|
|Neoplastic||Benign: osteoid osteoma|
|Malignant: primary (multiple myeloma), secondary (metastasis)|
|Infectious||Acute: pyogenic discitis, osteomyelitis|
|Inflammatory bowel diseases|
|Metabolic||Osteoporosis (with fractures)|
|Paget’s disease of bone|
|Visceral||Pelvic organs (endometriosis, prostatitis)|
|Renal disease (pyelonephritis, renal colic)|
|Nonspecific low back pain||Muscle|
Does the patient have sciatica and/or neurological signs?
Sciatica can be defined as pain radiating below the knee. It is a rare symptom, being reported by only 1% of patients with back pain, but its presence is usually associated with an identifiable aetiology. It typically results from compression of the spinal nerve originating between L4 and L5 (L5 nerve root) and/or L5 and S1 (S1 nerve root) by a herniated disc, bone, or a combination of the two (spinal stenosis). Tumours, infections, or epidural haemorrhage can very rarely produce similar symptoms and signs. The pain in a patient with a herniated disc tends to be aggravated by prolonged sitting as well as any manoeuvre that increases intrathecal pressure, such as sneezing, coughing, or defecation. It is often associated with paraesthesias and weakness in the distribution of the involved nerve.
Patients with spinal stenosis are usually older and typically complain of pain and/or paraesthesias in one or both buttocks, thighs, and/or legs that develop on standing or walking and are relieved by 15 to 20 min rest (neurological claudication). These patients often walk with the trunk flexed, as extension aggravates their symptoms by worsening nerve impingement. The neurological examination is most often normal or shows nonspecific abnormalities, such as reduced or absent ankle reflexes. Differentiating neurological from vascular claudication can be difficult, as both problems occur in the same age category, but pain from vascular claudication is typically relieved faster with rest than that of neurological claudication.
Does the patient have an underlying medical cause for their back pain?
The history is by far the most important diagnostic step in the search for potential medical causes of low back pain. A number of clues or ‘red flags’ should be looked for systematically. These include the presence of fever, chills, night sweats, weight loss, and nocturnal pain, which should direct the clinician towards the possibility of neoplasia or infection. An insidious onset of back pain accompanied by significant early morning stiffness in a young patient suggests a spondyloarthropathy and should prompt the clinician to enquire about the family history and undertake a detailed review of the ocular (conjunctivitis, iritis), cutaneous (psoriasis, mouth ulcers, balanitis, keratoderma blennorrhagica), gastrointestinal (diarrhoea, haematochezia, abdominal pain), genitourinary (urethritis), and musculoskeletal (peripheral arthritis, dactylitis, enthesitis, heel pain) systems. Risk factors for neoplasia (previous or current history of malignancy), infection (history of tuberculosis, AIDS, intravenous drug abuse, or recent genitourinary procedures), and metabolic bone diseases (previous fractures, menopause, corticosteroid intake, history of anorexia nervosa) should also be sought in patients suspected of having a medical problem underlying their back pain.
What are the key signs to look for in the physical examination?
A good examination of the lumbar spine and relevant nerves can be accomplished in less than 3 min if it is done systematically (Table 2). A full physical examination must be completed in patients suspected of having a medical cause for their back pain. The diagnostic utility of the many physical manoeuvres described to identify zygapophyseal and sacroiliac joint pain has been refuted when validated against diagnostic blocks with local anaesthetic. Waddell has described a number of nonorganic physical signs (Bullet list 1): psychological factors or secondary gains may be involved when a patient has three or more of these.
Who should be investigated and how?
There is a general agreement that the initial assessment should focus on the detection of ‘red flags’ suggestive of a medical aetiology, and that the vast majority of patients with back pain do not need any investigations. Recommendations for ordering a plain radiograph in a patient presenting with back pain include the following: age over 50, fever, weight loss, significant trauma, previous history of neoplasia, use of corticosteroids, drug or alcohol abuse, neurological symptoms and signs (particularly if widespread), night pain, morning stiffness (in which case a pelvic rather than a lumbar radiograph is recommended to detect sacroiliitis), and the persistence of pain after 1 month of conservative therapy.
|Table 2 Physical examination of the patient with back pain|
|Patient standing||Posture (protruding abdomen, hyperlordosis, loss of lordosis, scoliosis)|
|Spinal motion (flexion–extension–lateral flexion)|
|Walking on heels (L4–L5) and toes (S1)|
|Patient sitting||Straight leg-raising test (tripod sign)|
|Knee (L4) and ankle (S1) reflexes|
|Patient supine||Abdominal examination (mass, bruit)|
|L4: anteromedial knee and leg|
|L5: lateral leg, web space between first and second toes|
|S1: lateral aspect of the foot, heel|
|Motor examination (if abnormalities are noted in the standing position):|
|L5: dorsiflexion of first toe|
|S1: plantar flexion of foot and toes|
|Patient prone||Palpation (spinous processes, paraspinal muscles)|
|S2–S4: saddle anaesthesia|
|S1: contraction of gluteus maximus|
|Femoral stretch test (L2 to L4)|
Bullet list 1 Waddel’s tests for functional low back pain
- ◆ Tenderness to superficial touch
- ◆ Simulation testsa
- • Axial loading
- • Spinal rotation in one plane
- ◆ Distraction tests
- • Inconsistent results on confirmatory testing
- ◆ Regional disturbances
- • Abnormalities not following neuroanatomical structures
- ◆ Overreaction
- • Disproportionate verbalization
- a A positive test results in aggravation of low back pain.
All other tests should be restricted to patients in whom a medical aetiology is suspected from the history and physical examination, and patients with abnormalities on neurological examination who do not improve with conservative management. Ordering blood tests and imaging in any other situation can not be justified, as not only are these tests unhelpful but they contribute significantly to medical costs. In addition, as many as 25 to 50% of asymptomatic individuals have been shown to have abnormalities such as disc herniation on CT and MRI.
The erythrocyte sedimentation rate (ESR) is the most useful blood test in patients suspected of having spinal infection, as it is elevated in up to 80% of cases. Neutrophilia and anaemia are also commonly seen in patients with neoplasia and infection. Laboratory evaluation of patients with osteoporosis and/or pathological fractures should include serum calcium, phosphate and alkaline phosphatase, as well as serum and urine immunoelectrophoresis (to detect myeloma), particularly if the ESR is elevated.
MRI is the imaging modality of choice for the diagnosis of lumbar disorders. It provides a unique noninvasive means of studying the spine and is unsurpassed for imaging soft tissues. It is particularly helpful in the evaluation of spinal cord tumours, as well as infections of the spine, including discitis and epidural and paraspinal abscesses. CT is superior to MRI for the evaluation of bony structures and therefore is a good choice for spinal stenosis, particularly when combined with myelography. Plain myelography is rarely used today, except in patients who have contraindications to MRI or CT (claustrophobia in particular). The diagnostic accuracy of MRI, plain CT and CT myelography is comparable for the assessment of nerve root compression due to disc herniation. Although MRI is noninvasive and involves no radiation to the patient, the much lower cost of plain CT makes it an excellent choice in this context. CT-guided percutaneous biopsy is commonly used to obtain histological material from patients with tumour mass or infection.
As mentioned previously, injection studies done under fluoroscopic guidance are the only means of diagnosing back pain of discal, zygapophyseal, or sacroiliac joint origin. When normal discs are injected with contrast material, the individual does not experience pain. A provocative discography should be considered positive only if the injection reproduces the patient’s pain and no pain is experienced during the injection of adjacent discs. In a recent report, 40% of patients with chronic low back pain attending a large specialist spinal centre satisfied this strict definition and demonstrated a radial fissure on CT. Similarly, between 10 and 15% report a significant improvement in their pain when their zygapophyseal joints or their sacroiliac joints are injected with a local anaesthetic, but not with isotonic saline. Taken together, these figures suggest that the anatomical source of pain can be established in as many as 70% of patients with nonspecific back pain by using these invasive techniques. However, the impact of this approach on patient management is unclear, as no specific treatment has yet been demonstrated to be effective for these conditions.
Radionuclide bone scintigraphy with technetium-99m is helpful in conditions characterized by increased bone turnover. These include bone metastases, fracture, Paget’s disease, and infections. Gallium-67 binds to polymorphonuclear leucocytes and can be helpful in the evaluation of vertebral osteomyelitis and sacroiliac septic arthritis. Typically, bone scans are negative in patients with multiple myeloma, which is characterized by lytic lesions.
Neurophysiological studies are rarely indicated, except in patients in whom it is difficult to distinguish between a neuropathy, radiculopathy, or plexopathy. Fibrillations in the paraspinous muscles are the most common and earliest findings seen in radiculopathy. Their presence indicates a lesion proximal to the vertebral foramen and excludes a plexopathy.
How are patients with low back pain best managed?
As mentioned earlier, cauda equina syndrome and a ruptured vascular aneurysm are the only two conditions that must be managed surgically on an emergency basis.
Sciatica and neurological deficits
About 90% of patients with a herniated lumbar disc will improve significantly with limited rest, analgesics and anti-inflammatory drugs. The role of epidural steroids remains unclear: they may afford short-term improvement in leg pain, but they do not reduce the need for surgery. Indications for surgery include persistent disabling buttock and/or leg pain despite 2 to 3 months of conservative management, and/or severe or progressive worsening neurological deficit while on treatment. Surgery may also be indicated in patients with neurological claudication due to spinal stenosis, but only after all attempts with conservative management have failed. Patients with spinal stenosis who are more incapacitated by back pain than by neurological claudication should probably not be operated on, because surgery is rarely effective and may even worsen back pain.
Medical back pain
Primary and secondary tumours of the spine can be treated by surgery, radiotherapy, or chemotherapy, whereas antibiotics with or without surgical drainage are the treatment for discitis and osteomyelitis. Postural exercises and nonsteroidal anti-inflammatory drugs (NSAIDs) remain the cornerstone of treatment for patients with spondyloarthropathies. Sulfasalazine and methotrexate are helpful for the peripheral arthritis associated with these conditions, but they have no role in the treatment of the spinal disease. Biological agents—including etanercept, infliximab, and adalimumab—are the drugs of choice in patients with spinal disease associated with spondyloarthropathies who fail NSAIDs.
Nonspecific low back pain
A number of systematic reviews of randomized controlled trials of the most common interventions have been published and form the basis of the recommendations found in the many national guidelines published in the past two decades. The European guidelines for the management of low back pain are the most recently published (2006). They were developed with the main objectives of improving prevention and management of acute and chronic nonspecific low back pain.
Patients with acute back pain should be reassured and advised to stay active and continue normal daily activities, including work if possible. If necessary, medications for pain relief, including paracetamol and NSAIDs, should be prescribed and preferably taken at regular intervals. A short course of muscle relaxants to reduce pain may be tried in patients failing paracetamol or NSAIDs, and referral for spinal manipulation should be considered in patients failing to return to normal activities. Exercise therapy is ineffective in the acute phase but should be recommended for prevention of recurrence.
An important objective in managing acute low back pain is to reduce the likelihood of patients progressing to chronicity, not least because there are only a few modalities that have been shown to be beneficial in chronic back pain. The early identification of psychosocial risk factors, or ‘yellow flags’, should lead to appropriate cognitive and behavioural management in an attempt to influence positively some of these factors, although evidence of the effectiveness of this approach or of other psychosocial interventions at this stage is currently lacking.
In patients with chronic low back pain, cognitive behavioural therapy, supervised exercise therapy, brief educational interventions and multidisciplinary (biopsychosocial) treatment can each be recommended, and so can the short-term use of NSAIDs and weak opioids for pain relief. Noradrenergic or noradrenergic–serotoninergic antidepressants, muscle relaxants and capsicum plasters may also be considered for pain relief. Invasive treatments, including acupuncture, epidural corticosteroids, intra-articular steroid injections and local facet nerve blocks, intradiscal injections, and prolotherapy are not recommended. Surgery should be considered only in carefully selected patients with a maximum of two level degenerative disc disease who have failed 2 years of all previously recommended treatments.