R. Douglas Orr, MD
DESCRIPTION 
Back pain is a symptom and not a diagnosis. It is the final common pathway through which numerous pathologies can express themselves. Different pathologies can cause different patterns of pain and have different prognosis and treatment. The vast majority of back pain is benign and self limiting, but in some cases it may represent significant pathology or become chronic. Recently, numerous review and clinical practice guidelines have been published, which have greatly helped clarify diagnosis and treatment recommendations (Dagenais et al., 2010).
EPIDEMIOLOGY
Incidence
Axial back pain is very common. Approximately 80% of the population suffers at least 1 significant episode of back pain defined as back pain lasting more than a day that limits activities. In any given year, 38% of the population reports an episode of back pain (Hoy et al., 2010).
Prevalence
At any given time, 18% of the population is estimated to have back pain (Hoy et al., 2010)
RISK FACTORS
Although many different risk factors have been identified, recent reviews show that there are a few risk factors for onset of back pain. Genetics, smoking, and low-frequency vibration probably have the strongest associations with back pain. Although occupational exposures are widely accepted as causes of back pain, objective studies are inconsistent in the relationship between work-related factors and episodes of back pain (Hartvigsen et al., 2003)
Genetics
As noted above. No specific genetic markers.
GENERAL PREVENTION
Evidence is limited on the benefit of special training or equipment to avoid back injury. Maintaining good physical fitness and weight reduction may be beneficial in prevention.
PATHOPHYSIOLOGY
Most acute episodes of lumbar back pain are felt to be due to muscular injury or strain. The underlying findings of disk degeneration are weakly correlated with the acute episodes of back pain. The process of disk degeneration is ubiquitous. In asymptomatic individuals, the incidence of disk degeneration on MRI is essentially equal to age in years. Acute disk herniation is correlated with acute radiculopathies. Spinal stenosis is correlated with claudicant pattern leg pain.
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HISTORY
Elucidating the pattern of pain is often the first step in establishing a diagnosis. Acute injuries occurring with lifting or other work-related activities usually indicate a lumbar strain. Pain of more insidious onset is more typical of disk degeneration. Associated symptoms are important in establishing more ominous diagnoses.
Definitions
- Axial back pain: Pain located in the midline or paraspinal area of the back. It may be central or located more to 1 side.
- Mechanical back pain: Pain that occurs with mechanical strains on the back such as sitting, standing, or changes in position. Typically this pain is relieved by lying supine.
- Myofascial pain: Pain thought to arise from muscle or fascial tissue that often crosses dermatomes and may be associated with trigger points; may not be relieved by rest.
- Radicular pain: Pain radiating in the distribution of a nerve root.
- Sciatica Pain: Pain in the distribution of the sciatic nerve.
- Dermatomal pain: Pain in the cutaneous distribution of the nerve root.
- Myotomal pain: Pain in the muscular distribution of the nerve root.
Lumbar strain is the most common cause of episodes of acute low back pain. They are often associated with lifting, bending, or twisting injuries. Pain may begin immediately or after a delay of 24–48 hours.
Acute disk herniation will often present with axial back pain before the onset of radiculopathy, and this is thought to be due to an annular tear. Associated radicular pain will follow the distribution of the affected nerve.
- L
Upper thigh - L
Anterior thigh to knee and sometime anterior shin - L4/5 Posterior thigh and calf to dorsal surface of the foot
- L5/S1 Posterior thigh to lateral margin of the foot
Facet pain is axial back pain with activity such as standing or walking relieved by flexion or sitting and is often thought to be due to facet degeneration. The hallmark of this pain pattern is lack of symptoms when sitting; much more common in 7th and 8th decade.
Spondylolisthesis can lead to back pain and radicular symptoms. In younger patients, the isthmic form is more common and is typical at L5/S1. It may be associated with repetitive hyper extension. Sports such as gymnastics, figure skating, and football lead to increased incidence though there is a genetic component. In older patients, the degenerative form is more common and typical at L4/5.
Tumors and infections are much less common causes of axial back pain. They typically are associated with other symptoms and should be suspected in any patient with a previous history of malignancy or with recent systemic infections. Night pain in the absence of mechanical stresses is sometimes indicative of these diagnoses.
Fractures in older patients or patients on long-term corticosteroid therapy: Sudden onset back pain may indicate the presence of an osteoporotic vertebral compression fracture even in the absence of trauma. This pain generally worsens with changes in position and is often felt a higher in the spine such as the thoracolumbar junction.
Visceral diseases: Back pain may also be a symptom of visceral disease. Retroperitoneal pathology such as renal disease or vascular diseases may present with back pain. Pelvic pathologies such as rectal cancers and gynecologic malignancies may also present with back pain. Pain tends to be more constant and not as affected by activity.
PHYSICAL EXAM
The main goal of the physical exam is to rule out more significant causes of pain. The exam in an acute episodic low back pain tends to be benign. There may be some paraspinal tenderness or spasm noted. A detailed neurological exam should be performed to look for neurological signs or symptoms. Nerve root tension signs such as straight leg raise or femoral stretch may indicate the presence of an acute disk herniation.
DIAGNOSTIC TESTS AND INTERPRETATION
Lab
Initial Lab Tests
There are no lab tests that are indicated in a routine investigation of back pain. In patients with suspected malignancy or infection, these may be part of the workup. ESR and C-reactive protein are the best tests in the presence of a suspected infection. Serum protein electrophoresis (SPEP) is indicated in the workup of suspected multiple myeloma or plasmocytoma. HLA B 27 can indicate the diagnosis of ankylosing spondylitis, but it is important to remember that there will be many more false positives than true positives.
Imaging
Initial Approach
In the majority of cases of acute episodic low back pain, there is no indication for imaging. The Quebec Task Force on low back pain identified a series of ‘red flags’ that are indications for imaging at first presentation of acute low back pain. These red flags are:
- Age <15 or >50 at first onset of pain
- Any history of malignancy
- Recent history of significant trauma
- Constitutional symptoms such as fevers, chills, unexplained weight loss
- Duration of pain exceeding 6 weeks
- Progressive neurological deficit
Standing AP and lateral radiographs with a spot view of L5-S1 are the first screening test. They show abnormalities of alignment, disk degeneration, and any fractures. Very little is added by getting flexion extension films or oblique films.
MRI is the most sensitive test to look for lumbar pathology. Its drawback is relatively low specificity. Screening studies in asymptomatic individuals show high rates of MRI abnormalities. There is no role for routine use of gadolinium unless malignancy is suspected.
CT scan is excellent for assessing bony abnormalities. It can be used to assess the stenosis. When combined with myelography, it is a good substitute for MRI in patients for whom MRI cannot be obtained.
Bone scan does not have a lot of use in the diagnoses of acute low back pain. It may be used in assessing the acuity of compression fractures in patients unable to have MRI.
Diagnostic Procedures/Other
Although commonly used, there is really no indication for EMG testing in the workup of low back pain. It may have use in radicular syndromes or to differentiate peripheral from central causes of neurogenic symptoms.
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MEDICATION
Most back pain is self limiting in nature, and the goal of treatment is symptom control and maintenance of function. Bed rest is to be avoided. Chronic back pain is more complex and difficult to treat.
Nonsteroidal anti-inflammatories are effective in the early stages. They have both analgesic and anti-inflammatory effects. Numerous options exist and patient response may be idiosyncratic; so it is reasonable to try multiple options prior to moving on to other options.
Pulsed corticosteroids are sometimes used although definitive studies of their effectiveness are lacking.
Antidepressants have multiple effects and may be very beneficial as a component of polypharmacy in chronic pain:
Membrane stabilizers such as gabapentin or pregabalin may be useful for the treatment of radicular syndromes but in general have little use in axial back pain. They have been shown effective in treatment of spinal stenosis:
- Gabapentin 100–300 mg t.i.d.
- Pregabalin 50–150 mg q8–12h
Narcotic analgesics have been extensively used and misused. They should be used judiciously and ideally for only short periods of time. They may be valuable in allowing a quicker return to function, but the risks of dependency and tolerance are not insignificant. Long-term use of narcotics for uncomplicated back pain is controversial (Altman and Smith, 2010).
- For short term moderate pain:
- For short term severe pain:
- Long-term narcotic:
Should be done under strict supervision and a narcotic contract. Use long acting medications with short acting for breakthrough
- Oxycodone-sustained release 20–80 mg q8–12h
- Morphine-sustained release 20–80 q12h
- Methadone 5–30 mg q12h
A physical therapy program based on active exercise is the mainstay of acute treatment and long-term prevention of relapse or chronicity. If the patients have a directionality to their pain pattern, then it is recommended that the dominant exercise should be opposite the painful direction (i.e. those who have pain worsening with extension should exercise in flexion) Passive modalities such as heat, cold, ultrasound and transcutaneous electrical nerve stimulation have the primary goal of reducing symptoms to allow an active exercise program to be done. They are not in and of themselves sufficient treatment.
ADDITIONAL TREATMENT
Multiple injection therapies have been advocated. These include facet blocks, facet rhizotomies, epidural injections, selective nerve root blocks and trigger point injections. Although epidural injections and nerve blocks may be beneficial in the treatment of radicular syndromes, there is little evidence for their efficacy in the treatment of axial back pain. The effectiveness of facet blocks and facet rhizotomies in the treatment of chronic axial back pain has not been clearly established, but there is reasonable evidence for its use (Chou et al., 2009b)
COMPLEMENTARY AND ALTERNATIVE THERAPIES
Manipulation has been shown in some studies to be effective in the treatment of acute episodic low back pain irrespective of whether it is delivered by chiropractors, physical therapists, or osteopaths. It has not been shown to be effective for the prevention of recurrences or for chronic pain (Bishop et al., 2010)
SURGERY/OTHER PROCEDURES
Surgery is rarely indicated for the treatment of axial back pain. In the presence of documented instabilities or deformities or as an adjunct to decompressive surgery for radicular syndromes, it is well accepted. In the rare case of a patient with a relatively focal disease, who has not responded to other conservative therapies, fusion has been shown to be effective. Surgery for axial back pain in the absence of radicular syndromes really should not be considered until a minimum of 6 and more likely 12 months of conservative care has been tried. Results of psychometric testing have been shown to correlate highly with outcome from surgery. Patients who score high on measures of anxiety, depression, and hypochondriasis have poor outcomes and should not be considered candidates for surgery (Chou et al., 2009a)
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ICD9
- 724.2 Lumbago
- 724.4 Thoracic or lumbosacral neuritis or radiculitis, unspecified
- 724.5 Backache, unspecified
- 724.1 Pain in thoracic spine
And for multiple others see specific etiology.
Acute back pain is very common and early mobilization with judicious nonsteroidal anti-inflammatory treatment is appropriate in most cases.