When should patients be referred to a specialist?
Patients should be referred to a neurologist, neurosurgeon, orthopedist, or other specialist if they have cauda equina syndrome; severe or progressive neurologic deficits; infections, tumors, or fractures compressing the spinal cord; or, perhaps, no response to conservative therapy for 4 to 6 weeks for patients with a herniated lumbar disk or 8 to 12 weeks for those with spinal stenosis.
If there is profound motor involvement at the time of the initial evaluation, patients must be promptly given systemic corticosteroids such as methylprednisolone (Medrol) or dexamethasone (Decadron) to decrease spinal cord edema.
Are there signs of psychological distress?
Psychosocial factors can significantly affect pain and functional disability in patients who have low back pain.8,9 These are known as “yellow flags” and are better predictors of treatment outcome than physical factors. 10 Anatomically inappropriate signs may be helpful in identifying psychological distress as a result of or as an amplifier of low back symptoms.
Waddell et al11 proposed five categories of these nonorganic signs. These are:
- Inappropriate tenderness that is superficial or widespread
- Pain on simulated axial loading by pressing on the top of the head or simulated spine rotation
- Distraction signs such as inconsistent performance between straight-leg-raising in the seated position vs the supine position
- Regional disturbances in strength and sensation that do not correspond with nerve root innervation patterns
- Overreaction during the physical examination.
The occurrence of any one of the signs is of limited value, but positive findings in three of the five categories suggest psychological distress.11
Which diagnostic studies are useful, cost-effective, and supported by evidence?
Since most abnormalities found on imaging studies are nonspecific, such studies are not necessary during the initial evaluation of acute low back pain unless there are red flags that suggest a more ominous source of pain.
Routine plain lumbosacral spine radiographs with anteroposterior and lateral views may be appropriate initially if the patient has risk factors for vertebral fractures (Table 1), or if the patient does not improve after a course of conservative treatment (usually 4–6 weeks).
Magnetic resonance imaging (MRI) is the preferred test if one suspects a tumor, infection, disk pathology, or spinal stenosis.
Computed tomography (CT) shows bony details better than MRI does. Hence, it is preferred when one needs to evaluate bony details (fractures, scoliosis) and when there are contraindications to MRI, as in patients with metal implant devices and those who are claustrophobic (although now there are “open system” MRI machines, in which the feeling of claustrophobia is much less).
MRI and CT should not be ordered routinely, but only for specific indications to answer specific questions, when specific findings would indicate specific treatment.
In most cases, contrast is not needed for CT or MRI to rule out common causes of low back pain, except in cases of suspected intraspinal tumor. Patients with compromised renal function who need contrast for CT need to be hydrated before the scan to lower the risk of contrast-induced nephropathy. These patients are also at higher risk of nephrogenic fibrosing dermopathy when they receive gadolinium contrast for MRI.
Bone scans can be used to look for infections or fractures not noted on plain radiography. However, MRI provides similar or better diagnostic accuracy without radiation.
Electrodiagnostic studies may be used in patients with radiculopathy when clinical examination suggests multilevel root lesions, when symptoms do not match imaging studies, and when patients have breakaway weakness (fluctuating levels of strength in one or more muscle groups).
Other useful diagnostic and laboratory studies may include the erythrocyte sedimentation rate to screen for malignancy and infection when these are suspected, blood culture for osteomyelitis, and bone aspiration and biopsy for histopathologic diagnosis of infection, malignancy, or other lesions.
WHICH TREATMENTS ARE SUPPORTED BY ROBUST EVIDENCE?
The primary treatment of low back pain should be conservative care, reassurance, and education, allowing patients to improve on their own and helping them cope with their predicament.
Limited bed rest. While 2 or 3 days of limited bed rest may help improve symptoms in patients who have acute radiculopathy, several studies have shown that long periods of bed rest are not beneficial for acute or subacute low back pain.12 Encouraging activity modification allows patients with nonspecific back pain or radicular symptoms to remain active while avoiding activities that may aggravate pain and is shown to lead to a more rapid recovery than bed rest.13,14 The most common situations to avoid are prolonged sitting or standing.15 Low-stress aerobic activities, especially walking, are the best early activities.15
Exercise is one of the only evidence-based, effective treatments for chronic low back pain.16 The most commonly prescribed exercises are aimed at retraining the multifidus (a back muscle) and transversus abdominis (a deep abdominal muscle), supplemented with exercises for the pelvic floor and breathing control.
Nonsteroidal anti-inflammatory drugs (NSAIDs) and acetaminophen (Tylenol) are the drugs of choice for pain control in acute back pain17,18 and are as effective as muscle relaxants or opioids.
Muscle relaxants and opioids offer few advantages over NSAIDs and acetaminophen, except when there is severe muscle spasm associated with the back pain or if acetaminophen or NSAIDs do not relieve the pain. Muscle relaxants and opioids are both associated with more severe adverse effects. If prescribed, they should be used for a short, clearly defined period (1 to 2 weeks).19
Epidural corticosteroids, when used for sciatica, give mild to moderate short-term improvement in leg pain and sensory deficit but no significant long-term functional benefit or reduction in the need for surgery.20
Surgery may be considered in cases of cauda equina syndrome, which is a surgical emergency; severe or progressive neurologic deficit; infections, tumors, and fractures compressing the spinal cord; mechanical instability of the back; and, perhaps, intractable pain (leg pain equal to or greater than back pain) with a positive straight-leg-raising test and no response to conservative therapy.
The term “instability” implies an abnormal motion under physiologic loads. Lumbar instability is defined as translation of more than 4 mm or 10 degrees of angular motion between flexion and extension on an upright lateral radiograph.
Although Weinstein et al21 showed that patients with spinal stenosis who underwent surgery showed significantly more improvement in all primary outcomes than did patients treated nonsurgically, many patients can be effectively treated without surgery.