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9.06 Acute Lumbar Strain ("Mechanical" Low Back Pain, Sacroiliac Dysfunction)


Presentation

Suddenly or gradually after lifting, sneezing, bending, or other movement the patient develops a steady pain in one or both sides of the lower back. At times, this pain can be severe and incapacitating. It is usually better on lying down, worse with movement, and will perhaps radiate around the abdomen or down the thigh, but no farther. There is insufficient trauma to suspect bony injury (e.g., a fall or direct blow); and no evidence of systemic disease which would make bony pathology likely (e.g., osteoporosis, metastatic carcinoma, multiple myeloma). On physical examination, there may be spasm (i.e., contraction which does not relax, even when the patient is supine or when the opposing muscle groups contract, as with walking in place) in the paraspinous muscles; but there is no point tenderness over the spinous processes of lumbar vertebrae and no nerve root signs such as pain or paresthesia in dermatomes below the knee (especially with straight leg raising), foot weakness, or loss of the ankle jerk. There may be point tenderness to firm palpation or percussion over the sacroiliac joint, especially if the pain is on that side.

What to do:

What not to do:

Discussion

Low back pain is a common and sometimes chronic problem which accounts for an enormous amount of disability and time lost from work. The approach discussed above is geared only to the management of acute injuries and flareups, from which most people recover on their own, only about 10% developing chronic problems. With acute pain, reassurance plus limited medication may be the most useful intervention.

History and physical examination are essential to rule out serious pathologic conditions which can present as low back pain but which require quite different treatment--aortic aneurysm, pyelonephritis, pancreatitis, pelvic inflammatory disease, ectopic pregnancy, retroperitoneal or epidural abscess.

The standard five-view x ray study of the lumbosacral spine may entail 500 mrem and only 1 in 2500 lumbar spine plain films of adults below age 50 show an unexpected abnormality. In fact, many radiographic anomalies such as spina bifida occulta, single-disk narrowing, spondylosis, facet joint abnormalities and several congenital anomalies are equally common in symptomatic and asymptomatic individuals. It is estimated that the gonadal dose of radiation absorbed from a five-view lumbosacral series is equivalent to that from six years of daily anterioposterior and lateral chest films. The World Health Organization now recommends that oblique views be reserved for problems remaining after review of AP and lateral films. For simple cases of low back pain, even with radicular findings, both CT and MRI are overly sensitive and often reveal anatomic abnormalities that have no clinical significance.

While adults are more apt to have disk abnormalities, muscle strain and degenerative changes associated with low back pain, athletically active adolescents are more likely to have posterior element derangements like stress fractures of the pars interarticularis. Early recognition of this spondylolysis and treatment by bracing and limitation of activity may prevent nonunion, persistant pain and disability.

Malingering and drug seeking are major psychological components to consider in patients who have frequent ED visits for back pain and whose responses seem overly dramatic of otherwise inappropriate. These patients may move around with little difficulty when they do not know they are being observed. They may complain of generalized superfician tenderness when you lightly pinch the skin over the affected lumbar area. If you are suspicious that the patient's pain is psychosomatic or nonorganic you can use the axial loading test, in which you gently press down on the head of the standing patient. This should not cause significant musculoskeletal back pain. You can also perform the rotation test, in which the patient stands with his arms at his sides. Hold his wrists next to his hips and turn his body from side to side, passively rotating his shoulders, trunk and pelvis as a unit. This maneuver creates the illusion that you are testing spinal rotation, but in fact you have not altered the spinal axis and any complainst of back pain should be suspect.

References:


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from Buttaravoli & Stair: COMMON SIMPLE EMERGENCIES
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Craig Feied, MD
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