Acute Low Back Pain

Common Musculoskeletal Problems

ACUTE LOW BACK PAIN

The number of medical visits resulting from low back pain is sec-ond only to the number of visits for upper respiratory illnesses. Most low back pain is caused by one of many musculoskeletal problems, including acute lumbosacral strain, unstable lum-bosacral ligaments and weak muscles, osteoarthritis of the spine, spinal stenosis, intervertebral disk problems, and unequal leg length.

Older patients may experience back pain associated with os-teoporotic vertebral fractures or bone metastasis. Other causes in-clude kidney disorders, pelvic problems, retroperitoneal tumors, abdominal aneurysms, and psychosomatic problems.

In addition, obesity, stress, and occasionally depression may contribute to low back pain. Back pain due to musculoskeletal disorders usually is aggravated by activity, whereas pain due to other conditions is not. Patients with chronic low back pain may develop a dependence on alcohol or analgesics in an attempt to cope with and self-treat the pain.

Pathophysiology

The spinal column can be considered as an elastic rod constructed of rigid units (vertebrae) and flexible units (intervertebral disks) held together by complex facet joints, multiple ligaments, and paravertebral muscles. Its unique construction allows for flexibil-ity while providing maximum protection for the spinal cord. The spinal curves absorb vertical shocks from running and jumping. The trunk muscles help to stabilize the spine. The abdominal and thoracic muscles are important in lifting activities. Disuse weakens these supporting structures. Obesity, postural problems, struc-tural problems, and overstretching of the spinal supports may re-sult in back pain.

The intervertebral disks change in character as a person ages. A young person’s disks are mainly fibrocartilage with a gelatinous matrix. As a person ages, the disks become dense, irregular fibro-cartilage. Disk degeneration is a common cause of back pain. The lower lumbar disks, L4–L5 and L5–S1, are subject to the great-est mechanical stress and the greatest degenerative changes. Disk protrusion (herniated nucleus pulposus) or facet joint changes can cause pressure on nerve roots as they leave the spinal canal, which results in pain that radiates along the nerve.

Clinical Manifestations

The patient complains of either acute back pain or chronic back pain (lasting more than 3 months without improvement) and fa-tigue. The patient may report pain radiating down the leg, which is known as radiculopathy or sciatica and which suggests nerve root involvement. The patient’s gait, spinal mobility, reflexes, leg length, leg motor strength, and sensory perception may be altered. Physical examination may disclose paravertebral muscle spasm (greatly increased muscle tone of the back postural muscles) with a loss of the normal lumbar curve and possible spinal deformity.

Assessment and Diagnostic Findings

The Agency for Heath Care Policy and Research developed guide-lines for assessment and management of acute low back pain (Bigos et al., 1994). These safe, conservative, and cost-effective guidelines have reduced the use of noneffective therapeutic inter-ventions, including prolonged bed rest.

The initial evaluation of acute low back pain includes a focused history and physical examination, including general observation of the patient, back examination, and neurologic testing (reflexes, sen-sory impairment, straight-leg raising, muscle strength, and muscle atrophy). The findings suggest either nonspecific back symptoms or potentially serious problems, such as sciatica, spine fracture, can-cer, infection, or rapidly progressing neurologic deficit. If the ini-tial examination does not suggest a serious condition, no additional testing is performed during the first 4 weeks of symptoms.

The diagnostic procedures described in Chart 68-1 may be in-dicated for the patient with potentially serious or prolonged low back pain. The nurse prepares the patient for these studies, pro-vides the necessary support during the testing period, and moni-tors the patient for any adverse responses to the procedures.

Medical Management

Most back pain is self-limited and resolves within 4 weeks with analgesics, rest, stress reduction, and relaxation. Based on initial assessment findings, the patient is reassured that the assessment indicates that the back pain is not due to a serious condition. Management focuses on relief of pain and discomfort, activity modification, and patient education.

Nonprescription analgesics (acetaminophen, ibuprofen) are usually effective in achieving pain relief. At times, a patient may require the addition of muscle relaxants or opioids. Heat or cold therapy frequently provides temporary relief of symptoms. In the absence of symptoms of disease (radiculopathy of the roots of spinal nerves), manipulation may be helpful.

Other physical modalities have no proven efficacy in treating acute low back pain. They include traction, massage, diathermy, ultrasound, cutaneous laser treatment, biofeedback, and tran-scutaneous electrical nerve stimulation. Likewise, acupuncture and injection procedures have no proven efficacy (Bigos et al., 1994).

Most patients need to alter their activity patterns to avoid ag-gravating the pain. Twisting, bending, lifting, and reaching, all of which stress the back, are avoided. The patient is taught to change position frequently. Sitting should be limited to 20 to 50 minutes based on level of comfort. Bed rest is recommended for 1 to 2 days, with a maximum of 4 days only if pain is severe. A grad-ual return to activities and low-stress aerobic exercise is recom-mended. Conditioning exercises for the trunk muscles are begun after about 2 weeks.

If there is no improvement within 1 month, additional assess-ments for physiologic abnormalities are performed. Management is based on findings.