Low Back Pain
Low back pain is one of the most ubiquitous of ailments. About 80°Io of people are so afflicted at some time during their lives, and of these, 1-2% become chronically impaired. Low back pain may be associated with a variety of causes. These patients are subjected to a large number of diagnostic procedures with ambiguous or unrevealing results. This reflects inadequate clinical evaluation and a failure to utilize information obtained from properly con-ducted history and physical examination.
A history of the patient's illness should include occupation, injuries, onset of symptoms, pattern of pain and relationship to physical activity, aggravating and relieving factors, emotional status, loss of time from work, and possible litigation.
Inspection and palpation of the painful area are important. Since pain from nerve roots or nerves is commonly referred toward the periphery, the physician should explore the entire nerve lengths leading from the painful area and should note the presence of any masses or tenderness and, where possible, the size and consistency of nerves.
Muscle spasm and tenderness to percussion and deep pressure may give evidence suggesting radicular irritation, particularly when associated with local deformity or restriction of spinal motion. Lumbar para-spinal muscle spasm frequently is noted with local radiculitis, which is due to many causes, including herniated lumbar intervertebral disk.
Psoas muscle spasm usually indicates disease of the psoas muscle or of the lumbar vertebrae and soft tissue adjacent to this muscle. It may be tested with the patient prone and the pelvis firmly pressed against the table with one hand by the examiner. With the other hand grasping the ankle, the leg is moved to the vertical position with the knee flexed at a right angle. The hip is passively hyperextended by lifting up on the ankle. Limitation of motion is produced by involuntary psoas muscle spasm.
Limitation of passive lumbar flexion and resulting pain often accompany disease of the lumbar or lumbo-sacral articulations. With the patient supine, the examiner grasps one lower extremity with both hands, moves the thigh to a position of maximal flexion, and then presses firmly downward toward the table and upward toward the patient's head, passively flexing the lumbar spinal column.
The range of motion of joints and the effect of movement on the pain should be determined, since pain from areas such as the hip may be referred distally.
The regional blood vessels and those of the extremity should be checked for adequacy of pulsation and aneurysmal dilatation. Rectal and vaginal examination rule out local lesions and involvement of accessible lumbodorsal plexuses.
Sciatic stretch tests (eg, the straight leg-raising test and Lasegue's sign) should be elicited. With the patient supine, the relaxed, extended lower extremity is gently lifted from the bed or table. A test is positive if back pain and radicular radiation are duplicated. It is suggestive but not diagnostic of herniated nucleus pulposus.
Patrick's sign helps to differentiate sciatic from hip joint disease. The patient lies supine, and the heel of the lower extremity being tested is passively placed on the opposite knee. The knee on the side being tested is then pressed laterally and downward as far as it will go. The test is positive if motion is involuntarily restricted; pain frequently accompanies limitation of motion. The test is positive in hip joint disease and negative in sciatica.
Low Back Pain Without Characteristic Radiographic Changes
Disorders of the spine that may present without characteristic radiographic changes causing back pain include musculotendinous strain of the thoracic and lumbar spine, herniated nucleus pulposus, ankylosing spondylitis, osteomyelitis, and primary and metastatic bone tumors.
A. Musculotendinous Strain : Strain is generally related to postural or mechanical causes. Acute episodes of pain are severe and usually limited in duration, with decreased back motion and paraspinal muscle spasm, resulting in a list and loss of lordosis. Muscle trigger points can often be localized. Management includes bed rest, local heat, a firm sleeping surface, and analgesics. After 24 hours of pain-free recumbency without medication, walking activity is tried, with progression to full activity if symptoms do not recur. Patients with chronic symptoms present few objective findings, and stress is often implicated. Predisposing factors may include poor posture, obesity, poor abdominal muscle tone, and pregnancy. Ongoing management may include daily exercises or sport activities appropriate for age, a firm mattress, and a weight reduction program if needed.
B. Herniated Nucleus Pulposus : This is the most common radicular syndrome manifested in the lumbosacral region and occurs principally in young adult males. Backache, exacerbated by increased intra-abdominal pressure due to coughing, sneezing, and movement, usually antedates the sciatic syndrome. The latter is noted by a positive Lasegue and a negative Patrick sign. Intervertebral disks L4-5 and LS-S 1 are most commonly affected, causing weakness or atrophy of the thigh or calf, decreased sensation in a radicular pattern, and hyporeflexia. Except for an occasional narrowed intervertebral space, x-rays are not generally helpful. Pain from a herniated nucleus pulposus is almost always relieved by bed rest in recumbency, analgesics, sedation, and a firm sleeping surface. The duration of bed rest to be recommended is controversial; there is no evidence that more than 48-72 hours is beneficial, though some clinicians feel otherwise. The patient who does not respond to conservative treatment in 14-21 days or who demonstrates progression of neurologic deficits should undergo contrast myelography with CT scanning or MRI. Based upon these findings, operation may be indicated. Extradural corticosteroid injections are helpful in some cases, especially for the short term. Chemonucleolysis is a useful but controversial alternative to surgical diskectomy but should not preclude conservative treatment. Patients who are good candidates for surgical disk excision may benefit from this special technique.
C. Inflammatory Disorders : Ankylosing spondylitis occurs principally in men. Few significant radiographic changes are noted during the first 1-2 years following onset of symptoms. The disorder is progressive and leads to calcification of the anterior longitudinal ligaments.
Rheumatoid arthritis can cause severe low back pain from intervertebral disk degeneration.
D. Osteomyelitis : Osteomyelitis of the spine produces destructive lesions with localized pain and sensitivity to percussion. Indeed, the combination of both pain and fever should be considered to signify infection until some other cause is identified. In young patients, there is often a history of respiratory tract (staphylococcal or streptococcal) infection; in older patients, manipulation of the genitourinary tract (gram-negative bacilli) may be the precipitating event. Radiographs may show localized de-calcification of the vertebrae and subperiosteal calcification 10-14 days after an acute pyogenic episode. Postoperative infections following diskectomy may develop in 1-8 weeks. Management by immobili-zation of the back usually alleviates the pain. If antibiotic therapy does not control the infection, surgical debridement and drainage with or without bone grafting of the defect are required. Chronic pyogenic osteo-myelitis resulting from bacteria is more common in narcotic addicts. Brucellosis, coccidioidomycosis, and mycobacterial infection may follow an ill-defined or insidious course with low-grade fever; radiographic changes are evident even later than the symptoms. Back pain, constitutional symptoms, weight loss, and a list develop. Hyperemic osteoporosis of cancellous bone may result in vertebral collapse, producing neurologic symptoms. When abscesses form, they may dissect along fascial planes, affecting the psoas muscle and the gluteal and paravertebral areas. Management is similar to that of acute pyogenic infection. Abscess drainage may be needed. Occasionally, spinal fusion may be necessary for instability or progressive deformity causing neurologic deficit.
E. Neoplasms : Benign or malignant neoplasms may affect the spinal cord or the osseous vertebrae at any level. The patient who complains of constant night pain and worsening sleep difficulties due to pain should be suspected of having a tumor. The most common primary tumor in patients over 40 is multiple myeloma; secondary neoplasms are metastatic carcinoma from the breast, prostate, kidney, or lung. Neck or back pain may be the initial complaint, and x-rays of the spine may be normal until 30% of the bone has been destroyed. Tumors may be bone-producing or bone-destroying, depending upon the origin of the lesion. Serum alkaline phosphatase (elevated in bone-producing tumors), calcium, and phosphorus may help; and bone scanning is more sensitive than plain films for bone-producing tumors. Management includes symptomatic treatment, needle or open biopsy, and computer-assisted myelography or MRI. Radiotherapy is the initial treatment of choice for metastatic tumors compressing the spinal cord. Surgery is reserved for radiation failures or for cases in which the diagnosis has not been established. Prognosis is best if therapy is initiated before neurologic signs of cord compression develop.
Low Back Pain With Characteristic Radiographic Changes
These include osteoarthritis, spondylolisthesis, spi-nal stenosis, facet tropism, transitional vertebra, untreated scoliosis, and osteoporosis.
A. Degenerative Changes : Degenerative changes of the intervertebral disks (spondylosis) and the posterior articulating facets (osteoarthritis) and spinal stenosis are often interrelated and may affect the entire spine. They occur chiefly in patients of middle age or older. Early morning stiffness and pain aggravated by prolonged sitting and standing and improved by walking (except for spinal stenosis, which worsens with exertion) are often relieved by recumbency. Sciatic radiation may occur. Fatigue, obesity, and muscle tension or spasm aggravate the problem. Musculotendinous strain may be superimposed. The formation of osteophytes around the periphery of the vertebral body and facet joints may lead to entrapment of the lateral spinal nerve roots. Early radiographic findings show osteophyte formation lateral and anterior (traction spur) to the vertebral body, with later narrowing of the disk and facet joints and foraminal encroachment. CT scan with myelography is confirmatory. Management includes analgesics, anti-inflammatory agents, weight loss, modification of activities, and decompressive surgery.
B. Spondylolysis and Spondylolisthesis : A defect in the pars interarticularis (spondylolysis) and a bilateral defect with vertebral slippage (spondylolisthesis) are believed in most cases to be acquired disorders resulting from stress fractures. Although often asymptomatic, they may cause low back pain with or without sciatic radiation. Involvement of LS is most common, followed by L4. A depression above the sacrum is seen on physical examination. Radio-graphs (particularly oblique views) are necessary to confirm the diagnosis. Management of acute symptoms remains conservative, with bed rest and analgesics. Recurrent and increasingly severe symptoms with or without neurologic involvement and continuing radiographic evidence of slippage warrant surgical decompression or fusion.
C. Facet Tropism and Transitional Vertebra : Normally, the facets are symmetrically aligned at each vertebral level. Facet tropism occurs with asymmetry, adding rotational stresses to the joint. Asymmetric stress resulting from unilateral transitional vertebra (Bertolotti's syndrome) often causes a herni-ated nucleus pulposus one level above the sacralized or lumbarized segment. Both are diagnosed by radiography. When conservative measures fail, spinal fusion with or without decompression may be of benefit.
D. Compression Fractures : Compression fractures often result from trauma and are diagnosed by radiographic examination. The level and degree of injury determine the degree of neurologic involvement and the necessity for thorough and repeated neurologic examinations. The possibility of cancer or osteoporosis should be considered in patients with a history of fractures resulting from trivial trauma. Stable injuries respond to bed rest and conservative care; unstable ones require longer periods of bed rest and orthotic or surgical treatment (or both).
E. Untreated SCOliosis : Uncorrected scoliosis in adults can cause back pain. After skeletal maturity has been achieved, spinal curves can progress up to 2 degrees per year and up to 8 degrees per pregnancy or period of exogenous hormone use. Degenerative changes develop more rapidly. Symptomatic treatment may be helpful. Adult patients with progressive symptoms of pain in the area of the deformity may get relief from operative treatment.
F. Osteoporosis : Osteoporosis is the most common metabolic disorder causing back pain.
Miscellaneous Causes of Low Back Pain
Other causes of back pain not accompanied by radiographic abnormalities include aneurysms, visceral disorders, and functional problems.
A. Aneurysms : Atherosclerosis of the aorta, resulting in abdominal aneurysm of the terminal aorta, gives rise to back pain similar to that of herniated nucleus pulposus or neoplasm. Deep, boring and writhing pain in the lumbar or pelvic region and a pulsating abdominal mass suggest the diagnosis. Thrombotic occlusion of the terminal aorta, with or without associated aneurysm, may produce pain in the buttocks, thighs, or legs, with fatigue, weakness, or muscle atrophy along with male impotence; persistent peripheral pulses may still be present. Vascular surgery may provide symptomatic relief.
B. Visceral Disorders : Gastrointestinal and genitourinary disease may be a source of back pain. Pancreatic disease and duodenal ulcer may give rise to left thoracolumbar and midback pain. Flank pain can be caused by renal disease. Lumbosacral pain can be due to prostatitis, gynecologic disorders (pelvic inflammatory disease, uterine fibroids, and endometrisis), and retrocolic processes.
C. Functional Disorders : Complaints of a tired and weak back with pain (not necessarily severe) and no objective findings may suggest a psychologic problem. Hysterical back pain may be severe and dramatically exaggerated. A history of domestic or work-related problems and observation of a flat affect with a bizarre reaction to treatment will further suggest the disorder. Treatment may include reassurance and judicious use of mild analgesics and sedatives. Chronicity of complaints is common, and psychiatric referral may be necessary.
The patient with compensatory back or neck pain may be interested in monetary gain, whereas the ma-lingerer seeks a conscious real or imagined secondary gain. Subjective complaints in both types of patients are out of proportion to objective findings. The experienced clinician can often identify the malingerer or the patient with compensatory back or neck pain. These diagnostic impressions should not be conveyed to the patient. It is best to state simply that no organic disorder can be found that explains the patient's symptoms.
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