LOW BACK PAIN
I. Definition
A. Low back pain (LBP) is any pain perceived by the patient as originating from the lumbosacral region of the spinal column.
B. Pain usually in the lower back that causes discomfort, limited range of motion, varying degrees of neurologic symptoms, and inability to participate in or perform activities of daily living
C. May be localized or may radiate to lower extremities
D. LBP is the leading cause of lost workdays in the United States and costs the U.S. economy approximately $1 billion/year.
E. It is important to distinguish the causes of back pain because each back syndrome presents with varying symptoms, and treatment options differ for each of the four major syndromes:
1. Back strain
2. Disk herniation—See next section, Herniated Disk.
3. Osteoarthritis/disk degeneration: osteophyte (bone spur) formation of vertebral bodies
4. Spinal stenosis: narrowing of the spinal foramen leading to encroachment on spinal nerve roots
II. Etiology/incidence/predisposing factors
A. Most Americans experience LBP at least once in their lives.
B. Common causes include the following:
1. Mechanical strain
2. Obesity
3. Poor body mechanics
4. Trauma
6. Herniated lumbar disks
7. Spondylolysis: defect in neural arch of vertebral body
8. Spondylolisthesis: forward subluxation of vertebral body due to defect in the neural arch of the vertebral body
9. Spinal stenosis: narrowing of the spinal canal or the foramen in which spinal nerves exit the spinal cord
10. Degenerative disk disease
11. Osteoarthritis of the spine
12. Metastatic or primary tumors
13. Rheumatologic diseases such as ankylosing spondylitis
III. Subjective findings
A. Pain in lower back region; may include radicular (radiating) component in affected nerve dermatome
B. Numbness along specific dermatome
C. Bowel, bladder, or sexual dysfunction
1. If present, bowel/bladder dysfunction requires immediate referral for possible emergency surgical intervention.
D. Cauda equina syndrome: gradual to sudden weakness and/or inability to lift or move legs; bowel and/or bladder incontinence or retention; and loss of or diminished sensation in legs
1. May be first symptom of spinal cord compression from metastatic lesion to spine
2. Cauda equina syndrome is a surgical emergency and requires emergency referral.
IV. Physical examination findings
A. Back strain: paraspinal muscle spasms, listing to one side, decreased range of motion (ROM), positive bilateral straight leg raise test
1. Straight leg raise: With the patient in supine position, lift one leg at a time, forcefully dorsiflex the foot, and ask the patient if there is pain down the leg (radiculopathy).
2. Crossover straight leg raise: If the patient has a herniated disk, the crossover straight leg raise test will cause radicular pain down the affected leg, even if the other leg is raised.
3. Simultaneous bilateral straight leg raise: This test reproduces the back pain but does not cause radicular pain.
B. Herniated disk—See next section, Herniated Disk.
C. Osteoarthritis: decreased ROM, muscle spasm, possible positive bilateral straight leg raise, but rarely with radicular component
D. Spinal stenosis: often called “neurogenic claudication”; caused by back, buttock, and leg pain during ambulation
1. Pain is relieved with rest and sitting: thought to be relieved by sitting when the spine is flexed and the spinal nerve roots have less compression and more room in which to traverse the spinal foramen
E. Weak rectal tone
V. Laboratory/diagnostic findings
A. Serum blood work usually within normal limits, except in cases where underlying rheumatologic diseases exist
B. Plain x-rays (anteroposterior [AP] and lateral) to rule out bony defects; scoliosis, bone spurs
C. MRI best for soft tissue structures; reveals disk bulge
D. CT scan for detailed bony imaging
E. Myelography of spine with or without CT scan to show filling defects along spinal nerve roots
VI. Management
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A. Nonsurgical
1. Rest for 1 to 2 days only
2. Alternated ice/heat therapy
3. NSAIDs for mild to moderately severe injuries
a. Act by inhibiting the enzyme cyclooxygenase (COX), which is required for the synthesis of prostaglandins and thromboxanes
i. Two isoforms have been identified: COX-1 and COX-2.
ii. COX-1 is found tissue-wide and is believed to protect gastric mucosa.
iii. COX-2 is induced primarily at the inflammation site.
b. Older NSAIDs act by blocking both COX isoforms, leading to possible gastric ulceration. COX-2 drugs are selective, thus providing greater gastric protection.
c. Rofecoxib (Vioxx), 12.5-25 mg PO daily
d. Celecoxib (Celebrex), 100-200 mg PO twice daily
e. Concurrent use of zafirlukast, fluconazole, and fluvastatin may increase serum concentration of celecoxib.
4. May need antispasmodic for severe muscle spasms
a. Diazepam (Valium), 2-10 mg every 6 to 8 hours as needed
b. Cyclobenzaprine (Flexeril), 10 mg PO 3 times a day as needed
c. Metaxalone (Skelexin), 800 mg PO 3 or 4 times a day as needed
5. Opioids may be needed for short-term acute back strain to promote mobility.
6. Physical therapy for toning, strengthening muscles
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