A 55-year-old man complains of a 4-month history of lower back pain that is worsened by walking and relieved by lying down. He denies back trauma, heavy lifting, or urologic abnormalities. He states that at times the pain radiates to the back of his right leg. On examination, his blood pressure is 130/84 mm Hg and pulse rate 80 beats/min; he is afebrile. He is slightly overweight. The findings from his heart and lung examinations show no abnormalities. The back is without scoliosis. Raising either leg reproduces the pain, which radiates to the right leg. The results from the neurologic examination are normal.
What is the most likely diagnosis?
What is the best test to confirm the diagnosis?
ANSWERS TO CASE 52: Lumbar Prolapsed Nucleus Pulposus
Summary: A 55-year-old man complains of a 4-month history of lower back pain radiating to the right leg, which is worsened by walking and relieved by lying down. He denies trauma to the back, heavy lifting, or urologic abnormalities. He is slightly overweight. The back is without scoliosis. Raising either leg reproduces the pain, which radiates to the right leg. The neurologic examination is normal.
• Most likely diagnosis: Lumbar prolapsed nucleus pulposus.
• Best diagnostic step: Magnetic resonance imaging (MRI) or myelography.
1. Know the differential diagnosis for lower back pain.
2. Know the typical clinical presentation of lumbar prolapsed nucleus pulposus.
3. Understand that MRI and myelography are the imaging tests that confirm the diagnosis.
This 55-year-old man complains of lower back pain with radiation to the right leg. The pain is worse when walking and during straight leg raising. This is typical of herniated lumbar pulposus related to compression of the intervertebral disk causing impingement of the nerve root, typically at the L4-5 level. There is usually paresthesia or radiation of the pain in the leg, usually posterior and/or lateral. MRI is a very accurate test for evaluating the spinal cord and nerve roots.
APPROACH TO: Lower Back Pain
MECHANICAL BACKACHE: Usually chronic and may result in a long-term debilitating illness without any definite or demonstrable cause. Back sprains are usually associated with minor trauma producing ligamentous or muscular injury.
ENTRAPMENT NEUROPATHIES: Involve compression of a nerve, such as that produced in sciatica, when a prolapsed intervertebral disk applies pressure to an adjacent nerve in the lumbosacral plexus.
CAUDA EQUINA SYNDROME: Compression of the sacral nerve bundle, which forms the end of the spinal cord, with symptoms of bladder or bowel dysfunction and/or pain or weakness in the legs. This disorder should be diagnosed at an early stage to avoid permanent injury.
Because lower back pain is so common, it is of fundamental importance to differentiate significant from insignificant pain and thus to prevent the onset of chronicity. Spinal pain can be local or referred, or can occur along the distribution of nerves. Osteoarthritis and rheumatoid arthritis are associated with conditions such as spinal stenosis, spondylolisthesis, or ankylosing spondylitis that may cause chronic back pain.
Herniation of the nucleus pulposus, the softer inner part of an intervertebral disk, through the outer tough annulus fibrosus causes compression of adjacent nerves emanating from the spinal canal. On occasion, fragmentation of the disk may occur without protrusion of the nucleus pulposus; the annulus itself then protrudes. This condition may cause severe pain, weakness, and sensory loss. The problem may also be caused by the protrusion of osteophytes, bony spurs that occur in osteoarthrosis of the spine. Ultimately, spinal stenosis may develop.
With disk prolapse, the severity of symptoms may vary from mild, localized back pain to urgent cauda equina compression, resulting in the loss of motor and sensory function. The L4-5 and L5-S1 intervertebral disks are the most commonly involved; thus, pain down the posterior or lateral leg is characteristic (sciatica). Back pain frequently radiates into the buttock, posterior thigh, or calf. Coughing, sneezing, or straining tends to increase the pain. Other exacerbating factors are bending, sitting, and getting in and out of a vehicle, whereas lying flat characteristically relieves pain. Caudal equina compression may affect bladder and bowel function, and spinal stenosis may produce pain that radiates down both legs.
The paravertebral muscles are often in spasm, and there is loss of the normal lumbar lordosis. Straight leg raising is limited on the side of the lesion, and dorsiflexion of the foot at the limit of straight leg raising often exacerbates the discomfort. There may be tenderness to palpation of the central back or buttock. Sensory loss and muscular weakness may be present along the appropriate dermatomes; ankle or knee reflexes may be absent. The differential diagnosis includes fracture; joint subluxation; tumors of the bone, joint, or meninges; abscess; arachnoiditis; ankylosing spondylitis; rheumatoid arthritis; aortic occlusion; and peripheral neuropathies. MRI may demonstrate the disk protrusion, and plain radiographs of the lumbosacral spine may show narrowing of the intervertebral space, but these modalities cannot establish a definitive diagnosis.
Bed rest, the application of either heated pads or ice packs, administration of nonsteroidal anti-inflammatory drugs and muscle relaxants, and/or physical therapy represent the first line of conservative management. A back brace or corset may help the patient through the early stages of mobilization. The indications for surgical decompression are the development of an acute disabling neurologic deficit (bladder dysfunction) or intractable severe pain. A large multicenter randomized trial (SPORT [Spine Patient Outcomes Research Trial]) failed to show superior efficacy of surgery versus conservative therapy, with a large fraction of patients in both intervention groups improving over the 2-year study period.
After the site of the disk prolapse is precisely identified, surgery involves laminectomy and removal of the protruding disk. The overlying stretched nerve may show erythema and narrowing, and great care must be exercised in removing the offending protruding disk from underneath this nerve. If several disk spaces are involved, posterior spinal fusion in addition to removal of the disks may be indicated. This form of surgery has been performed with increasing frequency in recent years, using a minimally invasive approach with short incisions, meticulous and specific removal of the disk, and early mobilization. The results of surgery are excellent. Techniques under review are dissolution of the disk by the injection of chemicals, and sometimes steroid injections in the region of the disk may be helpful in the short term.
52.1 A 54-year-old man has lower back pain of 3 weeks’ duration that has not diminished with rest. He is diagnosed with a “herniated disk.” Which of the following describes the most common location of herniated disks in the lumbar spine region?
52.2 A 47-year-old woman complains of lower back pain with radiation to the right leg, and she is treated with ibuprofen and bed rest. Over the next 3 weeks, the patient’s pain worsens, and she complains of difficulty with voiding and bowel movements. Which of the following is the most likely diagnosis?
A. Spinal stenosis
B. Lumbar neoplasm
C. Cauda equina syndrome
D. Tuberculosis of the spine (Pott disease)
E. Compression fracture
52.3 A 56-year-old mailman is diagnosed with probable lumbar prolapsed nucleus pulposus. Which of the following is most consistent with his diagnosis?
A. Pain in the lower back radiating down the anterior thigh
B. Decreased patellar deep tendon reflex
C. Pain worsened with Valsalva
D. Decreased sensation in the medial thigh and weakness of the adductor muscles of the lower leg
E. Bilateral lower extremity paralysis
52.1 D. Herniated nucleus pulposus commonly impinges on the nerve roots in the lower lumbar or upper sacral region. Typically the symptoms will improve with bedrest. The L4-5 interspace is most commonly affected.
52.2 C. The bowel and bladder complaints are typical of cauda equina syndrome. Cauda equina involvement is usually a surgical emergency because permanent nerve damage can ensue without prompt correction.
52.3 C. Pain of lumbar disk disease is worse with Valsalva, straight leg raising, and the sitting position. The pain typically radiates from the back to the posterior or lateral leg, and not typically the anterior leg.
The most common locations of herniated lumbar disk disease are at the L4-5 and L5-S1 levels.
Bowel and bladder complaints with lower back pain are suggestive of cauda equina syndrome, which must be diagnosed early to avoid permanent damage.
The initial treatment for herniated lumbar pulposus is bed rest and the administration of nonsteroidal anti-inflammatory agents.
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Smith ML, Bauman JA, Grady MS. Neurosurgery. In: Brunicardi FC, Andersen DK, Billiar TR, et al, eds. Schwartz’s Principles of Surgery. 9th ed. New York, NY: McGraw-Hill; 2010:1515-1556.
Weinstein JN, Tosteson TD, Lorie JD, et al. Surgical versus nonoperative treatment for lumbar disk herniation. The Spine Patient Outcomes Research Trial (SPORT): a randomized trial. JAMA.