Lumbar disc herniation
Lumbar disc herniation is displacement of nucleus pulposus material through a defect in the annulus fibrosus that compresses an exiting lumbosacral nerve root, most often at L4-L5 or L5-S1, causing radicular leg pain (sciatica) diagnosed clinically by a positive straight-leg raise and confirmed by MRI when surgery or red-flag findings are in question.
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What this article covers
- Overview
Displacement of disc material that compresses a nerve root: lumbar disc herniation occurs when nucleus pulposus extrudes through a tear in the annulus fibrosus and impinges on an exiting or…
- Epidemiology
One of the most common identifiable causes of low back pain, alongside spinal stenosis and vertebral compression fracture, though most low back pain remains nonspecific; see low back pain.
- Risk factors
Repetitive lifting, twisting, or axial loading, particularly with poor lifting mechanics, the dominant modifiable mechanical risk factor.
- Pathophysiology
The disc's nucleus pulposus is contained by the surrounding annulus fibrosus; repetitive stress and degeneration weaken the annulus, most often posterolaterally where it is thinnest.
- Clinical features
Sciatica, sudden severe electric-like pain radiating down the leg past the knee, often preceded by weeks to months of milder aching axial back pain, is the hallmark presentation, distinguished from…
- Differential diagnosis
Cauda equina syndrome: bowel/bladder dysfunction, saddle anesthesia, and decreased anal sphincter tone with bilateral progressive deficits, unlike the unilateral radicular pattern of herniation; a…
- Diagnosis
Lumbar disc herniation with radiculopathy is a clinical diagnosis established by sciatica past the knee with a positive straight-leg raise (ipsilateral, sensitive; contralateral/crossed, specific)…
- Management
First, in a classic presentation without red flags, start an NSAID and advise the patient to remain active rather than resting in bed, since prolonged bed rest delays recovery: naproxen 500 mg PO…
- Complications
Cauda equina syndrome: the most feared complication of a large central or bilateral herniation, causing permanent bowel, bladder, and lower-extremity dysfunction if decompression is delayed.
- Prognosis
Favorable in most cases: radicular pain improves substantially within weeks with conservative management, and many herniated fragments regress spontaneously.
- Prevention
Maintain core and paraspinal strengthening 2-3 times weekly to support the lumbar spine and reduce recurrence.
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Related articles
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Low back pain is a symptom, not a single disease; roughly 90% is nonspecific mechanical pain treated with education, activity, and first-line NSAIDs, diagnosed by excluding red-flag features with imaging reserved for suspected fracture, infection, cancer, or neurologic compromise.
- Cauda equina syndrome
Cauda equina syndrome is compression of the lumbosacral nerve roots below the spinal cord causing saddle anesthesia, bladder or bowel dysfunction, bilateral leg weakness with areflexia, and low tone, most often from a large central lumbar disk herniation. It is a surgical emergency diagnosed by emergent MRI of the lumbar spine and treated with urgent decompression.
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Spinal epidural abscess is a suppurative infection of the spinal epidural space, most often hematogenous Staphylococcus aureus, presenting with fever, focal spinal pain, and, if missed, progressive weakness. The diagnosis is established by emergent MRI with contrast. Treatment is empiric intravenous vancomycin plus ceftriaxone or cefepime, with emergent surgical decompression whenever a neurologic deficit is present.