The human spine is constructed of vertically-stacked blocks of bone (vertebral bodies) that are separated by cushions (disks) composed of a soft center (nucleus pulposus) surrounded by a tough, fibrous outer ring (annulus fibrosis).
With age or injury, the annulus fibrosis weakens and sometimes tears. The nucleus pulposus may then protrude (herniate) through the defect in the annulus and press against surrounding structures.
When a herniated nucleus pulposus (“ruptured disk”) compresses the spinal cord or one of the nerves surrounding the spinal cord, it can cause neurologic deficits and generate pain that spreads outward from the point of herniation.
Herniated Lumbar Disks Are at the "Root" of Sciatica
Acute herniation of a lumbar disk often leads to sciatica (pain that radiates from the lower back and into the thigh) because the nucleus pulposus presses against one of the roots of the sciatic nerve that supplies the leg.
Sciatica is not always caused by a herniated disk; only 4% of persons with acute low back pain and sciatica have a detectable disk herniation when they undergo CT or MRI. Furthermore, injured disks don’t always cause symptoms, for many people without discomfort exhibit evidence of degenerative disks when radiographic studies are performed for reasons other than back pain.
However, although a degenerative disk doesn’t always cause symptoms, 99% of patients who have acute low back pain and who have documented disk herniations also complain of sciatica. (Kerr R, et al. "The value of accurate clinical assessment in the surgical management of lumbar disc protrusion." J Neurol Neurosurg Psychiatry. 1988;51[2]:169-73)
Conservative Management of Herniated Lumbar Disks
A variety of nonsurgical modalities have proven useful for treating the symptoms of acute lumbar disk herniation and sciatica; 90% of patients improve within six to 12 weeks, using the following treatments alone or in combination:
- Nonsteroidal anti-inflammatory (NSAID) medications
- Opioid (narcotic) medications
- Defined activity (bed rest is avoided, as it contributes to muscle deconditioning)
- Physical therapy (commonly employed, but little evidence supports its effectiveness for decreasing pain or improving functional status)
- Therapeutic ultrasound
- Transcutaneous electrical nerve stimulation
- Spinal manipulation (studies show conflicting efficacy, and some patients are at risk of disk extrusion during manipulation, but others show significantly improved pain scores)
- Invasive but nonsurgical procedures include injections of corticosteroids into the disk itself or the space surrounding the herniated nucleus pulposus
(Adapted from Gregory D, et al. "Acute lumbar disk pain: navigating evaluation and treatment choices." Am Fam Phys. 2008;78[7]:835-42)
In the absence of “red-flag” findings (see below) that indicate more serious underlying problems, conservative management should be continued for at least six weeks.
Surgical Management of Herniated Lumbar Disks
Although conservative management is first-line therapy for most patients with acute low back pain, certain "red-flag" findings and conditions indicate a need for immediate radiologic evaluation and, potentially, prompt surgical intervention:
- Urinary retention (inability to empty the bladder)
- Fecal incontinence (inability to control bowel)
- Saddle anesthesia (loss of sensation across the lower back and buttocks)
- A history of immunosuppression, intravenous drug abuse, or chronic corticosteroid use
- Unexplained fever
- Known osteoporosis
- Significant trauma
- A history of cancer or current unexplained weight loss
- Focal neurologic deficit on physical examination
- Progressive or disabling symptoms
Patients who haven’t improved after six weeks of conservative treatment usually undergo CT or MRI to detect “surgical lesions” that coincide with their symptoms. The decision to proceed to surgery or continue conservative measures depends on radiologic findings and the patient’s level of function.
Surgery is intended to relieve nerve root compression or irritation caused by herniated disk material. This material can be removed via open diskectomy, which involves the creation of an incision over the lumbar spine through which the disk is removed, or microdiskectomy, which involves the removal of the offending disk material through a surgical microscope.
Although surgery may lead to more rapid and dramatic improvement for patients with lumbar disk herniation and sciatica, it is important to remember that pain and disability two years after surgery are indistinguishable from pain and disability following prolonged conservative treatment.
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