Lumbar Disc Herniation & Sciatica
A lumbar disc herniation (herniated disc) is a rupture and/or bulge of an interverterbral disc in the low back. The intervertebral disc is a complex spongy structure which consists of a central sticky gelatinous portion, the nucleus, and an outer fibrous ring of tissue, the annulus. These discs are found along the entire spine from the neck all the way down to the lowest part of the back. The function of this disc is to permit motion of the spine while also acting as a shock absorber and connecting link between each vertebral body. The outer layer, the annulus, may actually tear and result in extrusion or bulge of the inner part of the disc, the nucleus. This is called a disc herniation.
The nerve may become irritated either as a result of chemical reaction to an injured disc and/or to compression from the herniated disc itself. The space in which nerves normally sit is quite small and there is not much free space. The symptoms from this irritation can range from numbness, tingling and pain to bladder dysfunction, weakness and even partial paralysis. The particular area of the body which is affected depends upon which nerve is being irritated by the herniated disc.
The four stages to a herniated disc include:
1. Disc Degeneration - chemical changes associated with aging causes discs to weaken, but without a herniation.
2. Prolapse- the form or position of the disc changes with some slight impingement into the spinal canal. Also called a bulge or protrusion.
3. Extrusion - the gel-like nucleus pulposus breaks through the tire-like wall (annulus fibrosus) but remains within the disc.
4. Sequestration or Sequestered Disc - the nucleus pulposus breaks through the annulus fibrosus and lies outside the disc in the spinal canal (HNP).
Disc herniations usually occur in the young adult population, age 20-50. Approximately 90% of disc herniations will occur in low back at L4-L5 or L5-S1. L5 nerve impingement can cause weakness in extension of the big toe and potentially in the ankle (foot drop). Numbness and pain can be felt on top of the foot, and the pain may also radiate into the buttocks. S1 nerve impingement may cause loss of the ankle reflex and/or weakness in ankle push off (e.g. patients cannot do toe rises). Numbness and pain can radiate down to the sole or outside of the foot.
Lumbar Radiculopathy (Sciatica)
Lumbar Disc Herniation Treatment
The first line of treatment is almost always non-surgical. The exception is when there is bladder or bowel incontinence or progressive weakness. A vast majority of patients suffering from leg pain will naturally recover given time and non-operative treatment. Non-operative treatments include strengthening exercises, physical therapy, chiropractic, acupuncture, traction, epidural injections, pain medications, and anti-inflammatory medications including steroids.
For buttock or leg pain and mild weakness (radicular symptoms), generally at least 6 weeks of non-operative treatment is pursued to monitor for natural recovery. The waiting period is based on the knowledge that 80-90% of radicular symptoms are known to spontaneously recover. If recovery is progressing, more non-operative treatment may be prescribed.
For isolated low back pain, generally at least 6 months of non-operative treatment is pursued to monitor for natural recovery. The waiting period is based on the knowledge that most midline low back pain is known to spontaneously recover within 6 months.
Surgical treatment may be suggested to treat pain that has not responded to non-operative treatment or if there is severe neurologic deficit such as bowel or bladder incontinence or progressive weakness in vital muscle groups. With the exception of the presence of severe neurologic deficits, the decision to proceed with surgery is a quality of life decision.
Surgical options for a lumbar disc herniation are listed below. These surgical options often include a combination of surgical treatments (i.e. decompression, fusion, instrumentation). For a detailed explanation of the individual treatments, please visit the Surgical Treatments section of the web site.
1. Lumbar Laminotomy/Foraminotomy:
This procedure is used to remove part of the lamina and overgrown facet joint to relieve unilateral leg symptoms and is usually performed with the aid of magnification (either surgical loupes or microscope). Lumbar laminotomy/foraminotomy is the most commonly performed procedure for a standard posterolateral disc herniation.
2. Minimally Invasive Procedures:
Posterior foraminotomy can be performed through tubes and with the use of endoscopes. Laser decompression and disc removal have also been performed with mixed results.
3. Far Lateral Discectomy:
If the disc herniation occurs far lateral (occurs in approximately 10% of all disc herniations), this procedure is often necessary to relieve the pressure on the exiting nerve root.
4. Lumbar Laminectomy/Foraminotomy:
With this procedure, the lamina and overgrown facet joints are removed to make room for the nerves. This is the most common treatment for lumbar stenosis where there is bilateral buttock/leg symptoms.
Lumbar Disc Herniation Case Study
38 year old laborer who had the immediate onset of left leg burning pain and weakness after lifting a heavy load. He had onset of some bladder incontinence (which is a surgical emergency).
Images A and B show the very large L4-5 lumbar disc herniation with marked impingement on the neural canal.
The patient underwent emergent microdiscectomy. He had improvement of his bladder incontinence and improvement of his leg burning pain and weakness. He did have some residual weakness and persistent pain due to the large size of the disc herniation and probable permanent nerve impingement.
Images C and D show a post-operative MRI scan which reveals removal of the large disc herniation. Note how the disc signal continues to be abnormal, since the disc cannot be returned back to ‘normal’. Although most patients have marked improvement of their leg pain, this patient did develop persistent back and leg pain that required further treatment.