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Focus on...Sciatica

Sciatica is defined as pain radiating down the sciatic nerve. It is characterized by either a sharp or dull aching pain that begins in the buttock and radiates down the thigh into the calf, ankle, and foot. Although the pain does not necessarily have to be present in the foot, true sciatic pain should be present below the knee.

The most common cause of sciatica is a herniated disc compressing a nerve that makes up the sciatic nerve. Other causes include sacroilitis, facet pain syndrome, piriformis syndrome, iliolumbar syndrome, and lumbar spinal stenosis. All of these conditions can cause irritation of the sciatic nerve.

The most common cause of sciatica is related to lumbar disc herniations compressing the nerves that comprise the sciatic nerve. As we age, the outer elastic covering of the intervertebral disc, the annulus fibrosis, degenerates and becomes thinner and weaker. Trauma can cause cracks or tears in the outer layers of the discs. If the tear is large enough the central gelatinous semi-solid nucleus pulposis can leak out, causing pressure or chemical irritation of the spinal cord or nerves supplying the sciatic nerve.

The diagnosis for sciatica can be made without any radiological investigations. The history of the problem and the distribution of the pain are usually enough for physicians to make the diagnosis. In fact, most physicians will treat this condition so frequently that they begin medical therapy without ordering any tests.

If the symptoms do not resolve with standard medical interventions or they linger beyond 4 weeks in duration then a magnetic resonance image (MRI) should be obtained. This radiological study can easily demonstrate the anatomy of the lumbosacral spine and nerve roots. It has become the main diagnostic tool for sciatica. In patients with pacemakers an MRI cannot be performed and therefore a myelogram with computed tomographic follow-up is the study of choice.

Over 80% of patients with sciatica related to herniated discs get better without surgery. Although bed rest was previously thought to be important for recovery, newer evidence suggests that this is not the case. Activity should be limited only to activities that do not irritate the pain. Walking is allowed provided it does not exacerbate the symptoms.

The mainstay medical therapy for this problem is non-steroidal anti-inflammatory medications such as Motrin or Advil. These medications target the chemical irritation of the nerves. Sometimes physicians will also prescribe oral steroids such as solumedrol or dexamethasone. These can also be supplemented with muscle relaxants and narcotics for pain relief.

Treatment using medication for sciatica should be considered a short-term therapy. Its goal is to eliminate the acute inflammation of the nerve. Over time, the herniated fragment will sometimes dehydrate and shrink further relieving the pressure and irritation on the nerve. If these medications fail to relieve symptoms after four weeks other therapies need to be considered, such as epidural steroid injections, physical therapy, and surgery.

After the acute inflammation has decreased, many patients will require physical therapy to maximize their recovery, return them quickly to previous functioning levels and prevent future injuries.

--Mark R McLaughlin MD practices neurosurgery in Springfield, Holyoke, and Greenfield, MA

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