Sciatica – All you wanted to know

Sciatica is a symptom in which there is pain, tingling, numbness or weakness in the lower back and/or legs. Sciatica is caused by pressure to, or injury to the Sciatic Nerve. Sciatica is not a medical disorder by itself rather a symptom due to an underlying medical condition.

A Brief Introduction to the Sciatic Nerve

The sciatic nerve is the largest nerve in our body. It starts from the lumbar spine (lower back), runs in the region of the buttocks, down to the back of our thigh and behind the knee onto our calf muscles at the back of the leg. There are two sciatic nerves in the body, one for each limb. The pain of the sciatic nerve is called sciatica and includes lower back pain, buttock pain, hip pain, thigh pain and leg pain.

Causes of Sciatica

The most typical cause is compression of the nerve due to a herniated intervertebral disc (slipped disc). A disc is like a flat cushion between two vertebrae to prevent them from rubbing against each other. When the disc slips from its original place it puts pressure on the adjoining structures, especially nerves that originate from the spinal column. It is called a pinched nerve and is seen in conditions like slipped disc and spinal stenosis (narrowing of the spinal canal).

Anything that irritates the nerve can cause sciatica. Infection, pelvic injury or fracture, tumours, irritation from adjacent bone and even irritation of the nerve during pregnancy are sometimes responsible.

Signs and Symptoms of Sciatica:

• Pain in the region of the buttocks and extending to the back of the thigh, knee and onto the back of the leg is the most common complaint.
• Lower back pain (lumbago) is a feature but may not always be present.
• Weakness of the affected leg, tingling, numbness and a burning sensation are other symptoms. It may affect one or both legs.
• Swelling at the back of the spine with or without redness and tenderness.
• Pain is worse at night, aggravated by walking or bending and may be relieved by lying down.
• The pain may be mild or unbearable. Sometimes the pain is treated completely but may return.

Diagnosing Sciatica

A detailed history of pain in the region of the affected nerve and a physical examination, which includes SLR (straight leg raising) and other manoeuvres points to the diagnosis. In the SLR test, a person with sciatica will complain of pain and cannot raise the leg to 90 degrees.

Investigations for sciatica will include:

• A CT scan, MRI or Electromyogram (to determine the state of the muscles) may be advised according to the cause suspected.
• Blood tests like CBC and ESR may point to an infection.

Treatment for Sciatica:

• Bed rest is not recommended as it does not appreciably lessen the pain. Changing the position may offer partial or total relief. Avoid pressure on the buttocks as this may irritate the nerve further.
• When the pain begins, a cold compress must be applied to the area for the first 48 hours, after which a heat compress should be applied.
• Avoid bending at the waist, lifting heavy weights and walking long distances.
• Analgesics like NSAID’s (nonsteroidal anti-inflammatory drugs) help in pain management. If they are ineffective, ask your doctor for alternatives.

Preventing Sciatica

Risk factors like degenerative arthritis of the lumbar spine and a slipped disc should be promptly treated. Injury to the lower spine or pelvis during sports or accidents should be minimised.