Doctor's Notes on Sciatica
Sciatica refers to a type of is nerve pain from irritation of the sciatic nerve, the largest nerve in the body. The sciatic nerve begins from nerve roots in the spinal cord in the low back and passes through the buttock and branches down the lower limb. Sciatica is most commonly caused by lumbar disc herniation, but any condition that irritates or causes inflammation of the sciatic nerve can lead to the symptoms of sciatica.
Characteristic signs and symptoms of sciatica include burning pain that radiates from the lower back and upper buttock down the back of the thigh into the back of the leg. Numbness and tingling may also be present. Associated symptoms can include hip pain if the pain radiates around the hip or buttock and low back pain. In severe cases, walking may be difficult. Sometimes, symptoms are relieved by lying down.
The most common symptom from sciatica is pain. Most people describe a deep, severe pain that starts low on one side of the back and then shoots down the buttock and the back of the thigh with certain movements. The medical term for nerve pain caused by a pinched nerve in the spine is radiculopathy. Sciatica can also cause knee pain, hip pain, and foot pain. Often there is muscle spasm in the low back or leg, as well.
- Sciatica pain is usually worse with both prolonged sitting and standing. Frequently, the pain is made worse by standing from a low sitting position, such as standing up after sitting on a toilet seat.
- In most people, sciatic pain is made worse by sneezing, coughing, laughing, or a hard bowel movement. Bending backward can also make the pain worse.
- People may also notice a weakness in their leg or foot, along with the pain. The weakness may become so bad they can't move their foot.
Sciatica is caused by irritation of the sciatic nerve. Usually, there is no specific injury that is related to the onset of sciatica. Occasionally, the pain will suddenly begin after lifting something heavy or moving quickly. The following are causes of sciatica:
- A herniated disc (sometimes called a slipped disc): Disc herniation is the most common cause of sciatica. When a disc herniates near the spinal nerve roots that form the sciatic nerve, it can cause pressure on the nerve, or irritation, which results in the symptoms of sciatica.
- Discs are the cushions between the bones in the back. They act like "shock absorbers" when we move, bend, and lift. They are the size and shape of checkers.
- There is a tough ring around the outside of each disc and a thick jellylike center inside (called a nucleus pulposus). If the outer edge of the disc ruptures, the center can push through and put pressure on the sciatic nerve, leading to the pain of sciatica (referred to as a herniated nucleus pulposus).
- Lumbar spinal stenosis, a narrowing of the canal that contains the spinal cord: With age, the bone can overgrow and put pressure on the sciatic nerve. Many people with spinal stenosis have sciatica on both sides of the back.
- Spondylolisthesis, a condition in which one backbone has slipped forward or backward over another backbone, can result in pressure on the sciatic nerve.
- A pinched or stretched sciatic nerve
- Piriformis syndrome can cause the sciatic nerve to become trapped deep in the buttock by the piriformis muscle. The symptoms of piriformis syndrome are the same as those of sciatica. Sciatica can also be caused by the nerves being pinched by osteoarthritis and fractures due to osteoporosis.
- Sciatica can also be caused by other effects of aging, such as osteoarthritis and fractures due to osteoporosis.
- Many women experience sciatica during pregnancy.
- Symptoms of sciatica can be caused by carrying large wallets or other hard objects such as golf balls in the back pocket of pants, or sitting on a hard surface for an extended period of time.
- Rarely, sciatica is a symptom of a far more serious diseases, such as a tumor, blood clot, or an abscess (boil).
Sciatica is a pain that radiates from the low back down a lower extremity; it is caused by irritation of the sciatic nerve. The sciatic nerve transmits sensation from the lower extremities and lumbar area of the low back. It is common for people to recover from sciatica without a surgical operation.
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Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.