Symptoms


Low back pain can be divided into two main types:

• Mechanical Type pain

• Compressive Type pain


Mechanical type back pain results from inflammation caused by irritation or injury to the disc, the facet joints the ligaments or the muscles of the back. A common cause of mechanical pain is disc degeneration. A typical muscle strain, or lumbar strain, can also be the cause of mechanical type symptoms. Mechanical type back pain usually starts near the lower spine. Mechanical type pain may also spread to include the buttock and thigh areas. It rarely extends below the knee.


Compressive or neurogenic (meaning nerve related) type pain occurs when the nerve roots that leave the spine are irritated or pinched. A common cause of compressive pain is a herniated disc. The nerves that leave the lower lumbar spine join to form the sciatic nerve. This nerve provides sensation and controls the muscles of the lower leg. Pressure or irritations on the nerve roots of the lumbar spine that come together to form the sciatic nerve can interfere with the normal function of the sciatic nerve. One of the earliest signs of pressure on a nerve root is numbness in the area supplied by the nerve. Pain is commonly felt in the same area, usually extending below the knee to the foot. In cases where there is pressure on a nerve root as it comes out of the spine, it is not unusual for the back itself to be painless. This can be confusing at times since there is no back pain but the problem is located in the lumbar spine. Finally, the muscles that the nerve controls may become weak and the reflexes may disappear. This is because the pressure on the nerve roots interferes with the signals from the brain to the muscles. There is no signal going from the brain to the muscle to tell it to contract.


Spinal stenosis can also cause compressive type pain. In some people, degeneration of the spine can result in a narrowing of the spinal canal—the bony tube where the spinal nerves are located. This causes all of the nerves within the spinal canal to become inflamed, and fail to work properly. One problem that occurs when the tube is too small, is that the nerves can not get enough blood supply to work properly. The nerves may be normal when the body is at rest, but once it is active the nerves need more blood flow to get more oxygen. If the tube is too tight, the blood supply cannot increase. One of the symptoms of this cause is numbness. It may be in one or both the legs. The numbness may become worse with activities. The pain can involve both of the lower extremities. The pain becomes worse on walking and gets better after short periods of rest. Weakness of the muscles of both legs may also occur, and again, this may get worse when activity increases.


In very few cases, a disc herniation can be so big that it fills the entire spinal canal. The immediate pressure on the nerves in the spine may cause paralysis of the muscles that control the bowels and bladder. When the control over the bowels or bladder is lost, it is better to contact the physician immediately. If the back pain is accompanied by any of the following, the doctor should be consulted:


• weakness or numbness in one or both legs
• pain going down one leg below the knee
• back pain from a fall orinjury
• back pain accompanied by fever
• pain that continues to interrupt sleep after three nights
• back pain that remains after six weeks of home treatment