Sciatica is pain radiates along one or both of the sciatic nerves, the longest nerves in the body. Symptoms include tingling, numbness or muscle weakness that can range from mild to severe and incapacitating. Many people with sciatica feel pain when they sit, sneeze or cough. Sciatica can affect both sides of the lower body - including the lower back, buttocks, legs and feet - but usually affects only one side.

Sciatic nerve roots originate from the spinal cord in the lower back and run from one side of the pelvis through the hip and buttocks and down the back of the leg. These two nerves control many of the muscles in the lower legs, along with sensation in parts of the thighs, legs and feet. Each sciatic nerve branches at the knee into the tibial and peroneal nerves.

Sciatica is a form of peripheral neuropathy, which involves damage to the peripheral nervous system (nerves outside the central nervous system, which consists of the brain and spinal cord). This system is the communications network that transmits information between the central nervous system and other parts of the body.

Most often, a herniated disc in the lower back compresses the spinal nerve roots that combine to form the sciatic nerve. This triggers pain that can range from mild to severe in intensity. However, other factors can also cause sciatica, including:

• Degenerative conditions such as spinal stenosis (narrowing of the spinal canal), degenerative disc disease or spinal arthritis
  
  
• Prolonged external pressure on the nerve
  
  
• Pressure on the nerve from nearby structures, such as a tight muscle or a pregnant woman's growing fetus
  
  
• Physical trauma such as a pelvic fracture
  
  

All these factors can cause pressure over the nerve, but inflammation of the nerve is required to cause pain in the back or leg.

Sciatica typically affects people between the ages of 30 and 50. Between 80 percent and 90 percent of people with sciatica get better over time without having to resort to surgery, according to the American Academy of Orthopaedic Surgeons.