Sciatica

Sciatica is defined as "A condition characterized by pain radiating from the back into the buttock and posterior/lateral aspects of the leg."

Sciatica or Sciatic Neuralgia is a term commonly used to describe symptoms of problems with the Sciatic Nerve, a large nerve that runs from the lower back down the back of each leg. The Sciatic Nerve controls muscles in the back of the knee and lower leg and provides feeling to the back of the thigh, part of the lower leg and the sole of the foot. Sciatica can manifest as pain, weakness, numbness or tingling. It can occur along any part of the Sciatic Nerve's path, often involving the buttocks and/or rear (posterior) and side (lateral) portions of the leg down to and including the feet and toes.

Cause/etiology

The true cause of sciatica can be any of a number of actual clinical problems. It can be:

• Sciatic neuropathy, a disease or damage involving the sciatic nerve...
  
• a radiculopathy, a disease involving a single spinal nerve root, particularly one of the L4, L5, S1, S2 or S3 roots. These have been found to result from compression related to intervertebral disk displacement (a slipped disk)...
  
• Piriformis syndrome, a rare neuromuscular disorder that occurs when the piriformis muscle compresses or irritates the sciatic nerve...
  
• lesions of the Cauda Equina...
  
• Spinal Stenosis, a narrowing that can occur at the center of the spine, in the canals branching off the spine and/or between the vertebrae...
  
• Spondylolisthesis, a condition in which a bone (vertebra) in the lower part of the spine slips forward and onto a bone below it...
  
• injury such as a pelvic fracture...
  
• Other causes may include "lumbar radicular herpes zoster, lumbar nerve root schwannoma, lumbar instability, facet hypertrophy, ankylosing spondylitis, sacroiliitis, sciatic neuritis, piriformis syndrome, intrapelvic mass and coxarthrosis."

In many cases, no direct cause can be found.

Diagnosis

95% of patients with a herniated disk will have sciatic.In the piriformis syndrome, MRI scan may show compression of the sciatic nerve at the "sciatic notch, at or just inferior to the level of the piriformis muscle."

The straight leg raise test may help distinguish the herniated disk and piriformis syndrome; however, the value of the straight leg raise in this role has not been studied.

Treatment

Successful treatment can depend on identifying the cause of the of the nerve dysfunction and successfully treating for it. In some cases, no treatment is required and recovery is spontaneous. Conservative treatment is usually considered appropriate if there was sudden onset, minimal sensation changes, no difficulty in movement, no history of trauma to the area, and no evidence of degeneration of the nerve axon.

For simple or slight inflammation, heat and cold applications may suffice. For more serious cases, corticosteroid injections can be used to reduce inflammation around the nerve. Over-the-counter or prescription analgesics may be needed to control pain. Surgical removal of lesions that press on the nerve, such as a herniated disk, may be needed to relieve symptoms. In cases of severe injury to the nerve, such as laceration, recovery may be not possible or may be limited.

In 1998, the National Institutes of Health acknowledged that Acupuncture appears to be effective at relieving a number of kinds of pain, including low back pain from sciatica. Certain physical exercises may also be beneficial and help maintain muscle strength. Braces, splints, orthopedic shoes, or other appliances may help compensate for lost or impaired function.

Epidural steroid injections

A systematic review concluded that "the available evidence suggests that epidural corticosteroid injections offer only short-term relief of leg pain and disability for patients with sciatica. The small size of the treatment effects, however, raises questions about the clinical utility of this procedure in the target population."

Included in this review above, in a randomized controlled trial, the relative benefit ratio of epidural steroid injections, as compared to saline injection, for 50% or greater leg pain relief and a positive global perceived effect was 1.5 and, the relative benefit increase was 50.0%. In populations similar to those in this study which 50% of patients improved with saline, the number needed to treat is 4.