If your back aches, join the club! Nearly 84% of people will experience back pain at some point in their lives. Back pain can be caused by many things, but remember, it is usually self-limiting. Common causes include muscle strains, arthritic conditions, and disc herniations. Less common causes include infections, fractures, and tumors.

Sciatica, the leg pain often associated with back pain, is less common and only occurs in about 40% of back-pain patients. Inflammation of the nerve caused by mechanical compression of the nerve or chemical irritation of the nerve root due to herniation of disc material is often the cause.

Treatment for back pain and sciatica include anti-inflammatory medications and a strengthening program along with aerobic exercise. However, severe pain may require more aggressive measures, such as epidural steroid injections (ESI), selective nerve root blocks (SNRB), or facet injections. Often, before an injection is prescribed, your physician will examine you and a magnetic resonance imaging (MRI) study will be taken to help evaluate the cause of your pain.  
 

Epidural steroid injections  An ESI may be done to relieve the severe leg pain associated with conditions such as degenerative disc disease, spinal stenosis, and postlaminectomy syndrome. This injection is done on an outpatient basis. Using x-ray guidance to determine its proper position, the needle is positioned above the sac containing spinal fluid. Its position is verified with an injection of a small volume of dye. Next, a mixture of steroid medication and an anesthetic is injected (Fig.1).  The steroid is a powerful anti-inflammatory medication that can relieve pain in as quickly as 15 minutes or take as long as 2 weeks, and the pain relief can last for as long as 3 months. Approximately 62% of patients experience relief with a single epidural steroid injection. However, some patients can require as many as 3 injections to experience relief.
Selective nerve blocks Selective nerve root blocks are similar to ESI, however, they are more effective for disc herniations. This procedure is done on an outpatient basis using x-ray guidance. During the procedure, the needle is positioned near the nerve as it exits the spinal column (Fig. 2). The injection gives temporary relief while the disc is healing. About 87% of patients experience relief for up to 3 months with this type of injection. Patients are more likely to experience numbness or slight temporary weakness after this type of injection.
Facet injections Facet injections are prescribed to relieve degenerative arthritis that affects the small joints in the spine. Facet injections are also done on an outpatient basis under x-ray guidance. A steroid medication and an anesthetic are injected into the capsule surrounding the small facet joints of the spine (Fig. 3). These injections are made on the side that is often the most painful and sometimes the treatment may require injections at multiple levels. The injections do not cure the underlying arthritis, but they may give pain relief for up to 3 months. They may be repeated, if good relief is obtained.

For more information on back pain and treatment options check the AAOS Web site at www.AAOS.org

Bobbi A. Farber, MD
Columbus, Georgia

References:
Riew KD, Yin Y, Gilula L, et al. The effect of nerve-root injections on the need for operative treatment of lumbar radicular pain. A prospective, randomized, controlled, double-blind study. J Bone Joint Surg Am. 2000;82-A:1589-1593.