Epidural space is a space overlying the membrane called dura mater, which covers the brain and spinal cord.  The epidural space can be injected with various medications and the injections are generally referred to as epidural injections.

An epidural steroid injection is a spinal injection procedure that deposits potent anti-inflammatory corticosteroid at the site of the painful reaction to disc injuries, arthritic bone spurs, or spinal stenosis. Approximately 50 - 80% of patients experience good to excellent results of decreased pain and increased function. The closer to the time of injury, the higher the success. The more the pain in the lower extremity (sciatica) the better the outcome generally. For a significant number of patients, the relief is long lived. Other patients may require repeated injections. For those with temporary relief, the diagnostic information is useful for planning other procedures or treatment.

These can be done straight through a midline approach (Inter laminar epidural injections), through the opening in the bottom of the tail bone (Caudal Epidural Injections), or through a side approach where a needle is advanced to the spine from a corner into the opening in the side of the spine (trans foraminal epidural injections/ selective nerve root blocks) where a specific nerve root comes out.  These injections are done with the help of x-ray machine and are called fluoroscopic-guided injections and the x-ray machine is called a C-Arm.  With the help of these injections we can generally treat various conditions, which cause significant lower back pain or sciatica.  Conditions commonly treated with epidural steroid injections include herniated discs, degenerative or bulging discs, bone spurs or other condition, which are bone spurs or other causes of pain such as cysts in the spinal canal, which are causing lower back pain and sciatica.

These injections generally tend to help patients who have more prominent sciatica than lower back pain although both subgroups are helped significantly when appropriate injection or injection combination is utilized.  In some cases, one may need to repeat the injection/injections for maximum benefit.  There is no limitation on how many injections one can have through the life as if they spaced appropriately, they can be done as needed.  The key is to do them on an as needed basis and not as standard where one has to get an injection every so and so period of time.

The most significant problems associated with the epidural injections can be nerve damage, spinal cord damage, infection, allergic reaction, bleeding and hematoma formation in the spinal canal or headaches.  Headaches are probably the most common of the above side effects. Hematoma formation can happen in one patient every 250,000 injections or so, which can be significant and may need surgical decompression to stop the bleeding and prevent paralysis.

Most patients tend to do quite well with epidural injections. The epidural injections done with the help of x-ray machine ( C arm) probably tend to be safer than the ones done in pregnant women without the x-ray machine where the patient is having contractions and lying in an uncomfortable bent position.  With the help of the x-ray machine and proper anesthetic use, these injections can be done with minimum pain and discomfort and can result in significant relief of pain.

For pictures of epidural injections, please see the link on spinal injections.