Epidural injections are used to treat pain that starts in the spine and radiates to an arm or leg. Arm or leg pain often occurs when a nerve is inflamed or compressed (“pinched nerve”).
Epidural injections involve injecting an anesthetic and an anti-inflammatory medication, such as a steroid (cortisone), near the affected nerve. This reduces the inflammation and lessens or resolves the pain. This type of epidural injection is a therapeutic one.
Sacroiliac Joint Injections
SI joint injections are similar to facet joint injections in many ways. The SI joints are located between the sacrum and ilium (pelvic) bones.
Problems in the SI joints have been shown to cause pain in the low back, buttock, and leg. Typically, one joint is painful and causes pain on one side of the lower body. It is less common for both SI joints to be painful at the same time.
This joint can also be injected for both diagnostic and therapeutic purposes. Anesthetizing the SI joint by injection under X-ray guidance is considered the gold standard for diagnosing SI joint pain. A diagnostic injection of the sacroiliac joint with anesthetic should markedly diminish the amount of pain in a specific location of the low back, buttock, or upper leg.
A therapeutic injection will typically include a steroid medication, with the goal of providing longer pain relief.
Facet Joint Injections
Facet joint injections can also be done for both diagnostic and therapeutic reasons. These types of injections are often used when pain is caused by degenerative/arthritic conditions or injury. They are used to treat neck, middle back, or low back pain. The pain does not have to be exclusively limited to the midline spine, as these problems can cause pain to radiate into the shoulders, buttocks, or upper legs.
For diagnostic purposes, facet joints can be injected in two ways: injecting anesthetic directly into the joint or anesthetizing the nerves carrying the pain signals away from the joint. If the majority of pain is relieved with anesthetic into the joint, then a therapeutic injection of a steroid may provide lasting neck or low back pain relief.
If anesthetic injections indicate that the nerve is the source of pain, the next step is to block the pain signals more permanently. This is done with radiofrequency ablation, or damaging the nerves that supply the joint with a “burning” technique.
Provocation discography is a type of spine injection done only for diagnosis of pain. It does not have any pain relieving effect. In fact, it is designed to try to reproduce a person’s exact or typical pain. This is to find the source of longstanding back pain that does not improve with comprehensive, conservative treatment. Discography is performed much less commonly than the other types of spinal injections reviewed above. It is often used only if surgical treatment of low back pain is being considered. The information gained from discography can assist in planning the surgery.
Discography involves stimulating and “pressurizing” an intervertebral disc by injecting a liquid into the jelly-like center (nucleus pulposus) of the disc. More than one disc is injected in order to distinguish a problem disc from one without symptoms. Criteria are used to identify a painful disc by provocation discography, including the type and location of pain and the appearance of the disc on an X-ray after the procedure.