Spinal injections have been used to as an alternative to surgery in treating back pain since the early 1900s. Studies have shown injections to be effective in up to 50% of patients. They are typically given after medication and physical treatments have been utilized, but before surgery. Injections tend to be more effective than oral pain medication because they deliver medicine right to the source of the pain.
Sacroiliac joint blocks are injections used to treat low back pain. The sacroiliac (SI) joints are located next to the spine and connect the sacrum to the pelvis. Painful joints cause pain in the lower back, buttocks, abdomen, groin, and legs. SI joint blocks work in three ways:
- 1) they are used to determine if the SI joint is the source of back pain (if the injection makes the pain better, thats where the pain is coming from)
2) the numbing medication used in the block gives temporary relief so the patient can have chiropractic or other physical treatments immediately after the block is administered
3) a time-release steroid gives extended pain relief by reducing inflammation.
During an SI block, the patient lies on his stomach and live x-ray, known as fluoroscopic guidance, is used to allow the doctor to see the joints. The skin is sterilized and numbed. The doctor then inserts a very small needle into the joint and injects it with lidocaine (a numbing agent) and a steroid (an anti-inflammatory). After treatment the legs sometimes feel numb or weak for a few hours. Side effects are rare and include allergic reaction, infection, excessive bleeding, nerve damage, and chemical meningitis.
Thoracic Facet joints are small joints about the size of a thumbnail and are located in pairs along the back of the spine. If they become irritated, middle back pain occurs. Thoracic facet joint injections have the same purpose as SI joint injections, are performed in exactly the same manner, and have the same side effects. The only difference is they treat middle back pain instead of lower back pain.
Epidural steroidal injections are similar to SI and thoracic facet join injections, except the cortosteroid is injected into the spinal canal surrounding the spinal cord. They are used to treat chronic and not acute low back pain. This procedure has the same side effects of other injections. Relief generally lasts anywhere from one week to one year.
Selective nerve root blocks (SNRB) are used primarily as a diagnostic tool and secondarily as treatment for pain. Back pain can occur when nerve roots become compressed and inflamed. While MRIs can be used to show which nerves are causing the pain, they dont always work successfully. In cases when this happens, an SNRB injection can be performed in order to isolate the source of the pain. SNRBs are also used to treat disc that rupture outside of the spinal canal, or far lateral herniated discs. The procedure is the same for other types of injections. As with other injections, SNRBs should not be performed more than three times per year. SNRBs are considered more difficult to perform than other types of injections and should be done only by a physician experienced in them.
Facet rhizotomy may be recommended if three facet blocks have been performed but more pain relief is needed. Facet rhizotomy injections disable the sensory nerves that lead to the facet joint, thereby providing pain relief. The procedure for facet rhizotomy injections is different from that of other injections. A needle with a probe is inserted just outside the joint, is heated with radio waves, and applied to the sensory nerve. This disables the nerve and keeps it from sending pain signals to the brain.