There are several types of spinal injections, often referred to as nerve blocks or blocks. They may be used for both pain relief and diagnostic purposes. Spinal injections are usually performed using a live x-ray (fluoroscopy) for guidance. Common spinal injections include: Epidural Steroid Injection, Facet Joint Injections, and Selective Nerve Root Block.
Epidural Steroid Injection
Epidural steroid injections are not usually performed until non-surgical treatments have been given a fair trial (about six weeks) and have not provided adequate relief of radicular pain (pain radiating down an arm or leg).
Epidural steroid injections are for temporary relief of pain; they are not a cure. Pain relief often lasts from a couple of weeks to months, although these injections are not always effective. There are rare but serious risks involved.
What is an Epidural Steroid Injection (ESI)
An epidural steroid injection (ESI) is a common type of spinal injection. An ESI is often referred to more generally as nerve block or simply a block.
An epidural steroid injection is an injection of a long lasting steroid combined with a local anesthetic into the epidural space. The medication travels up and down the epidural space to coat the spinal nerves and the facet joints near the area of the injection.
The epidural space is the space between the outermost membrane covering the spinal cord (the dura) and the wall of the spinal canal.
Epidural steroid injections are usually performed using a live x-ray (fluoroscopy) as guidance.
What type of pain is an Epidural Steroid Injection used for
Epidural steroid injections are commonly used to treat radicular pain (pain radiating down an arm or leg) caused by compressed or irritated spinal nerve roots. Pain radiating down the leg is referred to as sciatica. Herniated discs and spinal stenosis are common causes of spinal nerve compression / irritation. Epidural steroid injections also reduce inflammation of facet joints and are sometimes used to treat moderate to severe osteoarthritis of the spine. ESI injections are not used for musculo-skeletal pain.
When is an Epidural Steroid Injection used
When a short trial of conservative, non-surgical pain treatments does not provide adequate relief for severe pain involving compression / irritation a spinal nerve root, an epidural steroid injection may be considered.
Most radicular pain eventually gets better. An ESI may alleviate suffering in the meantime and allow the resumption of normal activities and rehabilitative exercises.
How does an ESI work
An epidural steroid injection relieves pain by reducing inflammation of the spinal nerve roots and tissue around the nerve roots. In spinal osteoarthritis, an ESI may relieve also pain arising from facet joints as the medication coats the facet joints as well as the spinal nerves as it travels up and down the epidural space.
How effectively does an ESI relieve pain
Results vary, with many people receiving significant relief that lasts from a few weeks to a few months. In some cases the injection is ineffective.
It often takes several days for pain relief to occur as the steroids in the injection gradually reduce inflammation. The pain may be temporarily increased for a day or two due to the irritation caused by the needle and the medication itself. Some people experience relief from one injection, others may need up to three.
Patients receiving epidural steroid injections are often prescribed rehabilitative back exercises to strengthen the muscles that support the spine to reduce the reoccurrence of pain.
Risks of Epidural Steroid Injections
There are rare but serious risks involved in all spinal injections. Side effects from corticosteroids may also occur though long-term systemic side effects are unlikely as only a small amount of corticosteroids enters the bloodstream. See Risks / Complications of Spinal Injections and Side Effects of Corticosteroids below for more information.
A facet joint injection is an injection of steroid medication into a facet joint (spinal joint) to reduce pain caused by inflammation of the facet joint. An injection may also be made around the small nerves that connect with the facet joint to help determine if the joint is the source of pain. In many cases, damaged facet joints are not the cause of back pain.
Facet injections may be used to treat moderate to severe spinal osteoarthritis (degenerative arthritis). (Epidural Steroid Injections are also used for spinal osteoarthritis). Facet injections are usually limited to three per year as too many injections may cause more degeneration of the joint cartilage or side effects of corticosteroids.
There are rare but serious risks involved in facet injections, as in all spinal injections, as well as possible side effects from the steroids.
A selective nerve root block is an injection near the affected nerve (outside the epidural space) as it exits the spinal column. Selective nerve root blocks are used both for diagnostic purposes (to determine if a specific nerve root is the source of the problem) and to relieve radicular pain caused by irritation of a specific nerve root.
If a specific nerve is actually the cause of pain the local anesthetic in the injection will give immediate relief. The steroids in the injection will reduce inflammation over the next few days and possibly provide relief of pain that lasts for weeks to months. Herniated disk in the lumbar spine causing low back pain with leg pain (sciatica) is a common condition treated by a selective nerve root block.
There are rare but serious risks involved in a selective nerve root block, as in any spinal injection, as well as the possibility of side effects from corticosteroids.
Risks / Complications / Side Effects of Spinal Injections
Some possible risks of a spinal injection are dural puncture, infection, bleeding, allergic reaction, arachnoiditis, worsening of pain, nerve damage or spinal cord damage, paralysis, death. Catastrophic complications are extremely rare, e.g. or paralysis or death.
The following list does not include all possible complications of spinal injections:
Dural Puncture: Perhaps the most common, but usually not too serious, complication that may occur in as many as one to two percent of epidural spinal injections is the accidental dural puncture (puncture of the membrane covering the spinal cord) resulting in a leakage of spinal fluid into the epidural space.
The resulting reduction of cerebrospinal fluid pressure causes a spinal headache, which worsens upon standing and is improved by lying down. The headache usually resolves within a few days but may last much longer. Most cases eventually resolve without treatment. Rarely, a persistent spinal fluid leak develops. A small amount of a persons own blood can be injected into the epidural space, where it will clot and usually seal the leak.
Infection: Minor infections occur in one to two percent of injections. Serious Infections / Epidural Abscesses are rare. Diabetics are at a higher risk of infection.
Bleeding / Epidural Hematoma: An epidural hematoma is a large pocket of blood that accumulates in the epidural space when bleeding continues after injury of epidural vein. This can compress the spinal cord and cause permanent damage if not treated quickly. Patients taking blood-thinners should not have spinal injections. This is a rare complication.
Allergic reaction to the medication in the injection is rare and is usually a reaction to the preservative or x-ray contrast dye in the injection and not the steroid.
Worsening of pain
Nerve damage or spinal cord damage Very rarely, the needle itself can cause injury to nerves; compression of nerves or the spinal cord from hematoma (pocket of blood) or pus (from infection) may result in damage. Obstruction of blood supply may also cause permanent nerve or spinal cord injury.
Arachnoiditis A painful condition caused by the inflammation the arachnoid membrane (the middle membrane of the three membranes covering the spinal cord) that may occur if medication is injected into the spinal fluid. Extremely rare.
Puncturing of an Artery is extremely rare.
Major Complications from spinal injections, though still extremely rare , may be higher in Cervical Epidural Injections.
Side Effects of Corticosteroids
Note: It is unlikely to develop long-term systemic side effects from steroids when used in spinal injections.
A local injection of corticosteroids delivers a high dosage of the medication where it is needed with little being absorbed into the bloodstream minimizing systemic side effects of steroids. However, since some medication is absorbed into the bloodstream, most physicians limit the number of Epidural Steroid Injections to three per year to prevent systemic side effects of steroids.
Corticosteroids (or steroids) are similar to cortisol, which is produced naturally by your own body, but these synthetically produced steroids are more potent and longer lasting. Corticosteroids have powerful anti-inflammatory effects.
Local Side Effects of Corticosteroids in Spinal Injections: Too many steroid injections into the same area may weaken tendons and ligaments and cause thinning of joint cartilage.
Short-term side-effects from the steroids in a spinal injection: There may be bouts of facial flushing with a feeling of warmth the day after the injection. For several days after a spinal injection diabetics need to monitor their blood sugar carefully as blood sugar levels may be elevated.
Systemic Side Effects of Corticosteroids
High dosages of oral corticosteroids taken daily for prolonged periods of time can have serious systemic side effects including bone loss ( osteoporosis), increased risk of infections and diabetes and cataracts, thinning of skin, stretch marks, increased facial/body hair growth, acne, fluid retention, weight gain with redistribution of fat (fat deposits on back and face, thinning of limbs), muscle weakness, decreased resistance to infections, stomach ulcers, mood swings, insomnia, suppression of the body's own production of cortisol, etc.
Many of the side effects go away within a few months after discontinuing the steroids. Some side effects, such as stretch marks, osteoporosis and cataracts (cataracts are fortunately a rare side effect) do not go away on their own.
Spinal Injections in Summary
Spinal Injections are not a cure, but may provide temporary relief of pain. Spinal injections are also used to help diagnose the cause/source of pain. Like any treatment, spinal injections are not always effective. There are rare but serious risks involved. Spinal Injections are usually performed only after conservative treatments have not provided adequate pain relief.