The success rates of epidural steroid injections can vary depending on several factors. While some patients experience significant pain relief,1,2 others may not experience any pain relief from this procedure.3,4 The effects of the injection may be short-term, such as a week, or may continue for a year.
Common Factors that May Affect the Success of the Injection
The efficacy of an epidural depends on many factors, including but not limited to:
- Underlying condition. This injection treatment is usually more effective in managing lower back pain with radiating leg pain or sciatica versus lower back pain alone.1,5 While the injection may also be used to treat non-radicular, localized back pain, the efficacy may be low.3
- Route of administration. Research indicates that the transforaminal and interlaminar routes may obtain more effective results compared to the caudal route.2,4,6
- Type of steroid. Poorly soluble or particulate steroids, such as methylprednisolone or triamcinolone, have a long duration of action. Water-soluble or non-particulate steroids, such as dexamethasone, are considered safer than particulate steroids but tend to have a short-term effect.5,7,8
The injection may sometimes be used in combination with a comprehensive rehabilitation program to increase the likelihood of longer-term pain relief and return to everyday activities.6
Other factors that may affect the outcome of this treatment include the physician’s skill and experience in administering the injection, the use of guided fluoroscopy, and the patient’s general health. The treatment may also be more effective in treating acute pain (versus chronic symptoms).
The success rates of epidural steroid injections for the treatment of a few common conditions are discussed below.
Success Rates for Sciatica
Sciatica, which is medically known as lumbar radiculopathy, is nerve pain that originates deep in the buttock and travels down to the thigh and/or leg. Sciatica is commonly caused when a herniated disc or narrowing of the bony opening for spinal nerves (foraminal spinal stenosis) compresses a nerve root in the lumbar spine.1
Clinical trial results in the treatment of sciatica pain with epidural steroid injections have the following success rates:
- Lumbar Herniated disc. An analysis of several large clinical trials indicated that 40% to 80% of patients experienced over 50% improvement in sciatica pain and functional outcome from 3 months up to 1 year when 1 to 4 injections were given in that year.6 Typically, a better outcome is seen in acute sciatica pain of recent onset with a lesser degree of spinal nerve compression.3
- Foraminal spinal stenosis. In a study group of 60 participants, sciatica pain was relieved in 87% of patients with mild to moderate stenosis and 42% of patients with severe stenosis. The treatment included 1 injection and the effects lasted up to 3 months.9
Other conditions such as spinal cysts or ligament thickening that cause spinal nerve compression and radicular nerve pain in the legs may also yield similar results when treated with these injections.
Success Rates for Axial Low Back Pain
In a study involving 120 participants with axial low back pain, treatment with 4 injections given over a span of 1 year showed more than 50% improvement in pain and functional outcome in 68% of patients.12 Other studies have reported pain relief for 2 years when 6 injections were spaced out and given during this period.13
Success Rates for Neurogenic Claudication
Neurogenic claudication, characterized by pain felt in both legs while walking variable distances, is usually treated with bilateral transforaminal epidural steroid injections (given on both sides of the spine).
A study involving 22 participants showed 30% of patients experiencing pain relief at 1 month, 53% at 3 months, and 44% at 6 months after receiving bilateral injections.14 Other studies have reported pain relief for 2 years when 6 injections were spaced out and given during this period.4
Guidelines for Number and Frequency of Epidural Steroid Injections
Research indicates that an additional injection may be given if the following criteria are met3:
- More than 50% of pain reduction was experienced after the first injection
- The effect of the first injection decreased after a considerable relief period, for example, over 1 month
Common guidelines recommend that if more than 4 epidural steroid injections are needed in 1 year, the underlying condition must be managed by other treatment methods.3
To improve the overall outcome of the procedure and reduce the risk of side effects, using a blunt needle, live fluoroscopy, and administering a small test dose initially may be helpful.15
Combining Epidural Steroid Injection with Physical Therapy
A guided physical therapy program may be combined with the epidural steroid injection treatment for an added benefit. Studies suggest that combining physical therapy with the injection treatment of herniated discs may improve the quality of pain relief and overall satisfaction in the patient.16 Injection treatment of lower back conditions such as spinal stenosis may benefit from improved quality of life and overall health when combined with physical therapy; with no direct effect on pain-relief values.17,18