Epidural steroid injections
How an epidural steroid injection works
The most commonly performed injection is an epidural steroid injection. In
this approach, a steroid is injected directly around the dura, the sac around
the nerve roots that contains cerebrospinal fluid (the fluid that the nerve
roots are bathed in). Prior to the injection, the skin is anesthetized by
using a small needle to numb the area in the low back (a local anesthetic).
Epidural injections help reduce inflammation
Injecting around the dura sac with steroid can markedly decrease inflammation
associated with common conditions such as spinal stenosis, disc herniation
or degenerative disc disease. It is thought that there is also a flushing
effect from the injection that helps remove or "flush out" inflammatory
proteins from around structures that may cause pain.
Epidural steroid injection success rates
An epidural steroid injection is generally successful in relieving lower back
pain for approximately 50% of patients. While the effects of the injection
tend to be temporary (one week to one year), an epidural can be very beneficial
in providing relief for patients during an episode of severe back pain and
allows patients to progress in their rehabilitation.
Frequency for epidural steroid injections
There is no definitive research to dictate the frequency of the epidural steroid
injections; however, a limit of three injections per year is generally considered
reasonable. There is also no general consensus in the medical community as
to whether or not a series of three injections need always be performed.
If one or two injections resolve the patient’s low back pain, some physicians
prefer to save the one or two additional injections for any potential recurrent
low back pain.
Generally, there are few risks associated with
epidural injections. The risks are remote and
include:
-
A wet tap may occur, which means that the
needle has penetrated the dural sac into
the cerebral spinal fluid (CSF). A wet tap
may result in a CSF leak and a spinal headache.
-
Infection into the epidural space is also
a remote risk.
-
While there is no risk of paralysis (since
the spinal cord ends at a higher level in
the spine), there is a remote risk of damage
to a nerve root.
Patients who should avoid epidural injections
Epidural steroid injections should not be performed on patients whose pain
is from a tumor or infection, and if suspected, an MRI scan should be done
prior to the injection to rule out these conditions. |
