Epidural steroid injections are a standard therapy in pain management designed to
reduce inflammation of nerve roots due to disc herniations or disc tears.  They are also
used frequently in the treatment of spinal stenosis.  The epidural space means the area
of the spine outside of the dura mater which is the tough covering of the spinal cord
which contains spinal fluid and the nerves leaving the spine.  The nerves must pass
through the epidural space.  

INDICATIONS:  Transient relief from pain due to chemical or mechanical irritation of
nerve roots in the spine, reduction in pain due to spinal stenosis, and reduction in pain
due to degenerative disc disease.  This irritation may be from a disc herniation which
spills inflammatory chemicals onto the nerve root or from mechanical abrasion of a
trapped nerve root.  While not permanent, the effects may last long enough to permit
the body's enzyme systems to repair a disc, especially if coupled with aggressive spinal
decompression such as VAX-D, inversion table traction, etc.
TYPES:  Interlaminar (sitting office epidural injections),  transforaminal, caudal, or
catheter directed.

Interlaminar sitting office epidurals are often performed by
low level physicians or nurse anesthetists who do not use x-ray guidance of the needle,
incorrectly believing the needle can accurately be placed without x-ray.  Using this
technique, in a normal spine, statistics show they will be wrong at least 36% of the time
and in a spine which has had surgery, they will fail to deliver the medication to the
proper area 75% of the time. Improper placement of these drugs may lead to permanent
paralysis or
arachnoiditis, so x-ray guidance (fluoroscopy) is critical.  Also, these
injections are expensive, therefore it is imperative that the medications be delivered
with accuracy into the spine.  The size of the needle used for this injection is twice the
diameter of the that used for transforaminal injections and can lead to long term back
pain in some patients.

Transforaminal injections (TFESI) are those in which the area
around the inflammed nerve is targeted using fluoroscopic guidance. These may be
performed in any part of the spine.  There is evidence transforaminal injections last
much longer and are more effective than the sitting office epidural steroid injections
(interlaminar).  Transforaminal blocks should be performed with contrast when possible
to outline the nerve root and assure the medication will reach the target.  The latest
advances in safety of this procedure is using live fluoroscopy with a special technique
called "digital subtraction" during the injection of the contrast to assure there is no
injection into the blood vessels.

Caudal approach epidural steroid injections are through a small opening in the tailbone
which connects to the epidural space.  These injections work best for L4-5 or L5-S1
disc herniations or spinal stenosis at those levels.  Caudal approaches should also be
performed with x-ray guidance since there will be incorrect needle placement in at least
17% of the time without x-ray.   

Finally
catheter guided injections are those in which a catheter is threaded through a
needle in the epidural space to the proper location.  Fluoroscopic guidance is required.  
Catheter directed injections provide accurate                         placement of steroids.   

The Injection Procedure:
Epidural steroid injections may be performed under local anesthesia, local anesthesia
with oral medical sedation, local anesthesia with IV sedation, or heavy IV sedation.  The
choices for anesthesia are dependent on many factors including the patient's health
status, location of the procedure, etc.  If there is to be given any sedation, we ask
patients not to eat food or drink liquids (except to take medications) 6 hours prior to
the procedure.  
Most epidural steroid injections are performed with the patient lying face down, except
for cervical transforaminal injections which require the patient to lie on their back.  
EPIDURAL INJECTIONS MUST ALWAYS BE PERFORMED WITH FLUOROSCOPY!!
After a antibacterial skin preparation is applied, a very small needle is used to place
local anesthesia in the skin, and a thin needle is inserted aiming towards the target.  
Usually this is not uncomfortable.  Once the nerve target is reached, a contrast agent
may be injected to outline the nerves, and then a steroid is injected.  If the block is an
attempt to determine if a specific nerve is transmitting pain, a small amount of local
anesthetic will be injected and the patient will be asked to assess the degree of pain
relief over the ensuing 6 hours and report to APM the following day.  After the needle is
removed, the patient without sedation may go home immediately whereas those with
sedation will be monitored for 15-30 minutes.  

Side Effects and Complications
After the injection, if steroids only are injected, the patient may not derive any relief for
the first 24 hours.  Side effects of steroid injections include a brief period of elevated
blood pressure and blood sugar (approximately 3-7 days for each),  mild skin irritation
at the site of the injection, occasional flushing and redness of the face, occasional
rash, brief period of water retention, and occasional brief emotional lability.  
Complications from steroid injections are uncommon and are usually related to
inaccurate needle placement or the presence of scar tissue in the spine prior to the
epidural steroid injection.  Serious complications are rare and include epidural abscess
(1:10,000), arachnoiditis which is an inflammation of the nerves inside the spine (approx
1: 1,000,000), nerve injury, hematoma formation inside the spine with nerve
compression, penetration of the dura with resultant spinal headache, and the formation
of epidural scar tissue.  The steroid preparations used for injection are not specifically
approved nor disapproved by the FDA for injection into the spine, primarily because the
practice is so common that manufacturers have elected not to spend the many millions
of dollars required by the FDA to perform the studies and submit paper work for an
already relatively safe and commonly performed procedure that has a 40 year track
record.
Known long term effects of repeated frequent epidural steroid injections: weight gain,
water retention, development of additional tissue under the skin over the upper back.
Potential but unproven long term effects of repeated frequent steroid injections:  
cataracts, avascular necrosis of the femoral head
Proven not to occur with repeated epidural steroid injections:  Osteoporosis, fractures
due to such


How Many Injections Can I Have?
If the first injection is successful, the injections may be repeated at up to monthly
intervals.  Closer intervals than one month may lead to adrenal suppression and
weakness.  There are potential complications from long term use of epidural steroids
therefore the frequency of injections is as few as possible to provide adequate pain
control.  Some patients derive up to one year of relief from the injections but this is
uncommon.  If the patient has a disc herniation which can be repaired through physical
therapy, exercise, traction, etc., then the steroid injections may prevent some patients
from having to undergo disc surgery.  However, even if surgery is necessary, there are
possibilities of using minimally invasive spine techniques when traditional surgery is
not possible.



   
Click on pics
below to enlarge


Epidural Steroid Injections
Spinal needle
in epidural
space
Interlaminar
Epidural Steroid
Injections
Typically
Performed
without
Fluoroscopy by
low level
physicians
Interlaminar
epidural spread
(central) does
not reach the
nerve roots
(drawn in)
Transforaminal
ESI: Medication
is delivered
directly to the
inflammed
nerve root
Needle
Placement
Caudal ESI Xray
Epidural
catheter
directed
injection
LITERATURE
REFERENCES