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| Introduction |
-
Epidural steroid
injections are used to reduce nerve root
irritation pain where the cause is thought to be within
the spine. The usual indications are nerve root
irritation caused by:-
- Epidural steroid injections can be performed at the
following levels:-
- Caudal - for nerve root irritation
between L4 and S4
(Sciatica = Lumbar and Sacral Radiculopathy
).
- Lumbar - for nerve root irritation
between L1 and L5
(Sciatica = Lumbar Radiculopathy ).
- Thoracic - for nerve root irritation
between T2 and T12
(Thoracic Radiculopathy).
- Cervical - for nerve root irritation
between C3 and T1
(Brachalgia = Cervical Radiculopathy
).
- Injecting steroid drugs
epidurally
at the site nerve root
irritation can reduce the degree of nerve inflammation
and relieve the nerve root irritation symptoms (pain,
numbness, tingling, mild weakness). They do not affect
the rate of healing of an annular tear or a disc
protrusion - this is controlled by healing processes in
the body.
- The aim of the treatment is pain relief through the
reduction of nerve root inflammation. Minor disc
disruptions and annular tears can heal naturally in about
6 months, and a series of 2 -3 epidural injections can
greatly reduce sciatic pain, allowing rehabilitation to
proceed more easily.
- The best results with epidural steroid injections are
seen in those patients with annular tears and small disc
protrusions. Roughly 66% of "surgical virgins" will
obtain relief lasting 6 -8 weeks for each epidural
performed.
- If the series of epidurals helps the nerve root pain,
but the spinal pain persists, it may be worth considering
Spinal Manipulation as the next
step.
- Large disc protrusions which are causing moderate to
severe nerve root compression, weakness, spinal cord
compression or bladder dysfunction need an urgent
surgical opinion for spinal decompression. I would not
advise having an epidural injection in this
situation.
- Epidural injections are often used after disc surgery
for residual nerve root symptoms symptoms. The success
rate is often lower than in "surgical virgins", but it
may be worth while trying one if the cause of the pain is
thought to be due to continuing nerve root irritation
(See Non Nerve Root causes of nerve root
pain).
- There is less convincing evidence for the use of
epidurals in Spinal Stenosis. Some practitioners
suggest that if spinal stenosis is associated sciatic
symptoms rather than just back ache, that it may be worth
trying a series of epidural injections.
- Nerve Root Blocks may be more useful for
Foraminal Stenosis.

|
| Caudal
Epidurals |
- Technique - Used for
nerve root irritation between L4 and S4. Injecting
through the sacral hiatus is the least complicated way to access the
epidural space, and may be performed as a day case
without the need for admission. The patient is usually
positioned face down with a pillow under the hips for
comfort. The buttocks and sacral area are cleansed using
anti-septic, and then the needle insertion point is
frozen with some local anaesthetic. A small needle is inserted through the sacral
membrane
into the epidural space. (N.B. the
needle normally used is a lot smaller in length and
diameter than those shown in the diagrams). Most
practitioners use the Minimal Entry
Technique with the needle at position "1" in the diagram.
Advancing the needle to position "2" increases the chance
of injecting the solution into the spinal fluid. The
epidural injection is injected 1-2 ml at a time with a
short pause in between each bolus, usually taking about 5
minutes to perform. Most patients feel a sensation of
mild pressure which builds during the injection, and
falls during the short pauses. Some people have
reproduction of the sciatica pain down the leg during the
injection, which subsides when the local anaesthetic
begins to work inside the epidural space.
- Epidural Mixture - 20 ml
of solution is injected containing 40 mg triamcinolone, a
long acting depot steroid lasting 21 days, mixed with
0.5% lidocaine. The triamcinolone exerts the
anti-inflammatory effect, while the lidocaine helps to
make the procedure more comfortable. Some practitioners
prefer not to use lidocaine in the mixture, to avoid any
leg numbness afterwards. In my experience 0.5% lidocaine
produces mild numbness in the buttocks and legs for up to
2 hours, but does not cause any leg weakness that
interferes with walking.
- Aftercare - you will be
asked to lie down on the treatment couch for 10 - 15
minutes afterwards. You may be observed for a longer
period according to frailty, and other medical
conditions. Vital signs measurements will be performed
where necessary. Leg strength and walking ability will be
assessed prior to discharge. You must not drive that day,
and you must be accompanied home by a responsible
adult.
- See Side
Effects and Complications for more information.

|
| Lumbar
Epidurals |
- Technique - Used for
nerve root irritation between L1 and L5. Performed using
x-ray screening, with the patient positioned left
lateral. An intravenous cannula is usually inserted and
intravenous sedation
used. The skin and needle track are numbed with
local anaesthetic, and the epidural
needle inserted between the spinous processes until it
reaches the epidural space. The space is identified by
loss of resistance to an air-filled syringe, with the
average depth being 5 cm (Range 3 cm to 11 cm).
After confirmation of correct needle position with an
Epidurogram , the epidural solution is slowly injected.
Injection may provoke the usual nerve root pain due to
volume effects within the epidural space - this is
usually short lived and not severe if the injection is
performed slowly. Afterwards the patient is positioned
affected side down for 2 hours to encourage spread of the
epidural mixture to the correct nerve root.
- Epidural Mixture - as
for Caudal Epidurals above.
- Aftercare - A lumbar
epidural injection is more likely to drop blood pressure
than the caudal version, but with the mixture described
above, this is very unusual. Vital signs observation are
performed, and leg strength checked before standing.
Usually done as a day case, but may need an overnight
stay on Meriden Wing
depending on frailty or concurrent medical
conditions.
- See Side
Effects and Complications for more information.

|
| Thoracic
Epidurals |
- Technique - usually
performed for nerve root irritation between T1 and T12.
As for lumbar epidurals, the injection is performed in
the left lateral position, under x-ray screening, using
local anaesthesia and intravenous sedation
. The mid thoracic levels are the most difficult
to perform because of the steep angulation of the
vertebral spinous processes. Average depth is longer
being between 6 and 11 cm. After confirmation of correct
needle position with an epidurogram, the epidural
solution is slowly injected. Injection may provoke the
usual nerve root pain due to volume effects within the
epidural space - this is usually short lived and not
severe if the injection is performed slowly. Afterwards
the patient is positioned affected side down for 2 hours
to encourage spread of the epidural mixture to the
correct nerve root.
- Epidural Mixture - as
for Caudal Epidurals above.
- Aftercare - as for
Lumbar Epidurals above.
- See Side
Effects and Complications for more information.

|
| Cervical
Epidurals |
- Technique - usually
performed for nerve root irritation between C3 and C8. As
for lumbar epidurals, the injection is performed in the
left lateral position, under x-ray screening, using local
anaesthesia and intravenous sedation
. The injection is usually performed at the C6/7
or C7/T1 level, as the other cervical levels are too
close together to allow the epidural needle to pass.
Technically cervical epidurals are easier to perform than
at the thoracic level because the spinous processes are
widely spaced and horizontal. Average depth is between 4
and 7 cm. After confirmation of correct needle position
with an epidurogram, the epidural solution is slowly
injected. Injection may provoke the usual nerve root pain
due to volume effects within the epidural space - this is
usually short lived and not severe if the injection is
performed slowly. Afterwards the patient is positioned
affected side down with 10 degrees head down tilt for 2
hours to encourage spread of the epidural mixture to the
correct nerve root.
- Epidural Mixture - as
for Caudal Epidurals above.
- Aftercare - as for
Lumbar Epidurals above.
- See Side
Effects and Complications for more information.

|
| Side Effects |
- Mild numbness and
tingling - usually lasts for 2 hours or less, and
is due to the local anaesthetic effect. Severe leg
numbness and weakness requires urgent medical assessment
and referral to hospital.
- Pain exacerbation - some
patients experience an exacerbation of their sciatica for
24 hours after the injection when the local anaesthetic
wears off. This is usually followed by a period of very
much improved pain relief, and so it is worth sitting it
out.
- Urinary difficulties -
some patients may experience difficulty passing urine for
a short time. This occurs in about 1:200 cases and is
more common with pre-existing bladder difficulties
(pelvic floor control, cerebral palsy, very large disc
prolapses). If you are not able to pass urine 6 hours
post-procedure then medical assessment is necessary.
- Menstrual Irregularity -
high doses of depot steroids can cause menstrual
irregularity due to interference with hormonal systems.
Post-menopausal bleeding may unexpectedly occur, but is
usually short lived. This is very unusual with
triamcinolone 40 mg, but quite common with triamcinolone
80 mg. The national average dose of triamcinolone is 40
mg at present.
- Don't be a hero - it is
important to remember that the epidural produces pain
relief and is not a cure for the disc problem. If you
have a known disc prolapse, then heavy lifting must be
avoided even if you feel wonderful afterwards, to prevent
increasing the size of the disc protrusion. Sensible
exercise like walking and swimming is advised.

|
| Complications |
- Epidural complications are very rare, but when they
do occur they can be serious.
-
Early Complications
(during or just after the injection)
- Post Dural Puncture
Headache (PDPH) - if the epidural needle
accidentally enters the space containing the
cerebro-spinal fluid (CSF) during the procedure this
is called a dural tap. If this is picked up at the
time, then the procedure is usually postponed. CSF
can leak out of the hole in the dura made by the
epidural needle causing a severe headache. The
headache occurs because the CSF around the spinal
cord communicates with the CSF around the brain. A
leak in the system causes the pressure to drop, with
increased tension on the supporting membranes of the
brain. The headache is usually worse with sitting and
standing, while being relieved by lying flat. When
the hole in the dura closes, the fluid leak slows,
and the headache resolves, usually between 1 -2
weeks.
- Dural puncture rates have been quoted as between
1 - 3% of all epidurals performed. There is a higher
risk in obstetrics due to maternal movement during
contractions. The risk is much lower for caudal
epidurals as the needle is further away from the dura
when using the minimal-entry technique. Dural
puncture rates are higher for lumbar, thoracic and
cervical epidurals as the needle is much closer to
the dural membrane. My personal dural puncture rate
for lumbar, thoracic and cervical epidurals is
1/1000, and zero for caudal epidurals.
- The recommended treatment for PDPH is :-
- Oral analgesics
- acetaminophen / codeine / NSAIDs.
- Oral or IV fluid
rehydration - dehydration makes the spinal
fluid pressure lower and increases the
headache.
- Anti-emetics -
sometimes the headache can cause nausea and
vomiting, and therefore anti-emetics help to
maintain hydration and minimise the
headache.
- Intravenous
caffeine - caffeine sodium benzoate (500
mg) can be given intravenously every 8 hours to
help the headache. It is thought to work by
causing constriction of the cerebral blood
vessels. Strong oral caffeine taken in the usual
way may also be useful, but should not be taken
at the same time as the intravenous version.
- Epidural blood
patch is used when PDPH fails to resolve
with conservative treatment and time. About 20 ml
of the patients own blood is collected
aseptically, and injected into the epidural
space, usually one level above or below the
original injection level. A different level is
used to avoid a possible second dural tap caused
by pre-existing epidural anatomical abnormalities
(this may be why the dural tap occurred in the
first place). As this blood coagulates, it forms
a plug to prevent further CSF leakage, helping
the PDPH to resolve fairly quickly. Occasionally
a second blood patch is required should the PDPH
fail to resolve. Epidural blood patches are
contra-indicated in the presence of suspected
infection e.g. pyrexia, raised white blood cell
count, or known source of infection elsewhere in
the body. Blood cultures are usually sent to the
lab at the same time as performing a blood patch,
so that if infection does occur (epidural
abscess), the organism will be discovered and
treated sooner.
- Total Spinal
Injection - if the epidural needle
accidentally enters the space containing the
cerebro-spinal fluid, and if local anaesthetic is
inadvertently injected, then the local anaesthetic
can rapidly travel up the spine towards the brain
stem and cortex. The local anaesthetic has a much
more potent action in this space, and can cause a
catastrophic drop in blood pressure, leading to
cardio-respiratory arrest, unconsciousness, and total
numbness of the head and body. With proper
cardio-respiratory support (artificial ventilation,
IV fluids, and blood pressure increasing drugs), the
total spinal effects are reversible after 1 -2 hours
depending on the local anaesthetic used. The
incidence of total spinal injections can be greatly
reduced by careful minimal entry technique (caudal
route), and by aspiration on the needle before and
during the injection. Prompt recognition and
treatment of the complication can reduce the harmful
effects.
- Seizures - 10% of
all epidural injections may be placed into a vein
rather than the epidural space. This is because the
epidural space has a rich supply of veins. If a large
volume of epidural solution is accidentally injected
intravenously which contains concentrated local
anaesthetic, then an epileptic fit may occur as blood
levels of the local anaesthetic rise. This can be
prevented by careful aspiration on the needle before
and during the injection. Using weak solutions like
0.5% lidocaine and injecting slowly over 5 minutes
greatly reduces the risk of having a seizure.
Treatment of a seizure involves stopping the
injection immediately, controlling the fit with
anti-epileptic drugs, and cardio-respiratory support
until the fit stops.
- Anaphylaxis - rarely
a massive allergic reaction can occur during or
shortly after an epidural injection. It usually
causes severe falls in blood pressure, severe wheeze,
urticaria (itchy skin rash), and rapid swelling of
the face and extremities. This is no more common than
after any other type of injection. Allergic reaction
to lidocaine is very rare. If you have had a reaction
at the dentist's to lidocaine then you should tell
your doctor before having the treatment. As steroids
are used to treat allergies, it is highly unlikely
that you could be allergic to triamcinolone. The
treatment of anaphylaxis includes drugs and fluids to
support the blood pressure, and drugs to reduce the
magnitude of the allergic response (steroids).
-
Late Complications
- No Pain Relief /
probably the most common late complication. The
causes are non/nerve root sciatica, the
needle missing the epidural space, or a large disc
prolapse causing nerve root compression rather than
irritation (surgical assessment advised).
- Worse Pain - a very
small number of patients develop worse sciatic pain
which does not resolve spontaneously. The cause of
this is unknown, and highlights the fact that all
medical treatment carries risks which should be
discussed with your doctor before hand.
- Salt and water
retention - depot steroids may occasionally
cause salt and water retention. This may cause
increased breathlessness in patients with congestive
cardiac failure. This may be treated by increasing
the dose of your diuretic medication for a short
time. Please see your GP for further advice.
- Spinal Haemorrhage
may occur if an epidural vein is inadvertently
punctured in the presence of a severe blood
coagulation defect. Epidural injections should not be
performed in this situation, as an unrecognized clot
can compress the spinal cord, producing paralysis and
incontinence. Patients with the following should
alert their doctor prior to treatment:- warfarin and
heparin therapy, low platelets, severe liver disease,
haemophilia, leukaemia and other bone marrow
disorders. There is no problem with low dose aspirin
therapy for the prevention of strokes.
- Spinal Abscess
formation may occur if bacteria enter the epidural
space during the injection. This can be greatly
reduced by proper sterile technique using gloves and
anti-septic skin preparation. In some patients the
cause of the abscess is due to the formation of an
epidural clot which then becomes secondarily infected
via the blood route. The caudal route is a
potentially more dirty area because of it's proximity
to the perineum. Diabetics have a reported greater
incidence of staphylococcal abscess formation. Left
untreated an abscess can cause paralysis and
incontinence. A persistently high temperature,
feeling unwell, with increasing back ache may suggest
an abscess, and requires urgent spinal surgical
investigation and treatment.

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