This document provides information about spinal injections, epidural injections, and potential nerve damage complications. It describes how spinal injections involve inserting a thin needle into the fluid surrounding the spinal cord, while epidural injections use a larger needle to insert a catheter in the space outside the spinal cord linings. Potential nerve damage complications include direct needle injury, blood clots pressing on nerves, infections near the spinal cord, low blood pressure reducing blood flow, and other rare causes. The majority of nerve damage cases are temporary, but permanent paralysis can occasionally occur.

1. Spinal injection
A very thin needle is inserted between the bones of your back, through ligaments
and then into the fluid surrounding the spinal cord. Spinal injections are usually
performed in the lower part of the spine. At this level, the spinal cord itself has
ended and a bundle of nerves is present which supplies the legs and genital area.
Nerves in this area are surrounded by a liquid called cerebrospinal fluid (CSF). A
single injection of local anaesthetic (sometimes with other painkillers) is given and
the needle is removed. This injection should make you feel numb in the lower part
of the bodyfor between about two and four hours.
Epidural injection
A larger needle is used to introduce a thin catheter (tube) into your back. The
needle is passed between the bones, through ligaments and into a spaceoutside the
linings of the spinal cord. The catheter is passed through the hollow needle into
this spaceand the needle is then removed. The catheter is taped securely to your
skin. You can lie on your back with this catheter in place. Local anaesthetic and
other drugs can be given through this catheter for a period of time perhaps several
days. An epidural is used for operations which are longer than two hours or when
pain relief is needed for several days. .
Nerve damage
Nerve damage is a rare complication of spinal or epidural injections. Nerve
damage is usually temporary. Permanent nerve damage resulting in paralysis (loss
of the use of one or more limbs) is very rare. More figures are given at the end of
this section.
 A single nerve or a group of nerves may be damaged. Therefore the area
affected may be small or large.
 In its mildest form you can get a small numb area or an area of 'pins and
needles' on your skin.
 There may be areas of your body that feel strange and painful.
 Weakness may occurin one or more muscles.
 The most severe (and very rare) cases give permanent paralysis of one or
both legs (paraplegia) and/or loss of controlof the bowel or bladder.The

2. majority of people make a full recovery over a period of time between a few
days and a few weeks. Permanent damage is very rare.
Nervedamage
The ways in which nerve damage can be caused by a spinal or epidural injection
are listed here and explained below.
 Direct injury caused by the needle or the catheter.
 Haematoma (a blood clot).
 Infection.
 Inadequate blood supply.
 Other causes.
Direct injury
This can occur if the epidural or spinal needle or the epidural catheter damages a
single nerve, a group of nerves or the spinal cord. Contactwith a nerve may cause
'pins and needles' or a brief shooting pain. This does not mean that the nerve is
damaged, but if the needle is not repositioned, damage can occur.Ifthis happens
you should try to remain still and tell your anaesthetist about it. The anaesthetist
will change the position of the needle and the sensations will usually improve
immediately.Most cases of direct damage are to a single nerve and are temporary.
Injecting drugs right into the nerve rather than into the area surrounding it can also
cause direct damage.
Haematoma (bloodclot)
This is a collection of blood near the nerve, which collects due to damage to a
blood vessel by the needle or the catheter. Small amounts of bleeding or bruising
are common, and do not cause damage to the nerve. A large haematoma may press
on a nerve or on the spinal cord and cause damage. This is a very rare problem, but
may require an urgent operation to remove the haematoma and relieve the pressure.
If your blood does not clot normally or you take a blood thinning medicine such as
warfarin, heparin or clopidogrel, you are more likely to get a haematoma. In most
circumstances you will be asked to stop these medicines, before you have an
epidural or spinal injection. If your blood does not clot for other reasons (eg,
haemophilia) you are also at increased risk of this complication. It is important that

3. you tell your anaesthetist about any problems with blood clotting that you have had
in the pastas you may not be able to have an epidural or spinal injection.
Infection
Most infections related to a spinal injection or an epidural are local skin infections
and do not cause nerve damage. Very rarely, an infection can develop close to the
spinal cord and major nerves. There may be an abscess (a collection of pus) or
meningitis. These infections are very serious and require urgent treatment with
antibiotics and/or surgery to prevent permanent nerve damage.If you already have
a significant infection elsewhere, or if you have a weak immune system, you have
a higher risk of these serious infections. You may not be offered an epidural or
spinal injection.
Inadequate blood supply
Low blood pressure is very common when you have an epidural or spinal injection.
This can reduce the blood flow to nerves and, rarely, this can cause nerve damage.
Anaesthetists are aware of this risk and use drugs and intravenous fluid to prevent
large drops in blood pressure.
Other causes
There have been cases of the wrong drug being given in an epidural or spinal
injection. This is an exceptionally rare event and all anaesthetists take precautions
to eliminate this type of error.
Nerve damage
If you have nerve damage, you should not assume that it is caused by the epidural
or spinal injection. The following list shows other causes of nerve damage related
to having an operation.Your nerves can be damaged by the surgery. During some
operations, this may be difficult or impossible to avoid. If this is the case, your
surgeon should discuss it with you beforehand.The position that you are placed in
for the operation can stretch a nerve and damage it.The use of a tourniquet to
reduce blood loss during the operation will press on the nerve and may damage it.
Tourniquets are used for many orthopaedic arm and leg operations. Swelling in the
area after the operation can damage nerves.Pre-existing medical conditions that
interfere with blood supply (eg, diabetes or atherosclerosis - narrowing of your

4. blood vessels) or with nerve function (eg, multiple sclerosis) can make damage
more likely or make it more difficult to determine the cause of complications.
prevent nerve damage
Anaesthetists are trained to be aware of nerve damage. Steps taken to prevent each kind of
damage are described here.
Direct injury
 All anaesthetists performing epidural and spinal injections are trained in
these techniques.
 Spinal injections are placed below the expected lower end of the spinal cord.
This should prevent damage to the spinal cord itself.
 Spinal injections are usually performed while you are awake or lightly
sedated. If there is pain or tingling due to contact with a nerve, you will be
able to warn the anaesthetist who will then be able to adjust.
 Your anaesthetist may wish to do your epidural injection while you are
awake. Direct nerve injury after an epidural injection is rare, and there is no
clear evidence about whether it is safer to do the epidural while you are
awake or after a general anaesthetic has been given. Anaesthetists vary in
their views on this matter and you should discuss your preference about this
with your anaesthetist.
Haematoma (bloodclot)
 If you take an anticoagulant (a drug which thins the blood, such as warfarin),
you will be asked to stop it several days before surgery if your doctors think
it is safe to do so. The anaesthetist and surgeon together will decide if and
when the drug should be stopped. A blood test will allow your anaesthetist
to decide if it is safe to have a spinal or epidural injection. If your
anticoagulation cannot be safely stopped, then you will not be able to have
an epidural or spinal injection.
 If you take clopidogrel (another drug which thins the blood by its effect on
platelets), you will usually be asked to stop it several days before planned
surgery. For urgent surgery, your doctors will think about whether it is safer
for you to have or to avoid a spinal or epidural injection.
 If you take aspirin, you can have an epidural or spinal injection.

5. Infection
 All epidural and spinal injections are performed under 'aseptic conditions' (ie
using special precautions to make the procedure as clean as is possible),
similar to those used during the operation. Your backshould be kept clean
and regularly checked over the next few days.
Anaesthesia
Anaesthesia is from the Greek and means 'loss of sensation'. Anaesthesia allows
invasive and painful procedures to be performed with little distress to the patient.
There are three main types of anaesthesia
 Generalanaesthesia:the patient is sedated, using either intravenous
medications or gaseous substances, and occasionally muscles paralysed,
requiring control of breathing by mechanical ventilation
 Regionalanaesthesia:this can be described as central where anaesthetic
drugs are administered directly in or around the spinal cord, blocking the
nerves of the spinal cord (eg, epidural or spinal anaesthesia). The main
benefit of this method is that ventilation is not needed (provided the block is
not too high). Regional anaesthesia can also be peripheral - for example:
o Plexus blocks - eg, brachial plexus.
o Nerve blocks - eg, femoral.
o Intravenous blocks whilst preventing venous flow out of the region -
eg, Bier's block.
 Localanaesthesia:the anaesthetic is applied to one site, usually topically or
subcutaneously.
Important complicationsof general anaesthesia
The practice of anaesthesia is fundamental to the practice of medicine. However,
anaesthesia is not without its problems. It is difficult to determine exactly the
incidence of deaths directly attributable to general anaesthetics, as the cause of
death is often multifactorial and study methodology varies making comparisons
difficult. Figures of anaesthetic related morbidity are more difficult to determine.
Estimates suggest that up to 2% of intensive care unit admissions at any one time
are related to anaesthetic problems.Although general anaesthesia is not without
risk, it should be remembered that it allows necessary procedures to be performed

6. in a humane way without which the patient might otherwise die. Along these lines,
if a patient is high-risk for a general anaesthetic (eg, pre-existing comorbidities)
then they should still be referred for surgery like any other patient. The decision to
operate and which form of anaesthesia to use should then be decisions made by the
surgeon and anaesthetist.
Some specific complications of general anaesthesia
Anaphylaxis
 Anaphylaxis can occurto any anaesthetic agent and in all types of
anaesthesia.The severity of the reaction may vary but features may include
rash, urticaria, bronchospasm, hypotension, angio-oedema, and vomiting. It
needs to be carefully looked for in the pre-operative assessmentand previous
general anaesthetic charts may help.
 Patients who are suspected of an allergic reaction should be referred for
further investigation to try to determine the exact cause. If necessary, this
may involve provocationtesting or skin prick testing and patients should be
referred to local immunologists. Anaphylaxis needs to be promptly
recognised and managed and patients should be advised to wear a medical
emergency identification bracelet or similar once they recover.
Aspirationpneumonitis
 A reduced level of consciousness canlead to an unprotected airway. If the
patient vomits they can aspirate the vomitus contents into their lungs. This
can set up lung inflammation with infection. The risk of aspiration
pneumonitis and aspiration pneumonia is reduced by fasting for several
hours prior to the procedureand cricoid cartilage pressure during induction
of anaesthesia. However, the evidence for the use of cricoid pressure is not
clearly documented and further investigation is required.
 Other methods of reducing aspiration pneumonitis associated with
anaesthesia are the use of metoclopramide to enhance gastric emptying and
ranitidine or proton pump inhibitors to increase the pH of gastric contents.
The evidence for the benefit of these methods appears promising.
 Aspiration pneumonitis may also occurin spinal anaesthesia if the level of
spinal block is too high, leading to paralysis or impairment of the vocal
cords and respiratory impairment.

7. Peripheral nerve damage
 This can occur with all the types of anaesthesia and results from nerve
compression. The most common cause is exaggerated positioning for
prolonged periods of time. Both the anaesthetist and the surgeons should be
aware of this potential complication and patients should be moved on a
regular basis if possible. The severity varies and recovery may be prolonged.
The most common nerves affected are the ulnar nerve and the common
peroneal nerve. More rarely, the brachial plexus may be affected.
 Injury to nerves can be avoided by prevention of extreme postures for
lengthy periods during surgery. If nerve damage occurs then patients should
be followed up and further investigations such as electromyography may be
required.
Damage to teeth
It is now common practice to check the teeth in the anaesthetist's pre-operative
assessment. Damage to teeth is actually the most common cause of claims made
against anaesthetists. The tooth most commonly affected is the upper left incisor.
Embolism
Embolism is rare during an anaesthetic but is potentially fatal. Air embolism
occurs more commonly during neurosurgical procedures or pelvic operations.
Prophylaxis of thromboembolism is common and begins pre-operatively with
thromboembolic deterrents (TEDS) and low molecular weight heparin (LMWH).
Some specificcomplicationsof regional anaesthesia
Post-duralpuncture headache
 Post-duralpuncture headache is very common after spinal anaesthesia and
especially in young adults and obstetrics. The headache results from CSF
leak from the puncture site. It is enhanced by use of larger-gauge needles
and reduced by pencil-tipped needles. Presenting symptoms may include
headache, photophobia, vomiting and dizziness.
 Post-duralpuncture headache is usually treated with analgesia, bed rest and
adequate hydration. The evidence does not suggest that bed rest prevents or
changes the outcome.Occasionally epidural blood patch is used where 15 ml

8. of the patient's blood are injected at the site of the meningeal tear.Caffeine is
also used and acts as a stimulant of the CNS and has shown benefit. Other
medications with benefit include gabapentin, theophylline and
hydrocortisone. Subcutaneous sumatriptan, adrenocorticotrophic hormone
(ACTH) and epidural saline have not shown consistent benefits.
Total spinal block
Total spinal block can occurwith the injection of large amounts of anaesthetic
agents into the spinal cord. It is detected by a high sensorylevel and rapid muscle
paralysis. The block moves up the spinal cord so that respiratory embarrassment
may occur, as can unconsciousness. In these situations the patient needs prompt
assessment and may need to be intubated and ventilated until the spinal block
wears off.
Hypotension
 Up to half of patients receiving spinal anaesthesia will develop transient
hypotension as sympathetic nerves are blocked. This usually responds to
prompt fluid replacement, usually starting with crystalloids followed by
colloids. Occasionally hypotension can be severe and may require
vasopressorsalong with fluids.
 Care must be taken in patients with a cardiac history, as they may develop
myocardial ischaemia with minor drops in blood pressure. It is suggested
that heart rate variability prior to spinal anaesthesia represents autonomic
dysfunction and may help determine patients who are more likely to develop
hypotension.
 Cases of bradycardia with asystole leading to cardiac arrest have also
occurred and it appears the underlying aetiology is complicated and not just
related to autonomic dysfunction.

Neurologicaldeficits
 Cauda equina syndrome may occurand can be transient or permanent. This
is a common reason for patients to refuse spinal anaesthesia. There may also
be traumatic injury to the spinal cord.

9.  Adhesive arachnoiditis is a longer-term sequela of spinal anaesthesia,
occurring weeks and even months later.It is characterised by proliferation of
the meninges and vasoconstriction of spinal cord blood vessels. This results
in gradual sensory and motor deficits from ischaemia and infarction of the
spinal cord.
.
spinal cord and the vertebra
The spinal cord is about 18 inches long and extends from the base of the brain, down the middle
of the back, to about the waist. The nerves that lie within the spinal cord are upper motor neurons
(UMNs), and their function is to carry the messages back and forth from the brain to the spinal
nerves along the spinal tract. The spinal nerves that branch out from the spinal cord to the other
parts of the body are called lower motor neurons (LMNs). These spinal nerves exit and enter at
each vertebral level and communicate with specific areas of the body. The sensory portions of
the LMN carry messages about sensation from the skin and other body parts and organs to the
brain. The motor portions of the LMN send messages from the brain to the various body parts to
initiate actions such as muscle movement. The spinal cord is the major bundle of nerves that
carry nerve impulses to and from the brain to the rest of the body. The brain and the spinal cord
constitute the central nervous system. Motor and sensory nerves outside the central nervous
system constitute the peripheral nervous system. Another diffuse system of nerves that controls
involuntary functions, such as blood pressure and temperature regulation, are called the
sympathetic and parasympathetic nervous systems. The spinal cord is surrounded by rings of
bone called vertebra. These bones constitute the spinal column (back bones). In general, the
higher in the spinal column the injury occurs, the more dysfunction a person will experience. The
vertebra are named according to their location. The eight vertebra in the neck are called the
cervical vertebra. The top vertebra is called C-1, the next is C-2, etc. Cervical spinal cord injuries
usually cause loss of function in the arms and legs, resulting in quadriplegia. The 12 vertebra in
the chest are called the thoracic vertebra. The first thoracic vertebra, T-1, is the vertebra where
the top rib attaches. Injuries in the thoracic region usually affect the chest and the legs, resulting
in paraplegia. The vertebra in the lower back between the thoracic vertebra, where the ribs
attach, and the pelvis (hip bone), are the lumbar vertebra. The sacral vertebra run from the pelvis
to the end of the spinal column. Injuries to the five lumbar vertebra (L-1 thru L-5) and similarly
to the five sacral vertebra (S-1 thru S-5) generally result in some loss of function in the hips and
legs.
Effects of a spinal cord injury
The effects of a spinal cord injury depend on the type and level of the injury.
Spinal cord injuries can be divided into two types of injury – complete and
incomplete. A complete injury means there is no function below the level of the

10. injury – no sensation and no voluntary movement. Both sides of the bodyare
equally affected.
An incomplete injury means there is some function below the primary level of
injury. A person with an incomplete injury may be able to move one limb more
than another, may be able to feel parts of the bodythat cannot be moved, or may
have more functioning on one side of the bodythan the other. With the advances in
acute treatment of spinal cord injuries, incomplete injuries are becoming more
common.
The level of injury is very helpful in predicting what parts of the bodymight be
affected by paralysis and loss of function. Remember that in incomplete injuries,
there will be some variation in these prognoses.
Cervical (neck) injuries usually result in quadriplegia. Injuries above the C-4 level
may require a ventilator for the person to breathe. C-5 injuries often result in
shoulder and biceps control, but no control at the wrist or hand. C-6 injuries
generally yield wrist control, but no hand function.
Individuals with C-7 and T-1 injuries can straighten their arms, but still may have
dexterity problems with the hand and fingers. Injuries at the thoracic level and
below result in paraplegia, with the hands not affected. At T-1 to T-8, there is most
often control of the hands, but poortrunk controlresulting from a lack of
abdominal muscle control. Lower thoracic injuries (T-9 to T-12) allow good trunk
control and good abdominal muscle control. Sitting balance is very good. Lumbar
and sacral injuries yield decreasing control of the hip flexors and legs.
Besides a loss of sensation or motor function, individuals with spinal cord injury
also experience other changes. Forexample, they may experience dysfunction of
the bowel and bladder. Very high injuries (C-1, C-2) can result in a loss of many
involuntary functions, including the ability to breathe, necessitating breathing aids
such as mechanical ventilators or diaphragmatic pacemakers.
Other effects of spinal cord injury may include low blood pressure, inability to
regulate blood pressure effectively, reduced controlof bodytemperature, inability
to sweat below the level of injury and chronic pain.