Angioedema is a spontaneous swelling up of
areas of skin or mucous
membranes. It is similar to urticaria,
and the mechanisms that cause it are the same, but deeper-seated
tissues are involved. Like urticaria it is caused by a build
up of fluid leaking from thin-walled blood vessels. It
may accompany
urticaria or it may occur alone.
Both conditions are caused by an allergy-like response that occurs in
the skin. In
angioedema, the redness that normally accompanies urticaria isn’t seen, but the swellings
are thicker and more obvious. These swellings generally occur on the head, neck,
face, fingers and toes. Attacks
of angioedema may be quite disfiguring. The
swellings can cause the lips to look like sausages,
and the eyelids may be completely closed. For the
vast majority of sufferers angioedema is a nuisance
rather than a life-threatening condition.
However, in some
cases, the mucous membranes of the mouth and throat,
and one or both sides of the tongue can be affected,
sometimes considerably.
When angioedema
affects the throat, the condition is called laryngeal
oedema.
Varying degrees of laryngeal oedema may accompany angioedema in about one case
in five, but in other cases, laryngeal oedema may occur alone. In most cases
throat swelling is milk, but significant swelling of
the tongue or throat (enough to affect the voice or
cause any degree of distress) should be regarded as
a emergency and urgent medical assistance should be
obtained (dial 999 for an ambulance). If this
has happened previously, an adrenaline injection for
emergency use (e.g. EpiPen) may have been provided.
If so this
is the time to use it.
When angioedema occurs in boys and in men, the
scrotum and penis may be involved. Angioedema is not usually itchy, but is
often described accompanied by mild pain
or by a burning sensation.
Angioedema, like urticaria, results when
specialised white cells ('mast' cells) release chemical messengers such as
histamine. In
angioedema the histamine-release is less superficial than in urticaria and this results in the characteristic tissue
swellings of the condition. Both conditions may result from allergy. Sometimes the
cause is obvious, for example a wasp sting could cause it in someone with
wasp venom allergy. Sometimes it can take detailed investigation to find a
cause, and in many cases (over half) no cause
is found even after detailed investigation. The latter condition is called
idiopathic
angioedema.
Angioedema is described by the length of time that
symptoms last. If there is just a single attack and it lasts less than six weeks it is called
acute angioedema.
When episodes last more than six weeks the condition is described as chronic
angioedema. In
rare cases it can be caused by a genetic defect and it is then
called
hereditary angioedema.
When no external or internal cause for the
urticaria can be found, the condition is called
idiopathic
angioedema.
Acute angioedema
Angioedema is called
acute if it happens on just a
single occasion, perhaps lasting for a few hours or even a few days. The commonest cause
for a single isolated attack is probably some kind of infection, viruses are usually blamed as
we can never be sure if an immune response
to microbe in the environment has taken an odd course and produced this kind of
response. This explanation is thought to be especially likely when this kind of episode
occurs in children. When the history includes only a single attack of angioedema,
or attacks have occurred only rarely, then allergy
investigations will probably be unhelpful.
It is when angioedema persists, and especially when
it consists of frequent but separate attacks, that the possibility of an environmental trigger such as a food or a drug
must be considered.
Chronic
angioedema
Angioedema is called
chronic
if it goes on for more than a few weeks. The word chronic simply means 'persistent', it has
nothing to do with the severity of the attacks.
In many cases of chronic angioedema no cause can be
found in spite of extensive testing. Doctors call this condition idiopathic
angioedema. The word idiopathic sounds very
scientific, however it simply means that doctors don't
know the cause!
In some cases the angioedema tendency
appears to be present the whole time, whilst in other case the patient is getting
recurrent attacks of acute angioedema. In both kinds of case, the
patient may strongly suspect a food or other allergy, although such an
explanation is often not found. As the list of things which can cause
angioedema is long, and
new causes are always turning up, the possibility that external triggers
are responsible should always be considered. A list of possible
causes follows.
Causes
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Food
allergy
Food allergy may cause angioedema, although true food
allergy probably causes less than 1 case in 20. Attacks are likely to
occur quite soon after the food has been eaten. Foods likely to
cause this kind of true food allergy include egg, milk, fish, shellfish,
nuts and seeds. Skin prick or allergy blood tests are usually
helpful.
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Pollen
food syndrome
Angioedema in or around the mouth, tongue or
throat may occur as a result of contact with the responsible food. This is
especially likely to happen with certain fresh fruits and raw vegetables
in people with two other types of allergy. People who have spring hay fever
caused by tree pollen
allergy may suffer from the pollen food syndrome, and people with latex rubber allergy
the latex food
syndrome.
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Medicines
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ACE-Inhibitors
Medicines belonging to the group ACE-Inhibitors
(the chemical names
end in -pril, e.g. drugs such as enalapril, perindopril, ramipril) are
used for high blood pressure and heart problems. They cause angioedema in about one
person in 100 who take them.
 Although
it might be expected that the angioedema would start shortly after commencing the drug
( and
occasionally this is true and the diagnosis is not difficult) in practice this is
often not the case. Regular daily intake of the drug may cause a pattern of occasional
attacks that may only start months or even years after the drug has
been started. When this happens, the relationship may not be spotted by the patient
or their
doctor.
The only way to confirm an ACE-inhibitor
drug as the cause of angioedema (allergy tests are of no help) is for a
doctor to agree to the substitution of an alternative drug from a different group for
a trial period. It is important to note that even if the ACE-inhibitor
drug is causing the angioedema, attacks may not stop for 2-3 months and
this will cause
confusion if it is not realised!
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Medicines
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Aspirin and NSAIDs
Aspirin,
along with the closely chemically-related pain-killers called non-steroidal anti-inflammatory drugs (NSAIDs), can occasionally cause angioedema and
even anaphylaxis. When a single dose of one of these drugs
causes a single attack of angioedema, the relationship will be obvious. However,
the relationship can be more difficult to spot in patients who take these
drugs frequently. It can also be difficult to spot the relationship in
someone who experiences regular angioedema attacks associated with taking
a small
daily dose of aspirin, a drug in common use for stroke and heart attack
prevention.
Attacks of angioedema may start happening
a little while after the aspirin treatment has started and this can mean that the relationship is not suspected.
In addition, naturally-occurring compounds called salicylates
(aspirin is itself a salicylate) are present
in certain fruits and vegetables and there is a theory that some
patients may need to avoid these also, together with certain food
dyes and preservatives, to lessen the
tendency to angioedema.
So why does this happen? When these drugs and foodstuffs cause this kind of problem,
allergy tests to these substances (e.g. skin prick or blood tests) are negative. It is thought to occur because of a direct
action of these compounds on the specialised white cells of the immune system, in effect
making them 'trigger happy'.
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Medicines
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Beta -blockers
Drugs belonging to the group beta-blockers (the chemical names
end in -olol, e.g. drugs such as metoprolol, sotalol) are used for high blood
pressure, certain other heart problems and anxiety. They work by blocking adrenaline-like
substances in the body. However, because of a side effect they increase the likelihood of
several other conditions. Angioedema, urticaria (hives), anaphylaxis and asthma all become more likely
if one of these drugs is being taken.
So patients at risk of angioedema are better
not to have beta-blockers, whether or not there is a suspicion
that they have caused previous attacks. There are two reasons for this. Firstly they make
the condition more likely to occur (whether or not there is a separate
external cause) and secondly, the beneficial effects of adrenaline (the
usual emergency treatment for a severe attack) are blocked by
beta-blockers.
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Medicines
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Other
drugs
The above examples of drug reactions are not due to true allergy,
and this is why skin prick and allergy blood tests are unhelpful. However,
true drug
allergy does
occasionally cause angioedema. Many different drugs can very
occasionally cause this type of problem, and this explanation should
always be considered if any drug was being taken at the time of an
angioedema attack.
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Rubber
latex
Rubber latex is the sap that oozes out of the trunk of rubber
trees. It is substance from which rubber is made, and it we
encounter it very commonly in everyday life. Household and surgical
'rubber' gloves are made from it, and it is commonly found in medical and
dental situations. It
is also what balloons,
contraceptive condoms and diaphragms, and rubber bands are made from. Those
most likely to suffer from true allergy to latex are nurses and other
medical personnel, and patients who have had many bladder operations
requiring catheters. A latex skin prick or blood test can identify those
with the allergy and such people may experience a swelling (angioedema) or
blotchy rash (urticaria) either at the site of contact (e.g. the
hands or lips) or at remote sites such as the throat (laryngeal
oedema).
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Idiopathic angioedema
Ĭdiŏpăth´ic
adj.
Describes a condition that
arises
spontaneously and without known cause
Although
the term idiopathic describes a disease or condition that is without known
cause, allergy specialists prefer not to make this diagnosis until all possible external
causes have been excluded. Many possible explanations have been put forward, and
amongst these are several that may be worth considering, particularly if
taking regular
antihistamines is unhelpful.
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Food
intolerance
A test elimination diet may be considered in the case of someone with very
persistent angioedema when no other cause can be found, and skin testing is
unhelpful. When this uncovers the cause, food
intolerance rather
than food allergy is considered to be the explanation. In this
situation,
allergy tests are negative even though a particular food or food
additives appears to be causing the
problem.
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Airborne
allergy
A further possible explanation for otherwise unexplained urticaria
and/or angioedema concerns allergy to airborne allergens such as house
dust mites or mould spores. Occasional patients who suffer from
urticaria and/or angioedema will have positive skin tests to one of
these allergens, and it is then impossible to say whether these agents
are causing the symptoms, or whether it is simply
coincidence.
Other patients with negative
allergy tests report that symptoms improve or
disappear when they go to a dry
climate, and re-appear when they return. In
addition, some patients report that changes in
the weather affect their symptoms in a similar
way, worsening in damp weather and improving
in dry weather. Allergy skin prick
and blood tests appear to under-diagnose mould
spore allergy (it is suggested that intradermal
skin tests may pick up missed
cases) and this may be an explanation.
The possibility that airborne allergy (house dust mites, mould spores)
provokes urticaria and angioedema has never been systematically
studied. Until it is, patients who suspect their condition is being
provoked in this way should consider taking avoidance
measures to reduce their exposure.
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Hereditary angioedema
Hereditary angioedema is quite rare and is caused by
deficiency of an enzyme called C1 inhibitor. Once the diagnosis has
been made by a special blood test, the management and treatment
of the condition may be different from other forms of angioedema.
So it is important to identify this
condition, and a check for it should be made in patients suffering
angioedema without
urticaria.
There
may be clues in the medical history.
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Patients
are prone to attacks of angioedema but not
urticaria (hives or nettle rash)
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Sufferers
may also be prone to unexplained
attacks of abdominal pain. These pains can be so troublesome that
exploratory surgery may have been considered or even undertaken
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Standard (antihistamine or steroid) drug
treatments may have been found to be ineffective or disappointing
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There
may be other family members may get angioedema
swellings or unexplained abdominal pains
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Patients
are prone to attacks of angioedema but not
urticaria (hives or nettle rash)
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Laryngeal oedema
When
angioedema
affects the throat the condition is known as
laryngeal
oedema
and the possible causes are the same.
Varying degrees of laryngeal oedema may accompany angioedema in about one case
in five. In other cases, laryngeal oedema may occur alone.
Whatever the cause, sudden internal throat
swelling, particularly in someone known to suffer the condition, is a medical
emergency similar to anaphylaxis and urgent medical attention (dial 999) should be obtained.
If this has happened previously, an adrenaline injection for emergency use (e.g. EpiPen)
may have been provided. If so this
is the time to use it.
