EXOSTOSIS
RISKS
In some circumstances, vigorous exer-
cise may pose a number of health risks.
For
example,
people
who
are
out
of condition
but
attempt
strenuous
activity
may
suffer
injury
and
put
themselves at increased risk of a heart
attack. Professional sportsmen, such as
footballers, may have an increased risk
of
osteoarthritis
in later life because of
the repeated m inor damage to struc-
tures such as the knee and the cervical
area of the spine.
exercise ECG
The use
of electrocardiography
(see
ECG
)
to assess the function of the heart
when it is put under the stress of exer-
cise. Exercise ECG is usually carried out
when a patient is suspected of having
coronary artery disease
.
The procedure
involves raising the heart rate by exer-
cising, usually on a treadmill with an
adjustable gradient or on an exercise
bicycle. The heart’s electrical activity is
then recorded for analysis.
exercise tests
Any of a variety of tests in w hich exer-
cise is used as a means of deliberately
stressing the heart and the lungs. The
use of exercise tests enables doctors to
assess an individual’s level of health
and fitness. (See also
cardiac stress test
;
exercise ECG
. )
exfoliation
Flaking off, shedding, or peeling from a
surface in scales or thin layers, as in
exfoliative dermatitis
.
exfoliative dermatitis
A skin disorder characterized by severe
inflammation, redness, and scaling of
the skin over most of the body. Exfolia-
tive dermatitis may be the result of an
allergic response to a drug (see
allergy
)
or it may be due to worsening of a pre-
existing skin condition such as
psoriasis
or
eczema
.
The condition sometimes
occurs in
lymphoma
and
leukaemia
.
In exfoliative dermatitis, there is a
widespread rash, accompanied by severe
flaking of the skin, w hich results in in -
creased loss of water and protein from
the surface of the body. Protein loss may
cause
oedema
(the accumulation of fluid
in tissues) and muscle wasting. Further
possible
complications
include
heart
failure
and infection. The treatment of
exfoliative dermatitis, and the outlook,
depend on the cause.
exhalation
The medical term for the process of
breathing out (see
breathing
) .
exhaustion
Extreme mental or physical
tiredness
in
w hich a person lacks energy. The state
of exhaustion may come about as a
result
of
overactivity
or
prolonged
insomnia
(difficulty in falling or staying
asleep) or it may be a symptom of a
mental or physical disorder, such as
anx-
iety
,
stress, severe
anaemia
,
or prolonged
labour
.
(See also
heat exhaustion
. )
exhibitionism
The habit of deliberately exposing the
genitalia
as a deviant sexual act. This
type
of behaviour is
almost always
confined
to
men.
Psychotherapy
or
behaviour therapy
may help to treat per-
sistent offenders.
existential psychotherapy
An uncommon form of
psychotherapy
in
w hich emphasis is placed on sponta-
neous interactions and feelings rather
than
on
rational
thinking. The psy-
chotherapist is involved in the therapy
to the same extent as the patient.
exocrine gland
A
gland
that secretes substances through
a duct (a tube or passage) either onto
the inner surface of an organ or the
outer surface of the body. Examples of
exocrine
glands
include
the
salivary
glands
and the
sweat glands
.
The release
of exocrine secretions can be triggered
by a
hormone
or a
neurotransmitter
.
(See
also
endocrine gland
. )
exogenous
A term referring to a disease or disorder
that has a cause external to the body.
Examples are infection, poisoning, or
injury. (See also
endogenous
. )
exomphalos
A rare
birth defect
in w hich a mem-
branous
sac
containing
part
of the
intestines protrudes through the
navel
.
In m ild cases of exomphalos, only one
or two loops of intestine protrude; in
severe cases, most of the abdominal
organs are exposed. An affected infant
may also have intestinal malformation.
Exomphalos is sometimes diagnosed
before birth by
ultrasound
examination.
The condition is treated using surgery,
the success of w hich depends on the
extent of the defect.
exophthalmic goitre
An alternative name for the thyroid
gland disorder
Graves’ disease.
exophthalmos
Protrusion
of one
or
both
eyeballs
caused by a swelling of the soft tissues
w ithin the
eye
socket.
Appearance of exophthalmos
The staring appearance in exophthalmos is caused
by swelling of the soft tissue in the eye socket,
which pushes the eyeball forwards.
CAUSES
Exophthalmos is most commonly associ-
ated with Graves’ disease, which also
causes
thyrotoxicosis
(overactivity of the
thyroid gland). Other causes include an
eye tumour
,
an
aneurysm
(ballooning of an
artery), or inflammation behind the eye.
SYMPTOMS
Exophthalmos may restrict eye move-
ment and cause
double vision
.
In severe
cases, increased pressure in the socket
may restrict blood supply to the
optic
nerve
,
causing blindness. The
eyelids
may be unable to close, and vision may
become blurred due to drying of the
cornea
(the transparent dome that forms
the front of the eyeball).
TREATMENT AND
OUTLOOK
In exophthalmos due to thyroid disease,
treatment of the thyroid disorder may
relieve the exophthalmos; however, exo-
phthalmos may persist even if thyroid
function returns to normal.
With early treatment, normal vision
is usually restored. Occasionally, surgery
may be required to relieve pressure on
the eyeball and optic nerve.
exostosis
The most common type of noncan-
cerous
bone tumour
,
in w hich there is an
outgrowth
of bone
tissue.
Exostosis
develops most commonly at one end of
the
femur
(thigh bone)
or the
tibia
(shin). The condition may be due to
hereditary factors or to prolonged pres-
sure on a particular bone.
E
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