CORN
injuries. Other types of contracture are
caused by inflammation and shrinkage
of
connective tissues
; examples of these
include
Dupuytren’s contracture
and
Volk-
mann’s contracture.
contraindication
Factors in a patient’s condition that
would make it unwise to pursue a cer-
tain line of treatment.
contrast enema
A
contrast medium
(opaque substance),
w hich is introduced through the anus,
that enables the colon and rectum to be
seen in outline on an X-ray. (See also
barium X-ray examinations.)
contrast medium
A substance that is opaque to
X-rays
and
is introduced into hollow or fluid-filled
parts of the body to render them visible
on X-ray film. Barium is one of the
most commonly used contrast media
(see
barium X-ray examinations).
controlled drug
One of a number of drugs that are subject
to restricted use because of their potential
for abuse. Controlled drugs include opi-
ates
such
as
cocaine
and
morphine,
amphetamine drugs,
and
barbiturate drugs.
controlled trial
A scientific method of testing the effec-
tiveness
of
new
treatments
or
of
comparing different treatments.
In a typical controlled drug trial, two
comparable groups of patients with the
same illness are given courses of appar-
ently
identical
treatment.
Only
one
group, however, actually receives the
new
treatment;
the
second
group
(known as the control group) is given a
placebo
(a harmless substance contain-
ing no active ingredients). Alternatively,
the control group may be given an
established drug that is already known
to be effective. After a predetermined
period, the two groups are assessed
medically. If the patients on the new
treatment show a greater improvement
than those on the placebo (or those on
an existing treatment), this result proves
that the drug has a beneficial effect.
Controlled trials must be conducted
“blind’’ (meaning that the patients do
not know w hich treatment they are
receiving). In a “ double-blind’’ trial,
neither the patients nor the doctors
who assess them know w ho is receiv-
ing w hich treatment.
contusion
Bruising to the skin and underlying tis-
sues from a “blunt” injury such as an
abrasion (graze) or an impact.
convalescence
The period of recovery following an
illness or a surgical operation during
w hich the patient gradually regains
strength before returning to their nor-
mal activities.
convergent squint
A type of
squint
in w hich the abnormal
eye is directed too far inwards towards
the other eye.
conversion disorder
A
psychological
disorder,
formerly
called
hysteria,
in
w hich
repressed
emotions appear to be unconsciously
converted into physical symptoms such
as blindness, loss of speech, or par-
alysis. Conversion disorder is generally
treated by
psychotherapy
.
convulsion
See
seizure
.
convulsion, febrile
Twitching or jerking of the limbs with
loss of consciousness that occurs in a
child after a rapid rise in body temper-
ature. Febrile convulsions are common
and usually affect children between the
ages of six months and five years.
CAUSES
The convulsions are due to immaturity
of the temperature-lowering mechan-
ism in the brain; the mechanism allows
the child’s body temperature to rise too
rapidly in response to infections such
as
measles
or
influenza
.
TREATMENT AND PREVENTION
Treatment involves lowering the tem-
perature by sponging the child’s face
and body with tepid water and using a
fan. Seizures can often be prevented in
susceptible children by giving
paraceta-
mol
at the first signs of fever.
OUTLOOK
Most children who have one or more
febrile convulsions suffer no long-term
effects. However, there is a very small
risk of developing
epilepsy
,
w hich is in -
creased in children with a pre-existing
abnormality of the brain or nervous
system, or children with a family his-
tory of epilepsy.
Cooley’s anaemia
See
thalassaemia
.
COPD
The abbreviation for chronic obstruc-
tive pulmonary disease (see
pulmonary
disease, chronic obstructive
) .
copper
A metallic element that is an essential
part of several
enzymes
(substances that
regulate
chemical
reactions
in
the
body). Copper is required by the body
in only minute amounts (see
trace ele-
ments
) .
An excess in the body may
occur as a result of the rare inherited
disorder
Wilson’s disease
.
co-proxamol
An
analgesic drug
(painkiller) contain-
ing
paracetamol
and the weak
opioid
analgesic
drug
dextropropoxyphene.
Co-proxamol is used to relieve m ild to
moderate pain that has not responded
to
paracetamol
or
other
nonopioid
analgesics alone. Side effects include
dizziness, drowsiness, constipation, and
nausea. The drug may be habit-forming
if taken over a long period.
cordotomy
A surgical procedure in w hich certain
bundles
of nerve
fibres
w ithin the
spinal cord
are severed. Cordotomy is
carried out to relieve persistent, severe
pain that has not responded to other
treatment. It is most frequently per-
formed to treat pain occurring in the
lower trunk and legs, especially in peo-
ple w ho have cancer.
cord, spermatic
See
spermatic cord
.
cord, testicular
See
spermatic cord
.
cord, umbilical
See
umbilical cord
.
cord, vocal
See
vocal cords
.
corn
A small area of thickened skin on a toe
or other part of the foot. A corn is
caused by the pressure of a tight-fitting
shoe. The dead skin cells form a hard
plug that extends down into the skin
tissues. Pressure on this plug can cause
pain. If a corn is painful, a spongy ring
or corn pad can be placed over it to
relieve the pressure. If the corn persists,
the
area
of thickened skin
can be
removed by a chiropodist.
C
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