CRUCIATE LIGAMENTS
CT SCANNING
badly decayed or weakened, it may be
necessary to remove the entire natural
crown of the tooth and then fit the arti-
ficial crown onto a post cemented in
the root canal.
cruciate ligaments
Two
ligaments
in the
knee that pass over each other to form a
cross. The ligaments form connections
between the
femur
and
tibia
inside the
knee joint and prevent overbending and
overstraightening at the knee.
crush syndrome
Damage to a large
amount of body
muscle
(usually as a
result of a serious accident) causing
kid-
ney failure
.
The damaged muscles release
proteins into the bloodstream, temporar-
ily impairing kidney function.
Dialysis
is
given while the kidneys recover.
crutch palsy
Weakness or
paralysis
of
muscles in the wrist, fingers, and thumb
due to pressure on the
nerves
that sup-
ply these muscles from a crutch pressing
under the arm. The condition does not
occur in people who use the more com-
mon elbow crutches.
crying in infants
A normal response in
babies to needs or discomforts, such as
hunger or thirst. Most healthy babies stop
crying when their needs are attended to.
In a few cases, persistent crying may be
due to a physical cause such as intoler-
ance of cow's milk or an illness (such as
an ear or throat infection, or a viral fever).
cryo-
A prefix meaning ice cold, used
medically to indicate that a procedure
uses freezing or low temperatures.
cryopreservation
The preservation of
living cells by freezing. The technique is
used to store human eggs for
in vitro
fertilization
, sperm for
artificial insem-
ination
, or
plasma
and blood belonging
to rare blood groups.
cryosurgery
The use of temperatures
below freezing to destroy tissue, or the
use of cold during surgery to produce
adhesion
between an instrument and
body tissue. Cryosurgery causes only
minimal scarring and is used to treat
cancerous tumours in sites where heavy
scarring can block vital openings such
as in the
cervix
, the liver, and the
intestines. It may be used in eye opera-
tions, for example in
cataract surgery
and treatment for
retinal detachment.
It
is also commonly used for removing
warts
,
skin tags
, some
birthmarks
, some
skin cancers, and to treat
haemorrhoids.
cryotherapy
The use of cold or freezing
in treatment. (See also
cryosurgery
.)
cryptococcosis
A rare infection caused
by inhaling the fungus
cryptococcus
neoformans
found especially in soil con-
taminated with pigeon droppings. The
most serious form the infection can take
is
meningitis
. Another form of infection
causes growths in the lungs, resulting
in chest pain and a cough, or on the
skin, causing a rash of ulcers. Most cases
of cryptococcosis occur in people with re-
duced immunity, such as those with
AIDS.
Cryptococcal meningitis is diagnosed
from a sample of spinal fluid. A combi-
nation of
amphotericin B
and another
antifungal drug,
flucytosine, is usually
prescribed. Most cases in which only the
lungs are infected need no treatment.
cryptorchidism
A developmental dis-
order of male infants in which the
testes fail to descend normally into the
scrotum (see
testis, undescended).
cryptosporidiosis
A type of diarrhoeal
infection caused by
protozoa
, which may
be spread from person to person or from
domestic animals to people. The disease
causes watery diarrhoea and sometimes
fever and abdominal pain. It is most com-
mon in children but also occurs in male
homosexuals. Treatment, apart from
re-
hydration therapy,
is not usually needed
except for people whose
immune system
is suppressed, in whom the infection may
be much more severe.
CT scanning
A diagnostic technique in
which the combined use of a computer
and
X-rays
passed through the body at
different angles produces cross-sectional
images of tissues. CT (computed tomo-
graphy) scanning has revolutionized the
diagnosis and treatment of
tumours
,
ab-
scesses
, and haemorrhages in the brain,
as well as
head injuries
and
strokes
. CT
scanning is also used to locate and image
tumours, investigate diseases, and aid
needle
biopsy
in organs of the trunk.
Newer types of CT scanners use a spi-
ral technique: the scanner rotates around
the body as the patient is moved slowly
forwards on a bed, causing the X-ray
beams to follow a spiral course. The
computer produces 3-D images. Injected
C
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