ACQUIRED
A
acquired
A term relating to a condition that
occurs after birth rather than being
attributable to heredity. Acquired con-
trasts with
congenital,
which means
present from birth.
acquired immunity
A form of
immunity
that develops after
birth through exposure to microorgan-
isms or through
immunization
.
acrocyanosis
A circulatory disorder in which the
hands and feet turn blue, may become
cold, and sweat excessively. Acrocyan-
osis is caused by spasm of the small
blood vessels and is often aggravated by
cold weather.
Acrocyanosis is related to
Raynaud’s
disease
, in which the skin of the fingers
and toes may be damaged by reduced
blood flow.
acrodermatitis
Inflammation of the skin, principally on
the hands or feet.
Acrodermatitis ent-
eropathica
is a chronic
(long-term),
inherited variety of the condition.
acrodermatitis enteropathica
A rare, inherited disorder in which
areas of the skin (most commonly of
the fingers, toes, scalp, and the areas
around the anus and mouth) are red-
dened,
ulcerated,
and
covered with
pustules
(pus-filled spots).
Acrodermatitis enteropathica is inher-
ited in an autosomal recessive manner
(see
genetic disorders
) and is due to the
inability to absorb sufficient zinc from
food. Zinc supplements usually bring
about a rapid improvement.
acromegaly
A rare disease that is characterized by
abnormal
enlargement
of the
skull,
the jaw, the hands and feet, and also of
the internal organs.
CAUSE
Acromegaly
is
caused
by
excessive
secretion of
growth hormone
from the
anterior
pituitary gland
at the base of the
brain and is the result of a noncancer-
ous
pituitary tumour.
If such a tumour develops before
puberty,
the
result
is
gigantism
(in
which growth is accelerated) instead of
acromegaly. More commonly, however,
the tumour develops after growth in the
long bones of the limbs has stopped.
This leads to acromegaly, although it
may take several years for the symptoms
and signs of the condition to appear.
SYMPTOMS AND SIGNS
Symptoms and signs
of acromegaly
include enlargement of the hands, feet,
ears, and nose; a jutting lower jaw; and
a long face. There may also be deepen-
ing or huskiness of the voice. Symptoms
common to any brain tumour, such as
headache and visual disturbances, are
also possible.
DIAGNOSIS AND TREATMENT
Acromegaly is diagnosed by the meas-
urement of blood levels
of growth
hormone before and after a quantity of
glucose has been administered. Glucose
usually
suppresses
the
secretion
of
growth hormone; if the glucose has no
effect on the blood level of the hor-
mone, uncontrolled secretion of growth
hormone by the pituitary gland can be
confirmed.
CT scanning
or
MRI
(tech-
niques that produce cross-sectional or
three-dimensional
images
of
body
structures)
may
be
carried
out
to
reveal a tumour or overgrowth of the
pituitary gland.
A tumour of the pituitary gland may
be removed surgically or treated by
radiotherapy.
The drug
octreotide
pre-
vents growth hormone production and
may be used to control symptoms by a
person awaiting surgery or until the
effects of radiotherapy are felt.
Bromo-
criptine
sometimes causes the tumour to
become smaller.
Appearance of acromegaly
Enlargement of the hands is a typical feature of
acromegaly. The condition is apparent when the
acromegalic hand, on the left, is compared to a
normal hand.
acromioclavicular joint
The joint that lies between the outer
end of the
clavicle
(collarbone) and the
acromion (the bony prominence at the
top of the shoulderblade).
INJURIES TO THE JOINT
Injuries to the acromioclavicular joint
are rare. They are usually caused by a
fall on to the shoulder and may result
LOCATION OF THE
ACROMIOCLAVICULAR JOINT
The joint lies at the junction of
the outer end of the clavicle and
the acromion.
Acromio-
Clavicle
clavicular
joint
Acromion
in subluxation (incomplete dislocation
with the bones still in contact)
or,
rarely, to
dislocation
(complete displace-
ment of the bones so that they are no
longer in contact).
In subluxation, the synovium (joint
lining) and the ligaments around it are
stretched
and
bruised,
the
joint
is
swollen, and the bones feel slightly out
of alignment. In dislocation, the liga-
ments are torn, the swelling is greater,
and the bone deformity is more pro-
nounced. In both cases, the joint is
painful and tender, and movement of
the shoulder is restricted.
TREATMENT
Treatment for subluxation is by resting
the arm and shoulder in a sling. If the
pain and tenderness persist, injection of
a
corticosteroid drug
and a local anaes-
thetic (see
anaesthesia, local)
into the
joint may help.
Dislocation of the acromioclavicular
joint requires strapping around the clav-
icle and elbow, for about three weeks,
to pull the outer end of the clavicle back
into position. Surgical correction may
occasionally be required.
acromion
The bony prominence at the top of the
scapula
(shoulderblade) that articulates
with the end of the
clavicle
(collarbone)
to form the
acromioclavicular joint.
acroparaesthesia
A medical term for tingling sensations
that occur in the fingers or toes (see
pins-and-needles).
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