TETANY
THALASSAEMIA
pulse, slight fever, and profuse sweating.
Painful muscle spasms then develop, and
may result in
asphyxia
if they affect the
larynx
or chest wall. The spasms usually
subside after 10 to 14 days.
About half a million cases of tetanus
occur worldwide each year, but fewer
than 20 occur in the UK. The diagnosis
is made from the symptoms and signs,
and a course of tetanus
antitoxin
injec-
tions is started. Most people recover
completely if treated promptly.
Prevention of tetanus in the UK relies
on the
DPT vaccination
being given rou-
tinely during childhood; booster shots
are given every 10 years.
tetany Spasms and twitching of the mus-
cles, most commonly in the hands and
feet, although the muscles of the face,
larynx
, or spine may also be affected.
The spasms are caused by a biochemical
disturbance and are painless at first; if
the condition persists, the spasms tend
to become increasingly painful. Muscle
damage may result if the underlying
cause is not treated. The most common
underlying cause is
hypocalcaemia
. Other
causes include
hypokalaemia, hypervent-
ilation
during a panic attack, or, more
rarely,
hypoparathyroidism
.
tetracosactide A drug used to test the
functioning of the
adrenal glands
. Tetra-
cosactide is a chemical analogue of the
natural hormone corticotrophin (
ACTH
).
ACTH stimulates the cortices of the
adrenal glands to secrete hormones such
as
cortisol
. To diagnose a disorder of the
adrenal glands, a tetracosactide injection
is given and the blood cortisol level
measured. Failure of the level to rise
indicates an abnormality.
tetracycline drugs A group of
antibiotic
drugs
commonly used to treat
bronchitis
,
acne
,
syphilis
,
gonorrhoea
,
nongonococcal
urethritis,
and certain types of
pneumonia.
If taken with milk, tetracyclines are not
absorbed effectively into the intestines.
Possible side effects include nausea,
vomiting, diarrhoea, worsening of kidney
disorders, rash, and itching. Tetracyclines
may discolour developing teeth and are
therefore not usually prescribed for chil-
dren under age 12 or pregnant women.
tetralogy of Fallot A form of congenital
heart disease
in which the heart has 4
coexisting anomalies: displacement of
the aorta, narrowing of the pulmonary
valve, a hole in the ventricular septum,
and thickening of the right ventricle wall.
These cause poor oxygenation of the
blood pumped to the body, resulting in
cyanosis
and breathlessness. Tetralogy of
Fallot occurs in about 1 in 1,000 infants.
Affected infants appear normal at birth.
Severely affected infants may become
cyanosed and breathless early in life.
Other symptoms include failure to gain
weight and poor development.
An
ECG
, echocardiogram (see
echo-
cardiography
), and sometimes cardiac
catheterization
are performed to confirm
the diagnosis and assess the severity of
the condition. The disorder is corrected
by
open heart surgery
.
tetraplegia An alternative term for the
condition
quadriplegia.
thalamus One of 2 structures within the
brain
consisting of a walnut-sized mass
of nerve tissue. The thalami sit at the
top of the
brainstem
and are connected
to all parts of the brain.
Each thalamus relays sensory infor-
mation flowing into the brain. Some
basic sensations, such as pain, may
reach consciousness within the thala-
mus. Other types of sensory information
are processed and relayed to parts of
the cerebral cortex (outer layer of the
brain), where sensations are perceived.
The thalamus seems to act as a filter
by selecting only information of particu-
lar importance. Certain centres in the
thalamus may also play a part in long-
term memory.
thalassaemia A group of inherited
blood
disorders in which there is a fault in the
production of
haemoglobin.
Many of the
red
blood cells
become fragile and
haemolyse (break up), leading to anaemia
(see
anaemia, haemolytic
). Thalassaemia
is prevalent in the Mediterranean, the
Middle East, and Southeast Asia, and in
families originating from these areas.
Normal adult haemoglobin contains 2
pairs of globins (protein chains): alpha
and beta. In thalassaemia, a recessive de-
fective
gene
results in reduced synthesis
of 1 of the chains. Usually beta-chain pro-
duction is disturbed (beta-thalassaemia).
Beta-thalassaemia minor (thalassaemia
T
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