French for “already seen” . A sense of
having already experienced an event
that is happening at the moment. Fre-
quent occurrence may sometimes be a
temporal lobe epilepsy
A rare neurological disorder, also called
thalamic syndrome or central pain syn-
drome, that results from damage to the
the part of the brain that pro-
cesses sensory information.
The main symptom is severe pain,
possibly accompanied by other abnor-
malities such as loss of sensation or a
“ crawling” feeling in the skin.
A type of
unlike most forms of
develop immediately on exposure to a
(a normally harmless
substance that causes a reaction in peo-
ple who have become sensitized to it).
Delayed allergies, also called type IV
hypersensitivity reactions, may result
from bacterial, viral, fungal, or proto-
zoal infections or from
a live virus vaccine. Examples of such
delayed allergic reactions include
and the body’s response
to infection in
eruption of teeth
“ delayed dentition” may refer to the
eruption of the first deciduous teeth
) after the end of the
13 th month of life or to the eruption
of the first
after the sev-
enth year of life. Delayed dentition is a
feature of various conditions that result
in generally restricted growth (see
after the age of 14. In most cases, the
child is simply developing at a slower
rate than normal, a tendency that often
runs in families, but in some cases
there may be an underlying disorder.
One possible underlying cause of
delayed puberty is underproduction of
sex hormones. Rarely,
results from a problem with the
are responsible for secreting sex hor-
mones; a genetic abnormality affecting
sexual development, such as
in boys or
girls; or a long-term illness, such as
Certain lifestyle factors,
such as excessive exercise or an inade-
quate diet, may also delay puberty.
Treatment depends on the underly-
ing cause. If delayed puberty runs in
the child’s family, no action may be
needed. In some cases, however, condi-
tions causing delayed puberty may also
so the child may need
further investigations in the future if he
or she wishes to have children.
A common term for severe mental or
physical reactions that may occur some
time after a traumatic event (see
traumatic stress disorder; shock
A popular name for
infective diarrhoea caused by ingesting
contaminated food or water.
Criminal behaviour in a young person
w hich he or she can be prosecuted.
The term is often extended to include
behaviour such as
truant, or running away from home.
Delinquency that occurs in juveniles is
probably a result of a combination of
social, psychological, and biological fac-
be recommended. Persistent offenders
may be sent to special schools, taken
into care, or made wards of court.
A state of acute mental confusion, com-
m only brought on by physical illness.
Symptoms vary according to personal-
ity, environment, and the severity of
illness. They may include
understand events or remember what
has been happening, physical restless-
ness, mood swings, hallucinations, and
panic. Fever and disturbances of body
chemistry are often contributory factors.
Children and older people are most
susceptible to delirium , particularly as
a result of infection, following surgery,
or when there is a pre-existing brain
elderly person). Drugs, poisons, and
alcohol are common precipitants.
A state of confusion accompanied by
trembling and vivid hallucinations. It
usually arises in chronic alcoholics after
withdrawal or abstinence from alcohol.
agitation, trembling, and sleeplessness.
The person may then develop a rapid
heartbeat, fever, and dilation of the
pupils. Sweating, confusion, hallucina-
tions, and convulsions may also occur.
Treatment consists of rest, rehydra-
tion, and sedation. Vitamin injections,
particularly of thiamine (see
may be given, as some symp-
toms are linked to thiamine deficiency.
The expulsion or extraction of a baby
cases, the baby lies lengthwise in the
uterus with its head facing downwards;
it is delivered head first through the
vaginal opening by a combination of
uterine contractions and the mother’s
If the baby is
in an abnormal position
ine contractions are weak, or if the
baby’s head is large in relation to the
size of the mother’s pelvis, a
required. If a vaginal delivery is im pos-
sible or dangerous to the mother or the
The triangular muscle of the shoulder
region that forms the rounded flesh of
the outer part of the upper arm, and