EFFUSION
E
HOW ELECTROENCEPHALOGRAPHY IS DONE
A number of small electrodes are
attached to the scalp. Shaving of the
scalp is unnecessary. The electrodes
are connected to an instrument that
measures the brain’s impulses in
microvolts and amplifies them for
recording purposes. The technique
is painless, produces no side effects,
and takes about
45
minutes.
Recordings are taken while the
subject is at rest, with the eyes open
and then shut, during and after
hyperventilation (overbreathing),
and while looking at a flashing light.
Electroencephalography is also
helpful to record activity as the
patient goes to sleep, especially
when epilepsy is suspected.
E l e c t r o d e s
c o n n e c t e d t o
c o n t r o l p a n e l
AA/WVVWA
EEG WAVE PATTERNS
Alpha waves
The prominent pattern of an awake, relaxed adult
whose eyes are closed.
Beta waves
The lower, faster oscillation of a person who is
concentrating on an external stimulus.
Delta waves
The typical pattern of sleep, also found in young
infants; rarely, delta waves indicate the presence
ofa brain tumour.
Theta waves
The dominant waves ofyoung children. In adults,
they may indicate an abnormality ofthe brain.
M o n it o r
effusion
The process by w hich fluid escapes. The
term effusion also describes an abnor-
mal collection of fluid (such as blood,
pus
,
or
plasma
)
in the tissues or a body
cavity. An effusion can form as a result
of inflammation or changes in pressure
w ithin blood vessels; alternatively, it can
be due to changes in the blood con-
stituents, such as in
nephrotic syndrome
(a kidney disorder).
Effusion commonly occurs around the
lung (see
pleural effusion
)
or heart (see
pericardial effusion
)
or within joints, caus-
ing swelling (see
effusion, joint
) .
effusion, joint
The accumulation of fluid in the space
around a
joint
,
resulting in swelling,
limitation of movement, and usually
also pain and tenderness. All joints are
enclosed by a capsule lined with a
membrane called the
synovium
. T h e
syno-
vium normally secretes small amounts
of fluid (known as synovial fluid) to
lubricate
the
joint.
However,
if the
synovium is damaged or inflamed (for
example, as a result of
arthritis
) ,
it pro-
duces excessive fluid.
The pain and inflammation may be
relieved by
analgesic drugs
(painkillers)
and
nonsteroidal anti-inflammatory drugs
and by having injections of
corticosteroid
drugs
.
The swelling usually reduces if
Location of knee joint effusion
Excessive production and accumulation of fluid
within the right knee joint (left in image) as a
result of injury or inflammation.
the affected joint is rested, bandaged
firmly, cooled with ice-packs, and kept
elevated. In some cases, the excess fluid
is drawn out of the joint using a needle
and syringe.
egg
See
ovum
.
ego
The
conscious
sense
of oneself.
In
Freudian
psychoanalytic theory
,
the ego
maintains a balance between the prim i-
tive, unconscious instincts of the
id
,
the
controls of the
superego
,
and the de-
mands of the outside world.
Ehlers-Danlos syndrome
An inherited disorder of
collagen
,
the
most important structural protein in the
body Individuals with Ehlers-Danlos
syndrome
have
abnormally
stretchy,
thin skin that bruises easily Wounds are
slow to heal and leave paper-thin scars,
and the joints are loose and prone
to recurrent dislocation. Sufferers bleed
easily from the gums and digestive tract.
Ehlers-Danlos
syndrome
is
most
commonly inherited in an autosomal
dominant pattern (see
genetic disorders
) .
There is no known specific treatment
for the condition, although unnecessary
accidental injury, such as that w hich
may occur in contact sports, should be
avoided by sufferers.
Eisenmenger complex
A condition in w hich deoxygenated
blood flows directly back into the circu-
lation rather than through the lungs.
This is due to an abnormal connection
between the left and right sides of the
heart
and to
pulmonary hypertension
(in
w hich there is abnormally high blood
pressure in the arteries supplying the
lungs). The resultant
hypoxia
(lack of
oxygen in the blood) causes
cyanosis
(bluish coloration of the skin), fainting,
and difficulty in breathing.
Eisenmenger complex occurs most
commonly in individuals
who
have
certain
uncorrected
congenital
heart
defects
(see
heart disease, congenital
),
such as ventricular
septal defect
.
The diagnosis of Eisenmenger com-
plex
may
be
confirmed
by cardiac
catheterization
(the insertion, under X-ray
control, of a thin tube into the heart via
a blood vessel). Once the condition has
developed, surgical correction of the
original defect w ill not help. Drug treat-
ment may help control the symptoms.
258
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