of the neck may develop. Even uncon-
scious patients may recover, but further
attacks are common and often fatal.
Diagnosis is by CT scanningand angio-
graphy. Treatment includes life-support
procedures and control of blood pressure
to prevent recurrence. Burst or leaking
aneurysms are usually treated by surg-
ery. About half of those people affected
survive, some recover completely, others
have residual disability such as paralysis.
subclavian steal syndromeRecurrent
attacks of blurred or double vision, loss
of coordination, or dizziness caused by
reduced blood flow to the base of the
brain when one arm (usually the left) is
moved. The cause is narrowing of the
arteries that carry blood to the arms,
usually due to atherosclerosis. Treat-
ment is by arterial reconstructive surgery.
subclinicalA term applied to a disor-
der that produces no symptoms or
signs because it is either mild or in the
early stages of development.
subconjunctival haemorrhageBleed-
ing under the conjunctiva that is usually
harmless and disappears in a few days
without treatment.
subconsciousA term describing mental
events (such as thoughts) of which one
is temporarily unaware but which can be
recalled under the right circumstances.
subcutaneousBeneaththe skin.
subdural haemorrhageBleeding into
the space between the outer and middle
layers of the meninges, usually following
head injury. The trapped blood slowly
forms a large clot within the skull that
presses on brain tissue. The symptoms,
which tend to fluctuate, may include
headache, confusion, drowsiness, and
one-sided weakness or paralysis. The
interval between the injury and the start
of symptoms varies from days to months.
Diagnosis is by CT scanningor MRI. In
many cases, surgical treatment is need-
ed. This involves drilling burr holes in
the skull (see craniotomy), so that the
blood can be drained out and damaged
blood vessels repaired. If treatment is
carried out at an early enough stage,
the person usually makes a full recov-
ery. A subdural haemorrhage that is
small and produces few symptoms may
not require any treatment. The affectedBreathing may be maintained by a ven-
tilator. With prompt treatment, recovery
usually occurs in about 24 hours.
stuffy noseSee nasal congestion.
stumpThe end portion of a limb that
remains after amputation.
stuporA state of almost complete un-
consciousnessfrom which a person can
be aroused only briefly and by vigorous
external stimulation. (See also coma.)
Sturge–Weber syndromeA rare, con-
genital condition that affects the skin and
the brain. Characteristically, a large pur-
ple birthmark (port wine stain) extends
over one side of the face, including the
eye. Malformation of cerebral blood ves-
selsmay cause weakness on one side of
the body, progressive mental handicap,
and epilepsy. Glaucomamay develop in
the affected eye, leading to loss of vision.
Seizures can usually be controlled with
anticonvulsant drugs. In severe cases,
brain surgery may be necessary.
stutteringA speech disorder in which
there is repeated hesitation and delay in
uttering words, unusual prolongation of
sounds, and repetition of word elements.
Stuttering usually starts before the age
of 8 and may continue into adult life. It is
more common in males, twins, and left-
handed people, and may occur with tics
or tremors. The severity may be related
to social circumstances. The exact cause
is unknown, although it tends to run in
families. Speech therapyoften helps.
St. Vitus’ danceAn outdated term for
Sydenham’s chorea.
styeA small, pus-filled abscessat the
base of an eyelash, caused by infection.
subacuteA term used for a disease that
runs a course between acuteand chronic.
subarachnoid haemorrhageA type of
brain haemorrhagein which a blood ves-
sel ruptures into the cerebrospinal fluid
that surrounds the brain and spinal
cord. It usually occurs spontaneously
but may follow unaccustomed exercise.
It is most common in people between
35 and 60. The most common cause is a
burst aneurysm (see berry aneurysm).
An attack may cause loss of conscious-
ness, sometimes preceded by a sudden
violent headache. If the person remains
conscious, symptoms such as photo-
phobia, nausea, drowsiness, and stiffnessSTUFFY NOSE SUBDURAL HAEMORRHAGES