BREAKTHROUGH BLEEDING
For primary and secondary tumours,
radiotherapy
or
anticancer drugs
may also
be given.
Corticosteroid drugs
are often
prescribed temporarily to reduce the
size of a tumour and any associated
swelling of brain tissues.
bran
relays signals to muscles involved in
speech and in tongue and neck move-
ments. The medulla also contains the
“vital centres” (groups of nerve cells
that regulate the heartbeat, breathing,
blood pressure, and digestion (informa-
tion on which is relayed via the 10th
cranial nerve (see
vagus nerve).
Reticular
formation
Throughout
the
brainstem
are
numerous
nerve-cell
groups known collectively as the reticu-
lar formation. This network alerts the
higher brain centres to sensory stimuli
that may require a conscious response.
Our sleep/wake cycle is controlled by
the reticular formation.
DISORDERS
The brainstem is susceptible to the
same disorders that afflict the rest of the
central nervous system (see
brain, dis-
orders of).
Damage to the medulla’s vital
centres is rapidly fatal; damage to the
reticular formation may cause
coma.
Damage to specific cranial nerve nuclei
can sometimes lead to specific effects.
For example, damage to the seventh cra-
nial nerve (the facial nerve) leads to
facial palsy.
Degeneration of the sub-
stantia nigra in the midbrain is thought
to be a cause of
Parkinson’s disease.
brain syndrome, organic
Disorder of consciousness, intellect, or
mental functioning that is of organic
(physical), as opposed to psychiatric,
origin. Possible causes include degener-
ative diseases, most notably
Alzheimer’s
disease;
infections; certain drugs; or the
effects of injury,
stroke,
or tumour.
SYMPTOMS
Symptoms of acute organic brain syn-
drome range from mild confusion to
stupor or
coma.
They may also include
disorientation, memory loss, hallucin-
ations, and delusions (see
delirium).
In
the chronic form, there is a progressive
decline in intellect, memory, and be-
haviour
(see
dementia
). Treatment is
more likely to be successful with the
acute form. In chronic cases, irrever-
sible brain damage may already have
occurred. (See also
psychosis
.)
brain tumour
An abnormal growth in or on the brain.
Although they are not always cancer-
ous, all brain tumours are serious due
to the buildup of pressure they cause
within the brain and the compression
of adjoining brain areas, both of which
may occur as the tumour grows and
expands. Expansion of a brain tumour
within the rigid skull may also result in
damage to the normal tissue that sur-
rounds the tumour.
TYPES
Brain tumours may be primary growths
arising directly from tissues within the
skull or metastases (secondary growths)
that have spread via the bloodstream
from cancerous tumours elsewhere in
the body, particularly from those in the
lung or breast.
The cause of primary brain tumours
is not known. About 60 per cent are
gliomas
(which are frequently cancer-
ous), and arise from the brain tissue.
Other primary tumours include
mening-
iomas,
which arise from the meningeal
membranes covering the brain;
acoustic
neuromas,
which arise from the acoustic
nerve; and
pituitary tumours,
which arise
from the tissue of the pituitary gland.
Most of these tumours are noncancer-
ous, but their relatively large size can
cause local tissue damage.
Some types of primary brain tumour
affect mainly children. These include two
types of glioma called
medulloblastoma
and cerebellar
astrocytoma.
Primary brain
tumours virtually never spread (metasta-
size) outside the central nervous system.
Secondary growths (metastases) are
always cancerous and may be found in
more than one organ.
SYMPTOMS
Compression of brain tissue or nerve
tracts near the tumour may cause mus-
cle weakness, loss of vision, or other
sensory disturbances, speech difficul-
ties, and epileptic seizures.
The presence of a growing tumour
can increase pressure within the skull,
causing headache, visual disturbances,
vomiting, and impaired mental func-
tioning.
Hydrocephalus
(excess fluid in
the brain) may occur if the circulation
of cerebrospinal fluid is obstructed by
the tumour.
DIAGNOSIS AND TREATMENT
Many different
brain imaging
techniques
may be used to locate the site of a brain
tumour and to establish its size and the
extent of its spread.
In some cases, complete removal of a
brain tumour may be possible using
guidance from MRI scanning during
surgery. In such cases, the patient may
be cured. However, many cancerous
growths are inaccessible or too exten-
sive for removal. In cases where a
tumour cannot be completely removed,
as much as possible of it will be cut
away to relieve pressure.
The fibrous outer covering of grain that
cannot be digested. The fibre is used as
a bulk-forming
laxative
to prevent con-
stipation (see
fibre, dietary).
Disorders due to abnormal develop-
ment, in an embryo, of the branchial
arches (paired segmented ridges of tis-
sue in each side of the throat). Such
disorders include branchial cyst and
branchial
fistula.
A branchial cyst is a soft swelling,
containing fluid that may be either clear
or puslike, that appears on the side of
the neck in early adulthood. Treatment
of a branchial cyst is usually with surgi-
cal removal.
A branchial fistula occurs between
the back of the throat and the external
surface of the neck, where it appears as
a small hole, usually noted at birth. A
hole in the neck that does not extend to
the back of the throat is a branchial cleft
sinus. A branchial fistula or cleft sinus
may discharge mucus or pus and may
be removed surgically.
Short relatively painless contractions of
the uterus during pregnancy. They may
be felt in late pregnancy and are some-
times mistaken for labour pains.
Two of the abnormal
genes
that are
thought to be responsible for inherited
breast cancer.
Women with these genes
may also have an increased risk of ovari-
an cancer (see
ovary, cancer of).
A tropical viral illness, which is also
called
dengue,
that is spread by mosqui-
toes. The symptoms include high fever
and severe joint and muscle pain.
Bleeding or staining (“spotting”) from
the vagina between menstrual periods
in women taking an oral contraceptive.
brash, water
See
waterbrash.
Braxton Hicks’ contractions
BRCA i and BRCA 2
branchial disorders
breakbone fever
breakthrough bleeding
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