Download What is acromegaly

It is a small pea size gland situated in a hollow bony pouch, at
the base of the brain, at the back of the bridge of the nose. The
pituitary gland is approximately the size of a grape. It hangs by
a stalk from the inferior surface of the hypothalamus of the
brain. It has two functional lobes_the anterior pituitary
(glandular tissue) and the posterior pituitary (nervous tissue). It
is the master gland of the endocrine system and controls the
functions of the other endocrine glands in the body.
View that shows the pituitary gland structure .
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Anntteerriioorr P
Piittuuiittaarryy::-1) Growth hormone (GH)Muscles and bones, or
somatotropin, produced by the anterior pituitary, affects the
physical appearance dramatically since it determines an
individual's size and height.
2) Prolactine (PRL)Mammary glands, Is producored by the
anterior pituitary only after childbirth. It causes the mammary
glands in the breast to develope and produce milk.
3) Follicle-stimulating hormone (FSH)Ovaries or testes,
Which stimulate the gonads-the testes in males and the ovaries
in females-to secrete sex hormones.
4) Luteinizing hormone (LH) Ovaries or testes, Which
stimulate the gonads-the testes in males and the ovaries in
females-to secrete sex hormones.
5) Thyroid-stimulating hormone (TSH)Thyroid glands,
Which stimulates the thyroid to produce thyroxin.
6) Adrenocorticotropic hormone (ACTH)Adrenal cortex,
Which stimulates the adrenal cortex to produce and secrete
hormones.
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Piittuuiittaarryy::-*Releases hormones made by the hypothalamus.
1) OxytocinUterus and mammary glands, is another
hormone made in the hypothalamus and released by the
posterior pituitary. Oxytocin causes the uterus to
contract and can be used to artificially induce labor. It
also stimulates the release of milk form the breast when
a baby is nursing.
2) Antidiuretic hormone (ADH)Kidney, also called
vasopression, promotes the reabsorption of water from
the kidneys, thereby preventing dehydration. The
hypothalamus is believed to contain cells that are
sensitive to blood solute consentrations. When these
cells detect that the blood lacks sufficient water, ADH
is produced by special neurosecretory cells and is
transported by their fibers to the posterior pituitary,
where it is released. As the blood becomes more dilute,
the hormone ceases to be produced and released.
View that shows anterior and posterior pituitary hormone effect .
An abnormal growth of the pituitary gland is called an
adenoma. It usually grows very slowly over many years. The
pituitary gland sits in a very limited space and surrounded by the
very important structures including blood vessels and nerves.
Therefore, when an adenoma enlarges it can have a compression
effect on the normal pituitary tissue which then fails to work
properly. Gradually the expansion of the adenoma can press on
surrounding areas causing headache and disturbed vision.
Is a general metabolic hormone. It is a hormone produced by the
pituitary and has effects on the various tissue of the body. In
children, it is essential to reach normal growth. In adult, it is
important to keep up with normal energy level and to keep body
tissues (e.g. muscles, bones) healthy.
Hyposecretion of GH
During childhood;; leads to pituitary dwarfism
Hypersecretion of GH
During childhood;; leads to gigantism
** GH is produced in greatest quantities during childhood and
adolescence, when most body growth is occurring, but is still
produced (though lower quantities) in adults to aid in continued
protein synthesis and normal cell division and replacement. If
GH production increases in an adult after full height has been
obtained, only the bones of the jaw, eyebrow ridges, nose,
fingers, and toes respond. When these bones begin to grow, the
person aquires a slightly grotesque look, with huge fingers and
toes. This condition is called acromegaly.
The hypothalamus, located beneath the thalamus in the lower
walls and floor of the third ventricle of the brain, helps regulate
the body's internal environment. For example, The
hypothalamus helps control the heart rate, body temperature,
and water balance, as well as the activity of the pituitary gland.
The pituitary gland is small-about 1 centimeter in diameter- and
lies just inferior to the hypothalamus. It has two portions: (1) the
anterior pituitary, or hypothalamus, and, (2) the posterior
pituitary.
PPoosstteerriioorr PPiittuuiittaarryy ::-The posterior pituitary is connected to the hypothalamus by
means of a stalk like structure. The hormones released by the
posterior pituitary are made in nerve cell bodies in the
hypothalamus. The hormones then migrate through the axons
that terminate in the posterior pituitary.
A
Anntteerriioorr PPiittuuiittaarryy ::-The hypothalamus controls the anterior pituitary by producing
hypothalamic-releasing and release-inhibiting hormones, Which
are transported to the anterior pituitary by the blood within a
portal system. Each of these hypothalamic hormones causes the
anterior pituitary either to secrete or to stop secreting a specific
hormone. The anterior pituitary produces at least six different
hormones. Since these hormones have an effect on other
endocrine glands, the anterior pituitary is sometimes called the
master gland.
View that show pituitary gland with hypothalamus .
*Acromegaly is the Greek word for "extremities" and
"enlargement". When the pituitary gland produces excess growth
hormones, this results in excessive growth --called acromegaly.
The excessive growth occurs first in the hands and feet, as soft
tissue begins to swell. It most commonly affects middle-aged
adults and can result in serious illness and premature death. In
children the related condition is called gigantism, because long
bones can still grow. The disease because of its slow and often
insidious onset, is frequently not diagnosed correctly.
Soft tissue swelling of the hands and feet (early sign)
Brow and lower jaw protrusion (enlarging jaw and hat
size).
Enlarging hands (ring size).
Enlarging feet (shoe size).
Arthritis and carpal tunnel syndrome
Teeth spacing increase.
Heart failure (major medical problem).
Compression of the optic chiasm leading to loss of
vision in the outer visual fields
Diabetes mellitus.
Hypertension.
Acromegaly is caused by prolonged overproduction of GH by
the pituitary gland. The pituitary is a small gland at the base of
the brain that produces several important hormones to control
body functions such as growth and development, reproduction,
and metabolism.
In over 90 percent of acromegaly patients, the overproduction of
GH is caused by a benign tumor of the pituitary gland, called an
adenoma. These tumors produce excess GH and, as they expand,
compress surrounding brain tissues, such as the optic nerves.
This expansion causes the headaches and visual disturbances
that are often symptoms of acromegaly. In addition,
compression of the surrounding normal pituitary tissue can alter
production of other hormones, leading to changes in
menstruation and breast discharge in women and impotence in
men.
Symptoms of acromegaly vary depending on how long the
patient has had the disease. The following are the most common
symptoms. However, each individual may experience symptoms
differently:
Swelling of the hands and feet
Facial features become coarse as bones grow
Body hair becomes coarse as the skin thickens and/or
darkens
Increased perspiration accompanied with body odor
Protruding jaw
Voice deepening
Enlarged lip, nose, and tongue
Thickened ribs (creating a barrel chest)
Joint pain
Degenerative arthritis
Enlarged heart
Enlargement of other organs
Strange sensations and weakness in arms and legs
Snoring
Fatigue and weakness
Headaches
Loss of vision
Irregular menstrual cycles in women
Breast milk production in women
Impotence in men
The symptoms of acromegaly may resemble other conditions or
medical
problems. Consult a physician for diagnosis.
Patient with acromegaly—years before presentation (a) and at presentation (b) .
View that shows lower jaw for patient with acromegaly .
Diseased hand on the left, normal hand on the right for comparison .
View for both hands R and L for a patient with acromegaly
Diseased foot on the left, normal foot on the right for comparison .
View for the foot for a patient with acromegaly AP and Lateral .
a) Exaggerated supraorbital ridges.
b) Exophthalmos.
c) Enlargement of:
i) Hands and Feet.
ii) Mandible (separation of teeth).
iii) Nose, Lips and Tongue.
d) Bitemporal hemianopsia to blindness.
e) Weight gain.
f) Hypertension.
g) Cardiomegaly.
h) Hepatomegaly.
i) Hypertrichosis.
j) Hyperthyroidism
i) Goiter.
ii) Thyrotoxicosis.
k) Diabetes Insipidus.
Small pituitary adenomas are common. During autopsies, they
are found in up to 25 percent of the U.S. population. However,
these tumors rarely cause symptoms or produce excessive GH or
other pituitary hormones. Scientists estimate that about 3 out of
every million people develop acromegaly each year and that 40
to 60 out of every million people suffer from the disease at any
time. However, because the clinical diagnosis of acromegaly
often is missed, these numbers probably underestimate the
frequency of the disease.
Several tests are useful in diagnosing acromegaly. The most
important are laboratory tests that measure the levels of GH and
IGF-I in the blood. There are different ways to measure these
levels accurately. You may have a series of blood tests. Or, you
may have blood taken after an overnight fast and an early
morning drink of a concentrated glucose solution. This is called
an oral glucose tolerance test (OGTT).
Other tests, such as head scans by magnetic resonance imaging
(MRI) or computed tomography (CT), are designed to look for a
pituitary growth or tumor, the most likely source of the
excessive GH secretion. Normally, these tests are performed on
an outpatient basis inside a hospital or clinic and involve no
special preparation on your part. Head scans are a way to
provide your health care provider with “photographs” of the
inside of your head.
Still other tests, such as an electrocardiogram (ECG), chest Xray, eye and visual field examination, and/or colonoscopy, will
help your doctor check your overall health. These tests also
usually do not require hospitalization and are performed by
health care specialists in different fields. These specialists
and/or technicians will send all test results directly to your
health care provider. Your health care professional will then
provide you with your test results, as well as specific
information regarding your current levels of GH and IGF-I. You
may want to understand the results of all of your tests and learn
your GH and IGF-I levels so that you can become an active
participant in your own treatment.
*We can take two type of radiographic projection :(1) AP axial sella turcica.
(2) Lateral R or L sella turcica.
*The sella turcica lying in the center of the inner aspect of the
base of the skull, It is a shallow depression called the Pituitary
fossa and contains the pituitary gland. The anterior clinoids are
on either side of the tuberculum sellae which forms anterior and
upper part of the pituitary fossa. The dorsum sellae with the
posterior clinoids forms its posterior boundary. The floor of the
pituitary fossa appears as a white line called the lamina dura
lying above the sphenoidal sinus.
The location of sella turcica in the skull .
*35 degree fronto-occipital view of sella turcica
(pituitary fossa). It is a basic projection.
Equipment required :a) 18×24 cm detail screen cassette, HD, lengthwise.
b) Table bucky.
c) Small foam pad.
d) Small localizing cone.
e) Lead protective waist apron.
Patient position :-
Lie the patient supine in the center of the x-ray couch. Rest the
hands and arms at the side of the body. Place the back of the
head in the midline in contact with the couch top or in a small
foam pad if necessary. Tuck the chin well in and position the
head so that the median sagittal plane and the radiographic
baseline are both at right angles to the film. Immobilize the
head. Place anatomical marker, collimate beam using small
localizing cone and apply protection.
Centering point :In the midline 7.5 cm above the nasion towards the foramen
magnum .
Direction of central ray Vertical with tube angled 35° towards
the feet (caudal).
80 KV, 22 MAS, 100 cm F.F.D, Use grid .
Special features :Expose on arrested respiration. An additional projection
using a slit diaphragm or narrow collimation may be
used to demonstrate the pineal gland more clearly if it
appears on the initial examination.
*Right lateral view of sella turcica (pituitary fossa) .
It is a basic projection.
Equipment required :a) 18×24 cm screens cassette, crosswise,detail.
b) Table bucky.
c) Sand bags.
d) Foam pads.
e) Small localizing cone.
f) Lead protective waist apron.
Patient position :-
Lie the patient in the center of the x-ray couch. Turn the head to
the lateral position with the side of the head in contact with the
couch top in the midline. Support the raised shoulder with
sandbags and pads and rest the arms in comfortable position.
Adjust the head so that the median sagittal plane is parallel and
the interorbital line is at right angles to the film. Immobilize the
head. Place anatomical marker, collimate beam using a small
localizing cone and apply protection.
Centering point :2.5 cm in front of and above the external auditory meatus
Direction of central ray  Vertical at 90° to the film
80 kV, 10 MAS, 100 cm F.F.D, Use grid .
Special features :-
Expose in arrested respiration. The opposite lateral may be taken
if difficulty is experienced in obtaining a satisfactory projection.
The patient may also be examined in the erect position using a
vertical bucky or skull unit.
The goals of treatment are to reduce GH production to normal
levels, to relieve the pressure that the growing pituitary tumor
exerts on the surrounding brain areas, to preserve normal
pituitary function, and to reverse or ameliorate the symptoms of
acromegaly. Currently, treatment options include surgical
removal of the tumor, drug therapy, and radiation therapy of the
pituitary.
a) Surgery.
b) Drug therapy.
c) Radiation therapy.
SSuurrggeerryy::
The only way to cure pituitary acromegaly is with
transsphenoidal surgery and adenoma removal. However, cure
may be difficult to achieve in patients with particularly large or
invasive tumors. In such instances, medical therapy and/or
radiation therapy may be necessary to control GH levels. In
general, the higher the pre-operative GH level, the lower the
chance for cure. Longterm cure of acromegaly after
transphenoidal surgery is seen in approximately 80-85% or
patients with microadenomas and in approximately 50-60% of
patients with macroadenomas.
M
Meeddiiccaall tthheerraappyy::
For patients with persistent GH elevation after surgery,
octreotide or stereotactic radiosurgery or both are generally
indicated. Octreotide (given three times a day by injection or by
one monthly injection) achieves long-acting suppression of GH
in about 70% of patients. It causes some degree of tumor
shrinkage in 30-50% of patients, and often improves symptoms
of soft tissue swelling, headache, joint pains and sleep apnea.
The preoperative use of octreotide also may facilitate tumor
removal and lessen the risks of general anesthesia. Side effects
may include loose stools, malabsorption, cholelithiasis (gall
stones), local pain at the injection site. Bromocriptine is a
"dopamine agonist" which lowers GH secretion in about 15% of
acromegalic patients. The major side effect is gastrointestinal
upset. Growth hormone lowering and tumor shrinkage are seen
in only 10 - 15% of patients with acromegaly.
R
Raaddiioo--tthheerraappyy::
For patients whose acromegaly is not controlled with surgery,
both conventional (external beam) and stereotactic radiosurgery
are relatively effective. However, the lowering of GH and IGF-1
levels takes significantly longer with external beam radiotherapy
(average 7 years) compared to stereotactic radiotherapy (average
18 months). Also, external beam radiation reliably causes loss of
normal pituitary function over 5 to 10 years. Neurologic
complications such as visual loss, weakness, and memory
impairment have rarely been reported with both external beam
and stereotactic radiotherapy.
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