Acromégalie
238713
31669477
2008-07-17T23:56:03Z
Lithium57
55594
Révocation de vandalisme par [[Special:Contributions/89.159.212.10|89.159.212.10]] ; retour à la version de [[Special:Contributions/Salebot|Salebot]]
{{CIM-10 |
Nom = {{PAGENAME}} |
ICD10 = E220 |
}}
L''''acromégalie''' (du [[Grec ancien|grec]] [[wikt:ἄκρος|ἄκρος]] ''(akros)'' "haut" ou "extrême" et de [[wikt:μεγάλος|μεγάλος]] ''megalos'' "grand" - agrandissement des extrémités) est un trouble [[hormone|hormonal]] qui provoque une augmentation anormale de la taille des [[pied (anatomie)|pied]]s et des [[main]]s et une déformation du visage au fil des ans.
[[Image:Acromegaly.jpg|thumb|250px|Acromégalie, et tumeur hypophysaire]]
Il apparaît lorsque la glande [[hypophyse]] produit un excès d'[[hormone de croissance]] (hGH). En général, il s'agit d'un '''adénome hypophysaire''', c'est-à-dire une [[tumeur]] bénigne (dérivée des [[somatotrophe]]s, un type distinct de cellules) qui produit de la hGH.
Son évolution est très lente et le [[diagnostic (médecine)|diagnostic]] est souvent retardé. La charge [[Hormone|hormonale]] soumet durement l'[[organisme vivant|organisme]] et cela provoque une grande fatigue. Le visage est très atteint par le [[syndrome dysmorphique]].
<!--Acromegaly most commonly affects middle-aged adults and can result in serious illness and premature death. Because of its insidious onset and slow progression, the disease is hard to diagnose in the early stages and is frequently missed for many years.
Features that result from high level of hGH or expanding tumor include:
* 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]]-->
==Causes==
Dans 90% des cas, la maladie est causée par une tumeur bénigne dans l'[[hypophyse]].
<!--In over 90 percent of acromegaly patients, the overproduction of GH is
caused by a benign tumor of the pituitary gland, called an [[pituitary adenoma|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.
There is a marked variation in rates of GH production and the
aggressiveness of the tumor. Some adenomas grow slowly and symptoms of
GH excess are often not noticed for many years. Other adenomas grow
rapidly and invade surrounding brain areas or the sinuses, which are
located near the pituitary. In general, younger patients tend to have
more aggressive tumors.
Most pituitary tumors arise spontaneously and are not genetically
inherited. Many pituitary tumors arise from a genetic alteration in a
single pituitary cell which leads to increased cell division and tumor
formation. This genetic change, or [[mutation]], is not present at birth,
but is acquired during life. The mutation occurs in a gene that
regulates the transmission of chemical signals within pituitary cells;
it permanently switches on the signal that tells the cell to divide and
secrete GH. The events within the cell that cause disordered pituitary
[[cell growth]] and GH oversecretion currently are the subject of intensive
research.
In a few patients, acromegaly is caused not by pituitary tumors but by
[[tumor]]s of the [[pancreas]], [[lung]]s, and [[adrenal gland]]s. These tumors also
lead to an excess of GH, either because they produce GH themselves or,
more frequently, because they produce GHRH, the hormone that stimulates
the pituitary to make GH. In these patients, the excess GHRH can be
measured in the blood and establishes that the cause of the acromegaly
is not due to a pituitary defect. When these non-pituitary tumors are
surgically removed, GH levels fall and the symptoms of acromegaly improve.
In patients with GHRH-producing, non-pituitary tumors, the pituitary
still may be enlarged and may be mistaken for a tumor. Therefore, it is
important that physicians carefully analyze all "pituitary tumors"
removed from patients with acromegaly in order not to overlook the
possibility that a tumor elsewhere in the body is causing the disorder.-->
==Traitement==
<!--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.-->
===Chirurgie===
==== Traitement des adénomes hypophysaires ====
Il reste le traitement de première intention dans un nombre important de cas. Un certain nombre de lésions ne peuvent en effet pas être traitées de façon médicale. Dans ces cas exceptionnels d’adénomes géants, le traitement consiste en une chirurgie transfrontale. Dans la plupart des cas la chirurgie transsphénoïdale permet une exérèse avec succès. Le taux de succès varie en fonction de la taille et le caractère invasif de l’adénome.
==== Voie d’abord trans-crânienne ptérionale ====
Elle nécessite la taille d’un volet crânien de trépanation, l’ouverture de la dure-mère. La région opto-chiasmatique est alors découverte et l’adénome est abordé par son pôle supérieur entre les deux nerfs optiques latéralement et le chiasma optique en arrière.
Actuellement elle n’est plus utilisée que dans de rares cas d’adénome présentant des expansions extra-sellaire inaccessibles à la voie transsphénoïdale (latérale vers le lobe temporal ou en arrière vers le clivus) ou dont l’expansion supra-sellaire est séparée de la portion intra-sellaire par un collet rétréci (tumeur en bissac).
Les complications de cette chirurgie crânienne consistent en diabète insipide, perte de vision, lésion de l’hypothalamus, hémorragie, méningite, épilepsie.
==== Voie d’abord transsphénoïdale ====
Cette voie sous-labiale ou trans-nasale rhinoseptale transsphénoïdale est réalisé sous contrôle télévisé des instruments par amplificateur de brillance. L’adénome est abordé par son pole inférieur et enlevé sélectivement sous microscope opératoire. Les complications de la voie transsphénoïdale (diabète insipide, infection, fuite de LCR) sont plus rares que la voie crânienne et il n’y a pratiquement pas de complication à caractère esthétique (sauf parfois une chute de la pointe du nez).
La voie transsphénoïdale est indiquée dans la grande majorité des adénomes hypophysaires.
==== Taux de réussite ====
Le taux de succès chirurgical dépend de nombreux facteurs dont le siège de l’adénome, son volume et son caractère invasif.
* Le syndrome de masse : la décompression de structures opto-chiasmatique est obtenue dans tous les cas sauf de rares exceptions, il en résulte une résolution plus ou moins complète des troubles visuels.
* Le syndrome hormonal : hypersécrétion de GH, de Prolactine et d’ACTH est selon les cas guéri dans plus de 90% des microadénomes. Dans les macroadénomes non-invasifs le taux de succès est voisin de 75%. En cas d’adénomes envahissants le taux de succès n’est plus que de 25% environ.
<!--Surgery is a rapid and effective treatment. The surgeon reaches the
pituitary through an incision in the nose and, with special tools,
removes the tumor tissue in a procedure called transsphenoidal surgery.
This procedure promptly relieves the pressure on the surrounding brain
regions and leads to a lowering of GH levels. If the surgery is
successful, facial appearance and soft tissue swelling improve within a
few days. Surgery is most successful in patients with blood GH levels
below 40 ng/ml before the operation and with pituitary tumors no larger
than 10 mm in diameter. Success depends on the skill and experience of
the surgeon. The success rate also depends on what level of GH is
defined as a cure. The best measure of surgical success is normalization
of GH and IGF-1 levels. Ideally, GH should be less than 2 ng/ml after an
oral glucose load. A review of GH levels in 1,360 patients worldwide
immediately after surgery revealed that 60 percent had random GH levels
below 5 ng/ml. Complications of surgery may include [[cerebrospinal fluid]]
leaks, [[meningitis]], or damage to the surrounding normal pituitary tissue,
requiring lifelong pituitary hormone replacement.
Even when surgery is successful and hormone levels return to normal,
patients must be carefully monitored for years for possible recurrence.
More commonly, hormone levels may improve, but not return completely to
normal. These patients may then require additional treatment, usually
with medications.-->
===Médicaments===
Deux médications sont utilisées à l'heure actuelle pour traiter l'acromégalie. Celles-ci réduisent tant la sécrétion d'hGH que la taille de la tumeur.
* La [[bromocriptine]] <!--(Parlodel)-->
* La [[somatostatine]] principalement sous forme d'[[octréotide]], une forme synthétique de somatostatine.
<!--Two medications currently are used to treat acromegaly. These drugs
reduce both GH secretion and tumor size. Medical therapy is sometimes
used to shrink large tumors before surgery. [[Bromocriptine]] (Parlodel)
in divided doses of about 20 mg daily reduces GH secretion from some
pituitary tumors. Side effects include gastrointestinal upset, nausea,
vomiting, light-headedness when standing, and nasal congestion. These
side effects can be reduced or eliminated if medication is started at a
very low dose at bedtime, taken with food, and gradually increased to
the full therapeutic dose.
Because bromocriptine can be taken orally, it is an attractive choice as
primary drug or in combination with other treatments. However,
bromocriptine lowers GH and [[IGF-1]] levels and reduces tumor size in less
than half of patients with acromegaly. Some patients report improvement
in their symptoms although their GH and IGF-1 levels still are elevated.
The second medication used to treat acromegaly is [[Somatostatin|octreotide]]
(Sandostatin). Octreotide is a synthetic form of a brain hormone,
somatostatin, that stops GH production. This drug must be injected under
the skin every 8 hours for effective treatment. Most patients with
acromegaly respond to this medication. In many patients, GH levels fall
within one hour and headaches improve within minutes after the
injection. Several studies have shown that octreotide is effective for
long-term treatment. Octreotide also has been used successfully to treat
patients with acromegaly caused by non-pituitary tumors.
Because octreotide inhibits gastrointestinal and pancreatic function,
long-term use causes digestive problems such as loose stools, nausea,
and gas in one third of patients. In addition, approximately 25 percent
of patients develop [[gallstone]]s, which are usually asymptomatic. In rare
cases, octreotide treatment can cause [[diabetes]]. On the other hand,
scientists have found that in some acromegaly patients who already have
diabetes, octreotide can reduce the need for [[insulin]] and improve blood
sugar control.-->
===Radiothérapie===
<!--Radiation therapy has been used both as a primary treatment and combined
with surgery or drugs. It is usually reserved for patients who have
tumor remaining after surgery. These patients often also receive
medication to lower GH levels. Radiation therapy is given in divided
doses over four to six weeks. This treatment lowers GH levels by about
50 percent over 2 to 5 years. Patients monitored for more than 5 years
show significant further improvement. Radiation therapy causes a gradual
loss of production of other pituitary hormones with time. Loss of vision
and brain injury, which have been reported, are very rare complications
of radiation treatments.
No single treatment is effective for all patients. Treatment should be
individualized depending on patient characteristics, such as age and
tumor size. If the tumor has not yet invaded surrounding brain tissues,
removal of the pituitary adenoma by an experienced neurosurgeon is
usually the first choice. After surgery, a patient must be monitored for
a long time for increasing GH levels. If surgery does not normalize
hormone levels or a relapse occurs, a doctor will usually begin
additional drug therapy. The first choice should be bromocriptine
because it is easy to administer; octreotide is the second alternative.
With both medications, long-term therapy is necessary because their
withdrawal can lead to rising GH levels and tumor re-expansion.
Radiation therapy is generally used for patients whose tumors are not
completely removed by surgery; for patients who are not good candidates
for surgery because of other health problems; and for patients who do
not respond adequately to surgery and medication.-->
==Gigantisme hypophysaire et acromégalie des enfants==
<!--This condition of growth hormone excess is rare in children and is referred to as [[gigantism|pituitary gigantism]], because the excessive growth hormone produces excessive growth of bones and the child can achieve excessive height. As an affected child becomes an adult, many of the adult problems can gradually develop.-->
==Patients célèbres atteints de la maladie==
* [[André the Giant]] et [[Paul Wight|Big Show]], catcheurs ;
* [[Richard Kiel]], acteur et producteur ;
* [[Georges Palante]], philosophe ;
* [[Carel Struycken]], acteur et scénariste ;
* [[Fernandel]], acteur ;
* [[Matthew McGrory]], acteur ;
* [[Goliath (Bible)|Goliath]], géant philistin terrassé par David, dans la Bible (thèse soutenue par certains scientifiques).
==Liens externes==
* {{fr}} [http://www.assomegalie.org Explication détaillée de l'acromégalie en français]
* {{en}} [http://www.niddk.nih.gov/health/endo/pubs/acro/acro.htm]
* {{en}} [http://www.endotext.org Endotext.org, an "online Endocrine textbook"]
* {{en}} [http://www.medstudents.com.br/endoc/endoc8.htm An article on Acromegaly and gigantism]
[[Catégorie:Trouble de la croissance]]
[[Catégorie:Hormone de croissance]]
[[bg:Акромегалия]]
[[cs:Akromegalie]]
[[de:Akromegalie]]
[[el:Μεγαλακρία]]
[[en:Acromegaly]]
[[es:Acromegalia]]
[[fi:Akromegalia]]
[[gl:Acromegalia]]
[[he:אקרומגליה]]
[[it:Acromegalia]]
[[ja:先端巨大症]]
[[nl:Acromegalie]]
[[no:Akromegali]]
[[pl:Akromegalia]]
[[pt:Acromegalia]]
[[ru:Акромегалия]]
[[sk:Akromegália]]
[[sq:Akromegalia]]
[[sr:Акромегалија]]
[[sv:Akromegali]]
[[tr:Akromegali]]
[[uk:Акромегалія]]
[[zh:肢端肥大症]]