Download 16- BENIGN_THYROID_DISORDERS_(lecture)

BENIGN THYROID
DISORDERS
Done by: bashayer m. AL-Dossari
Lulwah t. Al-Turki
Supervised by: Dr. H. Wadaani
Thyroid Anatomy
1-The gland as seen from the front is more
nearly the shape of a butterfly.
2-composed of 2 encapsulated lobes, one
on either side of the trachea,
connected by a thin isthmus.
3-The thyroid extending from the level of
the fifth cervical vertebra down to
the first thoracic. The gland varies
from an H to a U shape, overlying
the second to fourth tracheal rings.
4-The pyramidal lobe is a narrow
projection of thyroid tissue
extending upward from the isthmus
and lying on the surface of the
thyroid cartilage.
Thyroid Anatomy
5-The thyroid is enveloped by a thin,
fibrous, nonstripping capsule that sends
septa into the gland substance to
produce an irregular, incomplete
lobulation. No true lobulation exists.
6-The weight of the thyroid of the normal
nongoitrous adult is: 10-20 g depending
on body size and iodine supply.
7-The width and length of the isthmus
average; 20 mm,
and its thickness is ;2-6 mm.
8-The lateral lobes from superior to inferior
poles usually measure 4 cm. and their
thickness is 20-39 mm.
Histologically
thyroid tissue is composed of
spherical thyroid follicles. Each
follicle consists of a single layer of
cuboidal follicular cells
surrounding a lumen filled with a
homogenous material called
colloid. With stimulation, the
follicular cells become columnar
and the follicles are depleted of
colloid; with suppression, the
follicular cells become flat and
colloid accumulates. The thyroid
also contains parafollicular C cells
which produce calcitonin.
Relations of the Lobes
1-Anterolaterally:
*The sternothyroid
*The superior belly of the omohyoid
*The sternohyoid
*The anterior border of the
sternocleidomastoid.
2-Medially:
*The larynx & the
trachea.
*The pharynx & the
oesophagus.
*Associated with these
structures are the
cricothyroid muscle
& its nerve supply,
the external
laryngeal nerve.
*In the groove between
the esophagus and
the trachea is the
recurrent laryngeal
nerve.
Relations of the Lobes
3-Posterolaterally:
The carotid sheath with: The common carotid artery, the internal
jugular vein, and the vagus nerve.
Relations of the Isthmus
1-Anteriorly:
The sternothyroids
The sternohyoids
The anterior jugular veins
Fascia & skin.
2-Posteriorly:
The second, third, & fourth rings of the trachea.
The arterial supply to the
thyroid gland
1-Superior thyroid artery and superior
laryngeal nerve:
The superior thyroid artery is the first anterior
branch of the external carotid artery. In rare
cases, it may arise from the common carotid
artery just before its bifurcation.
the external branch of the superior laryngeal
nerve runs with the superior thyroid artery.
2-Inferior thyroid artery and recurrent
laryngeal nerve
The inferior thyroid artery arises from the
thyrocervical trunk, a branch of the
subclavian artery.
is closely associated with the recurrent laryngeal
nerve.
3-The thyroidea ima, if present:
May arise from the brachiocephalic artery or the
arch of the aorta to supply the isthmus.
Venous Drainage
1-The superior thyroid vein:
ascends along the superior thyroid artery and
becomes a tributary of the internal jugular
vein.
2- The middle thyroid vein:
follows a direct course laterally to the internal
jugular vein.
3- The inferior thyroid veins :
follow different paths on each side. The right
passes anterior to the innominate artery to
the right brachiocephalic vein or anterior to
the trachea to the left brachiocephalic vein.
On the left side, drainage is to the left
brachiocephalic vein. Occasionally, both
inferior veins form a common trunk called
the thyroid ima vein, which empties into the
left brachiocephalic vein.
Lymphatic drainage
The lymph from the thyroid gland drains mainly
laterally into the deep cervical lymph nodes.
A few lymph vessels descend to
the paratracheal
nodes.
innervation of the thyroid gland :
derives from the autonomic nervous system. Parasympathetic fibers come from
the vagus nerves, and sympathetic fibers are distributed from the superior,
middle, and inferior ganglia of the sympathetic trunk
Physiology
The thyroid follicles secretes tri-iodothyronine(T3)and thyroxin(T4)synthesis
involves combination of iodine with tyrosine group to form mono and diiodotyrosine which are coupled to form T3 andT4.
The hormones are stored in follicles bound to thyrogobulin .
When hormones released in the blood they are bound to plasma proteins and
small amount remain free in the plasma .
The metabolic effect of thyroid hormones are due to free (unbound)T3 and T4.
90%of secreted hormones is T4 but T3is the active hormone so, T4is converted
to T3 peripherally.
Physiological control of
secretion
Synthesis and libration of T3 and T4 is controlled by thyroid stimulating
hormone(TSH)secreted by anterior pituitary gland.
TSH release is in turn controlled by thyrotropin releasing hormone
(TRH)from hypothalamus .
Circulating T3and T4 exert –ve feedback mechanism on hypothalamus
and anterior pituitary gland .
So, in hyperthyroidism where hormone level in blood is high ,TSH
production is suppressed and vice versa.
Clinical presentation of
specific condition
HYPOTHYRODISM;
Hypothyroidism is the disease state in humans and animals caused by
insufficient production of thyroid hormone by the thyroid gland.
Fatigue
Depression
Modest weight gain
Cold intolerance
Excessive sleepiness
Dry, coarse hair
Constipation
Dry skin
Muscle cramps
Increased cholesterol levels
Decreased concentration
Swelling of the legs
Clinical presentation of
specific condition
Hyperthyroidism;
Hyperthyroidism is a condition caused by the effects of too much thyroid hormone on
tissues of the body. Although there are several different causes of hyperthyroidism,
most of the symptoms that patients experience are the same regardless of the cause.
Increase appetite ,weight loss
Palpitations
Heat intolerance
Nervousness
Insomnia
Breathlessness
Increased bowel movements
Light or absent menstrual periods
Fatigue
Eye: lid retraction,
lid lag,
exophthalmos ,
ophthalmoplegia,chemosis.
Clinical presentation of specific
condition
THYROIDITIS:
Thyroiditis is an inflammation (not an infection) of the thyroid gland. Several types of thyroiditis exist .
1-Hashimoto's Thyroiditis. Hashimoto's Thyroiditis (also called autoimmune or chronic
lymphocytic thyroiditis) is the most common type of thyroiditis.
Fatigue-Depression-Modest weight gain--Cold intolerance-Excessive sleepiness-Dry, coarse hairConstipation-Dry skin-Muscle cramps-Increased cholesterol levels-Decreased concentrationVague aches and pains-Swelling of the legs
2-De Quervain's Thyroiditis. (also called subacute or granulomatous thyroiditis). The thyroid
gland generally swells rapidly and is very painful and tender.]
Patients will experience a hyperthyroid period as the cellular lining of colloid spaces fails, allowing
abundant colloid into the circulation, with neck pain and fever. Patients typically then become
hypothyroid as the pituitary reduces TSH production and the inappropriately released colloid is
depleted before resolving to euthyroid. The symptoms are those of hyperthyroidism and
hypothyroidism. In addition, patients may suffer from painful dysphagia. There are multi-nucleated
giant cells on histology.Thyroid antibodies can be present in some cases.There is decreased
uptake on isotope scan.
Clinical presentation of
specific condition
3-Silent Thyroiditis. Silent Thyroiditis is the third and least common type of
thyroiditis..
Silent thyroiditis features a small goiter without tenderness and, like the other types of
resolving thyroiditis, tends to have a phase of hyperthyroidism followed by a phase of
hypothyroidism then a return to euthyroidism. The time span of each phase is not
concrete, but the hypo- phase usually lasts 2-3 months.
References
http://home.comcast.net/~wnor/lesson5.htm
en.wikipedia.org/wiki/Neck
www.answers.com/topic/sternothyroid-muscle
www.thyroidmanager.org
www.pitt.edu/~anat/Head/Thyroid/Thyroid.htm
Clinical medicine (kumar and clark)
Grant’s atlas of anatomy
Pressure effect:
Dysphagia.
breathlesness & orthopnoea.
Hoarseness.
Facial congestion.
Goitre
Enlargement of thyroid gland.
Classification:
Simple (non-toxic) goitre.
Toxic goitre.
Neoplastic goitre.
Inflammatory goitre.
Simple (non-toxic) goitre
include:
simple hyperplastic goitre (colloid goiter)
Cause: -physiological in pregnancy, puberty
-iodine definiecy.
Appearance: Large, smooth firm, non-tendern
goitre
Effect: eythyroid & pressure effect.
Multinodular goitre.
Cause: presence of areas of hyperplasia & areas
of hypoplasia in gland.
Appearance: Large, irregular, nodular goiter
Effect: eythyroid & pressure effect.
Toxic goitre
Grave’s disease
Cause: Autoimmune disease characterizeby
presence of antibodies stimulate TSH
receptors in gland.
Appearance: Diffuce, nodular, hyperemic gland.
Effect: hyperthyroidism.
Toxic Multinodular goiter
(plummer’s disease)
Cause: Toxic effect of MNG
Appearance: Large, irregular, nodular goiter.
Effect: hyperthyroidism
Neoplastic goitre
Include:
-benign: adenoma
-malignant: papillary, follicular, anaplastic, medullary and
lymphoma
Cause: -complication of MNG.
-radiation
Appearance: Enlarged goiter associated with
lymphadenopathy
Effect: -pressure effect.
-euthyroid.
-invasive effect
Inflammatory goitre
Rediel’s thyroditis
Cause: Fibrosis of thyroid
Appearance: Enlarged stony hard thyroid
Effect: Pressure effect
De quervain’s thyroiditis
Cause: Viral infection
Appearance: Diffuse, firm, tender swelling
Effect: Mild hyperthyroidism
Hashimoto’s thyroiditis
Cause: Autoantibody against thyroid gland.
Appearance: Diffuse, enlarged, non-tender goitre
Effect: Hypothyroidism
Investigation:
Laboratory investigation:
-serum T3, T4.
-serum TSH.
-serum LATS:
in grave’s disease
-thyroid antibodies:
in hashimoto’s disease.
-serum cholesterol
increase cholesterol level in hypothyroidism
Radiological investigation:
-chest and neck x-ray:
Show descend of thyroid gland to
thorax and mediastanal shifting in
retrosternal goitre.
-iodine isotopes
By i.v injection of I131. Then, use gama
rays to show hot and cold nodules.
-CT scan
Show thyroid size and if there is
compression to trachea
Endoscopic investigation:
-bronchoscopy: show compression and
infiltration of trachea by tumer
Biopsy:
-fine needle aspiration biopsy.
-true-cut biopsy.
Medical Treatment
Antithyroid drugs:
e.g: carbimazole, propylthiouracil.
It use to treat hyperthyroidism
Mechanism:
Inhibit thyroid hormones synthesis by block iodine
organification and also PTU inhibit conversation of T4
toT3
Side effect:
Drug rash
Lymphadenopathy
N/V
Agranulocytosis
Beta-adernergic blockers:
e.g: propranolol
it is control sympathetic over activty to control
cardiovascular feature.
Radioactive iodine:
Taken orally in solution
Given for 8-12 wks.
Use for recurrent hyperthyroidism
Contraindication:
Pregnant women
Nursing mothers.
Surgical treatment:
Indication:
Failure of medical treatment.
Drug sensitivity in young patients.
Large goiter with compression symptoms.
Malignancy.
Preoperative preparation:
Patient should become euthyroid before
surgery to prevent thyroid crisis.
Assimment vocal cord condition.
Operation:
For solitary benign nodule: lobectomy.
For cancer: total thyroidectomy.
For thyrotoxicosis: subtotal thyroidectomy
Complication of operation:
Hemorrhage
Recurrent laryngeal nerve damage.
Superior laryngeal nerve damage
Hypoparathyrodism
Hypothyroidism
Septesis
Postoperative infection
Hypertrofic scaring (keloid)
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