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 2-Medially: *The larynx & the trachea. 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 Relations of the Isthmus 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 innervation of the thyroid gland : 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 di-iodotyrosine 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 hair-Constipation-Dry skin-Muscle cramps-Increased cholesterol levels-Decreased concentration-Vague 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

Toxic Multinodular goiter (plummer’s disease) 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

De quervain’s thyroiditis Hashimoto’s thyroiditis 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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