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KHALED AJARMA MD FACS 17 TH NOV . 2012

KHALED AJARMA MD FACS 17 TH NOV . 2012. EMBRYOLOGY. Greek (shield-shaped)

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KHALED AJARMA MD FACS 17 TH NOV . 2012

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  1. KHALED AJARMA MD FACS 17TH NOV. 2012

  2. EMBRYOLOGY Greek (shield-shaped) Develops as a thickening in the pharyngeal floor at the base of the tongue at the foramen cecumthat elongates inferiorly as the thyroglossal duct, dividing into two lobes as it descends through the neck. medial anlage(endoderm) give rise to the thyroid follicular cells –fuse with- lateral anlage (neuroectoderm) which originate from 4th branchial pouch give rise to parafollicular (C) cells.

  3. ANATOMY Largest endocrine gland (20 grams) Brown and firm Two lobes , isthmus , pyramidal lobe (50%) Highly vascularized Location; anterior in the neck extends from middle of thyroid cartilage to just above clavicle C5-T1 2nd-4th tracheal ring(isthmus) Coverings; skin, platysma, strap muscle (sternothyroid, sternohyoid, superior belly of omohyoid), deep cervical fascia(pretracheal fascia), true inner capsule(lobules).

  4. ARTERIAL SUPPLY  -The superior thyroid artery is the first branch of the external carotid artery . -The inferior thyroid artery branch of the thyrocervical trunk, which comes off the subclavian artery. -Thyroideaima arises from aorta (from innominate 1-4 %) VENOUS DRAINAGE - The superior and middle thyroid veins drain into the internal jugular veins. - The inferior thyroid vein drains into the brachiocephalic vein. LYMPHATIC DRAINAGE Quite extensive and flows multidirectionally.  Immediate drainage flows first to the periglandular nodes, then to the prelaryngeal (Delphian), pretracheal, and paratracheal nodes along the recurrent laryngeal nerve, and then to mediastinal lymph nodes. INNERVATION - superior, middle, and inferior cervical sympathetic ganglia.  - parasympathetic fibers from the vagus nerves. 

  5. NERVES Recurrent laryngeal N: innervate all the intrinsic muscles of larynx except the cricothyroid Left: from vagus , crosses the aortic arch, loops around ligamentum arteriosum, ascends in the tracheoesophageal groove. Right: from vagus , crosses the RT subclavian artery (more oblique course). Non-recurrent LT: rare, in situs inversus. RT: 1%, associated with vascular anomaly Superior LN: (external branch) innervate cricothyroid muscle branch of vagus, travels with STA

  6. HISTOLOGY Follicle : structural unit of T. gland Lobule: 20-40 follicles. Adult thyroid: 3 million follicles

  7. PHYSIOLOGY IODINE daily requirement: 0.1 mg sources: milk, fish, eggs, salt converted to iodide (deoxidation) in stomach absorbed in jejunum stored in thyroid ( >90%) cleared by (thyroid 30%), (kidneys 70%)

  8. STIMULANTS - TSH - EPINEPHRINE - HUMAN CHORIONIC GONADOTROPHINS -pregnancy -gynecologic malignancies (hydatidiform mole) -AUTO REGULATION: -low iodine intake -iodine excess

  9. THYROID HORMONES FUNCTION • Fetal brain development. • Skeletal maturation. • Increase oxygen consumption, basal metabolic rate (Na+/K+ ATPase). • Heat production. • Positive inotropic and chronotropic effects on heart (Ca+ ATPase). • Maintain normal hypoxic and hypercapnic drive in resp. center in the brain. • Increase bone & protein turnover. • Increase the speed of muscle contraction & relaxation. • + Glycogenolysis, hepatic gluconeogenesis. • + Intestinal glucose absorption. • + Cholesterol synthesis & degradation.

  10. THYROID FUNCTION TEST • TSH : most sensitive & specific test for DX hypo-hyperthyroidism & for optimizing T4 therapy. • T4 (total) increase in – hyperthyroidism. - elevated Tg (pregnancy..). decrease in – hypothyroidism. - decreased Tg (nephrotic S.). • T3 (total) : important in – T3 thyrotoxicosis . (clinical hyperthyroidism with normal T4) - increased in early hypothyroidism. • T4 (free) -early hyperthyroidism ( normal total T4, high free T4). -Refetoff syndrome ; end organ resistance to T4 (high T4, normal TSH). • T3 (free) -important in DX of early hyperthyroidism with normal total T4 &T3 .

  11. THYROID FUNCTION TEST • THYROTROPIN-RELEASING HORMONE (TRH) To evaluate pituitary TSH secretory function • THYROID ANTIBODIES To diagnose autoimmune thyroiditis (hashimoto , graves) • SERUM THYROGLOBULIN ( Tg) Made only by thyroid tissues Important in DX of: -thyroiditis, graves, toxic MN goiter. -detect recurrence of diff. thyroid cancer (most important). • SERUM CALCITONIN Sensitive marker of medullary T. cancer.

  12. THYROID IMAGING • ULTRASOUND - Non invasive, no radiation - Solid vs cystic - Multicentricity - Assess lymphadenopathy - Guide FNAB

  13. THYROID IMAGING • RADIONUCLIDE IMAGING I 123 : - low dose of radiation - half-life 12-14 hours - image lingual thyroid tissues I 131 : - higher dose of radiation - half-life 8-10 days - screen & treat metastasis of diff. thyroid cancer “ both demonstrate the size , shape & the functional activity ” Tc 99m : - short half-life & low dose of radiation - sensitive for LN metastasis FDG PET Scan ( F-fluorodeoxyglucose Positron emission Tomography) - screen for mets when other IXs are negative - screen for non palbable thyroid lesions

  14. THYROID CT SCAN

  15. THYROID MRI

  16. DIFFUSE TOXIC GOITER(GRAVES DISEASE) -most common cause of hyperthyroidism 70% -male : female ( 1:5) -age 40-60 years -autoimmune with familial predisposition -extra-thyroidal pathologies (eye, skin, …) -treatment : -anti-thyroid drugs -radio-active iodine therapy (I131) -surgical

  17. INDICATIONS OF SURGERY -confirmed or suspicious of malignancy -young patients -pregnant or desire to conceive -reaction to anti-thyroid drugs -compressive symptoms -contraindicated RAI therapy TYPES OF SURGERY -total or near total thyroidectomy for severe cases -subtotal thyroidectomy (leaving 4-7 gms) - bilateral subtotal -total on one side &subtotal on the other side Hartley dunhill operation

  18. TOXIC MN GOITER -end stage of non-toxic MNG -needs several years to occur -same like GRAVES with no extrathyroidal manifestations -treatment is subtotal thyroidectomy

  19. TOXIC ADENOMA (PLUMMERS DISEASE) -solitary hot nodule with rapid growth -size usually > 3cm -younger pts -rarely malignant -treatment : lobectomy + isthmusectomy

  20. THYROID STORM -Hyperthyroidism + fever + agitation or depression + cardio-vascular dysfunction -causes : infection trauma surgery drugs (amiodarone) Treatment : medical (ICU)

  21. THYROIDITIS Thyroid is resistant to infection - extensive blood and lymphatic supply - high iodine content - fibrous capsule • -treatment : IV antibiotic + drainage of abscess

  22. 1- Acute (suppurative) thyroiditis -streptococcus + anaerobes 70% -more common in children -symptoms -severe neck pain -fever, chills -odynophagia -dysphonia -DX : leukocytosis FNAB ; gram stain, culture, cytology -treatment : IV antibiotic + drainage of abscess

  23. 2- Subacute thyroiditis -painful, painless -unknown etiology..viral, autoimmune -stages -initial hyperthyroid phase -euthyroid phase -hypothyroid phase 25% -resolution phase > 90% -treatment - medical - thyroidectomy (rare) -no response to medical RX -recurrent

  24. 3-Chronic lymphocytic (hashimoto) thyroiditis -most common inflammatory thyroid disorder -leading cause of hypothyroidism -autoimmune, inherited -male : female ( 1:15) -age 30-50 year -presentation –mild, diffuse & firm thyroid enlargement -painless -hypothyroidism 20% -hyperthyroidism 5% -treatment -medical -thyroidectomy(rare) indicated if -suspicious for malignancy -compressive symptoms -cosmetic

  25. 4- Riedels thyroiditis -invasive fibrous thyroiditis -replacement of thyroid T by fibrous T -rare -autoimmune -more in females -age 30-60 year -presentation -hard ant. neck mass (fixed) -compressive symptoms -hypothyroidism -hypoparathyroidism -DX : open BX -treatment -medical -surgical -wedge resection of isthmus to decompress the trachea -extensive resections are not advised

  26. GOITER(ANY ENLARGMENT OF THYROID GLAND) DIFFUSE, UNINODULAR, MULTINODULAR TOXIC, NON-TOXIC CAUSES -ENDEMIC : low iodine intake -MEDICATIONS: iodide, amiodarone, lithium -THYROIDITIS : sub-acute, chronic -FAMILIAL : enzyme defect -NEOPLASM : adenoma, carcinoma -GOITROGENS : kelp, cassava, cabbage

  27. INDICATIONS OF SURGERY IN SIMPLE GOITER -obstructive symptoms -substernalextention -suspicious of malignancy -increase in size despite T4 suppresion -cosmetic “ subtotal thyroidectomy”

  28. SOLITARY THYROID NODULE FNAB 1*NON DIAGNOSTIC … repeat 2*MALIGNANT…thyroidectomy 3*SUSPICIOUS(FOLLICULAR) =RAI scan -cold… thyroidectomy -hot … RAI / thyroidectomy

  29. 4*BENIGHN -Cyst.. Aspirate.. Reaccumulates#3 thyroidectomy -Colloid nodule.. Observe.. Continued growth or compressive symptom thyroidectomy

  30. THYROID CYST -Resolve with aspiration 75% -indication of thyroidectomy -failure to do complete aspiration - > 4cm -complex (solid-cystic).. 15% malig. -recurrence after 3 aspiration

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