Ms. Amira Zino

Embryology The thyroid gland arise from the foramen

caecum(floor of the pharynx ) at the base of the tongue & migrate in front of the foregut to lie anterior to trachea but remain attached to floor of mouth by thyroglossal duct which ultimately disappears , however it’s persistence result in :

Thyroglossal sinus Thyroglossal cyst

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Anatomical considerations:The thyroid is the largest single endocrine

gland.It weighs 20-25 g but it varies with age, sex,

& physiological condition.It is an only endocrine gland that does not

store its hormone within the cell but in follicular cavities surrounded by the cells.

Anatomical considerations:The thyroid gland is one of the neck’s viscera.Consists of right and left lobes connected by

a narrow isthmus.A very vascular organ,surrounded by a

sheath derived from the pretracheal layer of deep fascia wich attaches the gland to the larynx and the trachea.

Anatomical considerations:Each of the lobes is peared shape with an

apex being directed upward.Its base lies below at the level of the 4th or 5th

tracheal ring.The isthmus extends across the midline in

front of the 2nd, 3rd, &4th tracheal rings.Pyramidal lobe is often present & it projects

upward from the isthmus & to the left.

Anatomical relathions:Anterolaterally:

Sternothyroid, superior belly of the omohyoid, ant. border of the sternocleidomastoid.

Posterolaterally:Carotid sheath with the common carotid

artery, inetrnal jugular vein & vegus n..Medially:

Larynx, trachea, pharynx & esophagus,, also, cricothyroid muscle & its nerve supply, the ext. laryngial n. & recurrent laryngial n.

Topographic Anatomy of Larynx and Trachea

Anatomical relathions:Ant. To the isthmus:

Sternothyroids m., sternohyoids m., ant. Jugular viens, facia & skin.

Posr. To the isthmus:The 2nd, 3rd, and 4th tracheal rings.

Blood supply:The arteries to the thyroid gland are:Sup. Thyroid a. from the external carotid a.

Inf. Thyroid a. from thyrocervical trunk.

Thyroidea ima. From the brachiocephalic a. or the arch of the aorta.

Blood supply:The veins from the thyroid gland are:Sup. Thyroid vein, drains into internal

jugular v.Middle thyroid vein, drains into internal

jugular vein.Inf. Thyroid vein, drains into left

brachiocephalic vein.

Thyroid lymphatics drain into four groups of nodes:

- Prelaryngeal lymph nodes. - Pretracheal lymph nodes. - Paratracheal lymph nodes. - Deep cervical lymph nodes.

Histological features Thyroid is composed of follicles ( acini )

which are spherical , lined by epithelium which secrete thyroid hormones which are stored in the colloid of the follicle.

The cells are usually cuboidal but become columnar in response to pituitary (TSH)

C-cells secreting calcitonin (of neural crest origin ) a Calcium lowering hormone.

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PhysiologyT3 and T4 from thyroid

follicles.Tyrosine and iodine

T3 is the active form.T4 is converted to T3

peripherally.Controlanterior

pituitary T3 and T4 feedback mechanism and by TRH from the hypothalamus.

Hormones of the thyroid:Thyroixine (levothyroxine) T4.Tryiodothyrodine T3.Calcitonin.

RegulationHypothalamic thyrotropin-releasing hormone

(TRH) stimulates the release of thyroid-stimulating hormone (TSH or thyrotropin) from the anterior pituitary gland.

TSH acts on extracellular receptors on the surface of thyroid follicle cells.

Factors affect on the hormonesA number of factors affect thyroid hormone release.

Three main factors stimulate secretion: 1.Long-term exposure to cold temperatures

acting on the anterior pituitary. 2.Estrogens acting on the anterior pituitary. 3.Epinephrine acting directly on the thyroid

gland.

Transport of thyroid hormonesThe thyroid hormones circulate bound to

plasma proteins produced in the liver, which protect the hormones from enzymic attack:

- 70% are bound to thyroid-binding globulin (TBG).

- 30% are bound to albumin.- Only 0.1% of T4 and 1% of T3 are carried

unbound-this free (unbound) fraction is responsible for their hormonal activities.

The concentration of circulating T4 is much higher than that of T3 (50: 1).

There are two reasons:1. The thyroid secretes more T4 than T3.

2.T4 has a longer half-life (7 days vs. 1 day).

The major manifestations of thyroid disease are :Hyperthyroidism.Hypothyroidism.Goitre.

HyperthyroidismHyperthyroidism is a condition characterized

by increased levels of thyroid hormones in the blood.

The term thyrotoxicoisis is retained because hyperthyroidism i.e. symptoms due to a raised level of circulating thyroid hormones, is not responsible for all manifestations of the disease.

Thyrotoxicosis:Clinical types are:Diffuse toxic goitre (Graves’ disease). 1ry

thyrotoxicosis.Toxic nodular goitre. 2ry thyrotoxicosis.Toxic nodule.Hyperthyroidism due to rare causes:

exogenous thyroid hormone excessive, thyroiditis, metastatic thyroid ca., pituitary tumor secreting TSH, etc.

Diffuse toxic goitre (Graves’ disease):Affect young females.Associated with eye signs.The whole of the functioning thyroid

tissue is involved.The hypertrophy &hyperplasia are due

abnormal thyroid-stimulating antibodies (TsAb) of IgG immunoglobulins.

Toxic nodular goitre (2ry thyrotoxicosis):A simple nodular goitre is present for a

long time before hyperthyroidism.Affects middle-age or elderly.Very infrequently associated with eye

signs.In many cases the nodules are inactive,

and it is the internodular thyroid tissue that is overactive.

Toxic nodule:This is a solitary overactive nodule, which

may be part of a generalized nodularity or a true toxic adenoma.

It is autonomous & its hypertrophy & hyperplasia are not due to thyroid-stimulating antibodies (TsAb).

Because of TSH is suppressed by high levels of circulating thyroid hormones, the normal thyroid tissue surrounding the nodule is suppressed & inactive.

ThyrotoxicosisClinical features of thyrotoxicosis: Metabolic effects:

Hotness and intolerant to heat.Skin, especially of the palms, is sweaty and warm.Loss of weight despite the good appetite.

Sympathetic effects:Palpitation and tachycardia (even during sleep)Fine finger tremors.Lid retraction, lid lag and exophthalmos ( more in

primary)Anxiety and nervousness

Other features:Finger clubbing, proximal myopathy and menstrual

disturbancesInfertility or subfertility

ThyrotoxicosisDiagnosis:

Clinical features and raised serumT3 and/or T4 levels (low TSH).

Treatment:Antithyroid drugs (Carbimazole).ß- blockers (Propranolol)Radioactive iodine is an alternative andSubtotal thyroidectomy is indicated in certain,

specially young, patients.

HypothyroidismCondition characterized by complete or partial

thyroid failure & hence absent or low thyroid hormone production.

Cretinism (fetal or infantile hypothyroidism): Can be sporadic or endemic which is due to

maternal & fetal iodine deficiency.Immediate diagnosis & treatment with thyroxine

within a few days of birth are essential if physical & mental development are to be normal.

Female under treatment with antithyroid drugs may give birth to a hypothyroid infant.

Adult hypothyroidism:The term myxoedema is applied for severe

thyroid failure .Common causes of hypothyroidism:

Autoimmune thyroiditis, iatrogenic (after thyroidectomy , after radioiodine treatment or drug induced i.e. antithyroid drugs), 2ry to pituitary or hypothalamic diseases.

Clinical features of hypothyroidism include:Bradycardia, cold extremities dry skin &hair,

hoarse voice, tiredness, cold intolerance wt. gain, constipation & menstrual disturbance.

In hypothyroidism the thyroid function test show low T4& T3 levels with high TSH.

Treatment: oral thyroxine 0.1- 0.2 mg as single daily dose.

Goitre:Diffenition:Enlargement of the thyroid gland.

classifications of goitre:Simple goitre:Toxic goitre:Neoplastic goitre:Inflammotory:others

Classification1. Simple goiter (euthyroid):

• Diffuse hyperblastic : physiological, puberty, pregnancy.

• Multinodular.• Solitarynodular.

2. Toxic goiter (hyperthyroidism):• Diffuse toxic (grave’s disease).• Multinodular toxic.• Solitarynodular toxic .

Classification3. Neoplastic goiter:

• Benign ( adenomas ).• Malignant ( primary or secondary ).

4. Inflammatory goiter.• Autoimmune chronic lymphocitic

thyroiditis, Hashimoto’s diseases.• Grandulomatous.• Fibrosing.

Classification5. Infective :

Acute ; bacteria thyroiditis.

Chronic ; TB.

6. Other : amyloid.

Is the goitre diffuse or nodular?If nodular, is the gland multinodular?If multinodular is there a dominant nodule

suggesting malignancy?Is there retrosternal extension of the goitre?Is there enlargement of regional lymph

node?Are there any other features suggestive of

malignancy?

Questions to be asked in pt with goitre?

Is the pt. euthyroid, thyrotoxic or myxoedematous?

Is there evidence of thyroiditis?

Simple Goiter:Simple diffuse; develop due to stimulation of thyroid gland

by TSH, the most important factor is iodine deficiency. The goiter is soft and symmetrical.

Simple multinodular; usually multiple, forming a multinodular

goiter. Most occur in females due to present of estrogen receptors in normal thyroid tissue and in nodular goiter. Very large goiter may cause mediastinal compression with stridor, dysphagia &obstruction of the sup. vena cava.

Clinical features of simple goiterDiscomfortDysphagiaEngorgement of neck viensHorse voice

Toxic Goiter;Diffuse;Graves disease. Diffuse vascular goiter appears

in younger women associated with eye signs.Nodular; Goiter present for long time before

hyperthyroidism.

Clinical features of toxic goiter;Wt loss despite normal or increased

appetite.Diarrhea and steatorrhea.Vomiting.Palpitation.Heat intolerance.Nervousness,irritability,emotional lability.Tremor.Muscle weakness, proximal myopathy,Sweating, pruritus.

Solitary nodule:

Truly solitary nodules may be caused by, adenoma, carcinoma, or occasionally thyroiditis.

Female : male ratio is 4:1.Commonly in 30-40ys old pt.About 10% of solitary n. in middle-age are

malignant, this figure exceeds 50% in old age group pt.

Enquiries should be made into the rate of enlargement of the swelling & about breathing

Swallowing, pain & symptoms of thyrotoxicosis or myxoedema.

Neoplasmic Goiter;Benign;Follicular adenoma.Malignant;

Primary : Follicular epithelium.

Papillary Anaplastic

Parafolicular: medullary. Lymphoid: lymphoma.

Neoplasmic Goiter;Secondary;

Metastatic. Local lesion.

Clinical Features;Lymph nodes enlargement.Paralysis of the recurrent laryngeal nerve.

Thyroid tumor1\ Benign tumors:Follicular adenomas are benign tumor commonly occur in young adult . but may affect any age group , clinically appear as solitary discrete mass usually up to 4 cm in diameter .

2\ malignant tumors:Women are affected more than men in a ratio of

2: 1 .Peak incidence between the age of 40 _ 60 y.Thyroid cancer had tow important clinical

associations :1st large amount of radiation particularly to the

head and neck that lead to thyroid cancer .2nd prolonged TSH stimulation of the thyroid

may eventually lead to a malignant transformation.

Classification of thyroid neoplasm & their relative incidence :

Type Incidence %

Papillary carcinoma 61

Follicular carcinoma 18

Anaplastic carcinoma 15

Medullary carcinoma 6

Malignant lymphoma 4

:Histological classification

1\ Differentiated: • Follicular• Papillary • medulary

2\Undifferentiated:• Anaplastic

Clinical feature of the thyroid neoplasm:

1. Neck swelling.

2. Hoarsens of voice due to laryngeal nerve paralysis.

3. Enlarged cervical lymph nodes in papillary carcinoma.

4. Swallowing difficulties.

5. Occult carcinoma ( small papillary tumors may be impalpable )

6. Pain referred to ear in infiltrating growth.

7. Malignant lesions are often firm, irregular or fixed, but some papillary lesions are cystic. Follicular lesions may be soft as a result of haemorrhage.

8. A thyroid nodule with cervical lymphadenopathy is very likely to be malignant .

Papillary carcinoma: Commonest type 60%. Lymphatic spread. A disease of young adult & children. Increase incidence in iodine rich areas. Previous neck irradiation is a risk factor. Seldom encapsulated, & may have

fibrous & calcified areas (psammomas bodies).

May be multifocal.

May present as (occult ca.) with no palpable abnormality of thyroid gland but with LN. met.

Have excellent prognosis.Treatment is total thyroidectomy with

clearance of the involved nodes & with thyroxine replacement to suppress TSH.

Follicular carcinoma:Incidence is about 20%.Spread is mainly by blood.Affect older age group (mean age 50).Increase incidence in iodine deficient

areas.May be caused by previous irradiation.Is usually solitary encapsulatd lesion.Diagnosis of malignancy is based on

capsular penetration by tumor & vascular invasion.

FNAC has no place in diagnosis of the tumor.Multifocality is rarely seen.Prognosis is mainly dependent on the

presence of extrathyroidal spread.Treatment for tumor confined to one lobe is

total lobectomy. A frankly invasive lesion requires total thyroidectomy, radioactive iodine for met. & thyroxine to suppress TSH.

Medullary carcinoma:Accounts for about 5%.Arises from parafollicular C cells.Peak incidence is 50-60ys.In most cases the disease is sporadic but

in about 20% is familiar & consist of MEN type IIA & type IIB syndromes.

Tumor synthesis & secrete calcitonin which can be used as tumor marker.

Treatment is total thyroidectomy .

& regional lymph node clearance.Prognosis is slightly worse than

follicular ca.Other family members of the

affected pt. should be screened.

Anaplastic carcinoma:Account for about 5% of thyroid ca.Affect the elderly, with peak incidence 60-

70ys.Undifferentiated & highly aggressive.Higher incidence in areas of endemic goiter.Local met. And spread through blood &

lymphatics.Radiotherapy & doxorubicin chemo. are the

main modalities of treatment. Surgery is mainly to relief airway obstruction & to debulk tumor.

Patient dies within 6 month of diagnosis

Inflammotory goiter: Autoimmune thyroiditis, it is

associated with increase titer of thyroid antibodies.

Clinical Features: May be asymptomatic or so sudden

painful, mild hypothyroidism may present initially.

Thyroiditis:

Autoimmune (Hashimoto’s) thyroiditis: Commonest form of thyroiditis.Familial.High levels of thyroid antibodies against

thyroglobulin or thyroid cell microsomes.Affect young females.Diffuse thyroid enlargement, which is tender

initially & there may be signs of hyperthyroidism in some pt. but gradually hypothyroidism develop, with destruction of thyroid tissue & increasing atrophy & fibrosis.

Treatment is by thyroid replacement therapy.

Subacute (de Quervain’s) thyroiditis:Uncommon condition.Thyroid gland undergo diffuse painful enlargement.Cause ? Viral.Onset is acute, thyroid enlargement may be

associated with fever, general malaise & wt loss.ESR is high in the early stages of disease.The condition last weeks or months & may recur.Treatment consists of simple analgesia but

sometimes steroids are required for symptoms relief.

Riedel’s (struma ) thyroiditis:Very rare condition, gives rise to a very

hard irregular swelling of the thyroid gland with progressive fibrosis.

Resembles tumor & may give rise to pressure symptoms.

Resection may be necessary if signs of compression develops.

Management:1. History taking :-determine the status of the goitre .2. Clinical examination :-local.-general.-systemic.

HistoryThe thyroid gland can cause two groups of

sumptoms and signs:

1- those connected with swelling in the neck2- those related to the endocrine activity of

the gland

Neck symptomsA lump in the neck:The majority grow slowly and painlessly.In a few pts , a lump will appear suddenly

and may be painfullThis may caused by;Haemorrhage into a necrotic nodule.A fast-growing carcinoma.Thyroiditis.

Discomfort during swallowing:Large swellings may give tugging sensation.

Dyspnoea:Deviation or compression of the trachea by a

mass in the thyroid may cause difficulty in breathing

The whistling sound of air rushing through a narrowed trachea is called Stridor.

Pain:Is not common feature.Acute or subacute thyroiditis can present

with a painfull gland.Hashimoto’s disease often causes an

uncomfortable ache in the neck.Anaplastic carcinoma can cause local pain

and pain referred to the ear if it infiltrates surrounding structures.

Hoarseness:A change in the quality of the voice of a pt.It is probably caused by a paralysis of one of

the recurrent laryngeal nerves, which means that the lump is likely to be malignant and infiltrate the nerve.

Endocrine dysfunctionSymptoms and signs of thyrotoxicosis

1.Nervous system:

Nervousness, irritability, insomnia and nervous instability, and examination may reveal a tremor of the hands, and occasionally thyrotoxic psychosis may be apparent.

Cardiovascular system:Palpitation, breathlessness on exertion,

swelling of the ankle and chest painMetabolic and alimentary system:Increase in appetite but loss of weight,

change of bowel habit (usually diarrhoea), proximal muscle myopathies may occur with wasting and weakness, preference for cold weather, excessive sweating, change in menstruation usually diarrhoea.

Symptoms and signs of myxoedemaIncrease in weight, slow thought speech and

action, intolerance of cold weather, loss of hair, muscle fatigue, dry skin, and constipation.

Aim of the history is to state whether it is simple or toxic goitre +/- evidence of malignancy (pressure symptoms)

You must ask about:The swelling:Onset - duration - pain - change in size.Functional state:Symptoms of hyper and hypothyroidism.

Pressure – related symptoms:Stridor, choking, dysphagia.Change of voiceFamily history

ExaminationYour examination begins with the first

observation.a.Overall appearance of the pt: noisy, agitated,

nervous

b. Examination of the hand: hot or cold, dry or sweaty, tachycardia or bradycardia, thyroid acropachy.

c. Examination of the thyroid:Inspection:- Confirm the swelling to be arising from the

thyroid ( site and moves with swallowing )- Prominent neck veins- puckering of the skin

Palpation:- Palpate from behind the seated pt.

- Always start your palpation by asking yourself:

Is the trachea central or displaced to one side or the other?

- Comment on the swelling:Site, size, consistency, solitary, multinodular,

or diffuse.

Can you define the lower limit? (retrosternal extension).

- Lymph nodes along the jugular chain or in the posterior triangle.

- Palpate the thrill if present (thyrotoxicosis).Percussion:For retrosternal extension.Auscultation:a systolic bruit may be heared in Grave’s

disease

Special signs:Lid lagLid retractionStareThyroid associated ophthalmopathy

( TAO),ophthalmoplegiaProptosis and exophthalmousCoarse, brittle hairAnkle jerkDry, thickened cold skin

InvestigationsThyroid ultrasound (solid or cyst).Thyroid Function Test (TFT).Thoracic inlet X-ray.Chest CT-scan.FNAC: in case of solitary nodule or when

there is possibility of malignancy.

radioiodine study.Thyroid antibodies.Serum cholesterol = is usually raised in

myxoedema and may be normal or a little low in thyrotoxicosis.

ECG: - low electrical activity with small

complex in myxoedema - atrial fibrilation in hyperthyroidism.

Serum free T4 .Serum free T3 .T.S.H .

2. A thyroid scintigram or isotope scan This test measures the rate of

function of the gland. It is done by intravenous injection of dose of

a radioactive substance which is taken up by thyroid gland. The isotope emits gamma rays which are detected by a gamma camera.

Active nodules show up as “hot” with increased activity whereas “cold” nodules are inactive. Most thyroid nodules are cold.

And normal one shows neutral picture .

3.thyroid ultrasound :This is a painless test which uses the

principle of echoes to assess internal tissues and especially whether tissues are solid or fluid (cystic).

help to determine the size of the thyroid gland and location of abnormalities.

4-thyroid antibodies :It indicate an autoimmune pathology such as

Hashimotos thyroiditis or Graves disease .

*To obtain the diagnosis of suspicious lesions5. Fine needle aspiration :This is an extremely valuable test for

differentiating the type of goiter . A small sample of cells or fluid is removed from the thyroid gland by passing a needle through the nodule or cyst in the gland.

The aspirate is then taken for cytology and histology .

6. C.T scan .

Treatment: It depends on the type .1. Surgical treatment : Thyroidectomy a surgical procedure in which all or part

of the thyroid gland is removed. Indications :1. If it cause pressure symptoms.2. Suspicion of malignancy .

1. Cosmetic reasons .2. Thyrotoicosis which is not responding to

medical treatment .3. Retrosternal extension .

The anatomical structures likely to be injuried in thyroidectomy:

The Recurrent laryngeal nerve.The Superior laryngeal nerve.The Parathyroid glands.The cervical sympathetic chain (rarely),

which gives Horner’s syndrome

Types of surgeryOpen surgery

Laproscopic surgery

Types of surgeryPartial lobectomy thyroid surgery: A portion of

one lobe of the thyroid is removed Lobectomy thyroid surgery: An entire lobe of the

thyroid is removed Lobectomy with isthmusectomy thyroid

surgery: One lobe, along with the isthmus, is removed.

Subtotal thyroidectomy: Most of the thyroid is removed, but a functioning section remains (typically used for the treatment of Graves disease)

Total Thyroidectomy: Both lobes and the isthmus are removed

The Surgical Procedure

In the surgery, the surgeon will cut a 3- to 5-inch incision across the base of your neck in front.

The skin and muscle are pulled back to expose the thyroid gland. The incision is usually made

so that it falls in the fold of the skin in your neck, making it less noticeable. Blood supply to the

gland is "tied off," and the parathyroid glands are identified (so that they can be protected). The surgeon then separates the trachea from the thyroid, and removes all or part of the gland .

Management of patients who are undergoing thyroid surgeryRender patient euthyroid & treat other

toxicity effects such as AF & heart failureInvestigations Indirect laryngoscopy to assess vocal cdsBaseline plasma calcium concentrationWBC in patients receiving antithyroid dr.

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Information & consenting the patientContinue antithyroid medication up to day of

surgeryAt operation be careful about structures at

risk mentioned earlierComplicationsBleeding 2)hypocalcaemia: clinically present with

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Paraethesia around mouth & fingers later muscle spasm & then tetany (signs = Trousseu’s& Chvostek ) , condition is managed with IV calcium gluconate.

3) Nerve injury: RLN injury refer to ENT surgeon ,invasive treatment withheld for 9 months (it may recover) if not surgical lateral fixation

4) thyrotoxic storm (crisis):rendering patients euthyroid have abolished this prob.

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Mortality of condition is 10%Clinical featuresRestlessness confusion , tachycardia &

hyperpyrexia + hypotensionPrevention :render all patients euthyroidTreatment IV fluids , steroids , propranolol ,

antithyroid drugs ,potasium iodide & anti-pyrexic agents.

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Complications of thyroid surgery:General complications:1.Wound infection.2.Stitch abscesses.3.Hypertrophic or keloid scar formation.4.Respiratory infections.5.Deep vein thrombosis.6.Pulmonary embolism.7.Cardiac events .8.TIAs due to overenthusiastic retraction of

the common carotid artery.

Specific complications:1-Bleeding & airway obstruction.2-Nerve damage: Transverse cutaneous nerve of neck (C2-C3). External branch of superior laryngeal nerve. Recurrent laryngeal nerve. Cervical sympathetic plexus.3-Hypothyroidism.

Airway Complications and Management after Thyroidectomy

Intubation related complications

Tracheal tear laryngeal edema laryngeal nerve apraxia long term intubation: tracheomalacia, scarring,

granuloma

Airway Complications and Management after Thyroidectomy

Incidence of respiratory complications at extubation and in the recovery room is greater than at intubation

Hematoma (0.79% -1.2%) → airway obstruction

Laryngeal edema (0.19%) → airway obstruction

Hypoparathyroidism, temp.: 0.9-8.3%, perm.: <1.7% → stridor, hypocalcemia

Dysphagia (1.4%)Infection (0.3%)Tracheomalacia

Thyroid storm (thyroid crisis) A sudden and dangerous increase in

all of the symptoms of hyperthyroidism due to excessive amounts of circulating TH.

Symptoms include fever, rapid heart rate, high blood pressure, dehydration, nervousness, and tremors.

Precipitating factors include stressful situations, excessive intake of TH supplements, and trauma.

QUESTIONS

. When progressive enlargement of a multinodular goiter causes symptomatic tracheal compression, the

preferred management in otherwise good-risk patients is:

A. Iodine treatment.B. Thyroid hormone treatment.

C. Surgical resection of the abnormal thyroid.D. Radioactive iodine treatment.

2. The most precise diagnostic screening procedure for differentiating benign thyroid nodules from malignant ones is

:A. Thyroid ultrasonography.

B. Thyroid scintiscan.C. Fine-needle-aspiration biopsy (FNAB).

D. Thyroid hormone suppression.

What is your diagnosis ?How can you prepare these pt for surgery ?6 h after the operation she developed upper airway obstruction what is your immediate action ?