THYROID- BENIGN SWELLINGS

DR.B.SELVARAJ MS;MCH;FICS

MMMC;MALAYSIA

ANATOMY

PHYSIOLOGY

DEFINITIONS

• GOITER: any enlargement of thyroid gland

• Thyrotoxicosis : Symptoms of thyroid hormone excess due to increased synthesis or release due to destruction of thyroid follicles or exogenous thyroid hormone supplementation.

• Hyperthyroidism : Features of thyroid hormone excess due to increased synthesis of thyroid hormone by the gland.

CONDITIONS CAUSING

THYROTOXICOSIS

• Diffuse toxic goitre (Grave’s disease)

• Toxic nodular goitre (Toxic MNG)- Plummer’s disease

• Toxic nodule (Toxic adenoma)- Goetsch’s disease

• Thyrotoxicosis factitia (Due to excess exogenous thyroid hormone supplementation)

• Jod-Basedow thyrotoxicosis (Iodide induced)

• Thyroiditis

• Malignancies of thyroid.

• Trophoblastic tumor (Due to thyroid stimulating action of HCG produced by this tumor)

• Ectopic thyroid tissue (Struma ovarii)

Primary thyrotoxicosis Secondary thyrotoxicosis

Age Younger patients Middle age and elderly

Onset Goitre and Hyperthyroidism

appear simultaneously

Goitre present for many years prior

to hyperthyroidism

Symptoms Calorigenic (weight loss,heat

intolerance) and nervous

manifestations common

Cardiovascular manifestations

more common

Signs All eye signs present.

Diffuse goitre,highly vascular

(bruit+)

Only limited eye signs present

(spastic)-lid spasm and lid lag.

Nodular goitre

complications Obstructive symptoms

uncommon

Obstructive symptoms commoner

Treatment Start with anti thyroid

drugs.Subsequent surgery or

radio-iodine if needed

Definite role for surgery

GRAVE’S DISEASE

• Described by Irish physician Dr.Robert Graves in 1835

• Common in females

• Age : 20-40 years

• Pathogenesis:

• Thyroid stimulating immunoglobulins (TSI) of IgG class produced

by lymphocytes stimulate TSH receptor.

• Ophthalmopathy: Fibroblast proliferation and increased

glycosaminoglycans production induced by TSI (?antigenic

similarity between orbital tissues and thyroid.)

CLINICAL FEATURES - SYMPTOMS

• Calorigenic : Increased appetite,weight loss,heat intolerance,

increased sweating, tiredness

• Nervous : Tremors,anxiety,nervousness,increased activity

• CVS: Dyspnoea, palpitations, pedal edema (due to CCF)

• Ocular : Diplopia, pain and increased lacrimation (due to

corneal ulcer)

CLINICAL FEATURES- SYMPTOMS

• Menstrual : Amenorrhoea/ oligomenorrhoea

• Miscellaneous: Loose stools.

THYROTOXICOSIS- SIGNS

• Thyroid :Diffuse enlargement with bruit and visible

pulsations

CVS

• Pulse : Increased sleeping pulse rate with wide pulse

pressure.

• Stages of development of thyrotoxic arrhythmias : Multiple

extra systoles → Paroxysmal atrial tachycardia →

Paroxysmal atrial fibrilla?on → Persistent AF not responding

to digoxin.

EYE SIGNS

Seen in both Primary and secondary thyrotoxicosis (due to

increased thyroid hormone levels which sensitizes the

Muller's muscle to sympathetic system)

• Von Graefe’s sign (lid lag)

• Stellwag’s sign (characteristic stare with infrequent blinking)

• Dalrymple’s sign (widened palpebral fissure)

EYE SIGNS

• Naffziger’s sign : For proptosis

• Moebius sign : Loss of convergence (Due to ophthalmoplegia)

• Joffroy’s sign: Absence of wrinkling of forehead on looking up.

THYROTOXICOSIS- SIGNS

• Dermopathy : Pretibial myxedema due to increased

mucopolysaccharide deposition.

• Thyroid acropachy : Dermopathy associated with

clubbing of toes

• Tremors: Outstretched hands,tongue

• Grave’s disease is diagnosed when features of

thyrotoxicosis is associated with ophthalmopathy +/-

dermopathy

GRAVE’S DISEASE-OPHTHALMOPATHY

DIAGNOSIS

• Most cases can be diagnosed clinically.

• Thyroid function test : Raised T3,T4 with decreased TSH.

• Thyroid scan : I123 scan-Diffuse increased uptake.

• FNAC : Relative contraindication in the presence of

thyrotoxicosis.

HISTOPATHOLOGY OF GRAVE’S DISEASE-

FOLLICULAR HYPERTROPHY WITH SCANTY COLLOID

TREATMENT OPTIONS

• Medical

• Radio-Iodine

• Surgery

MEDICAL TREATMENT –DRUGS USED

• Anti thyroid drugs : Carbimazole and propylthiouracil

• Mechanism of action : Inhibit thyroid peroxidase and thereby interfere with

iodination of tyrosine residues in thyroglobulin and coupling of iodotyrosine

residues to form T3 and T4.

• Dose : Start with high dose (Carbimazole 10mg TDS ) once control is

achieved dose is reduced (5 mg BD or TDS)

• Alternatively block and replacement regimen is used – Continue with high

dose of antithyroid drugs with thyroxine supplementation (0.1 mg OD) .

Decreased risk of iatrogenic hypothyroidism .

• Adverse effects : Agranulocytosis less common but serious adverse effect.

Needs monitoring of counts.

MEDICAL TREATMENT- ADVANTAGES:

• Can be used even in children and young adults.

• Hypothyroidism if induced is reversible

• No complications associated with surgery.

Disadvantages:

• Prolonged treatment is required since relapse rate is high.

• Drug toxicity

BETA BLOCKERS

• Propranolol most commonly used

Indications :

• For symptomatic control

• When antithyroid drugs are initiated till biochemical

control is achieved

• Thyroid storm

• Along with iodide for preop preparation.

• Dose : 20-40 mg QID (Max dose – 600mg/day)

IODIDES

• Lugol’s iodine most commonly used preparation (5% iodine in 10% potassium iodide solution).

Mechanism of action :

• Inhibition of thyroid hormone release (Thyroid constipation)

• Decreases vascularity of the gland

Uses:

• Preop preparation : 10-14 days prior to surgery

• Thyroid storm :iodinated contrast agents (sodium ipodate ) given i.v.

Dose : Lugol’s iodine 5 drops TDS in milk.

RADIOACTIVE IODINE ABLATION

• I131 most commonly used

Indications :

• Patients with small to moderate enlargement of gland and antithyroid drugs have clearly not worked.

• Patients not willing for surgery or for whom surgery is contraindicated.

• Recurrence after surgical or medical therapy.

RADIOACTIVE IODINE ABLATION

Euthyroid state achieved by using antithyroid drugs for

3-4weeks before treatment.

↓

Interruption of antithyroid drugs for 3-4 days before and after Iodine treatment to permit adequate accumulation and retention of administered iodine.

↓

Pretreatment radioiodine scan done (25-100 micro curie of I131 given) to calculate therapeutic dose.

↓

Therapeutic dose of radio-iodine given (usually 8-12 milli curie) orally.

RADIOACTIVE IODINE ABLATION

• Patient rendered euthyroid by 8-12 weeks after treatment.

Disadvantages :

• Hypothyroidism : incidence 10-15% by 1 year which

increases by 3% in each succeeding year.

• Exacerbation of cardiac arrhythmias in elderly

• Fetal damage-hence contraindicated in pregnant and

lactating women

• Worsening of ophthalmopathy – avoided by using

prophylactic steroids

• Can induce Thyroid storm if patients are not rendered

euthyroid before radio-iodine administration.

RADIOACTIVE IODINE ABLATION

• Carcinogenic effect of radio-iodine has been

ruled out and hence radio-iodine can be safely

used in all individuals over 25 years i.e when

development is complete.

SURGERY

Indications :

• Failure of medical/radioiodine treatment

• Younger patients particularly adolescents

• Pregnant patients

• Patients with suspicious masses contained within the large thyroid.

• Patients with severe cosmetic deformities or tracheal compression causing discomfort.

SURGERY

• Extent of surgery : Subtotal or total thyroidectomy

Advantage of total thyroidectomy :

• Recurrence is avoided

• Patients with ophthalmopathy are stabilized most

successfully by total thyroidectomy.(Due to removal of

entire antigenic focus)

• Patients should be rendered euthyroid before surgery

to avoid thyroid storm.

THYROID STORM-TREATMENT

• Supportive measures : Correction of dehydration with I.v fluids and hyperpyrexia with cooling blankets

• Antithyroid drugs : Propylthiouracil preferred.Given through Ryle’s tube if patient can’t take orally.(Parenteral forms not available).

• Iodinated contrast agents (sodium ipodate)-1gm given I.v

• Propranolol 2mg I.v with ECG monitoring (if patient cannot take orally) or 40-80mg Q6h

• Large doses of dexamethasone : 2mg Q6h (inhibit hormone release,peripheral conversion of T4toT3 and provide adrenal support.

• Life threatening circumstances : Peritoneal or hemodialysis to lower T3 andT4 levels.

OPHTHALMOPATHY-TREATMENT

• Mild disease – Conservative measures: Elevating the head at

night ,Protection of eye ball and avoiding corneal drying by

applying 1%methylcellulose eye drops or plastic shields.

• Severe cases –large doses of prednisolone (100-120

mg/day)

• Malignant exopthalmos : Orbital decompression.

THYROTOXICOSIS IN

PREGNANCY

• Radio-Iodine : Contraindicated.

• Surgery : Can be done in second trimester

• Chance of miscarriage present with surgery.

• Antithyroid drugs : Propylthiouracil preferred

(Placental transfer less)

• Can cause fetal goitre.

• Avoided by keeping antithyroid drug dosage to

minimum to prevent rise in TSH.

TOXIC MULTINODULAR GOITER-

PLUMMER’S DISEASE

• Seen in long standing goitre when one or more nodules become autonomous.

• Cardiovascular symptoms predominate

• Radionuclide scan: Can demonstrate autonomous nodules.

• Treatment :

• Antithyroid drugs : Can control symptoms but relapse invariably occurs with discontinuation of medications.

• Propranolol can be used for symptomatic control.

• Radio-iodine : Effective.But larger doses are required 20-30 milli curie)

TOXIC MULTINODULAR GOITER-PLUMMER’S

DISEASE

• Chance of hypothyroidism with

radio-iodine is less compared to

grave’s disease due to variable

activity of different portion of the

gland allowing previously

quiescent area to function in

place of those destroyed by I131.

• Surgery : Preferred treatment

(Subtotal thyroidectomy)

TOXIC ADENOMA- GOETSCH’S

DISEASE

THYROID SURGERY

ROUTINE INVESTIGATIONS BEFORE

THYROID SURGERY

• X-ray soft tissue neck – AP and lateral view

• Indirect laryngoscopy

• Serum calcium : Baseline value to detect post-op hypocalcemia

due to hypoparathyroidism (Optional)

TYPES

• Hemithyroidectomy

• Subtotal thyroidectomy

• Near total/total thyroidectomy

TECHNIQUE

• Anaesthesia : GA with ET tube

• Position : Supine with table tilted up by 15 degree to reduce venous

engorgement

• Neck extended by placing sandbags under shoulder.

• Incision : Skin crease incision about 2 finger breadths above

suprasternal notch.

TECHNIQUE

• Flaps of skin,subcutaneous tissue and platysma raised upwards

to superior thyroid notch and downwards to the suprasternal

notch.

• Deep cervical fascia is divided in the midline between the

sternothyroid muscles down to the plane of thyroid capsule.

THE THYROID LOBE IS EXPOSED BY MOBILIZING THE

STRAP MUSCLES AWAY FROM THE LOBE BY MEANS OF

LATERAL RETRACTION ON THE MUSCLES

THE MIDDLE THYROID VEIN IS EXPOSED, DIVIDED, AND

LIGATED.

BABCOCK CLAMPS ARE APPLIED TO INFERIOR AND

SUPERIOR (NOT SHOWN) ASPECTS OF THE THYROID

LOBE TO FACILITATE MEDIAL RETRACTION ON THE

GLAND.

TECHNIQUE

DOWNWARD TRACTION ON THE SUPERIOR BABCOCK CLAMP EXPOSES

THE SUPERIOR POLE VESSELS, INCLUDING THE BRANCHES OF THE

SUPERIOR THYROID ARTERY.

THE EXTERNAL LARYNGEAL NERVE COURSES ALONG THE CRICOTHYROID

MUSCLE JUST MEDIAL TO THE SUPERIOR POLE VESSELS.

TO AVOID INJURY TO THIS NERVE, THE SUPERIOR POLE VESSELS ARE

DIVIDED INDIVIDUALLY AS CLOSE AS POSSIBLE TO THE POINT WHERE

THEY ENTER THE THYROID GLAND.

AS THE THYROID IS RETRACTED MEDIALLY, GENTLE

DISSECTION IS USED TO EXPOSE THE PARATHYROID

GLANDS, INFERIOR THYROID ARTERY, AND RECURRENT

LARYNGEAL NERVE.

TO PERFORM TOTAL LOBECTOMY, THE BRANCHES OF THE INFERIOR THYROID

ARTERY ARE DIVIDED AT THE SURFACE OF THE THYROID GLAND. THE INFERIOR

THYROID VEINS CAN NOW BE LIGATED AND DIVIDED. SUPERIORLY, THE CONNECTIVE

TISSUE (LIGAMENT OF BERRY), WHICH BINDS THE THYROID TO THE TRACHEAL

RINGS, IS CAREFULLY DIVIDED. THERE ARE USUALLY SEVERAL SMALL

ACCOMPANYING VESSELS, AND THE RECURRENT NERVE IS CLOSEST TO THE

THYROID AND MOST VULNERABLE AT THIS POINT.

THE DISSECTION OF THE THYROID FROM THE TRACHEA CAN BE

PERFORMED WITH THE CAUTERY BY DIVISION OF THE LOOSE

CONNECTIVE TISSUE BETWEEN THESE STRUCTURES. DISSECTION IS

EXTENDED UNDER THE ISTHMUS, AND THE SPECIMEN IS DIVIDED SO

THAT THE ISTHMUS IS INCLUDED WITH THE RESECTED LOBE.

SUBTOTAL LOBECTOMY NECESSITATES IDENTIFICATION OF THE PARATHYROID

GLANDS, INFERIOR THYROID ARTERY, AND RECURRENT LARYNGEAL NERVE, AS

PREVIOUSLY DESCRIBED. THE LINE OF RESECTION IS SELECTED TO PRESERVE THE

PARATHYROID GLANDS AND THEIR BLOOD SUPPLY AND TO PROTECT THE

RECURRENT LARYNGEAL NERVE. IT SHOULD BE BASED ON THE INFERIOR THYROID

ARTERY OR ITS MAJOR BRANCHES.

CLAMPS ARE PLACED ALONG THE LINE OF RESECTION AND THE

THYROID GLAND IS DIVIDED. THE DIVIDED TISSUE IS LIGATED OR

SUTURE-LIGATED WITH 3-0 SILK SUTURES.

DURING THYROIDECTOMY, THE RECURRENT LARYNGEAL NERVE IS AT

GREATEST RISK FOR INJURY (1) AT THE LIGAMENT OF BERRY, (2)

DURING LIGATION OF BRANCHES OF THE INFERIOR THYROID ARTERY,

AND (3) AT THE THORACIC INLET.

POST-OP COMPLICATIONS

• Hemorrhage : Tension hematoma deep to cervical fascia usually

result from slipping of ligature on the superior thyroid

artery.Requires emergency re-exploration.

• Respiratory Obstruction : Due to tension hematoma or

Tracheomalacia.

• Thyroid insufficiency- hypothyroidism

• Recurrent laryngeal nerve paralysis

• Superior laryngeal nerve paralysis

• Parathyroid insufficiency- hypocalcemia

• Wound infection

• Hypertrophic scar