Thyroid & Parathyroid

Question 1

supplies both the inferior and superior parathyroids

Answer 1

Inferior thyroid artery (off thyrocervical trunk)

Ligate close to thyroid to avoid injury to parathyroid glands with thyroidectomy

Question 2

Mechanism of TSH

Answer 2

Released from anterior pituitary actso n thyroid to release T3/T4 via increased cAMP

Question 3

Blood supply to thyroid

Answer 3

Superior thyroid artery (1st branch off external carotid a)

Question 4

Accessory blood supply to isthmus in 1% of population

Answer 4

Ima artery

Question 5

Venous drainage of thyroid

Answer 5

Superior/Middle thyroid v: drain into IJ

Inferior thyroid v: drain into innominate v

Question 6

Injury resulting in loss of projection and easy voice fatigability

Answer 6

Superior largyneal nerve

Question 7

Supplies motor to the cricothyroid muscles

Answer 7

superior laryngeal n

Question 8

MC injured n during thyroidectomy

Answer 8

superior laryngeal n

Question 9

Supplies motor to all larynx except cricothyroid

Answer 9

recurrent laryngeal n

Question 10

Anatomy of superior vs recurrent laryngeal n

Answer 10

superior: runs lateral to thyroid lobes
recurrent: runs posterior to thyroid lobes in tracheoesophageal groove, left loops around aorta, right loops around innominate

Question 11

Injury resulting in hoarsness or airway obstruction

Answer 11

rucurrent laryngeal

Question 12

posterior medial suspensory ligament close to recurrent laryngeal nerves requiring careful dissection

Answer 12

ligament of berry

Question 13

Plasma T4:T3 ratio

Answer 13

15:1 (T3 is more active form)

Question 14

T3 production

Answer 14

produced in periphery from T4 to T3 conversion by deiodinases (seperate iodine from tyrosine)

Question 15

Most common cause of death in thyroid storm

Answer 15

high output cardiac failure

Question 16

When does thyroid storm occur

Answer 16

after surgery in Graves patient

Question 17

Treatment of thyroid storm

Answer 17

beta-blockers, Lugol’s solution (KI), cooling blankets, oxygen, glucose

Question 18

How does Lugol’s solution (KI) work to treat thyroid storm

Answer 18

Wolff-Chaikoff effect - high dose of iodine inhibits TSH action on thyroid, inhibits coupling of iodine results in less T3/T4

Question 19

FNA: follicular cells

Answer 19

lobectomy

Question 20

FNA: cyst fluid

Answer 20

drain fluid (unless bloody or recurrent then lobectomy)

Question 21

FNA: colloid tissue

Answer 21

most likely goiter

Tx w/ thyroxine, lobectomy if enlarging

Question 22

FNA: normal thyroid tissue + elevated thyroid function tests

Answer 22

solitary toxic nodule

Tx w/ methimazole, iodine if symptomatic

Question 23

Indeterminant FNA

Answer 23

get radionuclide study,
If Hot: methimazole, iodine
If Cold: lobectomy

Question 24

Dysphagia, dyspnea, dysphonia

Answer 24

lingual thyroid (base of tongue) tx w/ thyroxine suppression and abolish w/ iodine (only thyroid tissue in most patients who have it

Question 25

Midline cervical mass between hyoid and thyroid isthmus that moves up w/ swallowing

Answer 25

thyroglossal duct cyst, at risk of infection/premalignant, needs to be resected w/ hyoid bone and thyroglossal duct cyst (Sistrunk procedure)

Question 26

• Most common location of an ectopic superior parathyroid gland:

Answer 26

tracheoesophageal groove

Question 27

• Most common location of an ectopic inferior parathyroid gland:

Answer 27

thyrothymic ligament (ie, the thymus)

Question 28

• Most common location of a missed adenoma if re-operating:

Answer 28

tracheoesophageal groove (“missed” here refers to a reopertion or a scenario where you are the surgeon to whom some other surgeon is referring his or her patient after being unsuccessful)

Question 29

• Most common location of a parathyroid gland if cannot find it:

Answer 29

normal anatomic position (ie, “continue exploration,” or, if you have meticulously searched, “closed and get a Sestamibi scan” [never do a sternotomy in this scenario!])
* Do not confuse “ectopic” with “missed”