Chapter 34: Thyroid Disease + Surgery

Question 1

How much does the thyroid weigh?

Answer 1

30 g

Question 2

Where does the isthmus usually lie?

Answer 2

Midline

Question 3

Main anatomical points of thyroid:

Answer 3

Right lobe, left lobe, isthmus

Question 4

What is most common issue with thyroid gland?

Answer 4

Enlargement

Question 5

Parathyroid glands: How many? Size?

Answer 5

4 4 mm x 6 mm

Question 6

Most common source of problems in parathyroid gland?

Answer 6

Endocrine disorder

Question 7

Which nerves are contiguous with the thyroid gland?

Answer 7

RLNs

Question 8

What increases risk for injury or loss of nerve?

Answer 8

Thyroid malignancy

Question 9

What adjunct is necessary when operating on thyroid?

Answer 9

Nerve testing and NMB monitoring

Question 10

Range of testing device for RLNs in thyroid surgery?

Answer 10

0.5-2 mA

Question 11

The thyroid gland is contiguous with what airway structure?

Answer 11

Trachea

Question 12

What is a goiter?

Answer 12

Enlargement of thyroid gland

Question 13

Where can goiters grow? What are they called in their respective positions?

Answer 13

Can grow in chest (intrathoracic) or in neck (extrathoracic)

Question 14

What is your biggest concern regarding goiters?

Answer 14

They tend to shift the trachea and therefore shift the glottis.

Question 15

What type of disease may deviate and/or compress the trachea?

Answer 15

Thyroid disease

Question 16

In what thyroid case would the patient require intubation post-operation?

Answer 16

Only the patient with tracheal malasia would remain intubated for 2-5 days as the surrounding tissue healed.

Question 17

Immediate risk to thyroid disease/surgery?

Answer 17

Interruption/injury to one/both RLNs

Question 18

This tool is used for:

Answer 18

Mediastinoscopy

Question 19

Condition demonstrated in this picture

Answer 19

Intrathoracic goiter

Question 20

Answer 20

Mediastinoscopy

Question 21

Pathway of the RLNs:

Answer 21

Transverses chest (right vs. left difference)

Ascends in neck lateral to airway

Question 22

Which cranial nerve is contiguous with thryoid gland?

Answer 22

Vagus (CN X)

Question 23

Origin of RLNs?

Answer 23

Vagus nerve (CN X)

Question 24

What anatomical structures protect RLNs?

Answer 24

Protected in larynx by thyroid cartilage

Question 25

RLNs serve what?

Answer 25

posterior cricoarytenoid muscle and other laryngeal muscles EXCEPT cricothyroid

Question 26

What muscle is the only primary vocal cord abductor?

Answer 26

posterior cricoarytenoid muscle

Question 27

RLN runs along track of which artery?

Answer 27

Laryngeal branches of superior and inferior thyroid arteries

Question 28

If the RLN is interrupted, position of the VCs?

Answer 28

Paramedian

Question 29

If RLN is injured (but not interrupted), VC at what position?

Answer 29

Abducted (lateral)

Question 30

What are some destructive effects of the thyroid gland on mechanical integrity of the upper airway? Where might these effects occur?

Answer 30

Cartilaginous destruction Extrinsic compression Can occur in neck and/or mediastinum

Question 31

What are three questions you should ask yourself if patient has previously had thyroid surgery?

Answer 31

Where is the lesion(?) Where will the ETT cuff be(?) What will happen after extubation(?)

Question 32

What routine actions may cause INJURY to RLNs?

Answer 32

Retraction, clamping, or electrocautery

Question 33

What routine surgical actions/tools may cause INTERRUPTION to RLNs?

Answer 33

scalpel or electrocautery

Question 34

INJURY to RLN: overall effect to vocal cords?

Answer 34

VC adduction

Question 35

In ACUTE UNILATERAL injury to RLN:

Answer 35

Affected VC will move to the median position, opposed by the normal VC

Question 36

In LONGTERM UNILATERAL injury to RLN:

Answer 36

Affected VC may force the normal VC away from the midline

Question 37

BILATERAL ACUTE injury to RLNs:

Answer 37

Upper airway obstruction

Question 38

Result of LONGTERM BILATERAL injury to RLNs:

Answer 38

Dyspnea, aspiration, but then resolution of edema, no problem

Question 39

Position of VCs during inspiration after RLN paralysis:

Answer 39

Normal

Question 40

Position of VCs during phonation during after RLN paralysis (compensated):

Answer 40

Closed (midline)

Question 41

Position of VCs during inspiration in the case of bilateral RLN paralysis

Answer 41

Paramedian

Question 42

What are some possible diagnoses for stridor after parathyroid or thyroid surgery?

Answer 42

Edema in the supraglottic or glottic regions RLN damage Hypocalcemia

Question 43

How much does a parotid gland weigh?

Answer 43

20 g

Question 44

Why must you use NMB monitoring when working with the parotid glands?

Answer 44

To ensure no damage was done to the facial nerve

Question 45

Name the two lobes of the parotid gland:

Answer 45

Superficial Deep

Question 46

Which duct mediates secretions from the parotid gland?

Answer 46

Stenson's duct

Question 47

What are the branches of the facial nerve?

Answer 47

Temporal Zygomatic Buccal Mandibular Cervical

Question 48

Branches of the buccal nerve?

Answer 48

Upper + lower

Question 49

What is the most common disease of the parotid gland? The other source?

Answer 49

Benign adenoma (75%) Other: malignancies (25%)

Question 50

What disorder do these images demonstrate?

Answer 50

Parotitis

Question 51

What is trismus?

Answer 51

Lock jaw (TMJ issue)

Question 52

Facial nerve branches require how many stimulators for each branch the surgeon wishes to monitor?

Answer 52

One

Question 53

Describe the optimal positioning of a NMB nerve monitor.

Answer 53

Close to the nerve being monitored Maximal current density Minimal current dispersion

Question 54

Best way to monitor sensory threshold while using an NMB nerve stimulator on the facial nerve?

Answer 54

Watch facial expressions prior to induction

Question 55

Explain the premise of the supramaximal stimulus using an NMB nerve stimulator:

Answer 55

Activate all muscle fibers served by the stimulated nerve without directly stimulating the muscle fibers

Question 56

Describe the empiric setting of the NMB nerve stimulator.

Answer 56

We want to set it to be 25 mA above motor threshold, which is 15 mA: so we set it to 40 mA.

Question 57

How should you give rocuronium? How long after dosing should you wait to test? What should your TOF ratio be?

Answer 57

Give in 5 minute increments. Wait 4-6 minutes in order to test. TOF ratio: \>0.4

Question 58

End point for ending case following reversal of NMB: TOF ratio should be what?

Answer 58

\>0.9