Chapter 95 - Carotid body tumors

Question 1

What are true carotid body tumours

Answer 1

1) paraganglioma

2) arise from chemoreceptive tissue at carotid bifurcation

Question 2

First description of carotid body tumor

Answer 2

Von Haller 1743

Question 3

First successful resection of carotid body tumor

Answer 3

Scudder (US) 1903

preserved carotid artery

Question 4

Causes of carotid body tumors

Answer 4

1) Sporadic (most common)
2) Familial (autosomal dominant)
3) hyperplastic (prolonged hypoxia

Question 5

Rate of bilateral carotid body tumors

Answer 5

2-20%

30% in familial type

Question 6

Anatomic location of normal carotid body

Answer 6

Periadventitia of posterior surface of carotid bifurcation

Question 7

Size of normal carotid body

Answer 7

Ovoid 5mm in length

Question 8

Blood supply of carotid body tumor

Answer 8

Branches of ECA

Question 9

Nerves supplying carotid body

Answer 9

Glossopharyngeal

Question 10

Embryologic origin of carotid body

Answer 10

1) Neural crest ectoderm
2) Mesodermal

From third branchial arch

Neural crest cells migrate in association with autonomic ganglion cells (therefore paraganglioma)

Question 11

What does neural crest ectoderm differentiate into in carotid body

Answer 11

Type I glomus cells = chemoreceptors

Question 12

What does mesoderm differentiate into in carotid body

Answer 12

Type II glomus cells = rich vascular stroma

Question 13

Stimulation of carotid body is by

Answer 13

1) partial pressure of O2 (most important)
2) partial pressure of CO2
3) arterial pH

Question 14

Afferent innervation from carotid body

Answer 14

1) Type I glomus cells
2) afferent nerve fibers
3) glossopharyngeal
3) medulla oblongata
4) efferent cardiopulmonary centers

Question 15

Other names for carotid body tumors

Answer 15

1) Carotid chemodectomas
2) Carotid paragangliomas
3) glomus tumors

Question 16

Define paragangliomas

Answer 16

Neoplastic tumors occuring along autonomic ganglion chain from head to pelvis

Question 17

Types of paragangliomas in neck

Answer 17

1) Carotid body tumor (most common
2) glomus typanicum
3) glomus vagale
4) glomus jugulare

Question 18

What is the splayed carotid bifurcation due to carotid body tumor called

Answer 18

Lyre sign

Question 19

Which vessel does carotid body tumor wrap around

Answer 19

ECA, rarely ICA

Question 20

How is malignancy of carotid body tumor identified

Answer 20

Clinical behaviour
Not histology

diagnostic if carotid body cells found in lymph nodes

Question 21

Metastatic spread of carotid body

Answer 21

1) cerebellum
2) thyroid
3) brachial plexus
4) lungs
5) kidney
6) pancreas
7) bones
8) breast

Question 22

Physical exam findings of carotid body tumor

Answer 22

1) firm
2) smooth
3) lobulated
4) mobile laterally but fixed longitudinally
5) 30-40% audible bruit

Question 23

Neurological deficits of carotid body tumor

Answer 23

local invasion

1) vagal
2) hypoglossal
3) cervical sympathetic (Horner)
4) dizziness

Question 24

Endocrine function of carotid body tumor

Answer 24

Rarely functional

but can sometimes have catecholamine release

Question 25

Differential diagnosis for carotid body tumor

Answer 25

1) congenital lesion (vascular malformation, brachial cleft cyst, hygroma)
2) inflammatory disorder (lymphadenitis, lymphadenopathy)
3) infection
4) benign lesions (lipomas, cysts, parotid, salivary tumors)
5) malignancies
6) carotid aneurysm, kinks, coils
7) cervical paragangliomas

Question 26

Limitation of ultrasound in carotid body tumor

Answer 26

1) cannot see chest or intracranial areas well

2) not sensitive for small lesions

Question 27

Indication for biopsy of carotid body tumor

Answer 27

Contraindicated due to hemorrhage, hematoma and pseudoaneurysm and nerve injury

Question 28

Shamblin classification

Answer 28

Group I: small, dissect off walls of carotid in periadventitial plane
Group II: large, adherent to adventitia and surrounding carotid vessels but not hypoglossal nerve
Group III: intimiate adherence to vessel and encase ICA and ECA and hypoglossal nerve

Question 29

Indication for treatment

Answer 29

Surgical resection as soon as diagnosed

Radiation if not surgical candidate ever

Question 30

Pre-operative workup for carotid body tumor

Answer 30

Document nerve status pre-op
Urine catecholamine if suspected
Look for synchronous lesions if indicated

Question 31

Evidence for pre-operative embolization

Answer 31

controversial

risk of cerebral embolization

Question 32

Techniques for high carotid exposure

Answer 32

1) extend incision across mastoid process
2) detach posterior belly of digastric from mastoid process
3) division of stylohyoid muscle with/without styloid process
4) subluxation or division of mandible

Question 33

Mortality following surgical resection of carotid body tumour

Answer 33

< 0.5%