Chapter 95 - Carotid body tumors Flashcards
What are true carotid body tumours
1) paraganglioma
2) arise from chemoreceptive tissue at carotid bifurcation
First description of carotid body tumor
Von Haller 1743
First successful resection of carotid body tumor
Scudder (US) 1903
preserved carotid artery
Causes of carotid body tumors
1) Sporadic (most common)
2) Familial (autosomal dominant)
3) hyperplastic (prolonged hypoxia
Rate of bilateral carotid body tumors
2-20%
30% in familial type
Anatomic location of normal carotid body
Periadventitia of posterior surface of carotid bifurcation
Size of normal carotid body
Ovoid 5mm in length
Blood supply of carotid body tumor
Branches of ECA
Nerves supplying carotid body
Glossopharyngeal
Embryologic origin of carotid body
1) Neural crest ectoderm
2) Mesodermal
From third branchial arch
Neural crest cells migrate in association with autonomic ganglion cells (therefore paraganglioma)
What does neural crest ectoderm differentiate into in carotid body
Type I glomus cells = chemoreceptors
What does mesoderm differentiate into in carotid body
Type II glomus cells = rich vascular stroma
Stimulation of carotid body is by
1) partial pressure of O2 (most important)
2) partial pressure of CO2
3) arterial pH
Afferent innervation from carotid body
1) Type I glomus cells
2) afferent nerve fibers
3) glossopharyngeal
3) medulla oblongata
4) efferent cardiopulmonary centers
Other names for carotid body tumors
1) Carotid chemodectomas
2) Carotid paragangliomas
3) glomus tumors
Define paragangliomas
Neoplastic tumors occuring along autonomic ganglion chain from head to pelvis
Types of paragangliomas in neck
1) Carotid body tumor (most common
2) glomus typanicum
3) glomus vagale
4) glomus jugulare
What is the splayed carotid bifurcation due to carotid body tumor called
Lyre sign
Which vessel does carotid body tumor wrap around
ECA, rarely ICA
How is malignancy of carotid body tumor identified
Clinical behaviour
Not histology
diagnostic if carotid body cells found in lymph nodes
Metastatic spread of carotid body
1) cerebellum
2) thyroid
3) brachial plexus
4) lungs
5) kidney
6) pancreas
7) bones
8) breast
Physical exam findings of carotid body tumor
1) firm
2) smooth
3) lobulated
4) mobile laterally but fixed longitudinally
5) 30-40% audible bruit
Neurological deficits of carotid body tumor
local invasion
1) vagal
2) hypoglossal
3) cervical sympathetic (Horner)
4) dizziness
Endocrine function of carotid body tumor
Rarely functional
but can sometimes have catecholamine release
Differential diagnosis for carotid body tumor
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
Limitation of ultrasound in carotid body tumor
1) cannot see chest or intracranial areas well
2) not sensitive for small lesions
Indication for biopsy of carotid body tumor
Contraindicated due to hemorrhage, hematoma and pseudoaneurysm and nerve injury
Shamblin classification
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
Indication for treatment
Surgical resection as soon as diagnosed
Radiation if not surgical candidate ever
Pre-operative workup for carotid body tumor
Document nerve status pre-op
Urine catecholamine if suspected
Look for synchronous lesions if indicated
Evidence for pre-operative embolization
controversial
risk of cerebral embolization
Techniques for high carotid exposure
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
Mortality following surgical resection of carotid body tumour
< 0.5%
