What are the spaces of the infra hyoid neck?
- Visceral
- Carotid
- Retropharyngeal
- Posterior cervical
- Perivertebral
What is the visceral space?
Central compartment containing several viscera: larynx, thyroid, hypo pharynx and cervical oesophagus.
Extends from hyoid to mediastinum; no supra hyoid extension.
What is the carotid space?
Paired space just lateral to the visceral compartment. Contains CCA, ICA, IJV, vagus.
What is the retropharyngeal space?
Small virtual space containing only fat; continuous with the supra hyoid space and the middle mediastinum
What is the posterior cervical space?
Paired space posterolateral to the carotid space
What is the perivertebral space?
large space completely encircling vertebral body, including pre and paravertebral muscles.
What is the approach to pathology in the infra hyoid neck?
1: Which space is lesion?
2: what is normally in this space?
3. What pathology arises from normal contents? Does it fit clinical picture?
What are the strap muscles?
TOSS:
- thyrohyoid
- omohyoid
- sternohyoid
- sternothyroid
What is the role of the strap muscles?
All connected to hyoid and depress hyoid bone and larynx during swallowing and speaking
Ddx of lesion in supraglottic larynx?
- Mucosal: squamous Ca
- Submucosal:
- -laryngocele
- -chondrosarcoma
- -paraganglioma
- -schwannoma
Pathology of hypopharynx / oesophagus?
- Zenker’s diverticulum
- squamous cell Ca
Pathology of trachea?
- carcinoma
- benign stenosis
Pathology of thyroid?
- Goitre
- colloid cyst
- carcinoma (papillary, follicular, anaplastic)
- Hashimoto’s
Pathology of parathyroid?
- Adenoma
- Hyperplasia
Embryological remnants which may be found in visceral space?
- Thyroglossal duct
- 3rd branchial cyst
How to distinguish paratracheal LNs from thyroid (e.g. tmng) on imaging?
LNs lie outside strap musculature
Where does the thyroglossal duct run?
From the base of tongue at foramen caecum to the thyroid gland
What is a thyroglossal duct cyst?
Persistence of thyroglossal duct enables development of cyst
DDx thyroglossal duct cyst?
- necrotic anterior cervical nodes
- thrombosed jugular vein
What is important to check on identification of thyroglossal duct cyst?
Thyroid is in normal position:
- thyroid anlage may never travel along duct
- remains at tongue base
- =lingual thyroid
Where does the carotid space extend?
Skull base to aortic arch
Contents (real and potential) of carotid space?
- carotid artery
- IVJ
- CNX
- Sympathetic plexus
- LNs (level 2-4)
- Congenital remnants of 2nd branchial cleft
Pathology of CCAs?
- Dissection
- Thrombosis
- Aneurysm
Pathology of IJV?
- Thrombosis
- Thrombophlebitis
Pathology of CNX?
- Schwanomma
- Neurofibroma
Pathology of sympathetic plexus?
-paraganglioma
Pathology of LNs of carotid space?
- Lymphoma
- Squamous/thyroid Ca mets
Congenital remnant pathology of carotid space?
Second branchial cleft cyst
Key features of a paraganglioma?
- aka carotid body tumor.
- Multiple in 4% of patients.
- 25% have a positive family history.
- Intense enhancement on CT and MR.
- Flow voids are frequently present.
How may the retropharyngeal space become infected?
- Classic: paeds ==> URTI spreads to retropharyngeal LNs
2. Penetrating trauma: FBs (fish bones) or iatrogenic (intubation)
Contents of posterior cervical space and pathology potential?
- fat (lipoma)
- CNXI (schwannoma, neurofibroma, MPNST)
- Brach Plex (as above + apical lung / breast Ca, lymphoma)
- LNs: lymphoma mets, TB
MPNST?
malignant peripheral nerve sheath tumour
Development pathology of posterior cervical space?
- primitive embryonic lymph sacs (cystic hygroma, lymphangioma)
- 3rd branchial cleft (cyst)
Homogenous enhancement of LNs suggestive of?
Lymphoma
What is lymphangioma?
- Benign non-capsulated lesion arising from expanding embryonic lymph ‘lakes’ that do not develop normal lymphatic drainage.
- 90% in children 10% in young adults.
- occur anywhere in the head and neck; mostly in posterior cervical space. -10% extend into the mediastinum.
- High signal on T2-weighted images
- Signal on T1-weighted images depends on protein content.
- Hemorrhage results in rapid growth and fluid-fluid levels as seen on MR
Contents and perivertebral space and potential path?
- Vertebra (osteomyelitis, 1/met bone Ca)
- Muscles (myositis, abscess, sarcoma, fibromatosis)
- BPlex: schwanomma, neurofibroma, MPNST
- Vert art/vein: aneurysm, dissection, thrombosis
