Head and neck Flashcards
Classify the differential diagnoses of neck lumps according to the triangle/area they present.
Anywhere:
- Epidermoid inclusion cyst, sebaceous cyst
- Lipoma
- Sarcoma
Midline:
- Thyroid
- Thyroglossal cyst
- Dermoid cyst (does not move with swallowing/tongue protrusion)
Anterior triangle:
- Lymph node
- Thyroid nodule
- Branchial cyst/fistula
- Carotid body tumour
- Carotid aneurysm
- Cold abscess
- Retropharyngeal abscess
- Sternomastoid pseudotumour
Posterior triangle:
- Lymph node
- Zencker’s diverticulum
- Cervical rib
- Subclavian aneurysm
- Cystic hygroma
What are the pharyngeal arches and pouches?
The pharyngeal arches appear in the 4th or 5th wk of development. Initially they consists of bars of mesenchymal tissue separated by deep clefts known as pharyngeal clefts on the external/ectodermal surface of the embryo (NB 5th arch rudimentary and only 4 clefts visible). Simultaneously a number of outpocketings, the phayrngeal pouches, appear along the lateral walls of the pharyngeal gut, the most cranial part of the foregut; these are on the endodermal side between the arches, opposite the clefts (4th and 5th pouches share a common opening into the lumen of the pharynx).
Each pharyngeal arch consists of a core of mesenchymal tissue covered on the outside by surface ectoderm and on the inside by epithelium of endodermal origin. In addition to the mesenchyme derived from paraxial and lateral plate mesoderm, the core of each arch receives substantial numbers of neural crest cells, which migrate into teh arches to contribute to skeletal components of the face. Original mesoderm of the arches gives rise to musculature of the face and neck. Thus, each pharyngeal arch is characterised by its own:
- muscular components
- the muscular components of each arch have their own cranial nerve, and wherever the muscle cells migrate, they carry their own nerve component with them
- arterial component
What are the msucular contributions, skeletal contributions, nerve and artery associated with the 1st pharyngeal arch?
- 1st pharyngeal arch also called ‘mandibular arch’
- skeletal contributions
- dorsal portion = maxillary process - gives rise to premaxilla, maxilla and zygomatic bone + part of temporal bone through membranous ossification
-
ventral portion = mandibular process
- contains Meckel’s cartilage; during further development Meckel’s cartilage disappears except for 2 small portions at its distal end that form the incus and malleus
- mandible is formed by membranous ossification of mesenchymal tissue surrounding Meckel’s cartilage
- also sphenomandibular ligament
- muscular contributions:
- muscles of mastication (temporalis, masseter, pterygoids), anterior belly of digastric, mylohyoid, tensor tympani, tensor veli palatini
- nerve supply to muscles of first arch: by mandibular branch of trigeminal nerve (?and maxillary branch)
- since mesenchyme from first arch also contributes to dermis of face, sensory supply to skin of face is provided by ophthalmic, maxillary and mandibular branches of trigeminal nerve
- artery: maxillary artery, external carotid artery
What are the components of the second pharyngeal arch?
- aka hyoid arch
- cartilage gives rise to: stapes, styloid process, stylohyoid ligament, lesser horn and upper part of body of hyoid
- muscles = stapedius, stylohyoid, posterior belly of digastric, auricular, muscles of facial expression
- facial nerve
- stapedial artery, hyoid artery
What are the components of the third pharyngeal arch?
- cartilage produces lower part of body and greater horn of hyoid bone
- musculature: stylopharyngeus
- glossopharyngeal nerve
- artery: common carotid, internal carotid
What are the components of the fourth and sixth pharyngeal arches?
- cartilaginous components of these 2 arches fuse to form the thyroid, cricoid, arytenoid, corniculate and cuneiform cartilages of the larynx
- other notes say 4th gives thyroid cartilage and epiglottic cartilage, while 6th gives cricoid, arytenoid, corniculate and cuneiform
- muscles
- 4th: cricothyroid, all intrinsic muscles of soft palate (including levator veli palatini) except tensor veli palatini
- 6th: all intrinsic muscles of the larynx except cricothyroid
- nerve
- 4th: vagus nerve, superior laryngeal nerve
- 6th: vagus nerve, recurrent laryngeal nerve
- artery
- 4th: right 4th aortic arch: subclavian artery, left 4th aortic arch: aortic arch
- 6th: right 6th aortic arch: pulmonary artery and ductus arteriosus
What are the pharyngeal pouches?
The pharyngeal pouches are formed on the endodermal side of the primitive pharynx between the arches, opposite the clefts. The last of the 5 pharyngeal pouches is atypical and often considered part of the 4th.
First pouch - forms Eustachian tube and middle ear cavity; comes into contact with epithelial lining of first pharyngeal cleft, the future external auditory meatus
Second pouch - forms tonsillar fossa
Third pouch - 3rd and 4th pouches characterised at their distal extremity by a dorsal and a ventral wing. in 5th week, epithelium of dorsal wing of 3rd pouch differentiates into inf parathyroid gland, while ventral wing forms thymus. Both gland primordia lose their connection w the pharyngeal wall, and teh thymus then migrates in a caudal and medial direction, pulling inf parathyroid with it. Parathyroid tissue of third pouch finally comes to rest on dorsal surface of thyroid gland and forms inf parathyroid gland
Fourth pouch - epithelium of dorsal wing of 4th pouch forms superior parathyroid gland. When PT gland loses contact w wall of pharynx, it attaches itself to dorsal surface of teh caudally migrating thyroid as teh superior praathyroid
Fifth pouch - ultimobranchial body, which is later incorporated into thyroid gland; cells of ultimobranchial body give rise to the parafollicular or C cells, of thyroid gland (these cells secrete calcitonin, a hormone involved in regulation of the calcium level in the blood)
What is the consequence of a complete facial nerve injury?
What is the course of the facial nerve?
What are the most common sites of facial nerve injury?
LMN deficit involving all muscles of the ipsilateral face
Course of facial nerve:
- arises in pons with a motor and sensory root
- travels through int acoustic meatus & leaves skull via course through temporal bone (the facial canal)
- exits facial canal via stylomastoid foramen just posterior to styloid process
- turns superiorly to run just anterior to the ear
- sensory branches come off early here (posterior auricular nerve)
- main root continues anteriorly and inferiorly from here within the parotid gland dividing it into superficial and deep lobes
- within the gland it branches into 5 main branches - temporal, zygomatic, buccal, marginal, mandibular, cervical
Most common sites of facial nerve injury:
- intratemporal as a result of petrous temporal bone fractures (most common)
- facial trauma - more likely to result in branch injury
- parotidectomy - main branch or multiple branches
- facial/anterior triangle surgery - most commonly injured is MM branch
What is Horner’s syndrome?
What are its common causes?
Horner’s syndrome = a combination of symptoms that arise when the sympathetic trunk is damaged. The signs and symptoms are ipsilateral to the lesion: miosis (constricted pupil), partial ptosis (a weak, droopy eyelid), apparent anhidrosis (decreased sweating), with or without enophthalmos (inset eyeball)
Can result from a lesion anywhere along a three-neuron sympathetic (adrenergic) pathway that originates in the hypothalamus
- first-order neuron descends caudally from hypothalamus to first synapse, which is located in cervical spianl cord (C8-T2)
- second-order neuron travels from sympathetic trunk, through the brachial plexus, over the lung apex, then ascends to the superior cervical ganglion, located near the angle of the mandible and the bifurcation of the CCA (C3-4)
- third-order neuron ascends within adventitia of internal carotid artery, through the cavernous sinus, where it is in close relation to the 6th cranial nerve
- oculosympathetic pathway then joins the ophthalmic (V1) division of the trigeminal nerve; in the orbit and the eye, these oculosympathetic fibres innervate the iris dilator as well as a small smooth muscle in the eyelids responsible for a minor portion of the upper lid elevation and lower lid retraction
- NB the sympathetic fibres responsible for facial sweating and vasodilation branch off at the SCG; remainder of the oculosympathetic pathway has only a few sudomotor fibres which supply a v small strip of skin along the forehead - thus anhidrosis isn’t a prominent feature of postganglionic or third-order lesions
Common causes
- Central/first-order syndrome (anhidrosis of face, arm and trunk) - lesions of sympathetic tracts in brainstem or cervicothoracic spinal cord; usu assoc w other neuro signs and sx
- syringomyelia
- MS
- encephalitis
- brain tumours
- lateral medullary syndrome
- Preganglionic/second-order syndrome (anhidrosis of face) - can occur w trauma or surgery involving the spinal cord, thoracic outlet or lung apex; often have ipsilateral axllary or arm pain too
- cervical rib traction on stellate ganglion
- thyroid carcinoma
- thyroidectomy
- goiter
- bronchogenic carcinoma of superior fissure (Pancoast tumour) on apex of lung
- delivery-related trauma in babies to neck and shoulder, often assoc w Klumpke paralysis
- trauma - base of neck, usu blunt trauma, sometimes surgery
- Postganglionic/second-order syndrome (no anhidrosis) - often indicate lesions of ICA
- cluster headache - combination termed Horton’s headache
- carotid artery dissection/carotid artery aneurysm
- acute Horner syndrome w neck or facial pain should be presumed to be caused by carotid dissection until proven otherwise; these pts at high risk for cerebral infarction
- cavernous sinus thrombosis
- often have abnormalities of eye movements epsec 6th nerve palsy
- middle ear infection
- sympathectomy
- nerve blocks, such as cervical plexus block, stellate ganglion or interscalene block
How to localise the origin of Horner syndrome – associated neurologic symptoms and signs may be helpful
- Brainstem signs (diplopia, vertigo, ataxia, lateralised weakness) suggest a brainstem location
- Myelopathic features (bilateral or ipsilateral weakness, long tract signs, sensory level, bowel and bladder impairment) suggest involvement of the cervicothoracic cord
- Arm pain and/or hand weakness typical of brachial plexus lesions suggest a lesion in the lung apex
- Ipsilateral extraocular pareses, particularly a 6th nerve palsy, in the absence of other brainstem signs localise the lesion to the cavernous sinus
- An isolated Horner syndrome accompanied by neck or head pain suggests an intenral carotid dissection
Describe the treatment of sialolithiasis
- Conservative
- Warm compress
- Analgesia
- Sialogogues (e.g. sherbert)
- Obtain imaging (USS, CT, Sialography)
- Sialoendoscopy where available
- Surgery
- Good for submandibular calculi
- Parotid more complicated
- Avoid surgery (especially difficult if chronic inflammation)
- Can use ESWL.
- Can surgically remove just the stone in the duct - uncommon to perform this procedure.
Describe your examination of a parotid mass.
- Inspect the mass for site, size, symmetry skin changes
- Assess for signs of inflammation
- Palpate the gland
- Palpate the duct
- Palpate the masseter muscle with teeth clenched
- Examine the FACIAL NERVE
- Examine the mouth and tonsils for lesions
- Examine the ductal orifice opposite second molar
- Watch orifice and apply pressure to gland to check for pus in inflammtory conditions
- Examine the neck
What are the complications specific to salivary gland surgery?
- Facial nerve palsy
- 25% temporary
- 1-5% permanent
- Most commonly marginal mandibular
- Frey’s syndrome (parotidectomy)
- Up to 60%!
- Salivary fistula
- 1%
- Lingual/hypoglossal nerve palsy
- Submandibular gland surgery
- ~1-3%
Discuss imaging in salivary gland masses.
Imaging of a salivary gland mass depends on the clinical indication, local availability, and expertise in imaging techniques and their interpretation.
Options include plain x-rays, sialography, USS, CT, MRI, and scintigraphy. Each has a place.
X-ray will pick up sialolithisis in the submandibular gland (90% stones opaque) but are less useful for parotid stones.
Sialography involves using a sialogogue first to stimulate saliva production to identify the duct, which is then cannulated & contrast injected under fluoroscopic control to ensure adeqaute filling; plain drays taken to identify filling defects, delays in emptying & extravasation. Digital subtraction sialography removes the pre-contrast image from post-contrast image to give improved identification of filling defects within the duct system.
Sialography is increasingly being replaced by USS and MRI for ductal pathology. USS is cheap, non-ionising, and excellent at imaging the superficial parotid and SMG. It allows for FNA. It is user dependent.
CT is distorted by dental artifact but is the modality of choice for bony involvement. MRI offers the best resolution for operative planning.
CT-PET is used to identify distant metastases.
The use of sialendoscopy is most applicable to pts who have sx of salivary galnd swelling on eating, indicative of a stone or stenosis; may distinguish between stones, stenosis, mucous plugs or debris within the duct, all of which may present in a similar manner
What are the causes of cervical lymphadenopathy?
L.I.S.T
Lymphoma
- Usually NHL in the neck
Infection
- Bacterial
- Viral
- Protozoal
- Toxoplasmosis
Sarcoidosis
Tumour
- Primary
- Lymphoma, primary lesions masquerading as lymphadenopathy
- Secondary
- Nodal metastses from SCC, Melanoma, Upper GI, Lung, Thyroid
Classify the cervical spaces affected by soft tissue infection.
- Suprahyoid spaces
- Masticator
- Buccal
- Parotid
- Submandibular
- below mylohyoid & deep to investing layer of fascia between hyoid bone & mandible
- communicates around posterior border of mylohyoid with sublingual space
- Sublingual
- under mucous membrane of floor of mouth
- Ludwig’s angina = rare but severe form of cellulitis that involves sublingual & submandibular space & spreads backwards into parapharyngeal space
- Parapharyngeal
- in lateral aspect of neck, shaped like inverted cone - base at skull & apex at hyoid bone
- (upper part of this space is in infratemporal fossa, bounded laterally by pterygoid muscles & parotid sheath)
- divided by styloid process & muscles into
- anterior (nothing) compartment
- posterior (CN IX, X, XI, XII) compartment
- communicates medially with retropharyngeal space
- Infrahyoid spaces
- Pre-tracheal
- behind pre-tracheal fascia
- Pre-tracheal
- Spaces that involve the entire length of the neck
- Retropharyngeal space
- bound anteriorly by constrictor muscles of the neck & posteriorly by alar layer of deep cervical fascia
- “Danger” space (alar-prevertebral space)
- between alar and prevertebral fascia
- potential space all the way down to mediastinum
- Prevertebral space
- infection in this space can track all the way down the spinal column
- Carotid space
- Superficial space
- superficial to investing fascia
- Retropharyngeal space
