6. Neuro (Head and Neck) Flashcards
- Temporal bones, Ear, Skull base, Sinuses, Mouth, Thyroid, Parathyroid, Suprahyoid Soft Tissue Neck, SCC, Infrahyoid Soft Tissue Neck, Orbit)
Petrous Apex - anatomic variants (3)
Asymmetric marrow,
Cephaloceles
Variant anatomy of the carotid artery
Asymmetric marrow (3)
Typically petrous apex contains significant fat, closely following the scalp and orbital fat (T1 and T2 bright).
Asymmetry can mimic infiltrative process.
Could also overlook a T1 bright pathology (cholesterol granuloma) thinking it’s fat.
Key is to use STIR or fat sat.
Cephalocele (4)
herniation of CNS content through a defect in the cranium.
In the petrous apex, they don’t contain brain tissue and represent cystic expansion and herniation of the posterolateral portion of Meckel’s cave into the superiomedial aspec of the petrous apex.
Usually unilateral and classically described as “Smoothly marginated lobulated cystic expansion of the petrous apex”
Variant anatomy of the carotid artery (3)
2 main variants are persistent stapedal artery and aberrant internal carotid.
DONT biopsy them.
They can cause pulsatile tinnitus.
Inflammatory lesions of the Petrous apex (4)
Cholesterol Granuloma
Cholesteatoma
Apical petrositis.
Grandenigo syndrome
Cholesterol granuloma (7)
commonest primary petrous apex lesion.
Likely due to obstruction of the air cell, with repeated cycles of haemorrhage and inflammation, leading to expansion and bone remodelling.
Most common symptom is hearing loss.
CT: Margins sharply defined.
MRI: T1 and T2 bright, with T2 dark haemosiderin rim and faint peripheral enhancement.
No diffusion restriction.
Faster growing ones need surgery.
Cholesteatoma (4)
Epidermoid (ectopic epithelial tissue).
They are congenital in the petrous apex.
Slow growing, with bony change similar to cholesterol granuloma.
MRI is T1 DARK, T2 bright, restricts diffusion.
Apical petrositis (9)
Infection of petrous apex is a rare complication of infectious otomastoiditis.
Has complications if it progresses, including:
- osteomyelitis of skull base,
- ICA Vasospasm,
- subdural empyema,
- CVST,
- tempral lobe stroke and
- meningitis.
Can present as primary process in kids.
In adults, usually in setting of chronic otomastoiditis or recurrent mastoid surgery.
Grandenigo syndrome (5)
Complication of apical petrositis, when Dorello’s canal (CN 6) is involved.
Causes lateral rectus palsy.
Classic triad of:
- Otomastoiditis
- Face pain (trigeminal neuralgia)
- Lateral rectus palsy
Petrous apex tumours (2)
Endolymphatic sac tumour
Paraganglioma
Endolymphatic sac tumour (5)
rare tumour of the endolymphatic sac and duct.
Most are sporadic, but also associated with VHL.
Usually grow into the CPA.
Internal amorphous calcifications on CT.
T2 bright with intense enhancement.
Very vascular, often with flow voids and tumour blush on angiography.
Paraganglioma (5)
Paraganglioma of the jugular fossa (glomus jugulare or jugulotmypanic tumours) can invade the occupital bone and adjacent petrous apex.
Hereditary in 40%, with multiple tumours.
Most commonly presents with voice hoarseness, from vagal nerve compression.
Very vascular and enhance avidly with “salt and pepper” appearance on post contrast MRI with flow voids.
FDG avid.
Large vestibuar aqueduct syndrome (6)
Vestibular aqueduct is a bony canal that connects the vestibule (inner ear) with the endolymohatic sac.
When it’s enlarged (>1.5cm), associated with sensorineural hearing loss.
This syndrome associated with absence of bony modiolus in more than 90%.
Result of failure of endolymohatic sac to resorb endolymph, leading to endolymphatic hydrops and dilatation.
Commonest cause of congenital sensorineural hearing loss.
Usually bilateral.
Associated with cochlear deformity
Labyrinthitis (2)
Inflammation of the membranous labyrinth, most commonly due to viral infection.
Cochlea and semicircular canals enhance on T1 post contrast
Labyrinthitis Ossificans (3)
Sequella of prior infection, usually meningitis.
Seen in kids 2-18 months.
CT: ossification of the membranous labyrinth.
Causes sensorineural hearing loss.
Otosclerosis (5)
Bone becomes more lytic.
Usually the cause of conductive hearing loss in a female adult.
2 kinds:
Fenestral: Bony resorption anterior to the oval window, at the fussula ante fenestram. Of not addressed, the footplate will fuse to the oval window.
Retro-fenestral: more severe form which has progressed to have demineralisation around the cochlea. Usually has sensorineural component and is usually bilateral and symmetric
Otitis media (3)
Common childhood disease, effusion and infection of the middle ear.
More common in children and Downs (more horizontal eustachian tube).
Chronic if fluid persisting for >6 weeks.
Otitis media complications (5)
Coalescent mastoiditis - erosion of the mastoid space with or without intramastoid abscess.
Facial nerve palsy - Secodnary to inflammation of the tympanic segment
Dural sinus thrombosis - Adjacent inflammation may cause thrombophlebitis or thrombosis of the sinus. This itself leads to other complications (venous infarct, Otitic hydrocephalus due to poor CSF resorption)
Meningitis and labyrinthitis.
Cholesteatoma (3)
Exfoliated skin debris growing in the wrong place, creating a ball of inflammation which damages the temporal bone and ossicles.
2 parts to the eardrum, pars flaccida (flaccid) and pars tensa (more rigid, inferior).
A “hole” with some inflammation or infection involving the pars flaccida can cause a cholesteatoma.
Cholesteatoma order of destruction (3)
The scutum,
The ossicles (long process of incus)
The lateral segment of the semi-circular canal
Pars flaccida vs Pars tensa cholesteatoma (6)
Pars flaccida
- Acquired is more common, typically involving pars flaccida. Can grow into Prissak’s space.
- Scutum is eroded early, considered specific sign of acquired cholesteatoma.
- Malleus is displaced medially.
- Long process of incus is most common segment of ossicular chain to be eroded.
- Fistula to semi-circular canal most commonly involves lateral segment
Pars tensa
- Inner ear structures are involved earleir and more often.
- Less common than flaccida type
Labyrinthine fistula (3)
Complication of cholesteatoma, can also be congenital or iatrogenic.
Bony defect between the inner ear and tympanic cavity.
Lateral semicircular canal is most often involved.
Relevant anatomy for cholesteatoma (6)
Coronal view of temporal bone:
Tympanic membrane usually too thin to see on CT.
Prussak’s space: space between incus and the lateral temporal bone. Most common location of pars flaccida Cholesteatoma. Incus is most commonly eroded bone.
Scutum is the first bone eroded by pars flaccida cholesteatoma.
Axial view:
Lateral portion of semicircular canal, first part the cholesteatoma will invade if it invades the semicircular canal
Superior semicircular canal dehiscence (2)
Due to longstanding ICP.
Causes “noise induced vertigo” or “Tulio’s phenomenon”
Necrotising Otitis Externa (2)
Aggressive infection, causing swollen external auditory canal tissues, with small abscesses and adjacent bony destruction.
Usually diabetic. Usually pseudomonas.
Pagets of skull base (6)
Osteolysis - well defined large radiolucent region, favouring frontal and occipital bones.
Inner table is affected more than outer table.
“Osteolysis circumscripta”
Complications
- Deafness is most common.
- Cranial nerve paresis
- Basilar invagination
- Secondary (high grade) osteosarcoma
Facial nerve trivia (5)
Cisternal, canalicular and labyrinthine segments should NOT enhance. The remainder will enhance, due to the perineural venous plexus.
Abnormal enhancement caused by Bell’s Palsy, Lyme’s, Ramsay hunt and cancer
Commonly damaged by transverse temporal bone fractures, more than longitudinal
Chordoma and chondrosarcoma (3)
Can also affect skull base.
Chordoma is midline.
Chondrosarcoma is off midline
Fibrous dysplasia (4)
Ground glass lesion, usually in younger person (30s) rather than pagets (80s).
Classically fibrous dysplasia of the skull spares the otic capsule.
McCune Albright syndrome: Multifocal fibrous dysplasia, cafe-au-lait spots and precocious puberty.
Juvenile Nasal Angiofibroma (4)
Male teenager with nosebleeds. Obstruction is a common symptom.
Mass centered on the sphenopalatine foramen.
Expansion of the pterygopalatine fossa.
Very vascular, angiogram will blush.
Primary vascular supply from ascending pharyngeal artery and/or internal maxillary artery
Antrochoanal polyp (6)
Seen in 30-40s, with nasal congestion and obstructive symptoms.
Arises within the maxillary sinuses and passes through and enlarges the sinus ostium (or accessory ostium).
“Widening of the maxillary ostium”.
No associated bony enlargement of the sinus.
Polyp extends into the nasopharynx.
Basically a large inflammatory polyp with a thin stalk arising from the maxillary sinus.
Inverting papilloma (5)
Uncommon tumour with distinctive imaging features.
Classic location is lateral wall of the nasal cavity, most frequently related to the middle nasal turbinate.
Impaired maxillary drainage is expected.
Focal hyperostosis at the tumour origin.
MRI: “cerebriform pattern”, sort of looks like brain on T1 and T2.
10% harbour a squamous cell cancer.
Esthesioneuroblastoma (4)
Neuroblastoma of olfactory cells, starts at cribriform plate.
Classically dubbbell appearance, growth into the skull and down into sinuses, waist at the cribriform plate.
Often cysts in the mass.
Octreotide scan positive, as it’s neural crest origin.
Squamous cell/SNUC (6)
Squamous is the most common head and neck cancer.
Maxillary antrum is most common location.
Highly cellular, and therefore low on T2.
Relatively little enhancement compared to other sinus masses.
SNUC (undifferentiated squamous cell) is more aggressive version of regular squamous cell cancer. Massive and seen more in the ethmoid air cells.
Epistaxis (5)
Usually idiopathic, can be iatrogenic.
Most common location is anterior septal area (Kiesselbach plexus), but because these are anterior they tend to be easier to manually compress.
Posterior ones are less common but tend to be the ones that bleed uncontrollably and need angio.
Most cases are given a trial of nasal packing before IR.
Main supply to the posterior nose is the sphenopalatine artery (terminal internal maxillary artery), tends to be first target.
Variant anastamosis between ECA ad ophthalmic artery is important, don’t want to embolise the eye.
Floor of mouth dermoid/epidermoid (2)
“Sack of marbles” - fluid sac with globules of fat.
Typically midline
Ranula (4)
Mucous retention cyst.
Typically lateral.
Arise from sublingual gland/space.
“plunging” once it’s under the myelohyoid muscle.
Torus palatinus (3)
Normal variant. Bony exostosis that comes off hard palate in midline.
Classic Hx of dentures not staying in
Sialolithiasis (4)
Stones in salivary ducts.
Most comonly in the submandubilar gland (wharton’s).
Can lead to infection (Sialadenitis)
Chronic obstruction can lead to fatty atrophy of the gland.
Odontogenic infection (5)
Can be dental or peridontal in origin.
Infection is more common from an extracted tooth than an abscess involving intact tooth.
Attachment of the myelohyoid muscle to the myelohyoid ridge dictates spread of infection to the sublingual and submandibular spaces - above the myelohyoid line (anterior submandibular teeth) goes to sublingual space, below the myelohyoid line (second and third molars) goes to the submandibular space.
Odontogenic abscess is commonest masticator space “mass” in adults.
Ludwig’s angina (2)
Agressive cellulitis in the floor of the mouth, gas forming.
Most cases start with orthodontic infection.
Osteonecrosis of the mandible (3)
Related to prior radiation, licking radium paint brush, or bisphosphonate treatment.
Cancer (mouth) (3)
Squamous cell cancer is most common.
Older - smoking and drinking. Younger - HPV.
HPV related SCCs tend to present with large, necrotic, level 2a nodes (NOT a brachial cleft cyst).
Thyroglossal duct cyst (3)
Can occur anywhere between the foramen cecum (base of tongue) and thyroid gland.
Usually found in midline at or above the hyoid.
Looks like thin walled cyst.
Thyroid anatomy (4)
Butterfly shaped gland with 2 lobes, connected by an isthmus.
Descends from the foramen cecum at anterior midline base of the tongue, along the thyroglossal duct.
Posterior nodular extension of the thyroid (Zuckerkandl tubercle) helps give a location of the recurrent laryngeal nerve (medial to it)
Thyroid nodules (4)
Usually seen on US. Very common and almost never cancer.
Suspicious features
- more solid
- calcifications (microcalcifications are a buzzword for papillary thyroid cancer)
Comet tail artefact is seen in colloid nodules.
Cold nodules on I-123 scans are 15% malignancy risk.
Thyroglossal duct cyst (5)
Can occur anywhere between foramen cecum (base of tongue) and the thyroid gland.
They are usually found in the midline at above the hyoid.
Looks like a thin walled cyst.
Can get infected.
Can rarely have a papillary thyroid cancer (if you cancer (if you see an enhancing nodule)
Ectopic and lingual thyroid (5)
Similar to thyroglossal duct cyst, found anywhere from base of tongue to central neck.
Most common location (90%) is the tongue base (lingual thryroid).
Looks hyperdense due to iodine content (just like normal thyroid gland).
Sometimes the actual thyroid can be absent.
3% risk of malignant transformation.
Goitre (4)
Thyroid is too big.
Low iodine in developing world, multinodular goitre or graves in the West.
Can compress the oesophagus or trachea.
Often asymmetric, one lobe bigger than the other
Graves (5)
Autoimmune disease causing hyperthyroidism (most common cause in West).
Primary from an antibody directed at the TSH receptor.
Actual TSH level is low.
Gland will be enlarged and hot on doppler.
- Graves orbitopathy: Spares tendon insertions, doesn’t hurt unlike pseudotumour. Increased intra-orbital fat.
- Nuclear medicine: Increased uptake of I-123 by usually 50-80%. Visualisation of pyramidal lobe is accentuated.
