Skull base/Temporal bones Flashcards
Which structures go through:
- Foramen ovale
- Vidian canal
- Foramen spinosum
- Foramen rotundum
- Inferior orbital fissure
- V3
- Vidian artery and nerve
- Middle meningeal artery
- V2
- Infraorbital artery/nerve
Imaging findings JNA
Benign, vascular, locally aggressive; adolescent M
Classic findings: Mass with avid enhancement, originates at medial aspect of pterygopalatine fossa causing expansion of fossa, ant bowing/displacement of post wall of maxillary sinus
Most common intracranial lesion to affect anterior skull base
Olfactory groove meningioma
Imaging findings enthesioneuroblastoma
Olfactory neuroblastoma
Bimodal age
Aggressive mass, slight hyper on CT, iso T1/T2, may have calcs, characteristic peripheral cysts in intracranial portion
Most common malignant neoplasms of paranasal sinuses and nose
SCC - mastoid antrum most common paranasal sinuses -avidly enhancing, destructive
DDx for soft tissue in external auditory canal
Narrowed EAC
- Congenital stenosis/hypoplasia
- Surfer’s ear (EAC exostosis)
Normal/enlarged caliber EAC
- Acute otitis externa
- Malignant otitis externa
- Cholesteatoma (more common in middle ear)
- SCC
- Keratosis obturans
Clinical and imaging findings of glomus tympanicum
Extra-adrenal pheo (paraganglioma)
Most common primary middle ear tumour
Red mass behind TM, pulsatile tinnitus and conductive hearing loss
Enhancing post contrast, +/- bony/ossicle destruction
Imaging findings and most common location of facial nerve schwannoma
Expansion of facial nerve canal, brisk enhancement
Geniculate>tympanic>labyrinthine
DDx middle ear lesions
Glomus tympanicum (most common) - red mass Cholesteatoma - white mass Cholesterol granuloma (cholesterol cyst) - blue mass
Imaging findings cholesteatoma
Extra-cranial epidermoid, most commonly middle ear
Acquired (98%) versus congenital
Soft tissue mass, blunting of sputum, erosion of ossicles
Signal same as intracranial mermaids - diffusion destruction, no enhancement
Most common form of cochlear dysplasia
Mondini deformity - incomplete development of normal two and half turns of cochlea (middle and apical segments are fused)
Incomplete partition type II
Sensorineural hearing loss
also see enlarged vestibule and vestibular aqueduct
What is Michel aplasia?
Complete lack of development of entire inner ear
Ddx cochlear demineralization
Retrofenestral otospongiosis, OI, fibrous dysplasia, Paget’s disease
Imaging findings in otosclerosis
Primary osteodystrophy of the otic capsule
Increased lucency primary feature
One of leading causes of deafness in adults - can result in both conductive and sensorineural hearing loss
2 subtypes: fenestral (more common) and retrofenestral
DDx for petrous apex lesion
ACGME’S MC
- Apical petrositis
- Congenital cholesteatoma
- Granuloma
- Meningioma
- EG
- Schwanomma
- Mets/Myeloma
- Chordoma/Chondrosarcoma (arise from clivus, extending into petrous apex)
