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149 Cards in this Set
- Front
- Back
A-antrum
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What is the antrum
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The antrum is a large aircell superior and posterior to the tympanic cavity and connected to the tympanic cavity via the aditus ad antrum.
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What are the relationship of the bones of the middle ear
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What does the aditus ad antrum connect
Short cus of the incus |
the antrum to the tympanic cavity
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Note that the jugular bulb and the carotid come into view inferiorly on the axial view. Also note that the auditory canal is anterior seen in this inferior view.
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Note that the jugular bulb and the carotid come into view inferiorly on the axial view. It runs just anterior to the carotid.
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Where is the utricle in relation to the semicircular canals and the cochlea
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Coronal
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Anterior to posterior
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yellow arrow- scutum (sharp bony spur)
orange arrow- head of malleous (medial to the incus at this point) green arrow- incus |
I-incus
H-head of malleous (Note that although the malleous attaches to the eardrum a portion of it is lateral to the incus which runs laterally to the stapes) |
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green-incus
orange-malleous white-geniculate ganglion (facial nerve) NOTE: the superior relationship of the geniculate and facial nerve to the cochlea |
blue-stapes
white-facial nerve in the IAC and tympanic segment NOTE: facial nerves is traveling in 2 directions in this pic...first the part in the IAC is traveling around the cochlea and then bends (geniculate) around the cochlea and comes back towards us |
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Blue lines- superior and lateral semicircular canal
blue arrow-stapes white arrow- facial nerve above oval window and below the semicircular canal green-posterior portion of maleous |
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white arrows- vertical trajectory of the facial nerve
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d
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What are the 2 fractures of the temporal bone
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longitudinal and horizontal
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What is the best way to visualize these fractures
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on coronal views
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Longitudinal (axial image)
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Transverse (axial image)
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What is typically fractured in a longitudinal fracture of the temporal bone
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the middle ear
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What is typically fractured in a transverse fracture of the temporal bone
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inner ear
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What is more common a transverse or longitudinal fracture of the temporal boen
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longitudinal (80%)
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Many temporal bone fractures are neither longitudinal nor transverse and a comprehensive description of the structures which are crossed by the fracture is needed.
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yes
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What are the causes of conductive hearing loss
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typanic membrane rupture, hemotypanum or ossicle damage
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Which type of T-bone fractures typically involve the facial nerve
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Longitudinal (20%)
Transverse (50%) |
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What are the symptoms of a transverse fracture (inner ear fracture)
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vertigo, sensorineural hearing loss
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What are the complications of t-bone fractures
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ossicular fracture/dislocation
tympanic membrane perforation hemotympanum CN 7 paralysis CSF otorhea meninigitis sinus thrombosis labyrinthitis ossificans |
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What are the labrinyths
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the part of the ear that house the vestibular system.
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What are indications for surgery in temporal bone fractures
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ossicular dislocations
decompression of facial nerves labyrinthine fistula CSF leaks |
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How is a diagnoses of mastoiditis made
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bony destruction and fluid filled mastoid aircells
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How is a diagnosis of otitis media confirmed
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edema fills the middle ear cavity (typmanic cavity)
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What are 3 types of labryinthitis
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serous, toxic, supporative
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What are potential complications of otitis media, mastoiditis, labryinthitis
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meningitis
sinus thrombosis epidural abscess petrositis (inflammation of petrous aircells) |
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What is seen in bells palsy in on MRI
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MRI there is enhancement along facial nerve involving
intracanalicular and labyrinthine segments of the facial nerve that normally do not enhance in normal individuals |
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What part of the facial nerve normally enhance on MRI
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Facial nerve can normally enhance in its tympanic and mastoid segments
due to right arterial supply |
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What should always be ruled out in a pt with bells palsy
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perineuronal spread of tumor
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What are 2 forms of mastoiditis
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uncomplicated and complicated
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What is seen in the complicated form of mastoiditis
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edema and fluid only
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What is seen in complicated form of mastoiditis
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Bone demineralization
Coalescent mastoiditis (cell breakdown) Thrombophlebitis Bezold's abscess Gradenigo's syndrome (petrositis) Sigmoid sinus thrombosis Epidural/ Subdural empyema Meningitis Focal encephalitis, brain abscess, otitic hydrocephalus |
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What is thrombophlebitis
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swelling and edema of a vein caused by a blood clot
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What is a Bezold Abscess
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an abscess in the sternocleidomastoid muscle where pus from a mastoiditis escapes into the sternocleidomastoid.
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What is gradenigo syndrome
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this is inflammation involveing the apex of the petrous bone
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What are S/S of gradenigo syndrome
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retroorbital pain due to pain in the area supplied by the ophthalmic branch of the trigeminal nerve (fifth cranial nerve),
ipsilateral paralysis of the abducens nerve (sixth cranial nerve), and otitis media. |
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What are the 5 sections of the temporal bone
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mastoid, petrous, squamous, tympanic, styloid
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What are the components of the middle ear
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the epitypanum, mesotympanum, hypotympanum
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anterior (a) and posterior (b) crura of the superior semicircular canal. The surrounding otic capsule is observed as dense white bone. The mastoid air cells (c) are lateral to the otic capsule. The squamous air cells are separated from the petrous air cells by the Koerner septum (d). The posterior margin of the temporal bone, or cerebellar plate, (e) forms the anterior margin of the posterior cranial fossa.
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The anterior limb of the superior semicircular canal can be observed (a). Posteriorly, the posterior limb of the superior semicircular canal forms the crus commune (b) by joining with the posterior semicircular canal (c). The mastoid air cells (d) and cerebellar plate again are visible.
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The sigmoid sinus indents the cerebellar plate posteriorly (a). More inferiorly, the sigmoid sinus forms the origin of the internal jugular vein inferiorly. The vestibular aqueduct (b) courses posterior to the posterior semicircular canal (c) and the more anteriorly located superior semicircular canal (d). The superior aspect of the lateral semicircular canal (e) is located lateral to the other semicircular canals. The most superior portion of the internal auditory canal (f), carrying the facial, cochlear, and superior and inferior vestibular nerves, is the lucency in the medial of the petrous bone
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An axial section through the vestibule (a) and lateral semicircular canal (b). The posterior semicircular canal (c) and vestibular aqueduct (d) still are visible posteriorly. The vestibular aqueduct is passing from the endolymphatic sac (e), which indents the posterior margin of the petrous bone, towards the vestibule. Posteriorly and laterally, the sigmoid sinus (f) is visible, and medially, the internal auditory canal (g) is the indentation on the medial border of the petrous bone. Note the middle ear space superior to the uppermost aspect of the tympanic membrane, the epitympanum, which houses the head of the malleus, as well as the body and short process of the incus (h). The petrous apex is visible (i).
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The facial nerve can be observed coursing from the internal auditory canal (a). From here, the facial nerve turns anteriorly as the labyrinthine segment (b). This segment ends at the geniculate ganglion anteriorly (c). The nerve then continues posteriorly as the tympanic segment (d). The section passes through the vestibule, horizontal semicircular canal, and posterior semicircular canal. In addition, the image better depicts the head of the malleus (e) and the incus (f).
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The basal turn of the cochlea (a) is demonstrated. The geniculate ganglion (b) and tympanic branch of the facial nerve (c) also are well visualized. The vestibule (d), internal auditory canal (e), and ossicles (f) are visible.
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The pyramidal eminence (a), which gives rise to the stapedius tendon, is shown. The space between the medial wall of the tympanum and the pyramidal eminence is the sinus tympani. The external auditory canal (b) and the tympanic membrane (c) are located laterally. The tensor tympani, which runs along the eustachian tube and attaches to the neck of the malleus, is visible anteriorly (d). Finally, the round window niche is observed (e).
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Continuing inferiorly, the superior aspect of the jugular bulb (a) is demonstrated. The carotid artery is located more anteriorly (b). Immediately anterolateral to the course of the carotid is the eustachian tube (c). The tensor tympani muscle shares a wall of the eustachian tube (d).
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Some of the inferior-most structures in the temporal bone. The glenoid fossa (a) is observed anteriorly. The carotid artery (b) courses medially and anteriorly. The sigmoid sinuses flow into the jugular vein (c). Anteromedial to the carotid, the sphenoid sinus is observed (d)
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Coronal section through the anterior temporal bone demonstrates the carotid artery (a) near the basal turn of the cochlea (b). The head of the malleus (c) lies in the epitympanum. The mastoid air cells can be observed superiorly and laterally to the superior margin of the glenoid fossa (d), and the supralabyrinthine air cells (e) can be observed superior to the otic capsule. The middle ear space is separated from the middle cranial fossa (f) by the tegmen tympani (g). To help orientation, note the condyle of the mandible inferior to the glenoid fossa (d).
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The carotid artery (a) and the cochlea (b) are shown. The labyrinthine (c) and tympanic (d) portions of the facial nerve are visible. The middle ear space extends quite inferiorly, creating the hypotympanum (e). This section passes through the ossicles in the epitympanum
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. This section demonstrates the internal auditory canal (a), the tensor tympani muscle (b), and the tympanic portion of the facial nerve (c).
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The facial nerve (a) courses just inferior to the lateral semicircular canal (b). The apex of the superior semicircular canal (c) is observed. Laterally, the ossicles are visible (d). The lateral boundary of the epitympanum is the scutum (e), which is a clinically important landmark because erosion of the scutum is often observed in patients with cholesteatoma.
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This section passes through the posterior semicircular canal (a). The tegmen tympani is well outlined (b). A short segment of the vestibular aqueduct is visible (c).
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What are the 3 components of the the middle ear
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What are the 5 portions of the temporal bone
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Mastoid (mastoid process: insertion for
sternocleidomastoid muscle) Petrous portion (inner ear structures, skull base) 0 Squamous portion (lateral inferior skull) Tympanic portion styloid portion |
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What does the stapes attach to
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the oval window
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What is the function of the round window
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counterpulsation of the fluid
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What does bills bar divide
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What does the falciform crest divide
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What does the falciform crest divide
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Where are the cranial nerves that enter the IAC located
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left is anterior
right is posterior the cochlea part is bottom left superior vestibular is upper right inferior vestibular is bottom right |
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What 3 structures may be mistaken for a fx line in the temporal bone
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Petromastoid (subarcuate) canal
Cochlear aqueduct Cochlear cleft |
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What is the usual cause of fx of the inner ear and through the facial nerve
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transverse (it can occur with longitudinal but this is usually middle iear)
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What are 3 variants which may simulate disease
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Cochlear cleft (otosclerosis)
Petromastoid canal (fracture) Cochlear aqueduct (fracture) |
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What are 2 variants which may cause problems during surgery
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High jugular bulb or jugular bulb diverticulum
Bulging sigmoid sinus |
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What does a cochlea cleft look like
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What does the petromastoid canal look like
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THIS IS AN AXIAL VIEW AT A SUPERIOR SLICE
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Compare this to the previous slide and now it is difficult to see the petromastoid canal, but notice the variation in pneumatization of the petrous ridge.
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Is the jugular bulb usually asymmetric
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yes, the jugular bulb is often asymmetric, with the right jugular bulb usually being larger than the left.
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When is the jugular bulb considered a high riding jugular bulb
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If it reaches above the posterior semicircular canal it is called a high jugular bulb.
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High riding jugular bulb on axial
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the jugular bulb is above the posterior semicircular canal which is the linear structure just to the right
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What is another normal variant that may be found when examining the jugular bulb
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What is a bulging sigmoid sinus
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THIS PT IS SP MASTOIDECTOMY
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What is the vestibular aqueduct
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The vestibular aqueduct is a narrow bony canal (aqueduct) that connects the endolymphatic sac with the inner ear (vestibule).
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What are the 3 canals we have discussed
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the petromastoid canal (superiorly)
The cochlea aqueduct (below the petromastoid canal) Vestibular aqueduct (most posteiorly) |
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What is more anterior the cochlea or the the vestibule of the semicircular canal
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cochlea
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What tube runs through the vestibular aqueduct
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Running through this bony canal is a tube called the endolymphatic duct.
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What is a congenital abnormality that occurs to the vestibular aqueduct
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enlargement
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What does an enlarged vestibular aqueduct look like
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What is an enlarged vestibular aqueduct associated with
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progressive sensineuronal hearing loss
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What is an enlarged vestibular aqueduct associate with
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The large vestibular aqueduct is associated with an absence of the bony modiolus in more than 90% of patients.
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What is the modiolus
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a central column of bone around which the cochlea twists
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What does the modiolus of the cochlea look like
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What is a second congenital anomaly of the temporal bone
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external auditory canal atresia
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What is the result of external auditory canal atresia
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A conductive hearing loss is the result.
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What are 2 tissues that may fill the cavity
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soft tissue or bone
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Is this assoicated with middle ear malfornations
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yes, ossicular chain malformation can vary from a fusion of the mallear head and incudal body to a small clump of malformed ossicles, which is often fused to the wall of the tympanic cavity.
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What is very important to note if a patient has external auditory canal atresia
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the position of the facial nerve because the mastoid portion of the facial nerve canal can be located more anteriorly than normal and this is important to report to the ENT surgeon in order to avoid iatrogenic injury to the nerve during surgery.
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What are the first 2 deformities we have discussed
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enlarged vestibular canal and atretic exeternal auditory canal
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What happens is there is early arrest in formation of the cochlea
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Early developmental arrest leads to an inner ear that consists of a small cyst, the so-called Michel deformity.
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What is a mondini malformation of the cochlea
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An incomplete partition of the cochlea is called a Mondini malformation
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What do you typically see in a Mondini malformation
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Instead of the normal two-and-one-half turns, there is only a normal basal turn and a cystic apex.
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What is the MC malformed semicircular canal
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the lateral
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What type of anomalies tend to happen to the semicircular canals
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Malformations of the vestibule and semicircular canals vary from a common cavity to all these structures to a hypoplastic lateral semicircular canal.
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What is an important difference between chronic otitis media and cholesteatoma
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bony erosion which occurs much more commonly in cholesteatoma
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In addition to bony erosion what also occurs in cholesteatoma
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displacement of the ossicle chain and may present as a non-dependent mass
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What does chronic ottitis media often look demonstrate
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chronic otitis shows thickened mucosal lining
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Why is it difficult to differentiate cholesteatoma and ottitis sometimes
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both diseases the middle ear cavity can be completely opacified, obscuring a cholesteatoma
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Can the mastoid have a very variable appearance
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yes
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What does tympanosclerosis look like
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this is calcification on the tympanic membrane
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Are most cholesteatomas acquired or congenital
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acquired
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What happens to a cholesteatoma over time
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it gets bigger
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What 3 structures are affected by a cholesteatoma
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Auditory ossicles, especially the long process and lenticular processes of the incus as well as the head of the stapes
Wall of the lateral semicircular canal Lateral epitympanic wall (the scutum) |
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Can a cholesteatoma erode the scutum
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yes
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What are the 2 patterns of cholesteatoma
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pars flacida cholesteatoma
pars tensa cholesteatoma |
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Where is a pars flaccida cholesteatoma arise
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The lesion starts anterosuperiorly in 'Prussaks space', the area just below the scutum, which is limited by the tympanic membrane, the malleus, and the lateral ligament of the malleus.
A cholesteatoma will then extend laterally towards the ossicular chain and into the epitympanum. |
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Where is a pars tensa cholesteatoma located
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The cholesteatoma begins posterosuperiorly and extends posteriorly towards the facial recess and tympanic sinus, and medially towards the ossicular chain.
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Is a pars flaccida anterosuperior in prussaks space and a pars tensa posterior superior
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yes, notice alphabetical (flaccida and tensa--> ant-->post)
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What are the radiographic findings of a cholesteatoma
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-soft tissue mass in the middle ear (especially if non-dependent or in prussaks space)
-Bony erosion (especially the scutum, tegmen tympani, long process of the incus and stapes) |
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Can a pars tensa erode the wall of the facial nerve
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yes, but erosion of the facial nerve canal is difficult to distinguish because the wall is often so thin that it is not visible at CT
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What type of cholesteoma tends to cause lateral displacement of the ossicular chain
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pars tensa (it occurs medially and pushes laterally)
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Are the pars tensa type of cholesteatoma usually aquired
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yes
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Is the scutum intact in pars tensa
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yes
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What is the signal intensity of a cholesteatoma on T1
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mixed
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What is the signal intensity of a cholesteatoma on T2
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high signal
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What are the T1 and T2 signal characteristics of a cholesteatoma
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T1 mixed
T2 high DWI- restricted |
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Do cholesteatomas demonstrate restricted diffusion
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yes
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What do you particularly want to evaluate in a patient with a cholesteatoma
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the extensiion of cholesteatoma. MRI is particularly useful for evaluating the extension of a cholesteatoma into the middle and/or posterior fossa
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What is otosclerosis
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Otosclerosis is a genetically mediated metabolic bone disease of unknown etiology.
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What is another name for otosclerosis
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otospongiosis
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What does the stapes touch
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the oval window which transmits sound to the vestibule
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What happens when otosclerosis involves the oval window
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When this process involves the oval window in the region of the footplate, the footplate becomes fixed, resulting in conductive hearing loss.
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What is the hallmark of otosclerosis
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Conductive hearing loss develops early in the third decade and is considered to be the hallmark of the disease.
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Where does otosclerosis typically begin
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he process starts in the region of the oval window, classically at the fissula ante fenestram, i.e. in front of the oval window (fenestral otosclerosis). This is a small lucency in the oval window.
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Why does conductive hearing loss occur in otosclerosis
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When this process involves the oval window in the region of the footplate, the footplate becomes fixed, resulting in conductive hearing loss
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Can otosclerosis also occur around the cochlea
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yes
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What makes detection of otosclerosis difficult sometimes
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it is bilateral and can be symmetric
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What do you see in an a patient with otosclerosis
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besides sclerosis you may see 'otospongiotic' foci. This is at the lucency at the fissula ante fenestram. Also spongiotic bone around the cochlea.
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What is lucency look like in otosclerosis
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What does a normal incudomalleolar joint look like
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ice cream cone.
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What are 2 clinical signs of vascular anomaly of the T-bone
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tinnitus
reddish mass behind ear |
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What are the vascular anomalies that are found in the T-bone
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Aberrant internal carotid artery
Dehiscent jugular bulb |
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What vascular anomaly can manifest as a retrotypamic mass
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glomus tumor
cholesterol granuloma |
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What does the ascending pharngeal artery branch off of
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the external carotid artery
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What is usually abscent in patietns with an aberrant
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In patients with an aberrant internal carotid artery the cervical part of the internal carotid artery is absent.
It is replaced by the ascending pharyngeal artery which connects with the horizontal part of the internal carotid artery. It courses through the middle ear. |
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What does an abberant ICA look like
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Why is it important for the clinician to know about a dehiscent jugular bulb
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if the patient has surgery this can result in complications
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What does a dehiscent jugular bulb look like
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Are tumors of the temporal bone common
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no
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What are the tumors of the temporal bone
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Exostoses
External auditory canal carcinomas Glomus tumor Adenoma Congenital cholesteatoma EndoLymphatic Sac Tumor (ELST) |
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What does exostoses of the auditory canal look like
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What does a glomus tumor of the middle ear look like
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What are the MR signal characteristics of a glomus tympanicum
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What does an enlarged endolymphatic sac look like
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