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This is a patient who had congenital

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conductive hearing loss.

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And when the ENT physician was

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looking through the ear,

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they saw that there was an obstruction

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in the external auditory canal.

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So as we scroll through the case,

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we identified a deformed appearance of the

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cartilaginous portion of the external auditory canal.

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And we have a very unusual appearance to this

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external ear without the normal appearance of

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the bowl and the helix of the external ear.

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So this would be characterized as microtia.

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And then we have an anomalous development

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of the external auditory canal.

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The external auditory canal has a membranous occlusion

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here at the entrance to what would be the bony

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portion of the external auditory canal.

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You notice that the air cell of the mastoid has

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assumed some of the location of what would

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normally be the external auditory canal.

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So if we try to identify the tympanic membrane,

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we're not able to do so.

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And we come to the level of

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the middle ear ossicles.

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So let me just identify the anatomy here.

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So we have this deformed ear,

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external ear.

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We have absence of an external auditory canal,

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but we have the expansion of the mastoid air cells

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into that space where normally you would

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have the bony external auditory canal.

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Coming more immediately,

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we see something that is identified

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as that ossicular mass,

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and that is a fused bony malleus and incus,

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both of which are developed from the first

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branchial apparatus, first branchial cleft.

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And this looks pretty abnormal.

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It's a funny shape, kind of triangular in shape.

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And we want to look for the other middle ear

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ossicles that includes the long

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process of the incus,

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which is in part developed from the second

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branchial apparatus and the stapes.

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So let's scroll down a little bit further here.

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And we're coming to something that... I'm going

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to try to magnify this a little bit more.

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And

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I think the windowing... I'll make it

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a little bit brighter. Okay,

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so here we have a very unusual appearance

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to the incudostapedial joint.

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I think most people would be comfortable with

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identifying this as the posterior crus of the

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stapes, and this being the anterior crus

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of the stapes.

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And

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here we have the incudostapedial joint,

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from what should be the long process of the

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incus to the capitulum of the stapes.

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Well,

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this looks like a very unusual

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long process of the incus.

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This doesn't look like our normal two parallel

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dots going down and leading to

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the incudostapedial joint. Nonetheless,

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the stapes looks normal.

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So a good example of how there is a

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differentiation between the development of

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the first branchial apparatus structures,

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the malleus and incus,

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versus the second branchial apparatus structures,

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which are the stapes and long process of incus.

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So the stapes inserts here on the vestibule

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in the oval window and that looks normal.

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We have a capacious space for them to

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reconstruct the middle ear ossicles.

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So we're going to comment on that.

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We're going to look at the inner ear structures.

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We have a normal aperture to

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the cochlea, and we have

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middle and apical turns.

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This is the basal turn of the cochlea.

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We have the round window here,

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which is appropriate.

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And we have a vestibule with semicircular canals

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that appear appropriate.

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We want to check the carotid artery,

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and make sure it doesn't extend into

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the middle ear cavity. It does not.

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We have a normal internal auditory canal,

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and we have a normal jugular foramen.

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So the vascular structures look good.

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The middle ear structures,

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we've described that we have an ossicular mass

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and problems with the malleus and incus,

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but a good stapes.

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We have good inner ear structures.

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The one thing that I haven't mentioned,

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that I should mention, is the facial nerve.

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So this is an interesting case because if we

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look at the anatomy of the facial nerve,

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we remember that there is an intracanalicular

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portion in the internal auditory canal.

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We have the labyrinthine portion,

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which is proximal to the geniculate ganglion.

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So this is the pre-ganglionic labyrinthine portion

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of the facial nerve in the fallopian canal.

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We have a tympanic portion of the

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facial nerve coming across.

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But the location of this facial nerve

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is further anterior than typical.

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So it should be back in this location,

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posteriorly located by the sinus tympani.

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Instead, it's anteriorly located, and you can see

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the proximity of this facial nerve to the middle

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ear ossicular mass. So as they are

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working here to reconstruct ossicles in a

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partial ossicular replacement prosthesis,

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they have to be very careful that

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they don't stray. Well,

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let's see how far could they be straying?

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If we just measure from here to here,

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we find that that's 1 mm.

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So 1 mm away from where they're working to

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reconstruct the ossicles is an anteriorly

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located facial nerve.

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And this descending portion of the facial nerve

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which comes out the stylomastoid foramen

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is anteriorly located in its entire course.

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So an important imaging finding that would be

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added to the description of the

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external auditory canal,

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membranous stenosis and atresia

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and ossicular anomaly.

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I'm just going to slide over briefly to show the

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contralateral side when I drop that down here, and

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here you see the normal cartilaginous portion

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of the external auditory canal,

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bony portion of the external auditory canal.

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Probably magnify this a little bit.

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And

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the normal

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ice cream and ice cream cone

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of the middle ear ossicles,

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the parallel dots of the neck of the malleus and

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long process of the incus extending to the

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incudostapedial joint, which is faintly seen here.

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And the normal middle inner ear structures.

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And if I can follow it,

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you can see how far more posteriorly located the

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normal facial nerve is on the right side compared

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to the anomalous anterior placement

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of the left facial nerve.