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Let's discuss some of the congenital lesions that

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may affect the external auditory canal.

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In addition to microtia,

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which is a small external ear,

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one can have external auditory canal atresias, and

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these may occur in concert with each other.

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Stenosis of the external auditory

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canal can also occur,

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but it doesn't occur as frequently as full

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atresia of the external auditory canal.

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That said,

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microtia with deformity of the external ear helix

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is more common than external

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auditory canal atresia,

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which is more common than external

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auditory canal stenosis.

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Because this is secondary to an

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injury that occurs in utero,

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it's frequent that you see bilateral abnormalities

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when one has external auditory

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canal atresia at around 30%.

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In addition,

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one will also frequently see middle ear ossicular

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anomalies associated with either microtia or

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external auditory canal atresia or stenosis.

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And this is because that remnant,

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that embryologic origin of the external auditory

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canal, is the first branchial apparatus.

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And the first branchial apparatus also leads to

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development or creation of the

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malleus and the incus.

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So having malleus and incus middle ear ossicular

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anomalies in association with external auditory

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canal atresia occurs in about 50%.

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Although its origin is from the otic placode

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and not from the branchial apparatus,

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inner ear anomalies can occur in about 20% of

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patients with external auditory canal atresia

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because that ischemic phenomenon or drug-related

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phenomenon that led to an injury to the

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branchial apparatus can also lead to injury

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to the otic pit and otic placode,

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which develop the inner ear structures.

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When we're looking at external

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auditory canal atresia,

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we want to be cognizant at all times of the

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position of the carotid artery

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and the facial nerve,

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and that is because they may be malpositioned as

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well due to the deformity of the bony anatomy.

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And identifying if they are displaced or in an

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unusual location will be something that will be

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helpful to the surgeons in avoiding the potential

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for hitting the carotid artery when they're

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doing surgery to correct the atresia.

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Or the same is true with the facial nerve,

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because having a facial nerve palsy

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during the correction or after the correction of

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the external auditory canal atresia would be

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something that would be quite

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deforming to the patient.

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And then we're also talking a little bit about

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branchial cleft cysts. And again,

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in the setting of external

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auditory canal pathology,

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we're usually dealing with the

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first branchial cleft cyst.

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Here we have an axial scan of a patient who has

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external auditory canal atresia bilaterally.

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And what one notices is the deformity on

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the left side of the external ear.

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So this does not look like normal ear

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cartilage sticking out there.

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This is a more normal appearance.

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And here we have something that looks a little

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bit like a nub of tissue. Again,

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we would call this microtia,

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which is associated with the absence

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of an external auditory canal.

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So this patient has bony external auditory canal

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atresia bilaterally and on the left side has an

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association with that external ear microtia.

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Now, as I mentioned,

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whenever we're looking at external

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auditory canal atresia,

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we also look at the middle ear cavity

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in order to identify ossicular anomalies.

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And what you are seeing again on the left side is

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the absence of the normal anatomy of the head of

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the malleus and the short process of the incus,

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the ice cfeam and the ice cream cone.

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We see that normal anatomy on the right side.

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So even though this patient has external

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auditory canal atresia on the right,

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the middle ear ossicles look more normal.

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Whereas on the left side, we got something that

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kind of looks like a diamond due to this

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ossicular abnormality in association with

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external auditory canal atresia.

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The term that we sometimes will use,

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and I guess it's not the best term,

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is that this is the ossicular mass.

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By that, we mean not normal ossicular anatomy but

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just a kind of clumping of ossified

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tissue that represents the ossicles.

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So the ossicular mass in association with

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external auditory canal atresia.

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The external auditory canal atresia may affect

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both the cartilaginous and the bony portion.

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We're usually referring to the bony portion, and

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it may be a soft tissue membranous occlusion

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or it can be a bony occlusion.

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As I mentioned,

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it is bilateral in around 30% of cases.

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When you look at all comers,

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the right side is usually affected more commonly

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than the left side. Because this is an obstruction

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rather than an abnormality of the sensory organ

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that is the cochlea or the vestibule,

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this presents with a conductive hearing loss

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rather than a sensorineural hearing loss.

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However, as I mentioned,

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about 20% of the time, the patient may have a

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coexistent problem with the inner ear in which

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case you may have a mixed both conductive, as well

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as sensorineural hearing loss.

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So we're going to talk about the congenital

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external auditory canal stenosis as well.

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This is narrowing of the external auditory canal,

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but it still has an opening as opposed to atresia.

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If we compare these two cases,

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we see that the patient has a wide right external

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auditory canal but a narrowed left

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external auditory canal.

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So here is the normal side on the right side with

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a normal caliber external auditory canal.

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And when we compare it with the left side,

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we see it has a decreased caliber.

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So this is external auditory canal stenosis, and

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external auditory canal stenosis may be associated

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with an increased risk of cerumen impaction

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because of that narrowing and the

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inability to clear the cerumen.

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The other soft tissue abnormality that may

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occur in the external canal in association

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with stenosis is an epidermoid.

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I use the term epidermoid in the description of the

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pathology,

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which some people call a congenital cholesteatoma.

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So I generally reserve the term cholesteatoma for

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the acquired abnormality that occurs in the middle

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ear cavity in association with tympanic membrane

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perforation and ingrowth of squamous epithelium.

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I use the term epidermoid,

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which is a congenital lesion,

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just like it is in the brain for those white

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structures that are occurring

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on a congenital basis.

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So some people will use the term cholesteatoma

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both for the congenital lesion, as well as the

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acquired lesion to keep them separated.

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I recommend using cholesteatoma when referring

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to the inflammatory process,

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whereas epidermoid is probably a better

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term for the congenital process.

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This image below is important to

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identify that this patient has

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external auditory canal atresia.

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So the differentiation between stenosis

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versus no opening at all, the atresia,

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and also to point out that the temporomandibular

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joint is in close approximation

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to the external auditory canal.

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And because the temporomandibular joint is

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part developed from branchial

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apparatus one tissue,

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it may also be deformed in external

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auditory canal atresia.

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So look at the TMJ and evaluate it in all cases

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of external canal stenosis or atresia.

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Here we have a coronal view.

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And on the right side, you're able to see the

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external auditory canal and the middle ear cavity.

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On the left side,

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you're missing the external auditory canal.

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So, no external auditory canal here.

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And in addition, you have something that is, again,

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an ossicular mass.

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So that's the fusion of the ossicles.

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And it is fairly common for this ossicular mass to

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be fused to the lateral wall of the attic

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of the middle ear cavity.

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So this connection to the lateral wall of the

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middle ear cavity is fairly typical of the middle

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ear ossicles in association with external

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auditory canal atresia. Below

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we're just seeing again ossicular mass, ossicular mass,

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not the normal anatomy of articulating

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middle ear ossicles.

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This patient has a deformity with calcification

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also of the pinna of the ear.