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When you are evaluating a patient with external

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auditory canal stenosis or atresia who is

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being considered for reconstruction,

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it's important to have a little bit of a checklist,

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if you will,

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of important structures that you want to mention as

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far as whether they are normal or abnormal

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or displaced. So, as I mentioned,

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because there is a 20% rate at which there are inner

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ear anomalies associated with

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external auditory canal atresia,

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you want to comment specifically about the presence of

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a normal appearance of the cochlea

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vestibule and vestibular aqueduct.

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The reason for that is that if they are reconstructing

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the external auditory canal to improve hearing,

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and yet the patient has an abnormal cochlea or

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doesn't have a cochlear nerve, for example,

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that would be of absolutely no benefit.

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They might still do the procedure for cosmetic

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reasons, particularly if the patient has microtia.

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But as far as trying to have a hearing ear on

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that side, it wouldn't make very much sense.

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The next structure is the stapes.

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Remember that I said for the first branchial

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apparatus, the malleus and the incus are developed.

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The stapes is not developed from

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the first branchial apparatus.

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It's actually developed from the second branchial

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apparatus. So you want to identify a normal stapes.

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If you don't have a normal stapes,

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then reconstructing the malleus and incus to

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articulate with something that abnormal,

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wouldn't make sense as well.

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It may suggest that instead they would have to have a

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full, a total ossicular replacement implant or a TORP

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(Total Ossicular Replacement Prosthesis) put in for

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those patients who have abnormalities also in the stapes.

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The other issues that we want to discuss are the

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presence and the openings of the oval

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window and the round window.

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Having an oval window stenosis with the stapes being

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unable to appropriately articulate with

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the vestibule would lead to, again,

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a surgery that would be different in that situation.

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And similarly, with the round window,

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if that is stenotic or the cochlear

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aperture is stenotic,

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that could lead to sensorineural hearing loss.

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You want to make a judgment as to the

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size of the middle ear space.

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If the middle ear cavity is completely obliterated

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with bone and just small ossicles with no airspace,

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it's very difficult for the surgeon,

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even using the microscope,

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to reconstruct those middle ear

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ossicles in that space.

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So an assessment of the middle ear space

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is an important feature as well.

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Let's continue on our checklist. The facial nerve.

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Again, in the setting of external

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auditory canal atresia,

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it is very common for the descending portion of

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the facial nerve to be anteriorly located.

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If it's anteriorly located,

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it can potentially be in the operative field of where

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they're working to reconstruct the middle

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ear ossicles. So that's another point to make

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in your report.

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I have mentioned the stapes.

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You want to comment about the malleus and the incus.

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If the malleus and the incus are normal in appearance,

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which does occur in about 50% of patients

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with external auditory canal atresia,

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then they may not have to do an ossicular replacement

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surgery or what people refer to as an ossiculoplasty.

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Next comes the big reds.

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So the big reds are the carotid

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arteries and the jugular vein.

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Anomalous development of the carotid artery is a

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possibility in external auditory canal atresia,

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where that aberrant internal carotid artery actually

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enters the middle ear cavity over

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the cochlear promontory.

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That's where they're operating on for the middle ear

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ossicles and/or to put a cochlear implant potentially

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at the round window niche. So,

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identification of the carotid artery and referring to

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it in its normal course versus an anomalous course is

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important. And the same is true with the jugular vein.

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The jugular vein has all kinds of congenital

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anomalies that can occur with it,

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including high-riding jugular veins above the external

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auditory canal or jugular vein dehiscence,

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where the vein is exposed in the middle

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ear to a jugular vein diverticulum,

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where there's actually a little bit of an aneurysm,

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if you will, of the vein into the middle ear cavity.

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All of these should be part of your checklist for the

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evaluation of patients who have external auditory

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canal atresia being considered for reconstruction.