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Superior canal dehiscence syndrome is an abnormal opening
between the inner ear and the brain cavity that causes
people to have either hearing symptoms or balance symptoms.
And those symptoms are different for different patients, but
in general they're either hypersensitivity to the wrong
bone conducted cells or vertigo caused by sound or
pressure changes.
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We don't really know what causes Superior canal dehiscence.
The best data we have suggests it's probably congenital.
People are probably born with thin or
missing bone over the superior canal.
It turns out that's the last part of
the inner ear to develop bone.
And there may just be a premature arrest in
the development of that bone during development.
Now in some cases we see SCDS first appear after a kind of
head trauma.
Sometimes not even a very violent head trauma.
Sometimes just a big pressure change and that may be the last
straw that breaks thin bone or stretches the lining of
the brain and gets that pressure transmission started.
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Superior canal dehiscence syndrome or
SCDS causes a variety of symptoms.
It can cause vertigo, from hearing loud sounds or
pressure changes like coughing, straining or
sneezing or it can cause hearing problems.
It can cause a type of hearing loss, but
more commonly it causes people to be hypersensitive to
their own voice and internal sounds like their eyes moving,
their heartbeat or even their footsteps on the ground.
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To get a proper diagnosis of superior canal dehiscence
syndrome of course you need a good CT Scan that
demonstrates the abnormal opening, but that's not enough.
There have to be some important tests done to show that there is
actually abnormal pressure being transmitted through
that opening.
And those include a very properly done audiogram, certain
vestibular tests like vestibular myogenic potential testing.
And a good exam by somebody who knows what they're looking for
in superior canal dehiscence syndrome.
It's basically a very expensive plumbing problem and
a very high risk plumbing problem.
It's an abnormal opening, a hole between the inner ear and
the brain cavity.
And we have to stop the pressure transmission through that
abnormal opening or we don't get rid of the symptoms.
Now, for reasons of long experience, we've come
to the conclusion that the best thing is to both plug the hole,
plug up the canal completely and resurface the area of
the superior canal, to give a belt and suspenders approach.
A repair that should not fail.
There's a lot of controversy about whether that's necessary.
Can we just resurface the superior canal, and
not completely plug off its lumen, and
somehow preserve it's natural function?
That sounds great in principle, and I would like to be able to
do that in every case, but the reality is the materials that we
have available to us are not fail safe enough for
me to trust that in most circumstances.
What we have found is that if we don't get a good repair on
the primary surgery and we have to go back there's a much higher
risk of losing one's hearing in a revision surgery.
For that reason we think the best approach is the belt and
suspenders approach of both plugging the canal and
resurfacing it.
Now this is a subject of great controversy,
is that the only option and other things have been proposed.
So there's a new procedure that's been proposed of
reinforcing the round window.
That is to say actually putting patching material against
the normal second window, the round window and somehow
altering the overall resistance of the ear to sound coming in.
I don't do that procedure.
It doesn't make physiologic sense to me.
It actually theoretically, would make the syndrome worse
because if you think about it, we're now
plugging up the natural second window and making all of that
sound energy go up through the abnormal third window.
Some other surgeons report success with it.
I'll be happy to see those long term outcomes reported
scientifically.
But for now, I don't think we have the data to support that.
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There are risks to doing any surgery and superior canal
dehiscence syndrome surgery is no exception to that and
of course, there are risks to specifically hearing and balance
function as well as the risk of operating in the brain cavity.
All that being said, this syndrome was discovered at
Johns Hopkins, and we worked out the surgery for it here first.
We have a tremendous experience over 200 cases, and patients who
choose to come to Johns Hopkins benefit from that experience.
Which I think gives them the safest possible surgery for
superior canal dehiscence syndrome.
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What should patients expect after the surgery?
Well first of all, we do it as an inpatient operation.
And patients typically spend two to three days with us after
surgery for their recovery.
That's to make sure there
are no complications from having operated in the brain cavity.
That make sure that they can walk well on their own and
they've begun their balance physical therapy.
And tapering off the steroids that we used to prevent
swelling and inflammation in the inner ear.
So they typically will see us again a week after surgery to
get the staples and stitches taken out,
check their hearing, make sure everything is progressing well.
They have a lot of physical therapy to do on their own at
home during that time.
Most patients find that they're walking outside within
a matter of days from surgery.
And most patients begin to drive in a couple of weeks after
the operation.
I tell most patients to wait six weeks to go back to full
activities at work just because it's easy to
underestimate how exhausting it can be to have
to actually work at your balance until it's automatic.
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The success rate is very good.
We've shown in several publications that we have
outstanding success at getting rid of specific
distributor symptoms like sound induced vertigo.
And we specifically helped the autophony that tremendously
annoying loud sound and distorted sound when one speaks.
Again though,
we have to be careful to pick patients properly and
counsel them properly as to what we can make better.
And what things may be reactions that need separate therapy.
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