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The symptoms of Superior Canal Dehiscene Syndrome or SCDS.
Come in two flavors,
they're either hearing systems or vestibular that is balance
symptoms and to understand them we really first need to
understand what's really wrong with the function of the inner
ear when we talk about superior canal dehiscence syndrome.
Let me refer to a model of the ear, so
he's a model of the left ear.
We see the outer and
the inner ear here and the middle ear here.
Here's the ear canal, the ear drum.
Sound comes in here, strikes the ear drum and
sets the chain of bones into motion.
The sound goes in to the inner ear through the stapes bone, and
then that sound pressure comes out lower down here,
at what's called the round window.
And normally, the inner ear, this structure,
is entirely a closed capsule.
There's only one way in and one way out.
The way in is the stapes bone here, and
the way out is the round window down here.
The ear essentially works like this, sound comes in,
and it comes out at the round window.
In a wave.
And that configuration makes the fluid movement from sound all go
down the cochlea, the hearing organ that looks like the snail.
The balance organs, these three semicircular canals and
the tilt and gravity sensors.
In the back part of the inner ear.
They happen to be linked to our hearing organ, but
sound should never make fluid move in those structures.
The problem is if we are missing the bone over this,
now we've got a third window.
Stapes at the oval window, the round window, and
now there's third mobile window up here.
That's an escape route for sound energy.
Some of the sounds that's coming in the eardrum
doesn't get directed down into the hearing organ, the cochlea.
Instead, it leaks out of the superior canal and
that creates havoc.
First of all, by making the fluid move in here
the brain gets a signal that the head is moving in this plain.
Because that's the job of the superior canal
to inform the brain that the head is moving like that.
Patients who have superior canal dehiscence syndrome,
will say a loud sound like my
two year old screaming will make the world bounce up and
down as if my head is bobbling, because of that.
The second flavor of symptom is the auditory manifestations.
We're stealing away some of the sound from the hearing organ, so
naturally there's a hearing loss.
For sound that's coming in the normal route through the ear.
On the other hand, sound that's already in our bones,
sounds like our pulse, our neck, creaking and our voice.
Those get into the inner ear through that whole
more readily than normal.
And so people report these crazy symptoms of hearing their eyes
move, hearing the blood rush in their veins around their ear,
hearing their neck creaking.
And their voice sounds very strange to them.
It may be too loud, which we call autophony, or
it may be distorted.
Because they're hearing it in two ways, not one.
They're hearing the voice come out of their mouth, come around,
and come back into the ear, the way we all normally hear
our voice, but they're also hearing their voice come
through their bones directly into their inner ear.
And that combination is a very distorting sound to most people.
Their voice sounds loud, uncomfortable and distorted.
And many patients
resort to whispering because they can't stand that.
So those are the flavors of symptoms caused by that abnormal
opening at the superior canal.
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