On Thursday’s episode of Grey’s Anatomy (titled “Shiny Happy People”), a teenage patient called Hayley is thought to have schizophrenia after trying to claw her own eyes out. Not unlike a House episode we recently covered, the diagnosis turns out wrong and instead she is found to have a condition called superior canal dehiscence syndrome.
Photo by ABC
Danger level: Medium
What is it?
Superior canal dehiscence syndrome (SCDS) is a rare condition affecting the ear which causes the person having it to hear sounds inside their body, among other things. It was first described in 1998.
Who gets it?
Since the condition was first described only in 1998, not much is known in that area. A study conducted on cadavers (dead bodies) found ears matching the condition in about 0.5% of bodies checked.
It appears to affect women and men alike. The condition usually affects people around the age of 40, although it may start earlier or later.
What causes it?
Our ear, as we described here before, is divided into 3 parts: The outer ear, middle ear, and inner ear. Our inner ear is the innermost part, and it’s responsible for hearing and balance.
The inner ear.
Our inner ear is composed of 3 canals filled with fluid that sense our position in 3D, which helps us
keep our balance. Just like a gyroscope that tells our brain the position of our head in real time. The superior canal is one of those canals.
Overlying the superior canal is one of our bones, called the temporal bone. In SCDS that bone is thinner than usual since it hasn’t developed properly.
Through a mechanism too complicated for this article, the symptoms of SCDS develop due to this bone defect.
How does it feel?
There are typical symptoms people with SCDS may experience:
- Autophony – This means the person can hear their own speech or other noises inside their body (such as the heartbeat, eye movements, chewing, etc.) very loudly.
- Dizziness/vertigo – Problems with balance, since, as mentioned above, our inner ear is responsible for keeping our balance. (You can learn about head spinning in our article published a while ago).
- Tullio phenomenon – In this case, sound can cause the patient to lose balance. Sound can also cause rapid movement of the eyes, called a nystagmus.
These are the main symptoms, although there are others as well. This fascinating video shows a true story:
How is it discovered?
One way is doing a CT scan of the temporal bone, which will show its thinning (or dehiscence).
There are other ways. Among them is the method shown in the Grey’s Anatomy episode, called a videonystagmography (VNG). In this method, hi-tech video goggles with infrared cameras are worn while doing things that can provoke rapid eye movements in the condition.
How is it treated?
The condition can be treated by a surgery, which repairs the gap in the temporal bone. Another surgical method is plugging the superior canal.
What happens after treatment?
The success rate of the operation is quite high. Most patients don’t have their old symptoms after the operation.
The bottom line – How do I avoid it?
There is no known way to prevent the condition.
If you happen to have SCDS, there’s a support group for you.