Superior Canal Dehiscence Syndrome
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What is superior canal dehiscence syndrome (SCDS)?
Superior canal dehiscence syndrome (SCDS) is a rare inner ear condition that can affect your balance and hearing. With SCDS, there’s an opening (dehiscence) in the bony wall that normally encloses the part of your inner ear called the superior semicircular canal.
The superior semicircular canal is one of three fluid-filled tubes coiled inside your inner ear. It’s the uppermost loop, closest to your brain. The fluid inside each loop shifts when you move. The shifting fluid alerts your brain to changes in movement. Your brain uses this information to sense and regulate your balance.
With SCDS, there’s an opening in the bony barrier that normally helps regulate these signals that control movement and balance. The opening may also allow sounds from your inner ear to travel to your brain, causing hearing problems.
Superior canal dehiscence syndrome (SCDS) is also called:
- Semicircular dehiscence syndrome (SDS).
- Superior semicircular canal dehiscence (SSCD).
- Superior canal dehiscence (SCD).
- Semicircular canal dehiscence (SCD).
How rare is SCDS?
Approximately 1% to 2% of the general population has SCDS. Around 33% of people diagnosed have SCDS in both ears. This is called bilateral superior semicircular canal dehiscence. Usually, one ear causes more issues than the other.
Symptoms and Causes
What are the symptoms of SCDS?
Not everyone with SCDS experiences all potential symptoms, which can make diagnosis difficult. Also, many people with thin or dehiscent bone don’t have symptoms of SCDS. Some people with only thin bones (and not a true opening) may experience the same symptoms as people with true dehiscence.
If you do have symptoms, they may cause problems like hearing loss or hearing changes. You may have issues with your balance. These symptoms can take a toll on your mental health, too.
- Autophony: Hearing your voice or self-generated sounds, like breathing or blinking, louder than normal.
- Hyperacusis: Heightened sensitivity to sound (meaning sounds may feel unusually loud, uncomfortable or even painful).
- Pulsatile tinnitus: Hearing noises in your head that occur in time with your pulse, or heartbeat.
- Hearing loss (especially at low frequencies).
- Vertigo: Feeling like your environment is moving even if you’re standing still.
- Oscillopsia: When stationary objects appear to move.
Common activities that change the pressure in your brain or middle ear (the part of your ear that contains your eardrum) and exposure to loud sounds can trigger vertigo and oscillopsia. These activities include straining, coughing, sneezing, heavy lifting, exercising and hearing loud noises.
Some people with severe SCDS symptoms report that their condition negatively impacts their mental health. Symptoms include:
- Brain fog.
- Memory problems.
Isolating to avoid exposing yourself to unpleasant sounds can lead to feelings of loneliness, anxiety and depression.
What causes SCDS?
The true cause of superior canal dehiscence syndrome is unknown. The dehiscence may, at least in part, be congenital (present from birth). During fetal development, the bone near your superior canal may not have thickened enough. Some researchers suggest that certain infections or head trauma (injury) may also cause SCDS.
It’s likely that multiple factors cause or contribute to SCDS. For example, from birth, you may have a thin area of bone near your superior semicircular canal that’s susceptible to trauma or infections. Or the bone may thin further as you age.
Diagnosis and Tests
How is SCDS diagnosed?
You’ll likely see a specialist called a neurotologist to diagnose and treat your condition. A neurotologist is a doctor who specializes in brain- and nerve-related concerns that also involve your ears. They’ll perform a thorough case history to better understand your symptoms. They may order several tests to rule out more common conditions with symptoms similar to SCDS.
Tests may include:
- Computed tomography (CT scan) of your temporal bone: This imaging procedure can show the opening in your bone covering the superior semicircular canal.
- Hearing test: A specialist in hearing and balance disorders called an audiologist will test your hearing.
- Vestibular-evoked myogenic potential (VEMP) test: This test provides information about how the various parts of your inner ear are working to control your balance. It’s a painless test that requires you to move your head to the left or right, or to look up, while staring at a target and listening to a series of tones.
Management and Treatment
What are the treatment options for SCDS?
Most people can manage symptoms by avoiding activities that trigger vertigo and oscillopsia, and steering clear of noisy environments. Many people with SCDS protect their ears if there’s a risk of exposure to loud noise. They may use earbuds or other forms of hearing protection to drown out noise.
Seeking treatment from a certified vestibular physical therapist can help manage symptoms. They can teach you exercises to help improve your balance and reduce your fall risk.
If symptoms are unmanageable or interfering with your quality of life, you may need surgery to plug the dehiscence.
The most common surgical repairs for SCDS include:
- Plugging the dehiscence (middle cranial fossa approach): Plugging closes the dehiscence. This procedure involves accessing your inner ear through an opening in your skull. An ENT specialist and a neurosurgeon perform this procedure.
- Plugging the dehiscence (transmastoid approach): This procedure accesses your inner ear through an opening behind your ear.
- Resurfacing: This repair technique covers the opening without closing it completely. It’s less common than plugging.
Your healthcare provider may use both plugging and resurfacing techniques during surgery.
Complications of SCDS surgery
The risk of major complications following SCDS surgery is low. As with any surgery, there’s a slight risk of infection. You may have problems with balance immediately after surgery as your body adjusts to the repair, but this usually improves within the first week following surgery.
Outlook / Prognosis
Does SCDS go away?
SCDS doesn’t go away without surgery. Unlike other bones in your body, the bone that surrounds your superior semicircular canal doesn’t repair itself. Your symptoms may improve once you learn techniques to manage them. But SCDS won’t go away without treatment.
What is the success rate of SCDS surgery?
SCDS surgery decreases or relieves symptoms for most people. Some studies show that certain symptoms resolve more quickly following surgery than others. For example, hearing loss, autophony, pulsatile tinnitus and vertigo may improve more readily than symptoms like headaches and brain fog.
Talk to your healthcare provider about likely outcomes of surgery based on your symptoms and the extent of your dehiscence.
How do I take care of myself?
Follow your healthcare provider’s guidance about how to cope if you’re living with SCDS. In most cases, people manage symptoms with lifestyle changes.
- Wearing ear plugs.
- Avoiding loud environments when possible.
- Whispering (if your voice sounds painfully loud).
- Avoiding activities that trigger balance problems, like heavy lifting.
- Avoiding activities that can cause pressure changes in your ear (like flying).
- Asking for accommodations at work (working in a private, quiet space instead of a shared one).
Ask your healthcare provider for guidance on how to apply for accommodations for work. People with hearing disabilities can request reasonable accommodations to do their jobs, according to the Americans with Disabilities Act.
A note from Cleveland Clinic
If you’re diagnosed with superior canal dehiscence syndrome (SCDS), take comfort that most people learn to manage their condition with lifestyle adjustments. Your healthcare provider can recommend ways to avoid triggering or worsening symptoms impacting your balance and/or hearing. Surgeries to plug the dehiscence often resolve or greatly improve symptoms. Talk with your provider about which treatment options are best for you.
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