Superior dehiscence canal syndrome is a rare condition of the inner ear that affects your balance and hearing. Surgery is typically used to alleviate symptoms and improve quality of life.

Some health conditions can impact your hearing and balance. One that you may have heard of is Meniere’s disease, which can cause dizziness, ringing in your ears, and hearing loss.

A rarer condition called superior canal dehiscence syndrome (SCDS) can also affect these functions.

People with SCDS may experience dizziness or vertigo in response to loud noises. They may also hear sounds from the inside of the body, such as heartbeats or digestive noises. Hearing loss is another potential symptom.

This article takes a closer look at SCDS, including what causes it, and how it’s diagnosed and treated.

Your inner ears each contain three liquid-filled semicircular canals. Their function is to detect the positioning of your head, making them important for maintaining your balance. SCDS happens due to a thinning or absence of bone above the top-most (superior) semicircular canal. This leads to an incomplete closure of this area.

Typically, the inner ear is a closed system. Sounds move through the inner ear and to the cochlea where they’re converted into electrical impulses that travel down the auditory nerve to the brain.

An incomplete closure of the semicircular canal can cause several issues:

  • sounds and pressure changes that can stimulate the semicircular canals, leading to feelings of dizziness or vertigo
  • sound movement through your inner ear possibly being interrupted, impacting your hearing
  • sounds coming from the inside of your body potentially entering the inner ear and being heard
  • being overly sensitive to sounds, feeling as if they are too loud (hyperacusis)
  • a rhythmic thumping or whooshing in one or both ears (pulsatile tinnitus)
Illustration showing superior dehiscence in the ear canalShare on Pinterest
Superior canal dehiscence syndrome occurs in the semicircular canals in the inner ear.. Medical Illustration by Bailey Mariner

SCDS typically impacts only one ear. However, in about 25% of people, it can affect both ears.

Symptoms of SCDS can include:

  • dizziness or vertigo in response to:
    • loud noises
    • changes in ear pressure, such as those caused by sneezing or coughing
  • autophony, where you hear bodily noises like:
    • a loud or distorted version of your voice when you speak
    • your eyeballs moving or eyes blinking
    • your heartbeat
    • the movement of your joints
    • chewing or other digestive noises
  • pulsatile tinnitus
  • a feeling of fullness or pressure in your ear
  • hearing loss

The exact cause of SCDS is unknown. Generally speaking, it’s believed to be a congenital developmental irregularity. It may also occur following an injury or trauma to your inner ear.

There’s some evidence that SCDS runs in families. For example, a 2017 study reported seven cases of SCDS across three families. This suggests that there may be a genetic basis for some instances of SCDS.

While we know that SCDS is rare, there are currently no studies exploring the demographics of the condition. Overall, the majority of people diagnosed with SCDS are adults.

Diagnosing SCDS can be challenging because it’s a rare condition and has symptoms that overlap with other conditions that also affect hearing and balance.

After requesting your medical history and doing a physical exam, a doctor can order several tests to help diagnose SCDS. They include:

  • hearing tests, which are used to assess how well you hear
  • vestibular evoked myogenic potential (VEMP) test, which uses pulsing or clicking sounds made by a sound generator to measure the reactions of your eye and neck muscles
  • electrocochleography, which evaluates the electrical impulses that your cochlea and auditory nerves make
  • CT scan, which can help a doctor visualize your inner ear structure

There are currently no medications that can treat SCDS. Surgery is used to treat SCDS when symptoms present that are disruptive to a person’s daily activities and quality of life.

Surgery for SCDS typically involves making a hole in the skull (craniotomy) to access the inner ear. This allows the surgeon to correct the developmental irregularity in the bone that’s causing your symptoms.

The superior semicircular canal may also be plugged, which helps close off any abnormal openings that may be contributing to symptoms.

SCDS can significantly impact quality of life.

In a small, 2020 study, people with the condition reported lower health-related quality of life compared to people without SCDS.

It’s important to know that surgery for SCDS can be very effective at alleviating symptoms.

A 2021 study involving 63 people who had surgery for SCDS found that two common surgical techniques for SCDS succeeded in reducing most symptoms by over 80%.

Since SCDS is quite treatable in many situations, the first step for relieving symptoms is seeing a doctor if you’re having concerning symptoms affecting your hearing or balance. They can determine what’s causing your symptoms and recommend treatment.