What is superior canal dehiscence syndrome?
Superior canal dehiscence syndrome is a condition that affects your hearing and balance.
‘Dehiscence’ means ‘opening’ or ‘hole’. If you have SSCD, there is a hole in, or a thinning of, the bone that covers one of the semi-circular canals of the inner ear, the part of the ear that helps you balance. This can also affect how sounds come into your ear.
It is rare: just 1-2% of people are diagnosed with SSCD. It affects both men and women, and people are usually diagnosed in their 40s, despite the condition being present since the few months following birth. About two-thirds of people with SSCD have it in just one ear.
People with SSCD may feel dizzy or see stationary objects ‘move’ when they hear loud noises or make sudden movements, such as sneezing. They may also hear their own voice or breathing particularly loudly.
Note – you may also come across the terms ‘superior semi-circular canal dehiscence syndrome’, SCD, SCDS or SSCD. They all relate to the same thing.
Superior canal dehiscence syndrome symptoms
Symptoms of SSCD may include:
- Dizziness (vertigo), caused by movement, sound or both
- Stationary objects seeming to move (oscillopsia)
- Over-sensitivity to noise (hyperacusis)
- Hearing your own voice, breathing, chewing or pulse unusually loudly (autophony)
- Ringing in the affected ear (tinnitus)
- Some hearing loss of low frequency sound
- Pressure within the ears
- Brain fog
Superior canal dehiscence syndrome treatment
Many people with mild SSCD can learn to cope with their symptoms and their triggers, avoiding loud noises, for example. Ear protection can be used if situations involving loud noise, such as concerts or large crowds, are unavoidable.
A therapist experienced in SSCD may be able to provide beneficial treatment and exercises to help improve balance and reduce the risk of falling. If you have hearing loss because of SSCD, your doctor may suggest that you are fitted with hearing aids.
When symptoms are more severe and interfere with daily life, you may benefit from surgery. There are different procedures to alleviate SSCD, but most commonly the hole (dehiscence) is repaired or plugged using a small piece of bone from your skull.
Superior canal dehiscence syndrome diagnosis
When you first go to your doctor, they will examine you and ask about your symptoms. Your doctor may request additional tests are carried out, including a hearing test. These will all help with their diagnosis. You may have one or more of them.
A CT scan uses a combination of many x-rays taken from different angles that are computer-processed into a three-dimensional image. A CT scan of your temporal bones – the sides and base of the skull that house your ears – can detect whether there is a hole in the bone covering any of the semi-circular canals, or any thinning of that bone.
You may have a videonystagmography (VNG), which helps to diagnose any problems with your balance. You will wear goggles that measure and record your eye movements as you watch moving objects, including with your head in different positions.
Your doctor may also request a vestibular evoked myogenic potential test, also known as a VEMP test. Electrodes are attached on your neck and by your eyes and sound is then played into one ear. The muscle reflexes are measured – people with SSCD have a greater muscle reaction – and the test helps indicate the site of any damage to your inner ear. The test is completely painless.
Causes of superior canal dehiscence syndrome
The cause of SSCD may have many factors. It may be genetic and present from birth, or it may occur during the child’s first few months when the inner ear is developing. It can be caused by an infection, or even by a blow to the head or other trauma.
It is possible that the bone has been thin from birth and therefore is more susceptible to infection or trauma. Or it may get thinner as part of the body’s natural ageing process.