Superior Canal Dehiscence Syndrome (SCDS) was first described over 70 years ago by Tullio and Hennebert, however, it took until the year 2000 for Minor to be able to co-relate symptoms of patients having vestibular reactions to auditory and pressure stimulus to an anatomic finding.
Under normal conditions the middle ear, which is responsible for auditory functions and maintaining a steady balance of the body, conducts sound pressure through two windows. These windows, the round window, and the oval window, conduct the perilymph or the fluid in the middle ear that helps maintains the body’s balance.
In people that are suffering from SCDS, an additional opening for the movement of this fluid is created due to the presence of a dehiscence (bony window) in the temporal bone above the Superior Canal.
This abnormal movement of the fluid is responsible for the symptoms that are associated with SCDS.
Studies have estimated that .5-.6% of people suffer from SCD while another 1% have a very thin temporal bone that may also result in similar symptoms.
Some of the most commonly observed symptoms include:
- A chronic difficulty in maintaining balance
- Dizziness brought on by loud sounds
- Twitching of the eye brought on by loud sounds
- Dizziness brought on by a change in pressure
- Twitching of the eye brought on by a change in pressure
- Loss of hearing (partial or complete)
- Blurriness of vision to pressure being exerted on the nearby nerves responsible for vision
- Increased sensitivity to sounds conducted through the bone
There are several possible causes that have been put forward as being responsible for the occurrence of SCDS.
- Developmental Defects
- Age-related thinning of the bone
- Vascular defects
- Trauma to the head
- Surgical complications
- Increased intracranial pressure in a patient who had a thin temporal bone
The doctors will take a thorough medical history and note the symptoms being displayed in detail before deciding which further tests are necessary. A number of auditory and vestibular tests will be carried out to ascertain the audio characteristics that bring about these symptoms.
Once the findings of these tests prove confirmatory, a high-quality CT scan would be required for final confirmation of an SCDS diagnosis.
The treatment for SCDS will vary with the severity of symptoms being displayed. It may require one or a combination of counselling, surgical intervention, and audio amplification.
For patients that are only suffering from mild symptoms, counseling is enough to make them understand about their condition and which kind of stimulus needs to be avoided. Surgical treatment will be reserved for those patients that have the most serious symptoms and will involve a procedure aimed at plugging the hole in the auditory canal and repairing the dehiscence.
For patients whose chief complaint has to do with a loss of hearing, aids to amplify sounds and help them hear normally again are all that will be required.
Most patients will fall into the category requiring minimal intervention, however, a progressive worsening of the condition can also occur and make it necessary to go in for surgery later on.
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