Superior canal dehiscence syndrome is often referred to as a newly recognized condition, but two doctors named Tullio and Hennebert described its symptoms about 70 years ago. What's new, at least since 1998, is that it is now recognized as its own disease. Until recently, it was considered to be a symptom of perilymphatic fistula, syphilis, Lyme disease, congenital deafness, Ménière disease, multiple sclerosis, migraine, toxic reactions to common medications (especially the antibiotic gentamicin), head trauma, or cholesteatomas with labyrinthine fistula, or complications fenestration (bone-opening) operations for other conditions of the inner ear.
I realize that casual readers may see the words "syphilis" and "Lyme disease" and respond with "He's saying I have syphilis! He's saying I have Lyme disease!" What I am saying is that the symptoms of superior canal dehiscence syndrome were confused with symptoms of those diseases for many years, and you can still run into some doctors who are not completely informed about the difference.
The main symptom of this condition is sensitivity to noisy environments. Loud sounds or changes in air pressure can provoke dizzy spells. Some people hear a swoosh when they turn their eyes. It can be necessary to remain still to avoid tinnitus, constant ringing or buzzing in the ears.
The cause of superior canal dehiscence syndrome is a thinning or "drying out" of the bone over the superior canal of the inner ear. Sound waves in the air cause a vibration of the ear drum, but we don't hear as a result of this vibration. The vibration of the ear drum is transferred to lymphatic fluid in the inner ear, and it's actually the fluctuations in this fluid that transmit sound and also give us our sense of balance. When the bone over this canal is thin, it can "leak," or it can be hypersensitive to the mechanical energy transferred by the ear drum. The result is a range of symptoms related to hypersensitivity to sound.
While this condition is relatively seldom diagnosed, somewhere between 1 and 2 percent of autopsies find deterioration of the bone related to it. It's possible that many people have mild symptoms of the disease that just don't get diagnosed. Only about 200 people, mostly in the UK, have been diagnosed with the disease. It's very rare before the age of 27, although a few cases have been found in children, and it's also very rare after the age of 70. It seems to occur in both men and women and in all races without about equal frequency, although better information about the condition may reveal patterns not yet observed.
The primary treatment for superior canal dehiscence syndrome is surgery. There is a procedure that is laparoscopic, that does not require opening the skull. It's not always possible to use this simpler procedure. There is a significant risk with surgery. About a quarter of patients who have surgery to repair the bone that is involved in superior canal dehiscence syndrome develop a condition called benign paroxysmal positional vertigo. When they move (1) from a standing position to a lying-down position (2) in the direction of the side of the head on which they had the surgery, they become dizzy. Because one is going to lie down anyway, the problem is considered "benign." However, it can cause severe nausea. If there is anything good about benign paroxysmal positional vertigo, it is that is tends to go away on its own.
What can you do to manage superior canal dehiscence syndrome while you are waiting for surgery, or if you have decided not to have surgery? Generally, limiting your sodium intake helps. Even your inner ear is responsive to "water weight." Tiny reductions in the amount of lymphatic fluid in your ear, along with reductions in fluid all over your body, make a big difference in how you feel. It's important to understand that you accomplish this by limiting sodium, not by limiting your water consumption. Your kidneys will take care of you better if you just reduce the amount of salt you consume.
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