Question
I have been contacted by a potential client who is seeking an analog hearing aid because she has Tullio's phenomenon and has been advised elsewhere that a digital instruments would not work. Is there some reason this might be so? It defies logic to me.Answer
The Tullio phenomenon consists of the combination of vertigo and abnormal eye and/or head movements provoked by sound. Dehiscence of the superior semicircular canal can also be found in certain patients with the Tullio phenomenon. When you go to PubMed and enter Tullio Phenomenon and Hearing Aids/Amplification, there are no citations from the peer reviewed published literature, which tells us that the relationship between hearing aid signal processing strategies and the Tullio phenomenon has not been studied very extensively.
When you use other search engines, such as Google Scholar and Scirus, you can learn a little more about it. In one particular study, published in the journal Neurology in 2000, five patients experienced the Tullio phenomenon when a relatively low intensity level (55-65 nHL) was used to elicit it. Dr. Timothy Hain, an Otologist in Chicago mentions the Tullio phenomenon on his website. Dr. Hain talks about the various sound generators (including a shower massager) used to diagnose it.
Based on this information, I think you can draw two conclusions:
- Hearing aid patients experiencing the Tullio phenomenon need to be referred to an otolaryngologist for monitoring
- It's unlikely that switching from a digital to an analog hearing aid is going to make any difference. (There is nothing I could find in the published literature to contradict this statement). Considering that the gain and output of a digital hearing aid can be fine tuned more easily with a digital device, you are more likely to set the output below the threshold in which dizziness is elicited.
