Second Cause of Hidden Hearing Loss Identified

Discussion in 'Research News' started by Samir, Feb 18, 2017.

    1. Samir
      Obedient

      Samir Manager Staff Benefactor Ambassador Advocate

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      Gabriel Corfas and his research team at University of Michigan have discovered that disruption in the Schwann cells that make myelin, which insulates the neuronal axons in the ear, leads to hidden hearing loss.

      They contrast this against loss of synapses which they have previously found to cause hidden hearing loss. Hence the title "second cause of hidden hearing loss identified".

      News article:
      https://www.eurekalert.org/pub_releases/2017-02/mmu-sco021717.php

      Here is the research paper:
      http://www.nature.com/articles/ncomms14487
       
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    2. AUTHOR
      AUTHOR
      Samir
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      Samir Manager Staff Benefactor Ambassador Advocate

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      The article on Eurekalert was not clear about what that previous research was that identified the first cause of hidden hearing loss (HHL). I thought they were referring to a previous work by Corfas at Michigan university. I now realize that they were referring to the work by Liberman at Massachusetts Eye and Ear. I thought it seemed familiar...

      nrneurol.2016.10-f2b.jpg

      You can see the location of IHC synapses in the image above.

      In other words the Schwann cell loss and axonal demyelination is not permanent (hence "transient"). But the natural restoration that follows is not perfect. Myelin is a protective sheath that surrounds nerve fibers.

      In other words there is no nerve fibre loss. There is a disruption in the Heminode which sits at the Habenula perforata. Heminode is a node of Ranvier situated at the junction of myelinated (protected) axons and bare (unprotected) axons. In the cochlea this happens at a place called Habenula perforata.

      In other words myelin defects are bad, there are two types or causes for HHL, and they can add up.

      To help you navigate around and better understand this I have include two images below.

      Location of Habenula perforata:

      slide_29.jpg

      Schematic view of cochlear nerve fibres:

      800px-Adult_cochlea_nerve_glia_cartoon.jpg

      Explanation:

      Schematic illustration of the peripheral glial cells in the adult human cochlea. Satellite glial cells (green) envelop all spiral ganglion neuron (SGN) cell bodies. Non-myelinating Schwann cells (light blue) ensheath both the central and peripheral processes of the type II SGNs (yellow) that innervate the outer hair cells (OHC). Myelinating Schwann cells (dark blue) ensheath and myelinate both processes of the type I SGNs (red) that innervate the inner hair cells (IHC). Beyond the habenula perforata, in the organ of Corti, neither Schwann cell types ensheath the most distal part of the peripheral processes of type I and type II SGNs.
       
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    3. tinnitube
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      tinnitube Member

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      damn virus
      this is very good finding thanks
       
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    4. Frédéric

      Frédéric Member Benefactor

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    5. JohnAdams
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      JohnAdams Member Benefactor Hall of Fame

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      The next drug frequency therapeutics is working on is for remyelination of nerves. I wonder if this could help that.

      Also I wonder if noise and or ototoxicity can cause this.
       
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    6. JohnAdams
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      JohnAdams Member Benefactor Hall of Fame

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      We need to back up and remember the ly411575 experiments in mice. They were deafened and their hearing was restored. Just because they showed the hair cells regenerated dosnt mean that's all that happened. there could easily be other down stream effects that contributed to the restoration of hearing.
       
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    7. PolishSoldier87
      Moonlighting

      PolishSoldier87 Member

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      acustic trauma, neuro-lyme/rx co-op toxins
      Prescription medicines can do demyelination for sure. Many of them are neurotoxic.
       
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    8. razo

      razo Member

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      I had very good effect of taking cod liver oil (omega 3 fat), but on my muscles. It made my back and neck soften up. Probably because my diet was seriously deficient before that.
       
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    9. katri
      Blah

      katri Member

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      Well fuck. Everything is toxic at this point
       
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    10. Frédéric

      Frédéric Member Benefactor

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