CPC #49: Mondini's dysplasia, Misophonia, and Tinnitus

• Mondini dysplasia can cause chronic tinnitus. This defect comes from a defect in the Fibonacci sequences during embryogenesis and can lead to defects in melanosis that can profoundly affect hearing and tinnitus generation in the dysplastic brain.
• The Fibonacci numbers form a sequence of numbers defined by a relationship mathematically.  What this means, in English, is that it is a sequence of numbers whose relationship is this: after the first two numbers, each proceeding number is the sum of the previous two numbers. For example 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233.....and so on. Quite simple, really.
• Fibonacci numbers are not purely artifacts, they are also found in nature in an uncurling fern, the branching of trees, and leaflets of the pineapple. The Fibonacci sequence also describes the "golden spiral," which is when a "golden rectangle" is subdivided into smaller and smaller golden rectangles the result being a predictable spiral.
• Fibonacci numbers have an interesting property. When you divide one number in the sequence by the number preceding it, you are left with a number very close to 1.618. This number is called the "golden ratio," and rectangle whose sides are equal to the golden ratio is known as a "golden rectangle."
• One example of a biological structure in the mammalian body which is very close to a "golden spiral" is the cochlea.  You can see that spiral below in blue.

• The Mondini malformation and Mondini defect is an abnormality of the inner ear that is associated with sensorineural hearing loss and tinnitus. This deformity was first described in 1791 by Mondini after examining the inner ear of a deaf boy. The Mondini dysplasia describes a cochlea with incomplete partitioning and a reduced number of turns, an enlarged vestibular aqueduct, and a dilated vestibule. A normal cochlea has two and a half turns, and a cochlea with Mondini dysplasia has one and a half turns; the basal turn is normally formed with a dilated or cystic apical turn to the cochlear. 
• I believe this defect occurs because of a lack of POMC neuron migration in the child.  This mimics the neurulation defects we see in autism.  I also believe it can occur pre and postnatally from incomplete melanization of the ear or melanin degradation due to heavy technology use  
• The hearing loss can deteriorate over time either gradually or in a step-wise fashion and it can lead to debilitating tinnitus as hearing is destroyed. Destroying the ear with deafness operations might actually make the tinnitus worse.  Cochlear implants might be a better way to deal with the dysplastic auditory cortex.
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About one in five people experience tinnitus, the perception of a sound—often described as ringing—that isn’t really there.  Tinnitus brain mapping has revealed just how different tinnitus is from normal representations of sounds in the brain.
Perhaps the most remarkable finding from the brain mapping experiments was that activity directly linked to tinnitus was very extensive and spanned a large proportion of the part of the brain that researchers measured during brain surgery.  This tells us that tinnitus is really not a peripheral disease but a sensory processing disorder.

Only a few groups in the world have the expertise and collaborative infrastructure to conduct these neurosurgical experiments. It is possible because patients who require invasive brain mapping in preparation for epilepsy surgery also volunteer to participate in research studies. The University of Iowa has the ability to do this because of its epilepsy program.

It is such a rarity that a person requiring invasive electrode monitoring for epilepsy also has tinnitus.  Some people do not have epilepsy but have been found to have other neurovascular abnormalities that might be the cause of tinnitus.

Iowa's epilepsy team puts a recording platform into the patient’s brain for clinical purposes and they can modify it without changing the risk of the surgery. This allows them to understand functions in the brain in a way that is impossible to do with any other approach.

Iowa researchers contrasted brain activity during periods when tinnitus was relatively stronger and weaker. They found the expected tinnitus-linked brain activity, but they report that the unusual activity extended far beyond circumscribed auditory cortical regions to encompass almost all of the auditory cortex, along with other parts of the brain.

The sheer amount of the brain across which the tinnitus network is present suggests that tinnitus may not simply ‘fill in the gap’ left by hearing damage, but also actively infiltrate beyond this into wider brain systems based on the findings of this paper below.

These new insights should help to inform treatments such as neurofeedback or optogenetic therapies, where patients learn to control their “brainwaves,” or electromagnetic brain stimulation.

A better understanding of the brain patterns associated with tinnitus may also help point toward new photobiomodulation approaches to treatment.

The team included the University of Iowa researchers Hiroyuki Oya, Gander, Sedley, Howard and Christopher Kovach, Kirill Nourski, and Hiroto Kawasaki, as well as Timothy Griffiths at Newcastle University. The research was supported by grants from the National Institutes of Health and the Wellcome Trust and Medical Research Council in the U.K.

Tinnitus appears to be a sensory processing disorder (like autism linked to melanin) whose causes are multiple but all lead to a sensory processing disorder in the thalamus and auditory cortex.  Mondini's dysplasia is one of many things that cause this cortical dysfunction in the auditory part of the brain.  I believe many people with this problem develop a new acoustic neurulation disease called misophonia.  

CITES:

https://www.cell.com/current-biology/fulltext/S0960-9822(15)00278-X