My name is Fatima Husain. I'm a professor in the Department of Speech and Hearing Science
and also a part-time faculty member here at the Beckman Institute.
A major focus of my lab is studying tinnitus and hearing loss.
Hearing loss is easy to understand, right? You can't hear very well.
So everybody knows what it is. Tinnitus is sometimes difficult to
understand if you don't know anybody who has it. Tinnitus is the perception of sound when there is no source.
So you're hearing this constant sound, often called ringing in the ears.
But it doesn't have to be ringing. It can be all sorts of sounds.
It can be very tonal. It can be like cicadas. It can be whooshing like a waterfall.
And, as one patient told me, it can be like a freight train through your head.
The great, great maturity of the cases are actually constant chronic tinnitus, which means
you're hearing it all the time, unless you're sleeping or you're very distracted by something else.
It does have a psychological impact on you. Some people are very used to it.
But for others, it interferes with their sleep. It interferes with their ability to concentrate.
It may cause depression and anxiety. It may interfere with even communication.
We call this bothersome or severe tinnitus.
So we study these individuals because they need the most help.
Because it is a very subjective disorder, we have become more innovative in how we approach tinnitus.
Brain imaging is an excellent tool to peer inside the brain as someone is hearing the
sound and the impact on them. So this is the first study of its kind with tinnitus
and arterial spin labeling. And what it does is allows us to measure perfusion, or blood flow,
in the brain using MRI.
ASL, or Arterial Spin Labeling, gives us an estimate
of absolute numbers of blood flow
that can differ between patients and controls. Is there anything different at all?
And we found that, yes, tinnitus does have an impact on the brain.
The first difference we found was that globally the patients showed reduced perfusion,
that is reduced blood flow. And then we found that the regions which showed these declines
were in the pecuneus and the posterior cingulate cortex.
This is nowhere near any of the auditory processing regions.
They are part of what we call the Default Mode Network, for instance.
And the Default Mode Network comes online when you are in quiet, when you're at rest, when you're
not doing any attention-challenging tasks. We have a lot of speculative hypothesis about it.
Perhaps it has to do with how, at rest, you're more aware of your tinnitus then when it is very
noisy around you and you don't really hear your tinnitus. But, again, this is the first study.
The second interesting result we found was when we said, okay let's consider clinically significant
hearing loss. About 90 percent of those with tinnitus also have hearing loss. The flip side
of this is that, if you consider just the hearing loss population, roughly about 50 percent of them
have tinnitus. We found that hearing loss alone also causes decreases in perfusion.
Hearing loss within the tinnitus group also leads to it. And tinnitus by itself leads to it.
So it's pointing to sort of this additive effect, perhaps, in decreases in perfusion.
The third thing we found was that severity of tinnitus has an impact. So the more bothersome
your symptoms, the lower is the perfusion, lower is the blood flow. But the fact that you have
changes in blood flow as a result of tinnitus is what we need to unpack. Right?
Is the decrease in blood flow allowing you to develop tinnitus? Or is it the fact that you have tinnitus
which has then resulted in this decrease in blood flow?
So we cannot unpack that.
This, again, points towards possible interventions.
With exercise, especially aerobic exercise, we actually improve these measures. Right?
There's greater blood flow to the brain,
which presumably leads to better cognitive health. Will that allow individuals to habituate better? Right?
We're trying to now think about future studies where we can put these things together
and actually see an improvement in blood flow, for instance in individuals with tinnitus.