In this second post, I will take cue from @kendraoudyk and step away from strict scientific writing, as it is good to take a breather. I will also encroach a little on the topic written by @emmaallingham regarding musical hallucinations, however I will inspect a less musical version of it: tinnitus. It comes from Latin, and means “to ring or tinkle” (American Tinnitus Association). It is another form of phantom sensations that human can experience without having an external stimulus (Diesch, Schummer, Kramer, & Rupp, 2012). Tinnitus is often linked to some form of hearing loss, especially in the higher frequencies (Henry, Meikle, & Gilbert, 1999).
About three years ago, on one of my many long canoe trips into the Canadian wilderness, I picked up a bad staphylococcus infection that required me to take a lot of antibiotics. After taking one of these in particular, I noticed an odd sound in my ears—the kind of sound that one notices after exiting a loud concert. I thought that it would disappear after I stopped taking the antibiotics, but, alas, I was not that lucky. It stayed with me, and given tinnitus is said to be chronic after 6 months (Diesch et al., 2012), I had accept that it was here to stay. Since then, tinnitus has been a large part of my life: effecting my thinking, my hearing, my overall focus, and my lack of ability to hear silence. I know in the grand scheme of things, my tinnitus is not that bad—I have never sought out therapy with which to deal with it, as I know others have had to do. And, fun fact, I think the frequency is between 700 and 800 Hz, and when it first began I determined it to be a B-flat (along with my refrigerator and a light that buzzed outside of my apartment door).
It is surprisingly difficult to find statistics on worldwide tinnitus sufferers, but, for those who are interested, it is the most prevalent health condition in the USA, according to the American Tinnitus Association, and approximately 360 million people worldwide, according to hearinghealthfoundation.org. Needless to say, it is prevalent and extremely common—and getting even more so with the constant noise and preference for loud concerts.
When I first realized that I was stuck with tinnitus for the rest of my life, I was very concerned at how it would affect my hearing: would I hear music the same? Would I have trouble hearing soft noises? Through the years since then, I have noticed changes in my hearing, of course. Being in quiet places make me uncomfortable because I cannot hear the little noises, and studying without some form of music or blue noise on is detrimental to my ability to focus. All of these are concerns, but I had not really looked into the long-term effects of tinnitus. From what I have read for this blog—the long-term effects vary quite a bit from person to person and tinnitus to tinnitus.
But first, what causes tinnitus? What is the neural and perceptual links to these hallucinations? I was told by my doctor that tinnitus was caused from damage to the cilia and hair cells in the cochlea. This could be caused by loud noises (sudden or sustained), head trauma, antibiotics (in my case), earwax blockage or pressure in the head or sinus system. It is common for people to experience tinnitus throughout their life, but it tends to disappear in a few hours or a few days. I am not sure I understand tinnitus, but it seems to be a complex situation.
In the world of neurons, tinnitus is from an increased rate of neural firing, increased neural synchrony and changes in the tonotopic make-up of the auditory cortex (Lagguth, Kreuzer, Kleinjung, & De. Ridder, 2013). This can be caused by an under stimulation of certain frequencies, which causes the neurons to fire without a stimulus. They then fall into sync, and eventually fire constantly, leading to the ringing or whistling in the ear (Lagguth et al., 2013).
Langguth (2011) suggested that tinnitus is related to emotional stress, depression and anatomical changes of the hippocampus (and speaking from experience, emotional distress is certainly related to tinnitus). In a fairly recent study, Diesch, Schummer, Kramer, & Rupp (2012) found that in participants with tinnitus, there were several brain regions that were structurally changed. One of these regions was part of Heschl’s gyrus (mHG) (site of primary auditory cortex), which appeared to be smaller in patients with tinnitus. Interestingly, these changes were ipsilateral (same side) as the affected ear. They also found that the posterior midbody of the corpus callosum (CC) was smaller in male tinnitus patients, and the isthmus, anterior midbody and genou were larger in female patients with tinnitus. Diesch et al. (2012) suggest these changes in the CC, and this stronger connectivity of the hemispheres may create and maintain a positive feedback loop of the tinnitus. Various studies propose that the sound could be caused by “disinhibition, increased spontaneous activity, neural synchronization, and tonotopic reorganization in the central auditory system” (Kraus & Canlon, 2011, p. 42).
In terms of effects outside of the brain anatomy, tinnitus does affect higher frequency hearing (Henry et al., 1999), and it can put extreme suffers into feelings of despair that lead to therapy and the necessity to play white, blue, violet or any type of noise that cover the persistent ring.
Can tinnitus be cured? That is a question still being looked at. So far, it doesn’t look promising. Each tinnitus and each ear is very different, and the cure is dependent upon the cause. Perhaps your hair cells are damaged, which may be incurable, unless scientists manage to use stem cells or something similar to heal the hairs. Perhaps tinnitus is caused by pressure in the head, which can be relieved through the Eustachian tube or clearing earwax. Perhaps the pressure is caused by a neck or head injury, which may be helped by massage, physio therapy, cranial therapy or seeing a chiropractor. Furthering this, a recent suggestion is the app TinnitusPro (http://promedicalaudio.com/ ). It works by identifying your tinnitus tone, and subsequently removing it from all the music on your ipod. The concept behind this, is that if you remove the tone from what you hear then those hair cells won’t be activated and be able to heal. The reviews I read are not extremely convincing, but it is an interesting idea. The app claims that after a year, patients have seen a difference (but this doesn’t take into account Apple Music, Spotify, youtube or anything like that. Just what is on your ipod).
Another recent develop I found is Acoustic CR Neuromodulation (https://thetinnitusclinic.co.uk/tinnitus-treatment/acoustic-neuromodulation/). Your tinnitus tone is identified, and then the tones of a band around your tone is determined. These tones are then presented to the patient in varying rhythms and patterns, and listened to for 6 hours every day. The varying rhythms and patterns of the tones are meant to cause the constant and synchronized neurons that fire to create the tinnitus to break out of their pattern. It sounds pretty hopeful, but it is only available in the UK.
There is a great deal of current research happening surrounding tinnitus, and I am excited to see if anything becomes clearer soon—I know I speak for many when I say that a cure couldn’t come fast enough.
One last question that is interesting to pose is this: some people have stable tinnitus, which doesn’t change day-to-day, but there are some types that get worse with tiredness caffeine, sugar, alcohol, extreme heat, and strong emotions. Has anyone heard anything from friends or colleagues regarding this?
Diesch, E., Schummer, V., Kramer, M., & Rupp, A. (2011). Structural changes of the corpus collosum in tinnitus. Frontiers in Systems Neuroscience, 6(17), 106-113. doi: 10.3389/fnsys.2012.00017.
Henry, J. A., Meikle, M., & Gilbert, A. (1999). Audiometric correlates of tinnitus pitch: Insights from the Tinnitus Data Registry. In J.W.P. Hazell (Ed.), Proceedings of the Sixth International Tinnitus Seminar, 51-57. London: The Tinnitus and Hyperacusis Centre.
Kraus, K. S. & Canlon, B. (2012). Neuronal connectivity and interactions between the auditory and limbic systems. Effects of noise and tinnitus. Hearing Research, 288, 34-46.
Langguth, B. (2011). A review of tinnitus symptoms beyond ringing in the ears: A call to action. Current Medical Research and Opinion, 27(8), 1635-1643.