Tinnitus: What causes it and how can it be cured?

Alan -   Tinnitus is the experience of sound in the absence of any real noise and it's estimated to affect 1 person in 5 and can have a devastating effect on some people's lives.

Thelma -   My tinnitus, I have two pulses and I have one that go boom, boom, boom and the other one goes whoom, whoom, whoom, slightly higher, bit crazy.  It causes me to panic at times.  During the day, it's fine because I have plenty of noise around me, but I find it mainly at night.

Alan -   Dr. Peyman Adjamian researches tinnitus at the MRC Institute of Hearing Research in Nottingham.  So Peyman, what exactly causes tinnitus?

Peyman -   Well actually, that is the 6-million dollar question.  The exact cause of tinnitus is I'm afraid, unknown.  The fact is, there is no single cause.  Very often, what is known are associated events.  So for example, people will say their tinnitus started when they heard a sudden loud noise or when they had earwax removed, or when they had a bad bout of flu, or an ear infection.  But in many cases, it just seems to appear from nowhere.

Alan -   So, how many people are actually affected by tinnitus?

Peyman -   Well, estimates tend to vary and the main reason for that is many people with tinnitus simply aren't bothered by it, so they tend not to report it or they tend not to seek help.  But in most studies, the prevalence is about 20% of the population and in about 10% of these, it can seriously affect the quality of their lives.

Alan -   And so, who is most likely to suffer from tinnitus?

Peyman -   In theory, anyone can develop tinnitus.  It's most common however in people with hearing loss.  And if I may expand on that a little, in the cochlea, sounds of different frequency are processed in order from high to low frequencies, and we think what happens is that in tinnitus', there are some hair cells that get damaged and the cochlea no longer transmits sounds to the brain that correspond to those frequencies.  So, neurons further up in the auditory system begin to produce their own random activity in order to compensate for the lack of external sounds, which the brain then interprets as tinnitus.

Alan -   So that's the physiological basis of tinnitus.  Is there any kind of psychological basis of it?  Are some of these sounds imaginary or are they actually there?

Peyman -   Well, I mean, if by psychological, you mean as you said, imaginary then no.  The tinnitus sound is not imagined.  The sound is very much real.  So there is definitely some physiological abnormality, either in the peripheral auditory system, which is the ear or the central auditory system, which is the brain.  But psychology definitely plays a role in that way a person reacts to their tinnitus, determines to a large extent whether the tinnitus goes on to become intrusive and bothersome or not.  Most people tend to panic when they first hear their tinnitus and it can be quite scary.  It's a little like a vicious circle where a negative reaction to the tinnitus leads to anxiety, stress, and very often sleep deprivation because the sound tends to be louder at night when the person tries to go to sleep.  And this in turn leads to depression in many cases and it tends to worsen the tinnitus.

Alan -   So, is it possible to cure tinnitus?  Is there any treatment available for tinnitus?

Peyman -   Unfortunately again, right now, there is no standard treatment and there is no magic pill.  Some hearing therapists and audiologists offer hearing aids to people with tinnitus when it is associated with hearing loss.  And the idea there is that when external sounds are amplified, they tend to mask tinnitus.  But also, if we can restore hearing to normal or near to normal, then there is external input to the auditory system and the neurons don't generate their own random activity anymore so the tinnitus goes away.  And I hasten to add that, it works in some people, but not in everyone and the benefits aren't universal.  So they aren't routinely offered by audiologists.

Alan -   Thelma's problem at the beginning there which she described in her tinnitus, what kind of tinnitus is that?  Is that the same as what you've been describing or is that different?

Peyman -   Well, that sounded like pulsatile tinnitus which is slightly different.  It's less common than the type of tinnitus that most people experience.  Pulsatile tinnitus is a rhythmical noise.  It usually has the same rate as the heart and as the name suggests, it is synchronised to the pulse.  Now, the causes of pulsatile tinnitus may have to do with blood flow changes near the ear or just simply an increased awareness of the blood flow near the ears.

[Thanks to the British Tinnitus Association for permission to use their simulated tinnitus sounds. More information can be found
here.]