Tinnitus

Tinnitus is the term used to describe a condition in which the person ‘hears’ sounds that are the result of changes in the auditory pathway not triggered by ‘genuine’ sounds arising in the world outside their head. The sounds certainly seem real enough and someone with tinnitus can spend hours or days looking for leaking pipes or poor electrical connections to explain the hissing or buzzing noises that suddenly develop, often heard for the first time at night when all else is quiet. Tinnitus can in turn bring on great psychological stresses, which seems strange at first sight because tinnitus is only ‘sound’ after all.

This chapter tries to explain why tinnitus can be so distressing, what causes it and how it can be managed.

WHY TINNITUS IS SO DISTRESSING

Animals have hearing as an early warning system as a first line of defence for survival, and which puts them on ‘alert’ (see box opposite). In humans, as well as the basic inbuilt ‘animal’ responses, we also have ‘thoughts, feelings and emotions’ piled on top and inter­acting with each orther.

There is a short time between the detection of sound by the cochlea and the perception of sound by the auditory cortex in the brain. Nevertheless, in this short period all sorts of interactions can occur. A quarter of a second is a long time for a fast computer and also for our brains.

Not only do we hear sound but we can also be affected by it both physically and emotionally in many ways.

There cannot be any one of us who has not felt that pleasant, exciting tingle down the spine when listening to a particularly enchanting passage of music.

We do not know all that much about the interactions and connec­tions between the auditory pathway and other parts of the brain. How they work is even less well under­stood. Suffice it to say that unusual electrical activity in the auditory pathway, anywhere from the cochlea to close to the auditory cortex, can have many and varied effects.

Changes in electrical activity in the auditory pathway, for whatever reason, are perceived by the brain as ‘sound’, even though no new sound may be present in the environment. The auditory cortex does not ‘know’ that this new activity is not external; it simply recreates it as sound. Likewise, the brain stem does not ‘know’ that the new electrical activity is not an external threat; it just responds as if it were.
Compare this to what would happen if I were to poke you in the eye: apart from the pain, you would almost certainly ‘see’ a flash of light. I have not flashed a light in your eye, but the altered electrical activity in the visual system is perceived by your visual cortex as ‘light’. In classic migraine, where the blood supply to the visual cortex is disturbed, flashes of light are a common experience.

Hearing ‘sounds’ when none is actually present can trigger quite severe additional symptoms because of the early warning effect contin­uing and the person remaining on alert (see box on page 89). Individuals can become on edge, bad tempered, irritable and unable to concentrate. If the onset of the tinnitus is associated with a bad event, such as an accident, an explosion, a whiplash injury, a family death, etc, this tends to accentuate its effect.

Other factors that raise the level of generalised brain-stem activity, such as anger, illness or tiredness when there is a need to remain alert, can all increase the awareness of the tinnitus and the distress that it is causing. Of course, thinking about the noises will tend to accentuate them.
This distress can start to affect individuals psychologically, depen­ding on their characters and personality. Some people have ordered, structured lives over which they have perfect control and they get extremely angry when they simply cannot command their tinnitus to go away. The more they concentrate on making it disappear, the worse it can get, driving them to greater anger, especially at night time in the quiet. Many individuals get up, switch on the radio, television, washing machine or tumble drier to drown out the noise, or may even go out and pace the streets.

Others despair that their world will never be quiet again and fear that they will always have this ‘noise’ with them wherever they go, and they may fall into a deep depression. Yet more will have great difficulty sleeping, and this lack of sleep and the need to function the next day leave them exhausted, which often tends to enhance the perception of the tinnitus. Many individuals are scared that they may have a brain tumour or some other terminal disease that is showing itself first by this noise. Indeed, in centuries past, noises in the head were often thought to be work of the devil. All in all, individuals can be affected in many different adverse ways depending on the impact that the tinnitus has on them personally.

Not all tinnitus is enduring; most people who go to over-loud clubs or concerts develop tinnitus but soon the noises fade into the back­ground and disappear. Some individuals have a relaxed, laid-back personality and just accept the sounds as ‘just another thing’ or ‘something to do with getting old’, and quickly come to accept their noises.

TYPES AND CAUSES OF TINNITUS

The different types of tinnitus

The vast majority of people with tinnitus have noises that can be heard only by them (subjective tinnitus). There is, however, a small group who hear sounds that are also audible to others; they have what is called objective tinnitus. These sounds are frequently the result of blood flowing through rough and narrowed arteries and causing a whooshing sound as it tumbles through the stricture. Sometimes abnormalities of veins, either malformations or benign tumours growing in or close to the ear (glomus tumours), can cause a similar whooshing, pulsatile sound, which can often be heard with a stethoscope held over the carotid artery and/or jugular vein in the neck. A woman once came to my clinic because her dog kept lifting its ears and listening to her right ear. She had, it turned out, a carotid artery narrowing and the high-pitched sounds of the blood rushing through the narrowed artery could be heard by her dog!

Clicking noises can also arise from the ear and seem to come from irregular, tic-like contractions of the muscles of the palate (palatal myoclonus) or of the middle-ear muscles. This phenomenon is similar to a facial tic when some of the facial muscles twitch, but in this case the closeness of the affected muscles to the ear makes the twitching audible. Some surgeons have attempted to cure these clicks, which can be extremely irritating to the sufferer, by cutting the muscles in the middle ear themselves, but this is rarely successful.

People whose noises are not pulsatile and cannot be heard by others describe what they hear in a huge variety of ways, including buzzing, ringing, whining and probably every possible sound that has ever been described. These sounds can also be located just outside the ear, in one ear or the other or all over the head. This type of tinnitus is called subjective and is the most common form of the condition.

CAUSES OF SUBJECTIVE TINNITUS

The ‘source’ of most forms of subjective tinnitus is not understood. It is easy to blame the hair cells by saying that they are malfunctioning, and that instead of detecting sound they are mischievously generating electrical signals that are then perceived as sounds. Scientifically, it is difficult to show that this is actually the case and, although it may be true in some people, it cannot be used as a general explanation.
However, there are some specific causes of subjective tinnitus that need to be excluded. This applies especially to tinnitus localised to one ear when, among other causes, middle-ear and mastoid disease must be ruled out. Investigations include a physical examination, audiometry and appropriate imaging by computed tomography (CT) or magnetic resonance imaging (MRI).

Tinnitus in one ear associated with some distortion of hearing is occasionally caused by an acoustic neuroma (see page 68). This is more likely if there is a sensori­neural hearing loss on the same side. The ideal way to find out whether a person has one of these benign but unpleasant tumours is to send him or her for MRI. This supplies sufficient detail to make certain that the person does not have one of the many other sorts of tumours and diseases in the head and, if this is the case, the tinnitus can be termed ‘idiopathic’ which, in effect, means without known cause – yet.

As technology improves and understanding of the mechanisms of tinnitus increases, the idiopathic group (without recognisable cause) – which is the majority at present – will probably get smaller as clear-cut causes will be found for many of those concerned. Once each clear-cut cause is defined, specific medical remedies should eventually become available.

However, at present for those people with idiopathic tinnitus without a hearing loss, all we can say is that somewhere along the line from cochlea to auditory cortex, irregular electrical signals are being generated. For people with a hearing loss, alternative mecha­nisms to explain their tinnitus have been proposed and this is how the argument goes: from the hair cell in the cochlea inwards, the hearing system is an electrical network with relays, junctions, enhancing devices, filters, etc. Any electrical system has electrical ‘noise’ in it. It is easy to demonstrate this by having a hi-fi amplifier turned to full volume with no input such as a CD or tape playing and, even if the system is extremely expensive, there will still be some noise heard through the speakers.

There will always be background electrical noise in the auditory system; normally you don’t hear this because your brain sets a threshold level that excludes it. For an incoming sound signal to be heard, it has to be greater than the background noise threshold. People have a wide range of hearing thresholds.

When a hearing loss occurs, whatever the cause, it may just be great enough to prevent normal external sounds reaching the brain. ‘Silence’ over the range of pitches represented by the deafness is therefore registered by the brain. The world is not a silent place – it may be quiet but silence is extremely difficult to achieve – and the absence of sound means that our early warning system cannot register change. The brain therefore reacts by dropping the threshold to ‘hear’ more, and by doing so strays into the internal noise levels so that the individual is hearing the workings of his or her own ear.

If placed in a totally silent space (an anechoic chamber) for experi­mental purposes, most people with normal hearing develop tinnitus, which slowly goes away when they return to a normal, noisy environ­ment. This effect will recur each time the experiment is repeated, but most people do not like the sensation of total silence because it gives them an uneasy, frightened feeling. This is presumably because they no longer have ‘hearing’ as their early warning system and they feel vulnerable at a primitive animal brain-stem level.

HOW THE BRAIN DEALS WITH CONTINUING EXTERNAL NOISES

Most of us have had the experience of sitting in a room, concentrating on something such as reading or writing, and then hearing the clock stop when we hadn’t previously noticed it ticking. Now, as the clock has stopped, there is actually nothing to hear but, previously, the brain stem filtered out the harmless repetitive noise of its ticking so that the sound did not reach the level of perception. This is more difficult to do with an irregular dripping tap, which can be a source of continued annoyance, partly because we tend to anticipate the arrival of the next drip and experience further brain­stem consternation when the sound does not occur.

Depending on the personality of the individual, he or she either learns to tolerate the irregularity or eventually gets furious and does something about it. The same thing occurs when you buy a new refrigerator. Initially the noise of it switching on and off in an irregular fashion and of the motor running can be irritating. Eventually, how­ever, almost everyone gets used to it and it stops being a problem.
The brain stem has awesome powers of processing incoming auditory signals. It can filter out those that it recognises as harmless in the light of experience. The early warning effect and all the additional emotional factors associated with unexplained and unexpected sounds do not arise, and the signal may eventually not even reach consciousness.

Humans have loaded on top of this complex survival computer an additional ‘higher level’ computer bank, which gives us sensations, feelings, thoughts and emotions that can, in turn, interact and influence the lower centres. The stage is thus set, in susceptible individuals, for an internal conflict with slightly unusual electrical activity in the auditory system awakening fear and anxiety in the ‘higher-level’ computer bank; this feeds back to promote general arousal of the brain stem and consequent distress. It is irrelevant whether the sounds are external or internal – the process remains the same.

DISRUPTION OF CONCENTRATION

Language is a very high-level skill and we use considerable brain power to understand speech. You can concentrate on only one conver­sation at a time and, although you may hear other voices going on around you, they are only sounds – you cannot understand the full sense. Almost everyone is familiar with the scene at a party when you are in deep conversation with some friends and there is a general babble around you. Someone behind your back mentions your name, which you hear, and immediately you shift the focus of your attention to this new and interesting sound. In doing so, you completely lose track of the first conversation.

Tinnitus is an attention thief. The unexplained sound tries to grab your attention. It is saying ‘Listen to me – I may be important’ and keeps distracting your brain from whatever it is doing at the time. People with tinnitus often have major difficulties in coping with complex mental tasks because of this unwelcome and persistent attention-grabber.

HELPING PEOPLE WITH TINNITUS

People who develop tinnitus can suffer serious distress and even psychiatric problems, including depression, anxiety and sometimes suicidal thoughts. Fortunately most people are not so severely affected and are referred by their GP to the ENT department of their local hospital.
At such a clinic, the ENT consultant will ask you questions to determine the nature of your problem and any associated symp­toms. If your symptoms suggest that you may have problems arising from local disease in your ear, nose and throat, your central nervous system or the major blood vessels of your neck, you will have a very thorough examination.

A pure-tone audiogram will probably be performed and, depending on the results and your symptoms, further investigations may be undertaken. In this way, the rare specific causes of tinnitus can be diagnosed and referred for appropriate treatment. For the vast majority of people, however, the tests will show that there is nothing life threatening or otherwise seriously wrong, and your doctor can be quite confident of this, whatever you may have feared. Such reassurance about the nature of the problem helps to allay inner fears, which are a potent source of the anxiety that keeps the tinnitus active. The next step is to find ways of managing the problem.

The aim of tinnitus management is to relieve the brain-stem ‘distress’ that comes with the sounds. The brain stem can be helped to ‘learn’ that the sounds are not a threat and that they can eventually be disregarded (acclimatisation), so that they no longer reach consciousness or activate the early warning effect. In many people, a careful examination, appropriate investigations and a clearly reasoned explanation are enough to set the process of acclimatisation in progress. However, the interaction between the higher centres of the brain and the brain stem are complex and poorly understood. Other people may need more help, depending on the severity and intrusiveness of their sounds and on their personality.

People with significant hearing loss

Restoration of hearing, usually with a hearing aid, often overcomes tinnitus by allowing the brain’s hearing thrshold to be reset, so that the tinnitus is no longer heard. This is the best result. Sometimes, restoring hearing is not immediately effective, but the level of the tinnitus drops significantly so that the internal sounds become less important in relation to newly heard external sounds.

Most forms of acoustic manage­ment of tinnitus now work in this way. Sounds are introduced to reduce the importance of the internal sounds, so that the brain stem ‘learns’ to push the tinnitus into the background and then into insignificance. Using loud sounds to drown out the tinnitus completely is known as full masking, but this is not now thought to be the best form of management; when the masking is removed, the tinnitus may still be present at the same level.

‘Masking’ techniques: sound generators

Hearing aids can be modified to incorporate a sound generator that produces an appropriate suppres­sing sound, perhaps wide-band white noise (a ‘shushing’ sound) at half the full-masking level. This combination is very effective in people with tinnitus and hearing loss if pure amplification is not enough to reduce the tinnitus level. Once the tinnitus levels have diminished, the degree of distress associated with them also lessens and the brain stem learns to filter out the intrusive sounds.

Pure masking devices set at half-masking levels are frequently helpful for those with normal hearing. The introduction of a not-unpleasant background sound provides a distraction, so that the primary ‘warning’ effects of the tinnitus start to diminish, and eventually the tinnitus stops being an irritation and is no longer heard.

Environmental aids

Many people find that getting to sleep in a quiet environment is a real problem. For these people, quiet environmental sounds, such as having a radio playing or a cassette with their favourite music or even something like an audio-book, are sometimes a great help. Some people find the low drone of speech quite soporific, whereas others listen to the sense and so cannot get to sleep. Everyone has his or her own special way of dealing with the problem, and some experimentation may be needed. Partners may get irritated by the chosen noise (in much the same way that tinnitus irritates the sufferer), but you can get pillow loudspeakers that can be heard only when your head is on your pillow and not by anyone else. Many high street electrical shops sell these relatively cheaply but in case of difficulty the RNID has a list of suppliers (see Useful addresses).

Quiet environmental sounds can also be used to relax you during the daytime. Many people who would normally work, read or do other things, such as knitting, in the quiet find that, once they have tinnitus, they need to have music playing in the background. There are now several useful tapes that provide soothing sounds, such as the waves of the sea, to help. The RNID can advise on where to buy these if your local audiology clinic or hearing aid centre cannot help.

PSYCHOLOGICAL HELP AND COGNITIVE THERAPY

Although the techniques described above help most people to manage their tinnitus, there is a minority whose personality makes it difficult for them to tolerate this imper­fection, or who cannot accept that there is something in their lives that they are unable to control. These people need additional help, because they tend to concentrate on the tinnitus in an attempt to make it disappear. This is like trying to make yourself go to sleep – you cannot succeed in this, you simply fall asleep despite your efforts. In trying to make ‘nothing’ happen it becomes ‘something’ and this philosophy applies to tinnitus exactly.

Distraction is needed, and various relaxation techniques are useful in deflecting concentration away from the tinnitus. These techniques usually need to be taught by hearing therapists or people who are trained in the techniques. Most NHS audiology departments or hearing aid centres have hearing therapists trained in these techniques. There are many relaxation tapes and yoga-type exercises that help people who are already using sound substitution devices such as maskers, hearing aids, pillow speakers, etc. Indeed, effective relaxation therapy alone may be enough to overcome the tinnitus-related distress.

There are also some simple techniques or tricks to help at night if tinnitus either stops you falling asleep or prevents you from dropping off again when you wake during the night. First, do not look at the clock. Next, do not get up and make a cup of tea or coffee. These actions bring awareness and the stimulants in tea or coffee prolong this. Find a simple word – I like rich-sounding words such as ‘implosion’ or ‘cartridge’ – and gently repeat them again and again with different emphasis.

People become deeply entwined with their tinnitus so that it becomes a focus of their lives, taking over most minutes of every day. They find that they cannot let go of the symptom, which comes to dominate them. Cognitive therapy is a technique directed at altering the way in which people think about their symptoms.

Imagine standing in a stuffy, noisy, crowded underground train. You are packed shoulder to shoulder, you cannot move and you cannot turn your head it is so crowded. Then you start to feel someone behind you poking you in the ribs with what must be a sharpish object as it is very painful. This is an irregular but recurring event. What do you feel? Pain, of course, but also anger, resentment, and fear perhaps, but why? People give many different reasons. They may feel out of control, threatened, invaded, that the other individual is so selfish and so on – you may have other thoughts.

Eventually the train reaches the station and enough people get off to allow you to turn around and speak your mind. As you turn you see that the person behind is a blind man and that it is his white stick that has been prodding you. Now what do you feel? I am sure it is not the same as before.

The essence of the plot is that symptoms (tinnitus/pain/dizziness, etc.) engender feelings (anger/ frustration/fear) because of the way we think about them. Cognitive therapy aims to alter that link between symptoms and feelings so that the symptoms become ‘acceptable’. Once they do the symptoms tend to evaporate. Cognitive therapy for tinnitus is a specialist skill that is available within the NHS, although the provision of services is very patchy. I refer you to some excellent short books by my colleagues, which are in the reading list on page 105.

SURGERY FOR TINNITUS

Avoid surgery for tinnitus like the plague. Tinnitus is a symptom and surgery is performed for conditions that give rise to symptoms. Since virtually all forms of tinnitus are without a truly known cause, surgical procedures claiming to be curative are not logical. The emotional effect of a major operation may displace the symptoms of tinnitus. The pain of surgery may act as a ‘masker’ much as acupuncture helps relieve tinnitus while it is in use. However, performing operations to ‘cut the cochlear nerve to prevent the hair cells from sending tinnitus signals to the brain’ simply does not work and may even make individuals worse, because a dead ear cannot be helped by hearing aids, sound generators or environmental aids.

Some conditions have tinnitus as part of their presentation. Examples are otosclerosis and acoustic neuromas. Indeed the tinnitus may well improve after successful surgery to restore the hearing in otosclerosis and may become much less marked after acoustic neuroma surgery with hearing preservation. However, it is an unwise surgeon who promises that the tinnitus will get better in these specific conditions; if it does then that is an unexpected bonus.