Tinnitus

Contributed by Dr Laurence McKenna, clinical psychologist specialising in tinnitus management at the Royal National Throat Nose & Ear Hospital, London.

Section 1: Epidemiology
Tinnitus is the perception of sound in the absence of an external auditory stimulation.

Often referred to as 'ringing in the ears' it is most commonly experienced as a high-pitched noise sometimes having a mechanical, electrical or musical quality.

Tinnitus is commonly associated with a hearing loss and hyperacusis, the latter producing a reduced tolerance for everyday loud sounds.

Low-pitched tinnitus is common in Meniere's disorder and conditions that cause conductive hearing loss such as otitis media and otosclerosis.

Transient tinnitus is common following exposure either to loud sounds or to silence, but is rarely a cause for concern.

Prevalence
Persistent tinnitus is experienced by approximately 10 per cent of the adult UK population1 making it one of the most common physical symptoms.

Prevalence increases with age, but tinnitus is also common in children.

There is a trend for more women than men to report tinnitus and for women to describe more complex tinnitus sounds.

It is slightly more common in unskilled rather than professional social groups and this difference is not explained by differences in noise exposure.

Bilateral tinnitus is the most common presentation, followed by left-sided tinnitus. The latter is not accounted for by greater noise exposure.

Effect on patients
Some patients describe tinnitus as central in the head and a few describe it as emanating from outside of the head.

The location and quality of tinnitus is not predictive of the distress experienced by the patient. Many people who experience tinnitus find they are not distressed by it.

Of the adult population, 1.6 per cent are severely distressed by tinnitus and 2.8 per cent are moderately distressed by the condition.

This means that approximately half of patients with tinnitus find it moderately or severely distressing.

About 7 per cent of the population consult a doctor for tinnitus but only 2.5 per cent seek specialist otological or audiological help.

Main reasons for tinnitus complaint
  • Intrusiveness.
  • Emotional distress.
  • Insomnia.
  • Auditory perceptual problems.
  • Concentration problems.

Section 2: Aetiology
Cochlear models of tinnitus are insufficient to explain the distress that can be experienced with the condition.

Tinnitus can occur in a seemingly normal cochlea and can persist even after auditory nerve section.

A variety of underlying mechanisms for tinnitus have been proposed (see box).

Imaging studies have pointed to the involvement of central structures involved in attention and emotion, as well as those involved in hearing and processing sound.

Whatever the cause of tinnitus, a fundamental issue is what makes it distressing to the patient.

There is a poor correlation between the psychoacoustical features of tinnitus, such as its perceived loudness and quality, and the level of distress that is experienced by the patient.

Habituation
The natural history of tinnitus is characterised by habituation. Tinnitus becomes problematic when this process is impeded or reversed.

There are two explanations for how habituation could fail.

A psychological model suggests that the patient fails to habituate to tinnitus when they have a high stress level and the tinnitus takes on an emotional significance (for example if the patient fears the tinnitus will stop them enjoying life).

The result is selective attention to the tinnitus, maintaining the beliefs that provoke anxiety and creating a vicious cycle.

This process is considered to be a conscious one that is amenable to psychological treatment.

A neurophysiological model suggests that habituation to tinnitus is prevented when the condition is associated, through a process of classical conditioning, with some other co-incidental stress, such as that of retirement.

Again, this establishes a vicious cycle of stress reaction and tinnitus detection.

Unconscious process
This process is seen as primarily unconscious, involving the development of neurophysiological reflex arcs that require removal through a conditioning extinction process.

There is considerable overlap between the models but they differ in scientific philosophy, and in particular in the extent to which they regard conscious or unconscious processes as central.

 

 Possible mechanisms underlying tinnitus
  • Mechanical effects in the middle ear.
  • Spontaneous otoacoustic emissions from the cochlear.
  • Loss of cochlear hair cells (selective loss in the case of tinnitus without hearing loss).
  • Altered spontaneous activity in the auditory nerve.
  • Increased spontaneous activity in more central structures such as the dorsal cochlear nucleus, the inferior colliculus and secondary auditory cortex.
  • Plastic reorganisation of central pathways including the cortex, thalamus and inferior colliculus.
  • Inappropriate feedback via descending pathways.

Section 3: Diagnosis
Tinnitus itself is now listed as a distinct disorder in the WHO international classification of diseases (ICD-10). In diagnosing tinnitus it is important to determine if it is symptomatic of another condition (see box) and if there are other symptoms such as hearing loss or hyperacusis.

Tinnitus can be a sign of a range of disorders of the auditory system, from head injury to presbyacusis. It may be caused by a number of medications, including salicylates and NSAIDs. Antidepressants and PDE5 inhibitors such as sildenafil may also trigger tinnitus.

Often there is no obvious otological trigger and a presentation is the onset of tinnitus after a period of stress.

A distinction is made between objective and subjective tinnitus. Subjective tinnitus is a phantom sound heard by only the affected individual.

Objective tinnitus, which affects a minority of cases, results from internal body sounds that can be heard by others, such as those produced by muscle twitches, breathing and pulse.

Diagnosis is made on the basis of the history and the exclusion of other possible causes.

Pulsatile tinnitus
Patients with pulsatile tinnitus experience a rhythmical noise, often at the rate of their heart beat. This form of tinnitus can arise following changes in blood flow due to exercise, heart failure, angina or drug treatment.

It can also be caused by localised blood flow changes due to atherosclerotic disease or vascular tumours. Conductive hearing loss from a perforated ear drum can cause pulsatile tinnitus by reducing external masking noises and increasing awareness of internal noises.

Pulsatile tinnitus may also be associated with benign intracranial hypertension. It can be investigated using ultrasound, CT, MRI, or magnetic resonance angiography scanning.

Anxiety and depression
There is a high co-morbidity between clinically significant tinnitus and anxiety and depression, however, care is needed in establishing whether a patient is suffering a psychological disorder. Many patients feel that a mental health assessment means that their tinnitus is not being taken seriously.

Tinnitus is distinguished from auditory hallucinations by its lack of intrinsic meaning.

Some patients describe their tinnitus in terms of distant voices or music but are unable to report what the voices are saying, and music tends to be restricted to the repetition of a few bars.

When patients complain of being persecuted by tinnitus they are referring to anxieties about the effects of tinnitus. Tinnitus patients do not report other symptoms of psychosis.

Psychometrics
Psychometric questionnaires, such as the Tinnitus Questionnaire2 and the Tinnitus Handicap Inventory3, are available for determining the severity of tinnitus. Psycho-acoustical tests are available but do not correlate well with the levels of distress that patients report.

Visual analogue scales referring to awareness and annoyance can be helpful in assessing severity and change.

Conditions that can cause tinnitus
  • Impacted wax.
  • Glue ear.
  • Perforation of the tympanic membrane.
  • Otitis media.
  • Otosclerosis.
  • Meniere's disorder.
  • Noise trauma.
  • Tempero-mandibular disorder.
  • Middle ear myoclonus.
  • Palatal myoclonus.
  • Eustachian tube dysfunction.
  • Vestibular schwannoma.

 

Section 4: Management
Surgical intervention for tinnitus is not usually appropriate, and there is no medication available to abolish or reduce the presence of tinnitus.

Treatment often leads to disappointing results. There is a common belief that nothing can be done to help the tinnitus patient, but this is not true. The point of tinnitus management is to remove the distress associated with tinnitus.

In primary and specialist care settings this is best achieved through education, reassurance, relaxation and counselling.

It is important to advise patients that any distress associated with tinnitus will ease as habituation takes place and, where necessary, treatments exist to facilitate habituation.

Antidepressants
Antidepressants, including low- dose amitriptyline, have been used to treat tinnitus without much success. They should only be prescribed in cases where a diagnosis of depression is made.

Patients can be anxious and suffer from insomnia. They will benefit more from antidepressants with a sedating or anxiolytic component.

Sound therapy
Within an audiology setting, psycho-educational counselling, together with sound therapy (through either noise generators or hearing aids), represents the mainstay of audiological rehabilitation.

The purpose of sound therapy is to partially mask tinnitus and so reduce the patient's reaction to it. Reduced reaction leads to reduced perception of the tinnitus, establishing a positive cycle.

This process may take many months. This approach is known as tinnitus retraining therapy.

CBT
The management approach for which there is the strongest evidence is cognitive behavioural therapy (CBT). This helps by identifying and modifying the patient's unhelpful thoughts and behaviours with regard to tinnitus.

Patients often seek to avoid tinnitus by using background sounds to mask it and make every effort not to think about it.

These strategies rarely work. Masking prevents habituation and trying not to think about something usually results in more unwanted thoughts.

CBT helps the patient to use structured thinking about tinnitus that results in less anxiety.

Insomnia
Insomnia is one of the most common reasons for a tinnitus complaint.

It is experienced by 50-70 per cent of patients who suffer with tinnitus.

CBT is the preferred method of management.

Special care is needed in prescribing hypnotics to these patients because withdrawal can aggravate tinnitus.

National Tinnitus Week runs 11-17 February. For more information see www.tinnitus.org.uk

Resources

  • The British Tinnitus Association (BTA): www.tinnitus.org.uk. (Helpline 0800 018 0527)
  • The Royal National Institute for Deaf People: www.rnid.org.uk. (Telephone: 0808 808 0123).

Further Reading
Andersson G, Baguley D, McKenna L & McFerran D. (2005) Tinnitus: A multidisciplinary approach. Wiley.

References
1. Davis A, El Rafaie A. Epidemiology of tinnitus; in Tinnitus Handbook. San Diego, Singular Publishing Group, 2000, pp 1-23.

2. Hallum R S. Manual for the tinnitus questionnaire, 1996. the Psychology Corporation, Harcourt, Brace & Company.

3. Newman C, Sandridge S, Jacobson G. Psychometric adequacy of the Tinnitus Handicap Inventory (THI) for evaluating treatment outcome. J Am Acad Audiol 1998; 9: 153-60.

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