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Dysphonia (voice disorder)

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Dysphonia (voice disorder)

Written by Dr Michael SW Lee, specialist registrar in otolaryngology, Ninewells Hospital, Dundee

What is dysphonia?

Dysphonia is a descriptive medical term meaning disorder (dys- ) of voice (-phonia). There are many causes of dysphonia. Fortunately more than half of people with voice complaints have a benign (non-cancerous) cause.

How is voice normally produced?

The generation of voice requires a sound-producing ('phonatory') system, a control centre and a network connecting the two.

Phonatory system The larynx (voice box) has a framework of cartilage with muscles attached to different structures. It also has a pair of vocal cords which move apart on breathing in (inspiration) and come closer together on breathing out (expiration).

The vocal cords resemble two small blinds that can be drawn across from the side of the larynx in to the middle, thus causing a variable restriction in the amount of air that can pass through.

According to how tightly the muscles tense the edges of the vocal cords and how much breath pressure is applied, the frequency of vibration of the cords can be changed very rapidly, which generates the tone of the sound being produced. The pharynx (area at the back of the throat) and oral cavity act together as a sound resonator.

Understandable voice is produced by co-ordinated movements of the tongue, lower jaw and soft palate â€“ the flexible part of the roof of the mouth. This process is called articulation. Clearly it is a complex system, depending for its success on sophisticated control.

Control centre

The brain acts as a control centre which receives and sends out signals to different parts of the body including the diaphragm, muscles of the chest wall, abdomen, larynx, pharynx, oral cavity, tongue, soft palate and lower jaw and co-ordinates their movements.

Connecting network

The crucial nerves that carry the brain's signals to the muscles of phonation are the laryngeal nerves, which are themselves branches of the 10th cranial nerve â€“ the 'vagus' nerve. As with the other cranial nerves, (which all exist in pairs) the vagus arises directly from the brain, rather than from the spinal cord, and travels through a specific opening in the skull to reach its location.

What symptoms do people with dysphonia have?

People with dysphonia may present with hoarseness and a sore or dry throat. A singer may notice that he or she is no longer able to sing in the upper range. There may be other associated symptoms such as a continuous drip at the back of the throat (nasal catarrh) and heartburn.

When should a patient seek treatment?

Any person who has been hoarse for four weeks or more should seek medical attention from their family doctor. They may require to be seen by an ear, nose and throat specialist for further examination including inspection of the larynx. This can be done quite easily (by the specialist!) using an angled mirror, or flexible fibre-optic 'telescope'.

Persistent hoarseness, difficulty in swallowing, sore throat, choking when swallowing (especially fluids), persistent earache, coughing up blood, weight loss and loss of appetite may indicate a more serious condition and should always be taken seriously.

Causes of dysphonia

Inflammation of the larynx (voice box) over a short (acute) or long (chronic) period of time.

Lumps (nodules) on the vocal cords (eg singer's nodules).

Underactive thyroid gland â€“ hypothyroidism.

Trauma - any kind of trauma, including surgery, to the vocal cords will inevitably cause scarring and hence affect the vocal fold function. The risk of permanent voice change therefore needs to be discussed prior to surgery on the larynx.

Vocal cord paralysis â€“ some other surgical operations including removal of the thyroid gland and heart or lung surgery can damage the nerves to the larynx causing either temporary or permanent vocal cord paralysis (palsy).

Reinke's oedema of the larynx.

Psychological - voice changes are not uncommon when people are under stress either at work or at home. The voice may be lost suddenly, usually overnight or following a cold. It is important to identify and remove the underlying stress. Speech therapy is very useful for this cause.

The above conditions are commonly seen in ENT (ear, nose and throat) specialist clinics but there are many other relatively uncommon and rare diseases not mentioned here.

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