Introduction

 

This short page relates to the ENT causes of chronic cough. You will have instruction from respiratory and paediatric medicine, amongst others, on other causes of cough. The page starts with a general recap of what a cough is, what it is for, and how is it generated. At the bottom there is a brief discussion on the ENT cases.

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What is a cough?

 

A reflex action causing a sudden, sharp expulsion of air from the lungs.

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How is it classified?

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Cough is categorised into acute (less than 3 weeks), subacute (between 3 and 8 weeks), and chronic (more than 8 weeks). CHEST 2006 cough guidelines.

 

What triggers a cough?

 

A cough is a response to irritation or inflammation in the airway. Its aim is to displace the irritant or infected material so that it can be removed from the airway and, usually, swallowed.

 

What is the mechanism of a cough? How does it work?

 

There are a number of simple steps in a cough:

 

1. An irritant stimulates sensory fibres in the lung, airways, pharynx or larynx. The afferent limb of the reflex is mediated by the vagus nerve. 

 

2. This sensory information is sent to the pons and upper brainstem to the ‘cough centre’.

 

3. The efferent part of the reflex involves motor activity being sent, via a number of different motor nerves, to the:

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a. Diaphragm

b. Intercostal muscles

c. Abdominal muscles

d. Glottic muscles

 

The reflex results in the familiar steps of a cough.

 

First, there is a breath inwards. The lungs fill with air through the action of the diaphragm and intercostal muscles.

 

Second, the vocal cords close, sealing off the airway.

 

Third, the diaphragm relaxes, expiratory muscles (abdominal and intercostal muscles) start to contract and the pressure in the airway increases because the glottis is closed.

 

Next, the vocal cords relax and air is ejected suddenly and at high speed – around 100mph.

 

You will learn more about cough and the diseases that cause it in your respiratory and paediatric modules. Here we will concentrate on the aspects of cough that relate to ENT diseases.

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What conditions do ENT departments see that cause cough?

 

In practice, in the UK, ENT only see chronic coughs referred from Primary Care. They are referred because GPs cannot fully rule out serious laryngeal or pharyngeal diseases that may provoke chronic coughing. There are also a number of ENT related conditions that we can help with, most of them in the nose or sinuses.

 

The common causes of chronic cough are: asthma, non-asthmatic eosinophilic bronchitis, gastroesophageal reflux disease (GERD) and upper airway cough syndrome (UACS) secondary to nasal and sinus disease.

 

It is the last of these that the ENT department can help with. We can also rule out malignancy in the pharynx and larynx, two conditions that might, very rarely, irritate the airway and cause cough without other symptoms.

 

Upper airway cough syndrome (formerly known as post-nasal drip syndrome)

 

The definition of UACS is a cough that has lasted more than 8 weeks i.e. is chronic, together with abnormal sensation in the throat (e.g. a feeling of something stuck in the throat, mucus or phlegm in the throat) and a postnasal drip sensation.

 

Nasal and/or sinus disease is the main causative factor in UACS and there are seasonal and occupational triggers for some. Some other non-specific triggers include aerosols, changes in room temperature, and air conditioning. These can trigger cough in other conditions too.

 

Treatment is aimed at controlling the triggers where possible and by managing upper airway sources of irritation such as rhinitis or chronic rhinosinusitis. Thus, antihistamines, inhaled corticosteroids, alone or in conjunction are important. Nasal douching is helpful in chronic rhinosinusitis too.

 

Other treatments include speech and language therapy to assist in controlling cough, and antacid medications for possible co-existent gastroesophageal reflux disease.

 

Laryngeal and pharyngeal malignancy

 

It should be said at the outset that an isolated chronic cough is very unlikely to be caused a laryngo-pharyngeal malignancy. Patients will almost always have some of the other symptoms of malignancy: dysphonia, dysphagia, neck lump, haemoptysis, referred otalgia, weight loss. Generally, they will also be smokers and may have problems with alcohol excess too.