Known by other names (chronic idiopathic cough, unexplained chronic cough), it is defined as:
A cough that persists despite specialist guideline treatment.
This of course means it is a diagnosis of exclusion.
It is either one form of cough hypersensitivity syndrome or another name for cough hypersensitivity syndrome (the article was a little contradictory but the former is what the main body of the article said, so I’m going with that), cough hypersensitivity syndrome being a type of hypersensitivity of the larynx/upper airway, caused by mucosal upregulation of cough receptors.
Other overlapping conditions include laryngeal hypersensitivity (which surely would be the same thing as cough hypersensitivity syndrome? Jeepers, this article isn’t clear) and paradoxical vocal fold movement, which actually is something different although associated. PVFM is an abnormal motor pattern of the larynx, with adduction of the vocal folds during inspiration after a stimulus, causing inspiratory dyspnoea, stridor, and throat tightness.
The main symptom is a dry irritated cough, localised to the laryngeal region, occurring in intermittent bouts through the day. Other associated symptoms can include:
It is often triggered by a viral infection.
Red flag findings in chronic cough
- Smoking history of >20 pack years
- Smoker >45 with a new or altered cough
- Smoker >45 with voice disturbance
- Prominent dyspnoea – especially at rest or at night
- Substantial sputum production. ‘Substantial’ here is definined as ‘>1 tablespoon/day’.
- Systemic symptoms – fever or weight loss
- Complicated GORD symptoms, not responding to normal GORD treatments, or associated with red flag upper GI symptoms
- Recurrent pneumonia
- Abnormalities on examination or CXR
Treatment – non-pharmacological
Speech pathology treatment. This consists of an initial assessment of 45 – 60 minutes, followed by four components:
- Cough suppression strategies/other symptom control techniques
- Vocal hygiene training
- Psychoeducational counselling
Treatment – pharmacological
- Centrally acting neuromodulators: gabapentin, pregabalin, amitriptyline, morphine, and baclofen. All of these have been found to improve quality of life for people with CRC, but the adverse effects can limit their use considerably.
- Inhaled ipratropium
Note that inhaled steroids do not appear to work – two out of three RCTs showed no benefit.
Combined pharmacological and non-pharmacological treatment may work better than either alone; one RCT compared pregabalin and placebo in patients receiving speech pathology therapy, and found significant improvement in both cough severity and cough-related quality of life in the pregabalin group.