Causes of dysphagia
Dysphagia can be either acute or chronic and can also have either a physical or psychological origin.
Swallowing difficulties become more common with increasing age. This is because as patients get older their ability to produce saliva reduces, there is a progressive weakening of the muscles involved in the swallowing reflex, and they are also more likely to be taking medication shown to cause difficulty swallowing. In a study of six hundred older people it was shown that 33% of them took at least one medicine that could cause dry mouth or xerostomia.1
Considering the relatively high prevalence of dysphagia in the elderly and its presence in patients with disabling conditions it is unsurprising that the incidence of dysphagia in care homes for the elderly is up to 75%.2
Physiological factors
Physical disturbance of any of the stages of the swallowing reflex will impair a person's ability to swallow.
The oral phase can be affected by sensory or cognitive disturbances that lead to an inability to detect food within the mouth. Altered muscle tone of the lips, tongue or soft palate can affect a person's ability to retain material within the mouth or shape the material into a bolus. For example a stroke can lead to hemiparesis of the tongue and this loss of sensation can cause food to be retained at the side of the mouth. Similarly, weakness of the oral musculature can cause difficulty retaining food within the mouth. Choking can occur where the patient is unable to create the correct size bolus or the throat muscles are too weak to force the bolus into the oesophagus.
A loss of sensation in the pharynx results in a delay to the pharyngeal phase; impaired closure or incomplete elevation of the larynx can lead to aspiration of food or liquids into the lungs. Repeated aspiration of food or liquid into the lungs can be associated with the development of pneumonia.
Any impairment of the peristaltic muscle contractions or obstruction of the oesophagus will prevent the movement of material into the stomach. This is frequently reported as a problem by patients with oral or oesophageal cancer.
Acute dysphagia can occur in a patient with a severe sore throat or an acute exacerbation of gastro-oesophageal reflux.
Chronic dysphagia can affect patients who suffer from neurological conditions such as Parkinson's disease, Huntington's disease, dementia, multiple sclerosis, cerebral palsy, or muscular dystrophy. Almost half of Parkinson's disease patients will experience some form of dysphagia.3 Neuropathic changes associated with chronic type 2 diabetes can also lead to the development of dysphagia.
Symptoms of dysphagia are common in patients who have had a TIA or stroke; studies have shown that in the early stages of stroke between 64% and 90% of patients will show signs of swallowing problems or dysphagia.4
Patients who are unable to communicate are at an increased risk of dysphagia which explains the high incidence of swallowing difficulties in patients with learning disabilities. This is attributed to a combination of complex physiological and psychological factors.
Patients may suffer from a psychological aversion to swallowing medicines. As this psychological aversion can occur at any age it is important that prescribers ask all patients about whether they have difficulty swallowing medication before prescribing. Pharmacists should also enquire whether patients experience difficulty swallowing their medication when counselling or undertaking advanced services such as MURs or NMS.
It is worth remembering that many patients experiencing difficulty swallowing their medication will not inform a healthcare professional that they are having difficulties or are modifying their medication. An Australian study showed that community pharmacy patients were reluctant to seek the advice of a healthcare professional before modifying their medication and were more likely to either take the advice of family and friends, or make the decision to modify their medication alone.5
This survey shows that community pharmacists may need to be assertive when questioning patients about difficulties with swallowing medication. This survey also demonstrated a concerning ignorance of the potential dangers of modifying medication.