Swallowing is a complex mechanism; we swallow at least 600 times each day and up to 1.5 litres of this can be subconscious swallowing of our own saliva. The process in which we move a bolus of food or fluid through the oral cavity, the pharynx and the oesophagus involves the use of six cranial nerves and more than 25 pairs of muscles. It is a process so natural to our everyday lives that we rarely take time to appreciate our ability to perform it safely, no matter what the circumstances. 

Dysphagia is a medical term used to describe a swallowing disorder, and is characterised by difficulty in oral preparation for the swallow, or in moving material from the mouth to the stomach. It is not a disease but a symptom of an underlying condition (see Table 1). 

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Oropharyngeal dysphagia is a highly prevalent condition, particularly in three main at-risk populations; elderly patients (30-40%),¹ patients with neurological injuries (40-81% in stroke)² or neurodegenerative diseases (52-82% in Parkinson’s  disease)^3,4 and patients with head or neck diseases (51% in head and neck cancer).⁵

Signs of dysphagia depend on the phase of swallowing in which the difficulty occurs. Food enters the mouth in the oral/preparatory phase, is chewed, and mixes with saliva to ease swallowing. The food forms a ‘bolus’, which is propelled to the back of the mouth by the tongue in preparation for swallowing. Signs of dysphagia during the oral/preparatory phase may include: 

• Poor chewing ability

• Drooling 

• Food escaping from mouth

• Residue in oral cavity.

The pharyngeal phase is an involuntary process in which the bolus passes down the back of the throat, controlled by the throat muscles. A small flap called the epiglottis flips over the trachea to direct food or fluid down the oesophagus and protect the airway. Signs of dysphagia during this phase may include: 

• Wet or gurgly voice

• Coughing or choking

• Frequent throat clearing.

During the oesophageal phase, smooth muscle contractions direct the bolus down the throat into the stomach. Signs of dysphagia during this phase may include:

• Heartburn

• Reflux

• Feeling of food ‘sticking’ in the throat.

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Aspiration, malnutrition and dehydration

As you might expect, when someone has difficulty swallowing, there are many implications on their ability to eat and drink. Poorly managed dysphagia is known to be associated with severe respiratory and nutritional complications which, when combined, create a heavy fiscal burden on the healthcare system, as well as a devastating effect on patients’ quality of life:

• 51%of patients with dysphagia suffer from aspiration; the entry of food or fluid into the airway that penetrates below the level of the vocal cords. Aspiration is strongly associated with pneumonia,^6,7 repeated and longer hospital admissions,⁸ significantly higher mortality rates,⁹ and a greater likelihood of being discharged into institutional care¹⁰

• 48% of patients with dysphagia are malnourished.¹¹ This may be explained by the physical effects of dysphagia which make the process of eating slow, difficult and tiring;¹² the quality and quantity of food consumed is often reduced;¹² preparation skills for texture modified diets can be limited;¹² and patients’ fear of choking can result in a reduced variety of foods being consumed¹²

• 75% of patients with dysphagia are dehydrated,¹³ and those requiring thickened fluids are significantly less likely to meet their fluid requirements.^14,15 Dehydration increases the chance of falls, the risk of urinary tract infections,¹⁶ renal failure, constipation, impaired mental status (irritability and confusion), respiratory infection, poor muscle strength, pressure ulcers and increased mortality in elderly patients.^17,18

Psychological impact of dysphagia

Eating and drinking is about much more than nutrition and hydration. They are fundamental pleasures in life – from the joy of experiencing crunchy, crackling, chewy, crispy textures or a refreshing chilled drink, to gathering with friends and family at social celebrations – eating and drinking are integral parts of our everyday lives. 

The social and psychological impact of dysphagia is often dwarfed by the risk of aspiration, malnutrition and dehydration. A study of 360 patients with dysphagia across Europe identified the crippling toll that dysphagia can have on quality of life:¹

• 50% of respondents claimed they were eating less

• 41% experienced anxiety or panic during mealtimes

• 36% avoided eating with others

• 55% said swallowing difficulties made their life less enjoyable

• 32% reported still being hungry after their meal.

Eating can become an unsociable activity, people with dysphagia can be embarrassed about eating a texture modified diet, or experience a loss of control over their own food choices. Meals often take longer to eat and may lack variety or flavour, falling into the lower end of the ‘meal appeal’ spectrum.

In summary, dysphagia is a disorder of the swallowing process which does not allow safe passing of food or fluid from the mouth to the stomach. 

It is highly prevalent in Ireland and a common consequence of neurological injury, learning disabilities, progressive neurological disease, mechanical or obstructive diseases, and ageing. 

The consequences can be serious, including aspiration pneumonia, dehydration, malnutrition and increased risk of mortality, as well as the social and psychological consequences of dysphagia. 

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References

1. Ekberg O, et al. Social and psychological burden of dysphagia: its impact on diagnosis and treatment. Dysphagia 2002; 17(2): 139-46
2. Martino R, et al. Dysphagia after stroke: incidence, diagnosis, and pulmonary complications. Stroke 2005; 36: 2756-2763
3. Clave P, et al. Approaching oropharyngeal dysphagia. Rev Esp Enferm Dig 2004; 96: 119–131
4. Michou E, et al. Oropharyngeal swallowing disorders in Parkinson’s disease: revisited. Int J Speech Lang Pathol Audiol 2013; 1: 76–88
5. Garcia-Peris P, et al. Long-term prevalence of oropharyngeal dysphagia in head and neck cancer patients: impact on quality of life. Clin Nutr 2007; 26: 710-717
6. Langmore SE, et al. Predictors of aspiration pneumonia: how important is dysphagia? Dysphagia 1998; 13(2): 69-81 
7. Heuschmann et al. Predictors of in-hospital mortality and attributable risks of death after ischaemic stroke: the German Stroke Registers Study Group. Arch Intern Med 2004; 13(16): 1761-8
8. Smithard DG et al. Complications and outcome after acute stroke: does dysphagia matter? Stroke 1996; 27(7): 1200-1204
9. Rofes L, et al. Pathophysiology of oropharyngeal dysphagia in the frail elderly. Neurogastroenterol Motil 2010: 22: 851-858
10. Rowat A, et al. Dehydration in hospital-admitted stroke patients, detection, frequency and association. Stroke 2012; 43: 857-859
11. Felt. Nutritional management of dysphagia in the healthcare setting. Healthcare Caterers International 2006; 1(2): 11-14
12. Copeman J, et al. In: Manual of dietetic practice. 4th ed. British Dietetic Association, 2014; 416-423
13. Leibovitz A, et al. Dehydration among long term care elderly patients with oropharyngeal dysphagia. Gerontology 2007; 53: 179-83
14. Finestone HM et al. Quantifying fluid intake in dysphagic stroke patients: a preliminary comparison of oral and non-oral strategies. Arch Phys Med Rehab 2001; 82: 1744-1746
15. Vivanti AP et al. Contribution of thickened drinks, food and enteral/parenteral fluids to fluid intake in hospitalised patients with dysphagia. J Hum Nutr Diet 2009; 22: 148-155
16. McKinlay J. Nutritional assessment: identifying patients’ needs. J R Coll Physicians Edinb 2004; 34: 28-31
17. Wotton K, Crannitch K, Munt R: Prevalence, risk factors and strategies to prevent dehydration in older adults. Contemp Nurse 2008; 31: 44-56
18. Stanga Z et al. Dysphagia: dehydration in dysphagia. Medical Radiology pp. 601-610. doi 10.1007/174_2011_349