Swallowing is a complex process, involving multiple sets of muscles being innervated by seven of the cranial nerves. The normal swallow process is described in four stages: the oral preparatory stage, oral stage, pharyngeal stage and oesophageal stage.
During the oral preparatory stage the individual anticipates food reaching the mouth. The oral phase begins as the bolus moves posteriorly, with the tongue moving forwards, elevating the bolus and carrying it back, in a 'stripping' action.1
The pharyngeal stage is triggered as the bolus passes the anterior faucial arches. The velum elevates and retracts, closing off the nasal cavity to prevent nasal regurgitation.
The larynx elevates and moves anteriorly. This suspends respiration by closure of true and false vocal folds, and by moving the epiglottis to cover the larynx.
The laryngeal movement also allows the cricopharyngeal sphincter to open for the bolus, which is propelled through the pharynx via the action of the base of the tongue retracting.1
The oesophageal stage starts as the bolus moves through the cricopharyngeus and continues to the stomach.
Contributing factors and consequences
An impairment of the swallow function is known as dysphagia; it can occur for a wide variety of reasons, to people of all ages.1 For example, there is a high incidence of dysphagia after stroke, with figures ranging from 40 to 70%.2,3
Dysphagia is common among the elderly, and in many progressive neurological diseases, such as Parkinson's disease and motor neurone disease. Many factors can contribute to dysphagia, including posture and position when feeding, cognition, fatigue, bolus size, bolus viscosity and poor oral hygiene.3
Dysphagia can lead to oropharyngeal material passing into the airway below the level of the vocal folds, known as aspiration. The consequences of aspiration can be significant, with pneumonia, airway obstruction, scarring in the lungs and death being recognised as possible outcomes.
Research has demonstrated that aspiration pneumonia can develop from aspiration, with the presence of pathogenic bacteria in the aspirated secretions causing infection.4
A link between dysphagia and the development of aspiration pneumonia in the elderly has been shown.5
There are a number of overt indicators that denote aspiration is occurring when eating or drinking. A reflexive reaction is to cough to protect the respiration system from the foreign object. Other markers include 'gurgly' voice quality after swallowing, expectoration of material and reoccurring pneumonia.1
Conversely, it is known that patients can also aspirate silently,6 placing them at higher risk of difficulties going undetected.
Speech and language therapy
If GPs suspect a patient is presenting with dysphagia, they can refer the patient to a speech and language therapist (SLT) who is trained in oropharyngeal dysphagia.
The SLT will then carry out a swallowing assessment to examine any contributing factors.
For example, the patient may have poor oral movements, the swallow trigger could be absent, delayed or uncoordinated, there may be reduced laryngeal elevation or high levels of swallow fatigue.1
The SLT may request the GP to refer the patient for a radiographic assessment known as a videofluoroscopy. This is a dynamic procedure which allows the clinician to see the swallow while the patient is eating and drinking.
This assessment can be instrumental in examining the swallowing difficulty and the effects of management techniques. It can also serve to educate the patient.
SLTs will make recommendations on how to manage the dysphagia. If a patient presents with reduced oral control, a slow or delayed pharyngeal swallow trigger, or if there is compromised airway protection,1 then modified fluids may be suggested as a compensatory technique.
Thickened fluids have increased viscosity and therefore the rate of the bolus is slowed down, reducing the risk of aspiration occurring. However, in some cases thickened fluids can create more difficulty as they require more strength to propel the liquid through the oral cavity and pharynx.7
If necessary, the SLT will recommend an appropriate level of fluid thickness and request a prescription for use of a thickening agent from the doctor.
Modifying the patient's diet may also be recommended, for example having soft or pureed foods. This will reduce the level of mastication required, decreasing fatigue, and the risk of residue becoming stuck in the pharynx and subsequently aspirated.
Specific techniques or manoeuvres may also improve swallow function. For example, the supraglottic swallow technique aids vocal fold closure before the swallow, increasing airway protection. The effortful swallow technique can improve the posterior movement of the tongue base and help clear residues from the valleculae. The Mendelsohn manoeuvre can enhance laryngeal elevation, allowing the cricopharyngeal opening to expand.1
It is increasingly recognised that early detection and management of dysphagia is important, as it can help to decrease hospital admissions, length of hospital stay, and lessen overall healthcare cost.8
- Naomi de Graff is a speech and language therapist in Wakefield, and a lecturer at Leeds Metropolitan University
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1. Logemann JA. Evaluation and treatment of swallowing disorders. Austin, Texas, Pro-Ed, 1998.
2. Martino R, Foley N, Bhogal S et al. Dysphagia after stroke: incidence, diagnosis and pulmonary complications. Stroke 2005; 36: 2756-63.
3. Marik PE, Kaplan D. Aspiration pneumonia and dysphagia in the elderly. Chest 2003; 124: 328-36.
4. Marik PE. Aspiration pneumonitis and aspiration pneumonia. N Engl J Med 2001; 344: 665-71.
5. Loeb M, McGeer A, McArthur M et al. Risk factors for pneumonia and other lower respiratory tract infections in elderly residents of long-term care facilities. Arch Intern Med 1999; 159: 2058-64.
6. Garon BR, Engle M, Ormiston C. Silent aspiration: results of 1000 videofluoroscopic swallow evaluations. Neurorehabil Neural Repair 1996; 10: 121-6.
7. Cichero JA, Jackson O, Halley PJ et al. How thick is thick? Multicenter study of the rheological and material property characteristics of mealtime fluids and videofluoroscopy fluids. Dysphagia 2000; 15: 188-200.
8. Smithard DG, O'Neill PA, Parks C et al. Complications and outcome after acute stroke. Does dysphagia matter? Stroke 1996; 27: 1200-4.