Abstract
The process of swallowing a bolus of food involves a complicated interplay between voluntary and involuntary mechanisms that enables the safe preparation and presentation of a food bolus to the alimentary canal. This process begins at the lips and ends at the stomach. To understand how to best manage the patient with swallowing difficulty, this process is deconstructed and used as a framework on which the relevant diagnoses leading to dysphagia can be determined.
The GP curriculum and dysphagia
Given the complicated nature of dysphagia, a multidisciplinary approach to its management is important for the clinician desiring holistic care.
Know how to interpret common symptoms in general practice, including dyspeptic symptoms (epigastric pain, heartburn, regurgitation, nausea, bloating), abdominal pain, nausea, vomiting, anorexia, weight loss, haematemesis and melaena, rectal bleeding, jaundice, diarrhoea and constipation, and dysphagia Be aware of the cancer risks associated with various symptoms and symptom complexes
Understand how to recognise rarer but potentially serious conditions such as oral, head and neck cancer Appreciate that pathology in other systems may lead to ENT-related symptoms. Examples include gastro-oesophageal reflux disease and cerebro-vascular accident Know that certain ENT, oral and facial symptoms may be manifestations of psychological distress, e.g. globus pharyngeus, atypical facial pain, burning mouth syndrome
Co-ordinate care with other primary care health professionals to enable chronic disease management and rehabilitation Know the indications for referral to a neurologist for chronic conditions that require ongoing specialist management and conditions that require early treatment to avoid permanent deficit Know the functional anatomy of the nervous system relevant to diagnosis
Background
Swallowing occurs in three phases: the oral phase, the pharyngeal phase and the oesophageal phase. Table 1 outlines a detailed summary of the nerves and muscles involved in swallowing. The oral phase is voluntary, whereas the pharyngeal and oesophageal phases are both involuntary. The oral phase can be further subdivided into the ‘preparatory phase’ and the ‘oral phase proper’. During the preparatory phase, the food bolus is broken down in the oral cavity and mixed with saliva until it is a suitable size and consistency to allow it to be transported through the pharynx and oesophagus without problem. The oral phase proper occurs when the suitably prepared bolus is voluntarily moved to the back of the oral cavity to enter the oropharynx and trigger the involuntary (or reflex) part of swallowing. Figure 1 shows the anatomical sub-sites of the upper aerodigestive tract.
Anatomical sub-sites of the upper aerodigestive tract. The muscles and processes involved in swallowing. Source: Whittaker (2014).
The involuntary nature of the pharyngeal phase is of particular importance, as this is where the bolus can potentially enter the airway; a number of reflexes are involved to ensure this does not happen. The soft palate seals the nasopharynx and the food bolus passes to the sides of the closed larynx posteriorly into the hypopharynx. The food bolus then passes through the cricopharyngeus muscle (superior oesophageal sphincter) and into the oesophagus. Peristaltic waves within the oesophagus propel the bolus towards the stomach in the oesophageal phase (Whittaker, 2014).
The oral phase
As we eat a variety of food types that have different consistencies, the preparatory phase varies in duration based on the time taken to adequately prepare a bolus of food for transit. An oral seal (orbicularis oris) keeps food in the oral cavity while the muscles of mastication breakdown the food to form the bolus (temporalis, masseter and medial pterygoids close the jaw, whereas the lateral pterygoids open the jaw with the help of gravity). Saliva moistens the bolus and somatic sensation in the mouth is used to assess the texture, consistency and temperature of the bolus.
The oral phase proper involves a sequence of muscle movements. Initially, the tip and dorsum of the tongue are lifted to the hard palate (intrinsic muscles of the tongue and genioglossus). The hyoid bone and the floor of the mouth are then elevated (stylohyoid, styloglossus and mylohyoid), and the intrinsic muscles of the tongue flatten and fill the oral cavity, drawing the bolus toward the oropharynx. The soft palate seals the nasopharynx, preventing nasal regurgitation of food.
The pharyngeal phase
Once the bolus touches the mucosa of the oropharynx, another sequence is triggered. This sequence consists in a number of reflexes. The first reflex involuntarily inhibits diaphragmatic contraction, making breathing during swallowing impossible (‘deglutination apnoea’). This is quickly followed by a reflex closing of the larynx. This is performed in three layers, from deep to superficial. The larynx is then lifted through contraction of the suprahyoid musculature antero-superiorly, squashing the epiglottis over the laryngeal inlet. This is coupled with a dilatation of all three pharyngeal constrictors (superior, middle and inferior), followed by a systematic constriction of the same pharyngeal constrictors from superior to inferior, thereby directing the bolus over the lingual surface of the epiglottis to the piriform fossae of the hypopharynx. These piriform fossae sit as a pair of inverted pyramids postero-laterally to the larynx, and act like funnels directing the bolus toward the cricopharyngeus muscle (superior oesophageal sphincter).
Oesophageal phase
The antero-superior movement of the laryngeal structures facilitates relaxation of the cricopharyngeus muscle (superior oesophageal sphincter). After food has successfully passed through the cricopharyngeus, it closes firmly to prevent regurgitation of contents in to the airway. Once the bolus enters the oesophagus it is propelled to the stomach by oesophageal peristalsis, which can take between 10 and 15 seconds. The fibres of the outer layer of oesophageal muscle run longitudinally and the fibres of the inner layer are circular. During this phase the soft palate and suprahyoid muscles relax and the larynx reopens. Deglutination apnoea ceases and normal breathing resumes. The bolus passes through the lower oesophageal sphincter and in to the stomach. The efficiency of the lower oesophageal sphincter is facilitated by its location under the diaphragm.
Three additional reflexes
The gag reflex will be initiated if an ingested bolus (or item) is too large to pass through the cricopharyngeus, or if the bolus runs the risk of occluding the laryngeal inlet. The cough reflex will be initiated if a small amount of fluid or bolus enters the glottis (between the vocal folds) and supraglottis (an area just superior to the vocal folds); this acts to initially protect the airway. Should a more significant volume of fluid (or food for that matter) penetrate the laryngeal inlet, then laryngospasm may be stimulated. This anti-drowning reflex is most concerning for patients, as the glottis can clamp shut for a number of seconds, leading to an inability to breathe followed by stridor as its grip gradually relaxes.
Take home message
Although the average GP does not need such a detailed knowledge of the process of swallowing, certain key aspects should be considered. First, swallowing is complex; it involves a number of different muscles from varying nerve supplies. It incorporates both voluntary and involuntary components. Should a patient suffer a neurological insult, they will be able to compensate by solely using the voluntary components. They may not, however, be able to compensate should an involuntary aspect of swallowing be involved (typically this manifests itself as aspiration of fluids).
The differential diagnosis for dysphagia
Differential diagnoses for dysphagia.
Source: Chevretton (2007).
Before pathology is discussed in detail, it is worth noting that it is entirely normal to experience swallowing difficulty with some of the larger powder-coated tablets, as well as dry bread, small fragments of rice or pasta, and the skins of some fruits. Sometimes these can stick to the pharyngeal wall during the involuntary phase of swallowing, causing an awkward sensation and occasionally stimulating the cough or gag reflexes.
Presbyphagia is a condition that affects all phases of swallowing; it is caused by the ageing process. The oral phase is affected through the loss of teeth and poor dentition, reduced strength of the muscles of mastication and soft palate. The pharyngeal phase is prolonged and laryngeal elevation can be limited, leading to aspiration of boluses that did not previously cause problems. There is prolongation of the oesophageal relaxation phase and transit time.
The most common cause for dysphagia seen in ear, nose and throat (ENT) outpatients is laryngopharyngeal reflux (‘silent reflux’). It is caused not only by the reflux of stomach contents (enzymes and acid) into the pharynx causing local inflammation, but also reflex constriction of muscles, often giving the sensation of tightness in the throat or lump-in-throat sensation (globus pharyngeus). This may be associated with either a dry or catarrh cough that is particularly worse on lying flat or after meals. Laryngopharyngeal reflux is treated using a 6-week course of a proton pump inhibitor BD (e.g. Omeprazole 20 mg BD, or Lansoprazole 15 mg BD; although higher doses can be given) as well as 5–10 ml of Gaviscon Advance after main meals and before bed. The diagnosis of laryngopharyngeal reflux is ultimately endoscopic; there are discreet findings that support the history to affirm the diagnosis. Laryngopharyngeal reflux is often a diagnosis of exclusion as head and neck cancer is the most common differential diagnosis in this patient group.
Case study 1.
A 40-year-old female presents with a 6-month history of hoarseness of voice associated with dysphagia to dry food stuffs (particularly bread and large tablets). She has central throat discomfort and complains of ‘catarrh’ that keeps her awake at night. She is a current smoker with a 20 pack-year history and does not drink alcohol. Oral examination and neck examination are unremarkable.
This lady probably has laryngopharyngeal reflux; however, one must be vigilant for head and neck cancer, particularly hypopharyngeal carcinoma. With the prolonged history, one would expect the patient to have symptoms and signs of a more advanced carcinoma, e.g. progressive dysphagia, weight loss, aspiration or a neck mass. The safest management option is to refer her urgently as a case of suspected cancer.
Indications for referral for suspected cancer.
Adapted from NICE, (2015) and NHS Scotland (2015).
Risk factors for head and neck cancers include increasing age, tobacco consumption and alcohol (Mehanna, Paleri, West, & Nutting, 2010). In Europe, 98% and 50% of patients diagnosed are over 40 and 60 years of age, respectively. Viral infection is a recognised risk factor for cancer of the head and neck as well. It must be noted that HPV-related oropharyngeal carcinoma is a distinct disease entity. Patients are usually younger (40–50 years old), and do not report the usual risk factors of smoking or high alcohol intake, which may lead to delayed diagnosis.
Pathology affecting the oral phase
Sjogren’s syndrome, radiotherapy to the head and/or neck and medications (e.g. anticholinergics, anti-hypertensives, angiotensin converting enzyme inhibitors, opiates) leading to xerostomia (dry mouth) are often to blame for causing problems during the oral phase. Without adequate saliva production, it is difficult to produce a bolus soft enough to effortlessly move through the pharynx and in to the oesophagus. Other causes may be related to poor coordination of the oral phase from a neurological disorder or more specific lower motor neurone palsies (CN V3 (trigeminal, mandibular): poor oral competence due to reduced sensation; CN VII (facial): poor oral seal; or CN XII (hypoglossal): impaired tongue movements).
Pathology affecting the pharyngeal phase
Infective causes for high dysphagia will have associated symptoms and signs (coryzal illness, raised temperature, pus on tonsils, cervical lymphadenopathy) over a short history (days). If a patient has high dysphagia and is septic, but has normal looking tonsils, consider the other infective causes of high dysphagia, particularly if there is voice change with or without stridor (supraglottitis or epiglottitis). Children who present with absolute dysphagia, drooling, difficulty breathing and an obvious infective cause should not be examined, due to the possibility of airway obstruction.
Peri-tonsillar abscesses (quinsy) require emergency referral to ENT for drainage. The typical history is a number of days of tonsillitis (usually 3–5 days) with lateralising pain, ipsilateral otalgia and restricted mouth opening. The usual clinical finding is a unilateral peri-tonsillar swelling, pushing the tonsil to the midline, with deviation of the uvula away from the affected side. These collections should not be treated with antibiotics alone, as they may rupture spontaneously, causing pus to spill in to the patient’s airway. Deep-neck-space infections may present in a similar way to peri-tonsillar abscesses, but will appear with a tender fullness of the neck, restricted neck movement, and potentially as a swelling posterior to the tonsil rather than directly adjacent to it. Vocal quality will become more muffled as the oropharyngeal and hypopharyngeal swelling gradually restricts the airway. Again, this requires emergency referral to ENT for surgical drainage.
Case study 2.
A 20-year-old female presents with a 5-day history of temperatures and pain on swallowing. She is able to swallow both solids and liquids, however, only with great difficulty. Over the past 24 hours, the right-hand side of her throat has become increasingly painful and now she complains of right-sided ear pain and difficulty opening her mouth. She smokes 10 cigarettes a day. Neck examination reveals multiple small, tender lymph nodes bilaterally. Oral examination is difficult due to restricted mouth opening; however, it reveals a right-sided peri-tonsillar swelling with deviation of the uvula away from this side.
This lady has a right-sided quinsy. Emergency referral to the ENT on-call is required.
A diagnosis of pharyngeal pouch is a possibility in the elderly: regurgitation of undigested food or tablets is a commonly occurring symptom, although patients may also present with halitosis, weight loss and episodes of aspiration (recurrent lower respiratory tract infections).
Neurological disorders may cause problems with the number of reflexes involved during this complicated phase of swallowing, most notably affecting the gag reflex or sensation to the larynx, leading to aspiration (which can be silent in these cases) or nasal regurgitation. Individual lower motor neurone palsies may also effect certain aspects of this phase e.g. CN V3 (trigeminal, mandibular): poor function of soft palate; CN IX (glossopharyngeal): reduced gag reflex; CN X (vagus): incomplete closure of larynx, non-sensate larynx and impaired cough.
Case study 3.
An 80-year-old female presents with a sudden onset voice change and difficulty swallowing water. When she tries to talk, she speaks slowly and slurs her words. She has a weak cough. On oral examination, the movement of her tongue and soft palate are significantly reduced and she has a very pronounced gag reflex. Neck examination is unremarkable.
This lady has a pseudo-bulbar palsy: with the sudden onset, it is likely to be the result of a cerebrovascular event. Emergency referral to the on-call medical or stroke team is required.
Pathology affecting the oesophageal phase
In a similar way to the pharyngeal phase, the first pathology to exclude is malignancy or structural anomalies when dealing with low dysphagia. Severe gastro-oesophageal reflux can cause spasm, ulceration and stricture formation; Barrett’s metaplasia can potentially lead to adenocarcinoma if reflux is left untreated over a number of years.
Alternative diagnoses affecting the oesophagus include achalasia (cardiaspasm), which is a failure of the lower oesophageal sphincter closure, leading to dilatation and hypertrophy of the oesophagus proximal to this sphincter. The cause for this condition is an idiopathic degenerative process of Auerbach’s plexus of nerves (responsible for coordinating oesophageal peristalsis). Barium swallow shows the classic ‘bird’s beak’ or ‘rat’s tail’ appearance. Chagas disease causes the same disease process, but it is infection with Trypanosoma Cruzi that causes degeneration of the same nerve plexus.
Diffuse oesophageal spasm can mimic cardiac chest pain and is often diagnosed on oesophageal manometry once angiography has failed to find a cause for the pain. In these cases, barium swallow shows a disordered pattern of oesophageal peristalsis.
History
The primary purpose of the history is to attempt to identify the cause of the swallowing difficulty. The secondary objective is to locate the anatomical area involved in the swallowing difficulty; this will aid the referring doctor to correctly organise the most appropriate referral.
Questions should focus on the onset, duration and progression of the symptoms. Infective causes typically have a short history (days). Malignant causes will be progressive over a number of weeks. The patient with laryngopharyngeal reflux or globus pharyngeus will have suffered with dysphagia for months, if not years. GPs should be vigilant for associated symptoms suggestive of malignancy and should have a low threshold for referring such patients as an USC.
If solids are initially a problem followed by liquids then a malignant process should be suspected. If liquids are more difficult than solids first, it is likely that a neurological cause for the dysphagia is more likely. The historian should make a note of exactly what constitutes the patient’s current diet, as these patients are at risk of malnutrition, starvation and death if a severe dysphagia is left untreated.
Other symptoms such as aspiration or coughing on swallowing (neurological or malignant) with or without recurrent episodes of pneumonia, voice change (reflux or malignancy), ipsilateral otalgia (malignancy) and regurgitation of undigested food (pharyngeal pouch) or stomach contents (reflux) can all be helpful to shed light on the diagnosis.
Case study 4.
A 50-year-old man presents with a 6-week history of hoarse voice. Over the last week he has developed dysphagia to solids and aspirates when swallowing liquids. He has also recently developed right-sided ear pain. He is an ex-smoker with a 30 pack-year history having given up 5 years ago. He drinks a moderate amount of alcohol. Oral examination and neck examination are unremarkable.
It is likely that this gentleman has a laryngeal carcinoma. He has a significant smoking history and demonstrates progressive symptoms over a number of weeks. USC referral to ENT outpatients is required.
Smoking history and alcohol history are useful indicators to assess the risk of malignancy. A record of the patient’s most up-to-date medication would also give clues to any undesirable side effects (particularly xerostomia) that may be contributing to the patient’s dysphagia.
Examination
The initial impression of the patient is important. Do they look like they have lost weight?
Examination of the oral cavity is useful; a tongue depressor can be touched against the buccal mucosa. If it sticks and the mucous membranes appear dry, one could assume xerostomia to be a contributing cause to the dysphagia. Careful assessment of dentition is important. If the patient has poorly fitting dentures or multiple missing teeth, they will struggle with the preparation phase of the oral phase of swallowing. The oropharynx can be examined at this point, also making note of the tonsils and any associated swelling or asymmetry.
Tender lymphadenopathy on neck examination is suggestive of an infective process; firm, non-tender masses are more indicative of a malignant process. You may also be able to feel a particularly large pharyngeal pouch or thyroid goitre. Cranial nerve examination is indicated if a neurological cause is suspected. One may seamlessly incorporate a lower cranial nerve (CNVII – XII) examination as part of their oral cavity and oropharyngeal examination.
Investigations
The role of the GP is to direct the patient to the specialist who is best equipped to deal with their swallowing needs, be it ENT, an upper gastrointestinal surgeon, gastroenterology or neurology. At this point, the specialist will arrange the most useful investigation. The GP is not expected to perform any tests prior to referral of such cases, however, certain blood tests may help the diagnostic process e.g. a full blood count could isolate anaemia as the cause or effect of swallowing difficulty, raised erythrocyte sedimentation rate or C-reactive protein could indicate a malignant or chronic inflammatory process. Renal and liver function tests (with calcium) are helpful in assessment of a patient’s nutritional status, as well as if metastases are suspected. Thyroid function testing is indicated if goitre is present.
The primary investigation in patients with persistent dysphagia should be endoscopy to exclude malignancy or structural abnormalities (pharyngeal: rigid, under general anaesthetic; or oesophageal: flexible, generally performed using topical local anaesthetic with or without sedation). A chest radiograph is a useful adjunct, especially if the patient has repeated lower respiratory tract infections. If consolidation is present, the patient should be rescanned to exclude malignancy. If malignancy is suspected, then further imaging will be obtained as part of tumour staging assessments.
A standard barium swallow is different from videofluoroscopy. A barium swallow involves following a cup of radiopaque barium through the upper aerodigestive tract and upper alimentary canal using plain film radiology: this investigation is generally performed by radiographers and reported by radiologists. Videofluoroscopy is a multidisciplinary investigation. The phases of swallowing for different consistencies of food bolus (including liquid, custard, mousse and solids) are imaged and analysed in real-time by a radiologist and a speech-and-language therapist. Images are acquired in the anteroposterior and lateral planes. The main benefit of this investigation is that the speech-and-language therapist present during the procedure can suggest different swallowing manoeuvres to see if they help improve the swallow on repeat imaging. It is accepted that videofluoroscopy is the gold-standard investigation for analysing the mechanism of swallowing. Referral for videofluoroscopy is normally done on a specialist level. Other tests, such as oesophageal manometry and 24-hour ambulatory oesophageal pH monitoring, can be helpful in diagnosing problems in the oesophageal phase.
Management
The decision to refer a patient as an emergency lies primarily in their ability to swallow. The patient who cannot swallow, or is not safe to swallow, should be referred to hospital for assessment and commencement of alternative feeding methods. Suspicion of a cerebrovascular event as a neurological cause for dysphagia should prompt emergency referral to the on-call medical team. If a peri-tonsillar abscess is present or if the patient has a suspected deep-neck-space infection, e.g. supraglottitis or epiglottitis, emergency referral to ENT is warranted.
If the cause is a malignancy or a structural abnormality, then the management of these is generally interventional. Behavioural modification (the mainstay of what speech-and-language therapists can offer patients), has almost no role in lower pharyngeal or oesophageal phases, however, it can create a great deal of benefit in the oral and higher pharyngeal phases of swallowing (Perry, 2007).
To rehabilitate a patient’s swallow, the medical or surgical treatment must have been completed and the patient allowed enough time to heal. This is a process that involves not only the patients themselves, but also their family and caregivers, as certain lifestyle changes may be necessary to facilitate rehabilitation. The patient may need specific changes to their diet, as well as help or supervision when eating, particularly if at risk of aspiration. Education of family and caregivers is also an important factor to ensure the patient’s safety and that compliance is achieved.
Treatment strategies employed by speech-and-language specialists.
Source: Perry (2007).
Key points
The causes for dysphagia are numerous, however, a priority should be to rule out a malignant process The nature of the dysphagia (high, low with/without associated neurology) will help you direct your referral to the most appropriate specialist Rehabilitation of the patient with swallowing difficulty is complicated and best reserved for when the medical or surgical elements of treatment have been completed Do not be afraid to refer a patient with dysphagia for admission to secondary care, especially if they are at risk of severe malnutrition