Overview of Dysphagia

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Introduction

Swallowing (deglutition) impairment effects individual's safety and efficacy during drinking or eating. The consequence of deglutition difficulties are malnutrition, dehydration, and increase the risk of aspiration pneumonia. Additionally, dysphagia has a significant impact on social and psychological well-being because eating and drinking are important social and pleasurable activities. Understanding dysphagia helps with its early detection and management and lead to reduction in patient's hospital stay, improvement in rehabilitation outcomes, and decreasing morbidity and mortality.This course discusses dysphagia as a dysfunction of one or more parts of the swallowing apparatus.

Definition

Dysphagia is defined as the difficulty or impossibility to swallow liquids, food or medication and can occur during the oropharyngeal or the oesophageal phase of swallowing.

Oropharyngeal Dysphagia

Oropharyngeal dysphagia is characterised by inability to initiate the swallow process.

Oropharyngeal dysphagia is associated with abnormalities in the structures (structural alterations) in the oral cavity and the pharynx , or it may result from functional disorder of deglutition.

Structural alterations effects bolus progression. The following abnormalities can lead to oropharyngeal dysphagia:

• oesophageal and ENT tumors
• neck osteophytes
• post surgical oesophageal stenosis
• as a complication following head & neck cancer

The normal swallow response in healthy humans ranges form 0.6–1 s. Functional disorder of deglutition affects oropharyngeal swallow response. It can be caused by:

• ageing
• stroke
• systemic or neurological diseases

Occurrence

The prevalence of oropharyngeal dysphasia varies as it depends on the screening method and the type of population tested. Symptoms may be often neglected by a patient or a caregiver and not reported to the physician.Percentage of patients with oropharyngeal dysphasia is high and include:

• over 30% of patients with a cerebrovascular accident
• 52%–82% of patients with Parkinson’s disease
• 84% of patients with Alzheimer’s disease
• up to 40% adults aged 65 years and older
• more than 60% of elderly institutionalised patients

Mechanisms of Dysphagia

1. Velopharyngeal incompetence occurs when " velum and lateral and posterior pharyngeal walls fail to separate the oral cavity from the nasal cavity during speech and deglutination." It can be caused by:
   • vagus nerve and pharyngeal plexus impairment due to neurological and neurosurgical conditions
   • brainstem stroke
   • decompression of the foramen magnum
   • head and neck cancer treatment due to intentional or inadvertent damage of the nerve supply to the palatal muscles
   • tumours of the oropharynx
   • radiotherapy to the nasopharynx
2. Absent, inefficient, or infrequent laryngeal elevation takes place when the thyrohyoid and suprahyoid muscles fail to assist with anterior and superior movement of the hyolaryngeal complex. As a result, the cricopharynx does not relax. This pathology arises with the following neurological and neurosurgical conditions:
   • posterior circulatory stroke
   • cerebellopontine angle surgery
   • high level spinal injuries or tumours
   • head and neck cancer surgery with removal of suprahyoid musculature and its nerve supply
   • floor of mouth resection
   • radiotherapy
3. Inappropriate laryngeal closure results in suboptimal diversion of the food bolus. It can be caused by:
   • partial or complete epiglottic resection
   • a high vagal injury with involvement of superior laryngeal nerves
   • brainstem lesions
   • brainstem surgery
4. Weakness or paralysis of the thyropharyngeal contraction leads to the stasis of the food bolus in the pyriform fossa on the affected side and can be caused by:
   • neurosurgery involving cranial nerves IX, X, and XI
   • stroke
5. Cricopharyngeal dysmotility as a primary or secondary cause affecting the proper functioning of the cricopharyngeus:
   • Primary due to problems in its neurological control
   • Secondary due to lack of elevation of the larynx
6. Idiopathic spasm of the cricopharyngeal which is characterised by simultaneous contraction of both thyropharyngeus and cricopharyngeus leading to development of a condition known as Zenker’s diverticulum.

Clinical Presentation

Clinical presentation can often provide helpful information for diagnosis of dysphasia:

• Nasal regurgitation is often associated with velopharyngeal incompetence, and occasionally with cricopharyngeal dysfunction.
• Multiple attempts to swallow are consistent with laryngeal elevation or cricopharyngeal dysmotility.
• Coughing immediately after the swallowing may indicate unilateral or bilateral laryngeal incompetence.
• A delayed cough implies a hypopharyngeal dysfunction
• Additional symptoms include hoarseness and breathing difficulty.

Oesophageal Dysphagia

"Oesophageal dysphagia is characterised by difficulty in transporting the food down the oesophagus."

Oesophageal dysphagia is associated with mechanical (structural ) problems, or motor disorders.

Mechanical (structural) disorders include a barrier that is obstructing the flow and can be suspected with a presence of a dysphagia when swallowing solids.

Motility (motor) disorders result in peristaltic failure.This disorders can lead to problems with both solid and liquid boluses, with solids usually more frequently affected.

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