Dysphagia, or difficulty swallowing, is any disruption with the process of swallowing or the swallowing reflex. It may either be a partial or total impairment of the swallowing process although the latter is less frequently seen. There are two types of dysphagia which may be due to a number of factors as discussed under thecauses of oropharyngeal dysphagia and esophageal dysphagia.
Assessing the cause of dysphagia involves both a physical examination by a doctor as well as additional diagnostic investigations that may be deemed necessary following this examination.
Examination and Testing
Examination of the oral cavity and pharynx is essential to assess any oropharyngeal causes of dysphagia. Dental problems, inflammation of the lining of the mouth and throat, sores, plaques and masses need to be identified. Anatomical abnormalities, like those of the the soft palate, should also be noted.
Problems with speech, either the production of sound (dysphonia), which may be evident as hoarseness or a whispering tone of the voice, or articulation (dysarthria), which may be evident as slurred speech, will also assist with identifying possible causes. Dysphonia or dysarthria may be indicative of neurological or muscular disorders which could also affecting the swallowing mechanism.
Testing of cranial nerves V (trigeminal), VII (facial), IX (glossopharyngeal), X (vagus) and XII (hypoglossal) is necessary to identify neurological causes of dysphagia.
- Trigeminal Nerve (CN V)
- The main nerve responsible for controlling the muscles of the mouth for chewing (mastication). Food that is not chewed sufficiently may not pass through the slit created by the palatopharyngeal folds.
- Carries impulses back to the swallowing centers in the brain stem to initiate the swallow reflex.
- Passes impulses from the swallowing center to the muscles of the throat to initiate swallowing.
- Facial Nerve (CN VII)
- Responsible for controlling the lips which helps to push food into the mouth for chewing and keeping the mouth cavity close during swallowing.
- Plays a role in carrying impulses back to the brain stem to initiate the swallow reflex although CN V and CN IX play a larger role in this function.
- Glossopharyngeal Nerve (CN IX)
- Carries impulses from the back of the throat (posterior pharynx) to the swallowing centers in the brain stem.
- Transmits motor impulses from the swallowing center back to the throat muscles to initiate the pharyngeal stage of swallowing.
- Vagus Nerve (CN X) and Hypoglossal Nerve (CN XII)
- Carries impulses from the swallowing center to the throat muscles.
Damage of the swallowing center in the brain stem is seen in diseases like poliomyelitis and encephalitis. Sensory impulses to the swallowing centers may therefore not trigger the swallowing reflex, although the cranial nerves are intact.
Assessment of Reflexes
The gag reflex and cough reflex may both be assessed. This indicates problems with sensory stimulation as well as motor actions as there are common factors between these reflexes and the swallow reflex.
An ’empty’ swallow is necessary to detect the movement of the larynx as described under the swallow reflex. This may indicate problems with the sequence of events that occurs in the pharyngeal stage of swallowing.
Swallowing a small amount of water allows the doctor to observe the process of swallowing. Failure of the act of swallowing to occur (water retained in mouth and larynx does not visibly move as expected), coughing as the glottis fails to close and the water enters the lungs or regurgitating water through the nose as the soft palate fails to close the posterior nares may be observed.
A range of diagnostic investigation may be necessary depending on the availability of facilities and clinical assessment.
Basic imaging techniques may include :
- Chest and neck x-ray
- CT (Computed Topography)
- MRI (Magnetic Resonance Imaging)
These investigations may illustrate :
- Consolidated areas of the lung due to pneumonia may arise as a result of aspiration.
- Structural abnormalities or masses that may be responsible for dysphagia.
Specialist investigations may include :
- Barium swallow and chest X-ray
- Barium swallow and videofluoroscopy (also known as a modified barium swallow, videofluoroscopy swallow study or videoesophagography)
These investigations provide still and dynamic images to assist with identifying any obstructions or dilated gullet (megaesophagus) as is seen in achalasia.
- Swallowing electromyography
- Laryngeal EMG
These investigations are used to assess muscle activity, either with oropharynx or esophagus, to assess impairment of pharyngeal or esophageal motility.
- Transnasal laryngoscope
- Upper GI endoscopy
These investigations allow the doctor intraluminal visualization to assess the lining of the pharynx and esophagus. A fiberoptic endoscopic examination of swallowing utilizes a transnasal laryngoscope will assess pharyngeal swallowing. An upper GI endoscopy allows the doctor to assess the alimentary tract all the way from the pharynx to lower end of the esophagus.