oral, pharyngeal and oesophageal physiology and dysphagia (lecture) Flashcards
What are the 3 normal phases of swallowing ?
- oral
- pharyngeal
- oesophageal
What type of muscle is used at each phase of swallowing ?
- oral = striated
- pharyngeal = striated
- oesophageal = striated/smooth
Where does the neural control stem from in each phase of swallowing ?
- oral = cortex/medulla (CN 5, 7, 12)
- pharyngeal = medulla (CN 9, 10, 11)
- oesophageal = medulla/enteric NS (CN V3, 9, 10, 12)
Say whether each phase of swallowing is under voluntary control or not …
- oral = voluntary control
- pharyngeal = some voluntary control
- oesophageal = no voluntary control
What are the main components of the oral phase of swallowing that prepare the bolus ?
- chewing = prepares solid food (teeth + mass water muscles)
- salivation = lubricates bolus and starts digestion (enzymes + water)
- movement of bolus = delivers prepared bolus to oropharynx (tongue)
Which muscular structure protects against laryngo-oesophageal reflux ?
upper oesophageal sphincter
Which zone is the most high-pressure zone in the oesophagus ?
upper oesophageal sphincter (100 mmHg)
What structures define the boundaries of the oesophagus?
- The upper oesophageal sphincter
- The lower oesophageal sphincter
Which cranial nerves are involved in swallowing ?
- 5 (trigeminal)
- 7 (facial)
- 9 (glossopharyngeal)
- 10 (vagus)
- 12 (hypoglossal)
accessory nerve (11) also has small input
Which brainstem nuclei are primarily involved in the afferent relay pathways of swallowing ?
- Nucleus solitarius (X)
- Nucleus of the spinal tract of trigeminal (V)
Which of the brainstem nuclei are the main efferent pathways of swallowing ?
- dorsal motor nucleus
- nucleus ambiguous
Damage to which brainstem nucleus would result in severe dysphasia ?
Nucleus ambiguous (the main efferent nucleus of swallowing)
Does taste have any influence on the swallowing system ?
taste system is integrated with the swallowing system
stronger taste = stronger swallow
What are the characteristics of oropharyngeal dysphasia ?
- abnormal bolus transfer to the oesophagus
- difficulty initiating a swallow
- only one manifestation of the primary disease (e.g stroke)
What type of MRI has been used to image swallowing ?
FMRI
functional MRI
What did FMRI show about blood flow during swallowing ?
Increased blood flow
What are the characteristics of oesophageal dysphasia ?
- Abnormal bolus transport through oesophagus
- Food stops after initiation of swallow
- Oesophagus is the location of the primary disease (e.g achalasia)
What are some causes of neurological dysphasia ?
- stroke (main)
- parkinson’s
- motor neurone disease
- neuro-degenerative disease
- head injury
- MS
- others
What is the most common method of imaging oropharyngeal dysphasia ?
Videofluoroscopy (VFS)
swallow barium then study dynamic images over time
What are the 2 main methods of imagine swallowing ?
- VFS (videofluoroscopy)
- FEES (Fiberoptic endoscopic examination of swallowing)
What is the method of FEES (fiberoptic endoscopic examination of swallowing) ?
- insert tube with camera on it through the nose
- look at base of tongue, pharynx and larynx
What % of stroke victims experience dysphasia as a result ?
about 50%
What type of dysphasia is most common after a stroke ?
oropharyngeal
What is the most important complication of oropharyngeal dysphasia following a stroke ?
Aspiration
foreign objects - e.g food - getting directed into the lungs
Does dysphasia after a stroke usually correct itself naturally or via surgery?
Natural recovery in most
What type of therapy can help recovery of dysphasia after a stroke?
SALT
speech and language therapy
What is the increased risk of death if a patient suffers aspiration due to dysphasia following a stroke ?
~ 3x increased mortality
What is acahlasia ?
A motility disorder of the oesophagus
= impaired ability to push food down the oesophagus due to failure of the sphincter muscles
What are the methods of testing for achalasia ?
- conventional manometry (pressure monitoring system using catheterisation during swallowing)
- high resolution manometry (more precise measurement than conventional)
- spatiotemporal (clouse) plot (pressure, time and distance travelled by the bolus plotted on a graph)
What are the potential causes of achalasia ?
- potentially a HLA association (genetic)
- potentially autoimmune due to circulating antibodies to enteric neurones
- potentially result of a chronic infection e.g herpes, measles (unconfirmed)
What is the prevalence of achalasia ?
1 in 100,000 cases
Is achalasia more common in men it women?
The same!
Men = Women
What is the most common age range for receiving a diagnosis of achalasia ?
25 - 60
childhood or adolescence is unusual
What are the symptoms of achalasia ?
- dysphasia
- difficulty belching
- weight loss
- coughing
- chest pain
- regurgitation
- reflux/heartburn
- sensation of fullness
What are the main steps of diagnosing achalasia ?
- History
- Endoscopy
- Radiology (fluoroscopy)
- Manometry
What might endoscopy reveal if achalasia is present ?
- dilated oesophagus
- build up of fluid
- oesophageal candiditis
- could appear normal !
Which is the most effective method of diagnosis achalasia ?
radiology (fluoroscopy)
swallow barium and use x-ray imaging to watch it travel through system
95% success rate
What is the classic sign of achalasia called in radiology/fluoroscopy ? What is the physiology behind this presentation ?
bird-beak sign
= creates a bulge in the lower oesophagus because the lower oesophageal sphincter isn’t opening properly so the liquid cannot pass into stomach
What is the gold standard method of confirming a diagnosis of achalasia ?
Manometry
What are the 3 primary findings in Manometry that indicate achalasia ?
- elevated resting LES pressure
- incomplete LES relaxation
- aperistalsis = loss of peristalsis
LES = Lower oesophageal sphincter
What reading is considered elevated LES pressure in manometry, and therefore indicative of achalasia ?
above 45 mmHg
Which manometric finding distinguishes achalasia from other disorders presenting with aperistalsis ?
The incomplete LES relaxation
Where does aperistalsis occur in the GI tract if achalasia is present ?
in the smooth muscle portion of the body of the oesophagus
How many subtypes of achalasia are there ?
3
Type I
Type II
Type III
What feature of achalasia occurs through all subtypes ?
incomplete relaxation of the LES
LES = lower oesophageal sphincter
What % of achalasia-related deaths are attributable to oesophageal cancer ?
19%
What are treatment options for achalasia ?
- Botox injection into LES
- Pneumatic dilation = balloon across LES, inflated to tear the muscle of the sphincter
- Hellers myotomy = surgical incision into the LES to widen the sphincter to allow for passage of food etc
LES = lower oesophageal sphincter
What is the MOA of botulinum toxin (botox) ?
inhibits acetylcholine release to relax muscle
inhibits Ca dependent release of acetylcholine from nerve terminals, thereby counteracting the effect of the selective loss of inhibitory neurotransmitters
How effective is botox at relieving symptoms of achalasia ?
effective in about 85% of cases
How frequently do symptoms recur in achalasia patients that were treated with botox ?
50% of patients within 6 months of their first treatment
What is the most effective non-surgical treatment for achalasia ?
pneumatic dilation
What is the process of pneumatic dilation ?
- place a balloon over the LES
- inflate it to a pressure great enough to tear the muscles of the sphincter
What % of achalasia patients gain good-to-excellent symptom relief from pneumatic dilation?
50 - 93%
How/where is Hellers myotomy performed ?
Laparoscopically, through the abdomen
= surgical procedure of the lower oesophageal sphincter
What % of achalasia patients experience good-to-excellent symptom relief from myotomy ?
80 - 100%
What is the main complication of myotomy ? How common is this complication?
uncontrolled gastro-oesophageal reflux
seen in about 10% of patients