Achalasia is a motility disorder which affects oesophagus and leads to symptoms.
Epidemiology
Achalasia is fairly uncommon, and the incidence is thought to be around 0.5-1.6 per 100,000, depending on the population being studied.[i]
Pathogenesis
- Normally, inhibitory neurotransmitters e.g. nitric oxide causes a delay in contraction of the lower oesophageal sphincter.
- In achalasia, it is thought that a degeneration of the nerves releasing such inhibitory neurotransmitters results in unopposed excitation of the lower oesophageal sphincter.
- It is thought the degeneration occurs in Auerbach’s plexus, though the precise mechanism by how this occurs in unknown.[ii]
- Neural degeneration will begin at the lower sphincter and begins to move upwards proximally, ultimately affecting the oesophagus itself.
This causes two problems. Firstly, the lower oesophageal sphincter remains contracted when it should be relaxed, which will cause ingested boluses to accumulate in the oesophagus.
Secondly, the nerve degeneration can affect peristalsis of the oesophagus, leading to difficulty swallowing.
Clinical Features
- Dysphagia which will affect liquids and solids from the onset of symptoms.
- Regurgitation of food
- Chest pain or chest discomfort
- Aspiration Pneumonia
Investigations
- Manometry is the gold standard diagnostic tool. Manometry assesses pressure changes in the upper and lower oesophageal sphincters as well as the oesophagus itself. A catheter is passed from the nose and into the stomach, measuring pressure differences along the oesophagus as it descends.[iii]
- Barium Swallow: Can reveal the classic ‘bird’s beak’ sign, which occurs due to the fact the lower oesophageal sphincter does not relax properly. There may also be visible inadequacy of peristalsis.
- CXR: Can show an extremely dilated oesophagus.
- OGD: Rule out an oesophageal malignancy
Management
Management of achalasia is primarily based on treating symptoms as there is no cure for the neural degeneration.
- Nitrates or calcium channel blockers such as nifedipine: Can help to relax the lower oesophageal sphincter
- Botulinum toxin injections can be used to achieve a similar effect.
- Balloon dilation of the lower oesophageal sphincter can also be done in order to relax the sphincter and aid swallowing.
- Surgical treatment is available in the form of a Heller’s myotomy: Involves cutting of the lower oesophageal sphincter to widen it and allow food to pass through.[iv]
References
[i] O’Neill OM, Johnston BT and Coleman HG. Achalasia: A review of clinical diagnosis, epidemiology, treatment and outcomes. [internet]. 2013.
[ii] https://rarediseases.org/rare-diseases/achalasia/#causes
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3386318/
[iii] https://patient.info/doctor/achalasia-pro#ref-7
[iv] https://www.nhs.uk/conditions/achalasia/
