21. Achalasia: diagnosis, differential diagnosis, treatment

Achalasia: diagnosis, differential diagnosis and treatment

Achalasia is an oesophageal motility disorder characterised by impaired relaxation of the lower oesophageal sphincter (LES) and absent or abnormal peristalsis.
Loss of inhibitory neurons in the myenteric plexus, particularly nitric-oxide-mediated pathways, causes failure of LES relaxation and functional obstruction at the gastro-oesophageal junction.
Chicago classification identifies type I (classic), type II (pan-oesophageal pressurisation) and type III (spastic) achalasia; subtype influences treatment response.

Progressive dysphagia to both solids and liquids is typical, often accompanied by regurgitation of undigested food, nocturnal cough, aspiration, chest pain and weight loss.
Patients may adapt by eating slowly, drinking water with meals or changing posture. Severe disease can cause malnutrition and recurrent aspiration.
Rapid onset, marked weight loss and older age raise concern for pseudoachalasia from gastro-oesophageal junction cancer.

High-resolution oesophageal manometry is the diagnostic gold standard and demonstrates impaired LES relaxation with absent normal peristalsis.
Barium swallow may show a dilated oesophagus with smooth distal tapering ('bird-beak'), delayed emptying and retained contrast.
Upper GI endoscopy is required to exclude mechanical obstruction and malignancy; it may show retained saliva/food and a tight but traversable gastro-oesophageal junction.
Differentiate from pseudoachalasia, peptic stricture, oesophageal cancer, systemic sclerosis, Chagas disease and other motility disorders. CT or endoscopic ultrasound may be needed if pseudoachalasia is suspected.

Treatment aims to reduce LES outflow resistance; it does not restore normal neuronal function. Options include pneumatic balloon dilation, laparoscopic Heller myotomy with partial fundoplication, and peroral endoscopic myotomy (POEM).
POEM is particularly useful for type III/spastic disease but may carry a higher reflux risk. Heller myotomy is commonly combined with Dor or Toupet partial fundoplication to reduce postoperative reflux.
Botulinum toxin injection is generally reserved for patients unfit for definitive therapy or as a temporary option because benefit often wanes. Nitrates or calcium-channel blockers have limited efficacy.
Advanced sigmoid megaoesophagus with severe failure may require oesophagectomy in highly selected cases.
Follow-up assesses dysphagia, weight, reflux and oesophageal emptying. Complications include aspiration, oesophagitis, perforation after dilation, reflux after myotomy and persistent/recurrent symptoms.