01OverviewDefinition, clinical context and the essential points that orientate the chapter.
Degeneration of inhibitory myenteric neurons prevents appropriate lower-sphincter relaxation and abolishes coordinated peristalsis. Food and saliva accumulate, dilating the oesophagus and sometimes making it markedly tortuous. Patients may report dysphagia to liquids and solids from early in the disease, regurgitation of bland undigested food, chest discomfort, slow eating and weight loss. Heartburn-like symptoms can reflect fermentation or retention rather than acid reflux.
Endoscopy rules out mucosal and mechanical disease and assesses retained fluid, resistance at the junction and cancer. Chicago Classification v4.0 is applied only after structural obstruction is excluded and normal foregut anatomy is established. Conclusive achalasia has a device- and posture-specific abnormal median integrated relaxation pressure with 100% absent normal peristalsis: type I has failed peristalsis without panesophageal pressurisation, type II has panesophageal pressurisation in at least 20% of swallows, and type III has premature or spastic contractions in at least 20% with no normal peristalsis. Inconclusive patterns need supportive timed barium swallow with tablet and/or FLIP rather than a universal IRP cutoff.
Treatment lowers the junction barrier but cannot restore destroyed peristalsis. Type I and especially type II respond well to pneumatic dilation, Heller myotomy or POEM when performed in an experienced service. Type III needs a longer myotomy tailored to the spastic segment, making tailored POEM or Heller myotomy preferable to pneumatic dilation in a fit candidate. POEM is associated with more post-procedure reflux, so counselling and objective assessment of new reflux or oesophagitis belong to follow-up. Choice also reflects age, anatomy, previous therapy and patient values.
Key points
- Achalasia combines absent or abnormal peristalsis with impaired lower-sphincter relaxation, causing liquid and solid dysphagia, regurgitation and weight loss.
- Endoscopy with careful junction inspection and biopsy precedes manometry to exclude cancer and structural obstruction.
- High-resolution manometry confirms the physiological diagnosis and subtype; a barium study quantifies morphology and emptying.
- Pneumatic dilation, laparoscopic Heller myotomy and POEM disrupt junction resistance by different techniques and should be selected through an experienced service.
- Botulinum toxin gives temporary benefit and is generally reserved for people unsuitable for durable intervention.
- After treatment, evaluate both recurrent retention and newly induced reflux; symptom improvement alone can conceal poor emptying or acid injury.
02AetiologyUnderlying causes, associations and risk factors, with why each one matters.
Idiopathic neuronal loss
Most primary achalasia reflects progressive loss of inhibitory myenteric neurons within the distal oesophagus without a single identifiable initiating infection or autoimmune event.
Secondary pseudoachalasia
Junctional cancer, infiltrative disease and selected infections or operations can mimic achalasia by preventing normal relaxation.
03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.
- 1Failed inhibitory signalling
Loss of nitric oxide-mediated inhibitory signalling prevents complete lower oesophageal sphincter relaxation during swallowing, leaving persistent outflow resistance at the junction.
- 2Absent organised peristalsis
The oesophageal body no longer propagates coordinated contractions, so gravity, retained-column pressure and compensatory pressurisation replace effective peristaltic clearance into the stomach.
- 3Progressive retention
Accumulated food and saliva cause progressive dilatation, tortuosity, fermentation, regurgitation, aspiration and chronic mucosal irritation within a poorly emptying oesophageal reservoir.
04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.
Difficulty with both textures from early on supports motor outflow failure, especially with bland regurgitation.
Coughing when supine, chest infection and undigested food on waking indicate oesophageal stasis and aspiration.
Short rapidly progressive history, disproportionate weight loss or a resistant irregular junction requires renewed cancer exclusion.
Long-standing retention can produce marked dilatation and tortuosity, making endoscopic and surgical therapy more complex.
Sphincter disruption can exchange retention for acid exposure, so new burning is not simply treatment success.
05InvestigationsWhat to request, why it matters and how to interpret it.
Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.
- 01
Upper-GI endoscopy and biopsyFirst step - Why
- Exclude obstructing tumour and mucosal mimics before physiological classification.
- Interpretation and limitations
- Retained saliva and a tight but traversable junction support achalasia; irregularity or difficult passage strengthens pseudoachalasia concern and warrants further imaging.
- 02
High-resolution manometry - Why
- Confirm impaired junction relaxation and classify peristaltic phenotype.
- Interpretation and limitations
- Apply Chicago Classification v4.0 only after excluding mechanical obstruction and accounting for anatomy, catheter system, posture and opioid exposure. An abnormal device- and position-specific median IRP plus 100% absent normal peristalsis establishes the core pattern; panesophageal pressurisation separates type II and premature spastic contractions separate type III. Use timed barium swallow with tablet and/or FLIP when the pattern is inconclusive.
- 03
Timed barium swallow - Why
- Measure bolus retention and oesophageal shape at defined times.
- Interpretation and limitations
- Persistent column height after treatment indicates incomplete emptying even if the patient has learned to eat differently.
- 04
CT or endoscopic ultrasound - Why
- Assess wall thickening or extrinsic disease when pseudoachalasia remains possible.
- Interpretation and limitations
- Normal cross-sectional imaging reduces but does not eliminate early infiltrative cancer; repeat endoscopy and tissue may remain necessary.
- 05
Reflux testing after therapy - Why
- Clarify acid exposure when symptoms or endoscopy suggest postoperative reflux.
- Interpretation and limitations
- Retained fermenting material can confound pH interpretation before adequate emptying; choose timing and method with physiology expertise.
06Differential diagnosisRealistic alternatives and the features that help distinguish them.
Junctional carcinoma
Rapid progression, older age, major unintended weight loss and resistance to endoscope passage across the junction support infiltrating malignant pseudoachalasia over primary motor disease.
Peptic stricture
Chronic reflux injury can heal by fibrosis, producing a fixed distal narrowing with solids-first progression and a visible structural lesion at endoscopy.
Opioid-related dysfunction
Chronic opioid exposure can increase junction tone and create spastic manometric patterns that require medication context.
07ManagementImmediate care, first-line treatment, alternatives and escalation.
01Worked case: subtype selects myotomy lengthTreat type III achalasia as spastic outflow obstructionFirst stepA fit 46-year-old has liquid and solid dysphagia with chest pain; endoscopy and biopsies exclude a junctional lesion.+
- 1High-resolution manometry tests both supine and upright positions. The primary-position median IRP is above the laboratory’s validated normal limit, with no normal peristalsis and premature contractions in 40% of test swallows: a conclusive Chicago v4.0 type III pattern rather than type I, type II or the stricter inconclusive outflow-obstruction category.
- 2Timed barium swallow confirms impaired emptying with a retained column at five minutes and maps oesophageal morphology, while the endoscopy and imaging record is rechecked for structural obstruction.
- 3The specialist MDT recommends a long, tailored POEM across the measured spastic segment after discussing Heller myotomy, the poorer performance of pneumatic dilation for type III disease, perforation and the higher reflux burden after POEM.
- 4At three months dysphagia has resolved, weight has increased and timed barium shows near-complete emptying. Endoscopy nevertheless identifies reflux oesophagitis, so acid treatment is started and healing is scheduled for verification rather than equating symptom relief with an uncomplicated result.
02Pseudoachalasia checkDo not trust one smooth testA 78-year-old has six weeks of dysphagia and major weight loss; manometry appears achalasia-like.+
- 1Reopen the structural diagnosis because the clinical tempo is atypical for primary neuronal disease.
- 2Arrange expert repeat endoscopy, targeted biopsy and CT or EUS of the junction.
- 3Treat through the cancer pathway if infiltration is identified rather than proceeding to routine myotomy.
- 4Confirm a documented benign explanation before finalising primary achalasia.
03Recurrent symptomsSeparate retention from refluxMonths after POEM, chest discomfort and regurgitation recur.+
- 1Reassess symptom timing, weight and aspiration and perform endoscopy.
- 2Use timed barium and manometry if recurrent obstruction is possible and pH testing when reflux remains uncertain.
- 3Tailor redilation, repeat myotomy or acid treatment to the demonstrated mechanism.
- 4Verify mucosal healing or improved emptying rather than relying on symptom language alone.
08ComplicationsImportant consequences, why they occur and why they matter clinically.
Aspiration pneumonia
Nocturnal regurgitation of retained food and saliva contaminates the airway, especially when the oesophagus is markedly dilated and supine emptying is poor.
Treatment perforation
Pneumatic dilation, endoscopic myotomy or surgical myotomy can breach the wall, producing mediastinal contamination, pleural infection and rapidly progressive systemic sepsis.
Post-myotomy reflux
Lowering junction resistance permits new acid exposure, erosive oesophagitis, peptic stricture and Barrett metaplasia unless post-treatment reflux is sought and managed.
09Monitoring and follow-upTreatment response, safety checks and longer-term review.
- Track an achalasia symptom score, weight, eating time, nocturnal regurgitation and chest infections.
- Use timed barium emptying when symptoms and treatment success do not align.
- After dilation or myotomy, monitor immediately for perforation, bleeding and aspiration.
- Assess reflux symptoms and oesophagitis after sphincter disruption and treat documented acid injury.
- Maintain long-term review because retention, megaoesophagus and cancer risk do not disappear after initial improvement.
10Special situationsVariants, exceptions and circumstances that change the usual approach.
Heartburn can be retained food
Fermentation and stasis create burning or sour fluid, so pre-treatment symptoms do not prove acid reflux.
Manometry needs anatomy first
An infiltrating cancer can reproduce failed relaxation; pressure patterns do not exclude pseudoachalasia.
Subtype influences choice
Spastic contractions may benefit from a longer tailored myotomy, while age and previous therapy alter dilation outcomes.
Success needs verification
Patients adapt by chewing and drinking with meals, which may improve reported dysphagia despite continued retention.
11Common pitfallsFrequent interpretation and management errors.
- 01
Diagnosing primary achalasia from manometry without adequate endoscopic cancer exclusion.
- 02
Using a normal early chest radiograph to dismiss post-dilation perforation.
- 03
Offering botulinum toxin as a durable default to a fit patient without discussing established interventions.
- 04
Treating every symptom after myotomy with a PPI without checking recurrent obstruction.