Distinguish impaired junction relaxation, premature contractions, and weak clearance, then choose diagnostic tests and treatment for esophageal dysphagia.
Food and water both hang up, but the pressure tracing decides why. Achalasia combines failure of junction relaxation with loss of normal peristalsis. Distal spasm has premature contractions while the junction relaxes normally.
A high resting sphincter pressure is not the defining test for achalasia. The important measurement is how the esophagogastric junction relaxes during swallowing. Read that first, then read the body of the esophagus.
A swallow needs contraction behind and relaxation ahead
The proximal esophagus is predominantly striated muscle, the middle segment transitions between striated and smooth muscle, and the distal esophagus and lower esophageal sphincter are smooth muscle. These are gradual regional transitions, not sharply marked boundaries. Initial pharyngeal transfer and upper sphincter opening are different motor tasks from passage through the distal esophagogastric junction. [9]
Pressure relationship during one swallow. This is a functional sequence, not a scaled manometry tracing.
Upper sphincter opens and the bolus enters.
Swallow-induced inhibition relaxes distal smooth muscle and the lower sphincter ahead of the bolus.
Contraction propagates behind the bolus and provides propulsive pressure.
The bolus passes through the relaxed lower sphincter into the stomach.
Junction tone returns between swallows to help limit reflux.
Excitatory cholinergic activity and inhibitory pathways coordinate this pressure gradient. Nitric oxide, with vasoactive intestinal peptide in inhibitory enteric signaling, helps the distal segment and sphincter relax. In primary achalasia, inhibitory myenteric function is lost. The junction does not open normally, and the esophageal body loses normal propagated peristalsis. Human tissue studies support loss of nitrergic innervation. This is not a disorder caused by excess gastric acid or an isolated lesion of upper esophageal skeletal muscle. [1][3]
Retained food, fluid, and saliva explain regurgitation of undigested material, nocturnal cough, aspiration, weight loss, and eventually dilation. Treatment lowers resistance at the outlet. It does not regenerate the lost neurons or guarantee normal peristalsis.
Symptoms choose the workup, not the final label
Difficulty initiating a swallow, coughing immediately on swallowing, or nasal regurgitation suggests an oropharyngeal problem. A sensation that swallowed material lodges behind the sternum suggests esophageal dysphagia. Solids-only difficulty raises concern for a structural narrowing; difficulty with solids and liquids from early in the course raises concern for motility disease. These are useful patterns, not exclusions. A severe structural lesion can eventually impede liquids, and patients may describe symptom order imperfectly. Suspected oropharyngeal dysphagia needs prompt swallowing-safety assessment because of aspiration risk. [10]
Upper endoscopy assesses rings, peptic strictures, inflammation, eosinophilic disease when appropriate biopsies are obtained, and malignancy. All patients with suspected achalasia should undergo endoscopy to exclude a mechanical cause or pseudoachalasia. Retained saliva and food in a dilated esophagus and a tight, puckered junction support suspicion but do not replace the rest of the evaluation.
A barium esophagram can show smooth distal tapering, often called bird-beak narrowing, and retained contrast. A timed barium esophagram measures emptying after a standardized swallow over several minutes. High-resolution manometry usually confirms and subtypes the motor disorder. Functional lumen imaging probe testing, or FLIP, assesses junction opening and distensibility and can help when results are borderline or manometry cannot be completed. [1][2]
A bird-beak shape describes outflow failure; it does not prove an idiopathic cause. Older age, short symptom duration, marked weight loss, or unusual resistance at endoscopy should prompt a deliberate search for malignancy, sometimes with CT or endoscopic ultrasound despite nondiagnostic mucosal biopsies.
Separate outlet relaxation, timing, and strength
The Chicago version 4.0 framework applies to adults with native foregut anatomy, without prior foregut surgery or large hiatal or paraesophageal hernias. Mechanical obstruction must be excluded. Use a validated protocol with the appropriate positions, swallows and system-specific normal limits before assigning these primary motor diagnoses. [2]
The integrated relaxation pressure, or IRP, estimates junction relaxation after swallowing. Normal limits depend on the manometry system and patient position. Do not apply one numerical cutoff to every device. Basal LES pressure and IRP answer different questions. An impaired-relaxation pattern can exist without a dramatically high basal pressure.
Type I achalasia
Abnormal median IRP with 100% failed peristalsis, without the qualifying panesophageal pressurization pattern of type II.
Type II achalasia
Abnormal median IRP, 100% failed peristalsis, and panesophageal pressurization in at least 20% of swallows.
Type III achalasia
Abnormal median IRP and premature or spastic contractions in at least 20% of swallows, with no normal peristalsis. Remaining swallows are failed or premature.
Distal esophageal spasm
Normal median IRP and at least 20% premature contractions, plus dysphagia or noncardiac chest pain for a clinically relevant diagnosis.
A premature contraction has distal latency below 4.5 seconds with sufficient contractile vigor, conventionally a distal contractile integral of at least 450 mmHg·s·cm. Low-latency contractions below that vigor threshold are inconclusive for spasm. A corkscrew barium pattern can support suspicion but is neither required nor sufficient.
Hypercontractile esophagus is a strength problem rather than a timing problem. At least 20% of swallows have a distal contractile integral above 8,000 mmHg·s·cm, with normal junction relaxation and clinically relevant symptoms. Mechanical obstruction and criteria for achalasia or distal spasm must be excluded. Jackhammer is one hypercontractile pattern, not a synonym for every strong swallow. [2]
Pressure throughout the esophagus is not the same as a propagated contraction. In type II, a retained bolus can become pressurized between a closed upper and lower outlet despite failed peristalsis. In type III, premature muscular contractions create a different pattern and influence the required treatment length.
A weak esophagus and an obstructed outlet need different treatment
Systemic sclerosis commonly weakens the distal smooth-muscle esophagus and lowers LES tone. Poor clearance plus an incompetent reflux barrier explains severe reflux and dysphagia. Histologic smooth-muscle atrophy is well established. Fibrosis may occur, but it should not be taught as uniform replacement of all affected muscle or as the only established mechanism. Primary controlled pathology studies found atrophy more consistently than a single inflammatory or vascular explanation. [6]
Absent contractility is a manometric pattern of 100% failed peristalsis with normal median IRP in both supine and upright positions. It is associated with systemic sclerosis but is not specific to it. When the IRP is near the upper normal limit and dysphagia is prominent, a timed barium study or FLIP can help distinguish an inconclusive achalasia pattern from a nonobstructed weak esophagus.
Ineffective esophageal motility requires normal median IRP and either more than 70% ineffective swallows or at least 50% failed peristalsis. Weak contractions, failed contractions, and fragmented swallows contribute to the ineffective category. When fewer than 50% of swallows fail, a finding of 50% to 70% ineffective swallows is inconclusive and may need supportive evidence of poor transit or reduced contraction reserve. [2]
EGJ outflow obstruction, or EGJOO, preserves evidence of peristalsis while showing abnormal relaxation. The manometric criteria include high median IRP in both tested positions and elevated supine intrabolus pressure in at least 20% of swallows. A clinically conclusive diagnosis additionally requires symptoms and supportive obstruction on timed barium testing or FLIP. Catheter artifact, structural disease, prior surgery, and opioid effects must be considered. An isolated high supine IRP is not a sufficient reason to cut the LES. [2]
Establish the cause before lowering outlet resistance
Primary achalasia is usually idiopathic, with no single proven trigger. A junctional or gastric-cardia tumor can produce pseudoachalasia through obstruction or infiltration. Chagas disease is another cause of an achalasia-like syndrome. Trypanosoma cruzi can damage intramural neurons, producing megaesophagus and megacolon; cardiomyopathy may coexist. Exposure history supports testing, not an automatic infection label based on ancestry. Chronic infection is assessed with at least two different serologic tests. Antiparasitic therapy does not reverse established megaesophagus. [4][5][8]
For a suitable patient with type I or II achalasia, graded pneumatic dilation, laparoscopic Heller myotomy, or peroral endoscopic myotomy (POEM) can be effective. Choose with the patient according to subtype, anatomy, fitness, local expertise, and reflux tradeoffs. Pneumatic dilation disrupts the sphincter muscle and carries a perforation risk; it requires a setting able to recognize and treat that complication.
Type III usually needs a longer myotomy that addresses the spastic distal segment as well as the LES. Tailored POEM or surgical myotomy is generally favored over dilation alone. A partial fundoplication commonly accompanies Heller myotomy to reduce reflux. POEM lacks that accompanying antireflux wrap and has a greater reflux burden than Heller with fundoplication or pneumatic dilation. [1]
Botulinum toxin inhibits excitatory acetylcholine release and offers temporary relief, particularly for people unfit for definitive therapy. It does not replace missing inhibitory neurons. Oral nitrates and calcium-channel blockers have limited efficacy and tolerability in achalasia. They are not interchangeable with durable outlet treatment. In systemic sclerosis, acid suppression treats reflux injury, not the absent contractions; EULAR supports considering PPIs for reflux and esophageal complications. [1][7]
Recurrent symptoms deserve another mechanism check
Dysphagia after treatment may reflect incomplete outlet disruption, recurrent resistance, advanced dilation with poor emptying, reflux esophagitis, or a peptic stricture. The symptom score alone cannot establish which mechanism is responsible. Timed barium esophagram is a recommended first assessment for continued or recurrent symptoms after definitive achalasia therapy; endoscopy can identify reflux injury or a structural lesion. Further testing depends on those findings. [1]
New severe chest pain, fever, or respiratory symptoms after pneumatic dilation requires prompt evaluation for perforation. This is different from ordering a contrast leak study routinely in every asymptomatic patient. Following myotomy, discuss reflux surveillance and treatment according to the procedure and findings, even when swallowing has improved.
Longstanding achalasia is associated with increased esophageal cancer risk, particularly squamous-cell carcinoma from chronic stasis and inflammation. Increased risk does not by itself establish benefit from a routine surveillance program. The ACG guideline recommends against routine endoscopic cancer surveillance because benefit has not been demonstrated. New or worsening dysphagia, bleeding, or weight loss still requires diagnostic evaluation. Individual follow-up decisions may differ from population-level screening recommendations. [1]
Establish esophageal versus oropharyngeal symptoms and exclude structural disease.
Read junction relaxation before body timing and strength.
For a borderline pattern, seek supportive evidence before irreversible treatment.
For achalasia, tailor outlet treatment to subtype and fitness.
For recurrence, reassess emptying and mucosa rather than assuming the original mechanism persists.
Interpret the swallow, tracing, and treatment
Case 1
Show answer and explanations for case 1
A. Loss of inhibitory myenteric signaling, especially nitric oxide (Best answer)
Loss of inhibitory function impairs LES relaxation and normal distal peristalsis.
B. Selective loss of excitatory cholinergic input alone (Why this does not fit)
Isolated loss of excitation would not best explain failure of inhibitory LES relaxation characteristic of achalasia.
C. Primary distal smooth-muscle atrophy with a hypotensive LES (Why this does not fit)
This pattern better resembles systemic sclerosis-associated motor failure with reflux rather than an obstructed outlet.
D. Excess inhibitory nitric oxide signaling at the LES (Why this does not fit)
Increased inhibition would favor relaxation rather than the impaired opening and retention described.
Takeaway: Achalasia is an inhibitory motor disorder.
A. FLIP alone as the usual subtype test (Why this does not fit)
FLIP can support diagnosis, especially when manometry is inconclusive or not tolerated, but HRM is the usual reference test for confirmation and subtype assignment.
B. High-resolution manometry (Best answer)
It measures junction relaxation and body contraction patterns to identify subtype.
C. Ambulatory esophageal pH monitoring (Why this does not fit)
Reflux monitoring measures acid exposure rather than LES relaxation and body contraction patterns.
D. Repeat diagnostic endoscopy alone (Why this does not fit)
Endoscopy is essential to exclude a mechanical cause, but it does not classify pressure patterns into the achalasia subtypes.
Takeaway: Barium assesses transit; HRM characterizes the motor failure.
A. Established megaesophagus does not reverse with antiparasitic therapy (Best answer)
Antiparasitic treatment decisions and management of established digestive motor damage are separate needs; treatment of infection should not be presented as restoration of normal anatomy.
B. Defer management of dysphagia until the serologic tests become negative (Why this does not fit)
Established swallowing and nutritional problems need their own assessment; waiting for serologic conversion does not treat motor damage.
C. Expect the esophageal dilation to resolve once parasite treatment is completed (Why this does not fit)
CDC distinguishes treatment of infection from irreversible established megastructure; persistent dilation is not unexpected.
D. Interpret persistent dysphagia after therapy as proof of microbiologic failure (Why this does not fit)
Symptoms can persist from established structural and neural injury and do not by themselves establish treatment failure.
Takeaway: Treating infection does not erase established organ damage.
The proximal esophagus is predominantly striated, the middle transitions between muscle types, and the distal segment is smooth muscle. Regional boundaries vary.
B. The lower esophageal sphincter (Why this does not fit)
The LES is a smooth-muscle sphincter; it is not the usual striated-to-smooth transition zone.
C. The distal smooth-muscle segment immediately above the LES (Why this does not fit)
This distal region is smooth muscle rather than the typical mixed transition.
D. The pharyngeal constrictor region (Why this does not fit)
Pharyngeal musculature is striated and is proximal to the esophageal transition being sampled.
Takeaway: A mixed specimen supports the middle transition region, with gradual rather than sharp boundaries.
A. Empiric repeat pneumatic dilation before reassessment (Why this does not fit)
Recurrent symptoms can reflect several mechanisms; objective evaluation should guide another outlet-directed treatment.
B. HRM alone without a timed emptying study (Why this does not fit)
Manometry can add information, but the ACG recommends timed barium esophagram first for persistent or recurrent symptoms and cautions against HRM alone to define failure.
C. Ambulatory pH testing alone as the first measure of emptying (Why this does not fit)
Acid testing may help evaluate reflux, but it does not directly quantify retained barium and bolus emptying.
D. Timed barium esophagram (Best answer)
It assesses emptying and retention; endoscopy can then complement evaluation for reflux injury or stricture.
Takeaway: Recurrent dysphagia requires reassessment of the mechanism.
