Achalasia
Solids and liquids; absent peristalsis; impaired LES relaxation; bird-beak.
GI
Achalasia and Esophageal Motility Disorders
Solids-and-liquids dysphagia with impaired LES relaxation is achalasia; normal relaxation plus premature contractions is distal spasm.
- Recognize achalasia from inhibitory-neuron loss
- Distinguish distal esophageal spasm and scleroderma physiology
- Use solids-versus-liquids dysphagia and LES pressure to classify disease
Key distinctions
Separate the closest diagnoses
The figure compares the nearest alternatives and highlights the finding that separates them.
Quick check
A patient has progressive dysphagia to solids and liquids, nocturnal regurgitation of undigested food, and a dilated esophagus tapering to a bird-beak at the gastroesophageal junction.
Which neural defect causes this disorder?
Reason it through
- Which two motor functions are abnormal?The LES fails to relax, and the distal esophageal body loses normal peristalsis.
- Which missing transmitters normally provide that inhibition?Nitric oxide and VIP relax the distal smooth muscle and LES.
Manometry makes the diagnosis
Barium shows shape, but manometry separates impaired junction relaxation from premature or weak contractions.
Achalasia is diagnosed by high-resolution manometry showing impaired gastroesophageal-junction relaxation plus absent normal peristalsis, with subtypes based on pressurization or spastic contractions.
Distal esophageal spasm requires premature distal contractions in a setting of normal junction relaxation.
Scleroderma typically shows low-amplitude or absent distal contractions with a hypotensive LES rather than an obstructed high-pressure junction.
Which finding defines achalasia rather than distal esophageal spasm?
Read manometry in order: junction relaxation first, esophageal-body pattern second.
Achalasia, spasm, scleroderma, and obstruction
Solids alone suggests structure; solids plus liquids redirects attention to junction relaxation and motor timing.
Achalasia produces dysphagia to solids and liquids, impaired LES relaxation, absent distal peristalsis, regurgitation, and progressive esophageal dilation.
Distal esophageal spasm produces intermittent dysphagia and chest pain from premature contractions while gastroesophageal-junction relaxation remains normal by modern manometric criteria.
Scleroderma causes distal smooth-muscle atrophy and fibrosis with weak or absent peristalsis and low LES pressure, promoting severe reflux; a mechanical lesion usually begins with solids before progressing to liquids.
Switch among the motility patterns.
Distal esophageal spasm
Intermittent chest pain and dysphagia; premature contractions; normal junction relaxation; corkscrew may appear.
Scleroderma esophagus
Weak distal peristalsis plus hypotensive LES; reflux and stricture risk.
Mechanical obstruction
Solids first, then liquids as the lumen narrows; endoscopy seeks ring, stricture, or tumor.
Achalasia is obstructed and aperistaltic; scleroderma is hypotensive and weak; spasm contracts too early.
LES pressure points in opposite directions
The LES points in opposite directions: poor relaxation obstructs in achalasia, while low tone permits reflux in scleroderma.
Achalasia raises functional outflow resistance because the LES does not relax adequately, even when resting pressure varies by subtype.
Scleroderma lowers LES tone through smooth-muscle atrophy and fibrosis, while distal esophageal spasm preserves normal junction relaxation despite abnormal body contractions.
Classify each disorder by relative LES tone or outflow resistance.
Impaired relaxation is achalasia; low pressure is scleroderma; normal relaxation with premature contractions is spasm.
Muscle type changes down the esophagus
Distal disease follows muscle type: achalasia and scleroderma target the smooth-muscle segment and spare initial pharyngeal transfer.
The upper esophagus is predominantly striated muscle, the middle has a transition, and the lower segment and LES are smooth muscle controlled by enteric inhibitory and excitatory pathways.
Achalasia and scleroderma therefore chiefly disrupt distal smooth-muscle function while preserving the initial pharyngeal transfer and much proximal contraction.
Food stasis above the LES explains the dilated esophageal body and aspiration risk seen when patients lie down.
Open each segment and failure pattern.
Upper esophagus
Predominantly striated muscle; coordinates with pharyngeal swallowing.
Mid-esophageal transition
Mixed striated and smooth muscle.
Distal esophagus
Smooth muscle governed by myenteric pathways; site of spasm, achalasia aperistalsis, and scleroderma weakness.
Lower esophageal sphincter
Tonic smooth muscle that must relax with swallowing and resist reflux between swallows.
Normal swallowing requires timed inhibition
Propulsion requires a pressure gradient: contraction behind the bolus and nitric-oxide/VIP relaxation ahead.
A swallow initiates a coordinated primary peristaltic wave from striated proximal esophagus into smooth distal esophagus.
Inhibitory myenteric neurons relax the LES and the esophageal segment ahead of the bolus, while excitatory cholinergic neurons contract behind it.
Achalasia removes the inhibitory limb, leaving unopposed tone, incomplete junction opening, retained food, and secondary dilation.
Reveal normal transport and the achalasia failure.
- Swallow opens upper esophageal sphincter
The bolus enters the esophageal body.
- Peristaltic contraction begins proximally
Circular muscle contracts behind the bolus.
- Inhibitory neurons relax the distal segment
Nitric oxide and VIP create receptive relaxation ahead.
- LES relaxes
The bolus enters the stomach.
- In achalasia inhibition degenerates
LES relaxation fails and distal peristalsis disappears.
- Food and fluid collect
Regurgitation, aspiration, dilation, and weight loss follow.
Primary achalasia has important mimics
Bird-beak narrowing describes outflow physiology; rapid weight loss, short duration, or megaviscera redirects the cause.
Most achalasia is idiopathic, but Trypanosoma cruzi infection can destroy enteric ganglia and produce secondary achalasia with other megaviscera.
Tumors at the gastric cardia or gastroesophageal junction can infiltrate or compress the plexus and create pseudoachalasia, particularly with rapid weight loss or short symptom duration in an older patient.
Long-standing food stasis and mucosal inflammation increase risk of esophageal squamous-cell carcinoma, while treatment that lowers LES pressure can introduce reflux.
Open the cause or complication.
Progressive loss of inhibitory myenteric neurons without a proven single trigger.T cruzi-related enteric neuronal destruction can cause megaesophagus and megacolon.Junctional malignancy or infiltrative disease mimics motor failure; endoscopic exclusion matters.Retained food and saliva regurgitate, especially supine.Chronic stasis is associated with increased squamous-cell-carcinoma risk.Myotomy or dilation improves outflow by weakening the LES and can permit acid reflux.
Decisive finding
Pick the discriminator
Choose the finding that separates the closest competing diagnoses.
Which neural defect causes this disorder?
- Key finding. solids and liquids
- Answer. Loss of inhibitory nitric-oxide and VIP neurons in the myenteric plexus
- Why. Achalasia results from loss of inhibitory ganglion cells, causing impaired LES relaxation and absent distal peristalsis.
- Board rule. Achalasia removes nitric-oxide and VIP inhibition, leaving an LES that cannot relax and an aperistaltic distal esophagus.
Stage 1 of 3: Overview
Overview
Achalasia and Esophageal Motility Disorders
Propulsion requires a pressure gradient: contraction behind the bolus and nitric-oxide/VIP relaxation ahead.
Separate the competing diagnoses
Five original clinical and imaging vignettes make the learner derive the relationship before the explanation appears.
Cross out mimics and highlight the finding that separates the diagnoses. Shuffle to compare a new case order.
A patient from rural Latin America has progressive dysphagia to solids and liquids, severe constipation, and marked dilation of both the esophagus and colon.
Which infection is the most likely cause?
Reason it through
- What links the esophageal and colonic dilation?Both reflect loss of enteric ganglion function and failure of coordinated propulsion.
- Which exposure context narrows the cause?Rural Latin America plus megaviscera raises Chagas disease.
- Which organism causes this secondary achalasia pattern?Trypanosoma cruzi destroys enteric ganglion cells and can produce megaesophagus and megacolon.
dilation of both the esophagus and colonWhich exposure context narrows the cause?
- What links the esophageal and colonic dilation?Both reflect loss of enteric ganglion function and failure of coordinated propulsion.
- Which exposure context narrows the cause?Rural Latin America plus megaviscera raises Chagas disease.
- Which organism causes this secondary achalasia pattern?Trypanosoma cruzi destroys enteric ganglion cells and can produce megaesophagus and megacolon.
A patient has episodic chest pain and intermittent dysphagia. Barium swallow shows a corkscrew pattern, and manometry shows premature distal contractions with normal junction relaxation.
What diagnosis unifies premature distal contractions with normal junction?
Reason it through
- Did the gastroesophageal junction relax normally?Yes. Junction relaxation is preserved.
- What is abnormal in the esophageal body?Distal contractions occur prematurely, disrupting coordinated propulsion.
- Which diagnosis combines normal relaxation with premature contractions?Distal esophageal spasm matches the manometric pattern.
premature distal contractions with normal junction relaxationWhat is abnormal in the esophageal body?
- Did the gastroesophageal junction relax normally?Yes. Junction relaxation is preserved.
- What is abnormal in the esophageal body?Distal contractions occur prematurely, disrupting coordinated propulsion.
- Which diagnosis combines normal relaxation with premature contractions?Distal esophageal spasm matches the manometric pattern.
A patient with systemic sclerosis has severe reflux and dysphagia. Manometry shows absent distal peristalsis and low LES pressure.
Which tissue change caused the pattern?
Reason it through
- Is the LES obstructive or incompetent?It is incompetent because pressure is low, which promotes reflux.
- Which esophageal segment is failing?The distal smooth-muscle esophagus lacks effective peristalsis.
- Which tissue change explains both findings?Atrophy and fibrosis of distal esophageal smooth muscle weaken peristalsis and LES tone.
absent distal peristalsis and low LES pressureWhich esophageal segment is failing?
- Is the LES obstructive or incompetent?It is incompetent because pressure is low, which promotes reflux.
- Which esophageal segment is failing?The distal smooth-muscle esophagus lacks effective peristalsis.
- Which tissue change explains both findings?Atrophy and fibrosis of distal esophageal smooth muscle weaken peristalsis and LES tone.
During evaluation of swallowing, the sampled esophageal segment contracts with the pharyngeal phase and contains predominantly striated muscle.
Which esophageal segment is being evaluated?
Reason it through
- Which muscle type dominates this segment?Striated muscle predominates.
- Which phase coordinates with its contraction?Its contraction continues the pharyngeal swallowing sequence.
- Which location has both features?The upper esophagus is predominantly striated muscle and coordinates with pharyngeal swallowing.
predominantly striated muscleWhich phase coordinates with its contraction?
- Which muscle type dominates this segment?Striated muscle predominates.
- Which phase coordinates with its contraction?Its contraction continues the pharyngeal swallowing sequence.
- Which location has both features?The upper esophagus is predominantly striated muscle and coordinates with pharyngeal swallowing.
During a normal swallow, a peristaltic contraction has begun behind the bolus in the proximal esophagus.
Which event must occur ahead of the bolus next?
Reason it through
- What pressure pattern propels the bolus?Contraction behind the bolus must pair with lower resistance ahead.
- Which neurons lower resistance distally?Inhibitory myenteric neurons release nitric oxide and VIP.
- What action do those neurons produce next?They relax the distal segment ahead of the advancing bolus.
contraction has begun behind the bolusWhich neurons lower resistance distally?
- What pressure pattern propels the bolus?Contraction behind the bolus must pair with lower resistance ahead.
- Which neurons lower resistance distally?Inhibitory myenteric neurons release nitric oxide and VIP.
- What action do those neurons produce next?They relax the distal segment ahead of the advancing bolus.
Rapid review
Three questions to check
Which neural defect causes this disorder?
Loss of inhibitory nitric-oxide and VIP neurons in the myenteric plexus. Achalasia results from loss of inhibitory ganglion cells, causing impaired LES relaxation and absent distal peristalsis.
What links the esophageal and colonic dilation?
Both reflect loss of enteric ganglion function and failure of coordinated propulsion.
Which exposure context narrows the cause?
Rural Latin America plus megaviscera raises Chagas disease.
Medically reviewed
Fatima Ali, DO
PGY-1 Resident Physician in Psychiatry
University Hospitals, Columbia
DO from Kansas City University
Resident physician and founding medical reviewer at Bone Wizardry, focused on clinical accuracy, clear diagnostic reasoning, and practical board-oriented teaching across the curriculum.
Languages: English, Urdu
Primary reviewerFull physician profile
Medically reviewed
Sources
Bone Wizardry is a study resource for medical students. It is not medical advice.