Achalasia is a primary esophageal motility disorder characterized by failure of the lower esophageal sphincter to relax and absent peristalsis in the esophageal body due to degeneration of inhibitory neurons in the myenteric plexus.

Exam domain	One-glance essentials
Definition / diagnosis	*Primary oesophageal motility disorder with failure of LES relaxation and absent normal peristalsis* ^[2] HRM triad: elevated IRP, impaired LES relaxation and absent normal peristalsis ^[2] Type II has pan-oesophageal pressurisation; Type III has premature spastic contractions ^[2]
Epidemiology / risks	*Usually idiopathic primary achalasia; secondary causes include EGJ malignancy, Chagas disease and infiltrative disorders* ^[1]^[2] Suspect pseudoachalasia with age >60, short symptom duration, rapid disproportionate weight loss or difficult scope passage ^[2] Long-standing stasis increases oesophageal SCC risk ^[1]^[2]
Core mechanism	*Degeneration of inhibitory NO/VIP myenteric neurons leaves unopposed excitatory cholinergic activity* ^[2] This causes a tonically contracted, poorly relaxing LES and loss of coordinated peristalsis ^[2] Food stasis progressively dilates the oesophagus, potentially producing sigmoid megaoesophagus ^[2]
Clinical picture	Progressive dysphagia to solids and liquids from early disease is characteristic ^[2] Regurgitation of undigested food or saliva, worse supine, may cause halitosis and nocturnal cough ^[2] Chest pain reflects oesophageal spasm; treatment may improve dysphagia but not reliably pain ^[2] Weight loss, aspiration or respiratory signs suggest advanced disease; rapid severe weight loss suggests malignancy ^[2]
Investigations	*OGD is mandatory before diagnosing primary achalasia: exclude tumour/stricture and assess retained food or mucosal disease ^[2] HRM is definitive*: IRP ≥15 mmHg plus absent normal peristalsis; classify Chicago types ^[2] Barium may show smooth bird-beak tapering, delayed emptying or sigmoid oesophagus ^[2] Shouldering/heaping or an impassable EGJ warrants EUS ± CT for pseudoachalasia ^[2]
Management	*Definitive therapy lowers LES resistance but does not restore lost neurons or normal swallowing* ^[2] Type I/II: pneumatic dilation, laparoscopic Heller-Dor or POEM; Type III generally favours POEM for a longer myotomy ^[2] Elderly or high-risk patients may receive Botox; nitrates/CCBs are least effective temporisers ^[2] Counsel that dysphagia usually improves, whereas chest pain may persist ^[2]
Complications	Food stasis causes oesophagitis/candidiasis, aspiration pneumonia, diverticula and sigmoid megaoesophagus ^[2] *Achalasia is a risk factor for oesophageal SCC*, especially after long disease duration ^[1]^[2] Pneumatic dilation and Heller risk perforation; POEM’s major disadvantage is reflux without fundoplication ^[2]
Prevention / follow-up	Definitive LES disruption reduces stasis and aspiration risk but is not curative of neuronal loss ^[2] Consider periodic OGD surveillance with biopsies after approximately 10–15 years of disease, according to local protocol ^[2] Treat post-POEM reflux with PPI therapy and reassess recurrent dysphagia for incomplete therapy or pseudoachalasia ^[2]
Exam traps	Heartburn can result from fermentation and mucosal irritation; it is not proof of GERD or acid reflux ^[2] Mechanical obstruction usually causes solids-first dysphagia; achalasia causes solids-and-liquids dysphagia ^[2] Normal OGD does not exclude achalasia; HRM is required, while manometry alone cannot exclude pseudoachalasia ^[2] DES/jackhammer have preserved LES relaxation with normal IRP; scleroderma typically has low LES pressure ^[2]

References

^[1] Lecture slides: GC 189. I can't swallow oesophageal cancer.pdf ^[2] Senior notes: maxim.md (Section 3.4 — Achalasia)

Achalasia

Achalasia — from the Greek "a-" (without) + "khalasis" (relaxation). The name literally tells you the disease: failure of relaxation.

Achalasia is the most common primary oesophageal motility disorder, characterised by a triad of ^[1]^[2]:

Aperistalsis with uncoordinated contraction of the oesophageal body
Increased LES (lower oesophageal sphincter) tone at rest (elevated basal LES pressure)
Poor LES relaxation in response to swallowing

The net result: food cannot pass efficiently through the oesophagus into the stomach. The oesophagus dilates progressively over time, loses its coordinated peristaltic function, and essentially becomes a baggy, non-propulsive tube sitting above a persistently tight sphincter.

Why does this matter clinically?

Achalasia is a chronic, progressive condition. It increases the risk of oesophageal squamous cell carcinoma (SCC) — the chronically dilated, stagnant oesophagus with retained food and chronic mucosal irritation drives metaplastic and eventually dysplastic change. This is why long-term surveillance and definitive treatment matter ^[3]^[4].

Feature	Detail
Incidence	~1–3 per 100,000 per year worldwide
Prevalence	~10 per 100,000
Sex	Males and females equally affected ^[3]
Age	Most common age 35–45 ^[2], but can occur at any age; onset before adolescence is rare ^[3]
Geography	No strong geographic predilection for primary achalasia; secondary achalasia from Chagas disease is predominantly South/Central America ^[3]
Hong Kong relevance	Primary (idiopathic) achalasia; Chagas disease essentially non-existent in HK. Pseudoachalasia from carcinoma of the cardia/EGJ is an important differential in the local population given the prevalence of gastric/EGJ malignancy in East Asians ^[1]

Exam Pearl

Unlike most oesophageal conditions (e.g., oesophageal cancer has strong male preponderance), achalasia has no sex predominance. If a question mentions equal male:female ratio + progressive dysphagia to solids AND liquids, think achalasia.

Anatomy & Functional Review

To understand achalasia, you need to understand normal oesophageal swallowing physiology from first principles.

Length: ~25 cm from the cricopharyngeus (C6) to the cardia (T11)
Wall layers (inside → out): mucosa (stratified squamous epithelium), submucosa, muscularis propria (inner circular + outer longitudinal), adventitia (no serosa in most of the oesophagus — this is why oesophageal perforation is so catastrophic and why oesophageal cancers spread easily)
Muscle type transition:
- Upper 1/3: striated (skeletal) muscle
- Lower 2/3: smooth muscle — this is the portion affected in achalasia
Sphincters:
- Upper Oesophageal Sphincter (UOS): cricopharyngeus muscle (striated); prevents air swallowing
- Lower Oesophageal Sphincter (LES): 3–4 cm zone of tonically contracted smooth muscle at the gastro-oesophageal junction (GOJ); resting pressure ~15–25 mmHg; prevents gastric acid reflux

The key to understanding achalasia lies in the myenteric (Auerbach's) plexus — the neural network sandwiched between the inner circular and outer longitudinal muscle layers of the oesophagus.

Normal physiology of the LES during swallowing:

A food bolus triggers the swallowing reflex
The vagus nerve activates the myenteric plexus
Inhibitory neurons (releasing nitric oxide [NO] and vasoactive intestinal peptide [VIP]) cause the LES smooth muscle to relax — this is called receptive relaxation (or deglutitive relaxation)
Simultaneously, sequential activation of excitatory neurons (releasing acetylcholine [ACh]) above the bolus creates a peristaltic wave that propels the bolus distally
After bolus passage, the LES regains its tonic contraction

In achalasia, it is specifically the INHIBITORY neurons (NO/VIP) that degenerate. The excitatory neurons (ACh) are relatively preserved or unopposed. This creates the perfect storm:

LES cannot relax → functional obstruction at the GOJ
Peristalsis is lost → the oesophageal body cannot propel food downward
Basal LES pressure is elevated → due to unopposed excitatory (cholinergic) tone

First Principles: Why Dysphagia to Both Solids AND Liquids?

In mechanical obstruction (e.g., stricture, cancer), solids are affected first because they are physically too large to pass. Liquids can still trickle through until the obstruction is very tight.

In achalasia, the problem is neuromuscular — the LES doesn't relax AND there's no peristalsis to push anything through. Both solids and liquids are affected from the outset. Gravity helps liquids somewhat, but the fundamental propulsive mechanism is gone. This is why simultaneous dysphagia to solids and liquids is the hallmark of a motility disorder, not a mechanical obstruction.

Aetiology

Cause: primary/idiopathic ^[2]^[3]
Result of inflammation and progressive degeneration of ganglion cells in the myenteric (Auerbach's) plexus of the oesophageal wall ^[3]
Specifically targets inhibitory neurons (NO/VIP-producing neurons)
The trigger for this neural degeneration is unknown, but hypotheses include:
- Autoimmune: anti-myenteric neuronal antibodies have been found; association with HLA-DQw1; chronic inflammatory infiltrates (predominantly T-lymphocytes) found in the myenteric plexus on histology
- Viral trigger: some evidence for herpes simplex virus (HSV-1) and measles virus as potential triggers of the autoimmune process
- Genetic: rare familial cases; association with Allgrove syndrome (triple A syndrome: achalasia, alacrima [absent tears], adrenal insufficiency — autosomal recessive, AAAS gene)

Cause	Mechanism	Notes
Chagas disease	Degeneration of myenteric plexus due to Trypanosoma cruzi infection ^[2]^[3]	Protozoan parasite; occurs predominantly in South and Central America ^[3]; oesophageal involvement in ~7–10% of infected patients; also affects colon (megacolon) and heart (cardiomyopathy)
Pseudoachalasia — Malignancy at EGJ	Malignancy can cause pseudoachalasia by invading the oesophageal neural plexus directly (e.g., adenocarcinoma of cardia/EGJ) ^[2]^[3]	Important differential in HK given prevalence of gastric cardia tumours
Paraneoplastic syndrome	Release of uncharacterized humoral factors that disrupt oesophageal function as part of paraneoplastic syndrome ^[3]	Associated with small cell lung cancer, lymphoma; anti-Hu antibodies (ANNA-1)
Infiltrative disorders	Deposition/granuloma formation disrupts neural plexus	Amyloidosis, sarcoidosis ^[3]
Post-surgical (e.g., Nissen fundoplication)	Mechanical disruption/over-tightening at GOJ	Mimics achalasia functionally
Eosinophilic oesophagitis	Eosinophilic infiltration of oesophageal wall	Rare cause

Pseudoachalasia — The 'Red Flag' Mimic

Pseudoachalasia has the same manometric findings as primary achalasia but is caused by malignancy ^[2]^[3]. It accounts for ~4% of cases presenting with achalasia-like features. Clinical red flags for pseudoachalasia:

Age > 60 with short duration of symptoms (< 1 year)
Rapid, significant weight loss disproportionate to dysphagia severity
Difficulty passing the endoscope through the GOJ (in primary achalasia, the scope usually "pops" through with gentle pressure)
CT/EUS showing a mass at the GOJ

Differentiated by upper endoscopy and endoscopic ultrasound (EUS) ^[2]^[3]. Always perform OGD before committing to a diagnosis of primary achalasia.

In Hong Kong ^[1]^[4]:

Primary (idiopathic) achalasia is the dominant form
Chagas disease is essentially non-existent (no endemic transmission of T. cruzi)
Pseudoachalasia from malignancy (particularly gastric cardia/EGJ adenocarcinoma) must always be excluded — this is especially important given that SCC is the most common oesophageal cancer in HK (90%) ^[4], and achalasia itself is a risk factor for oesophageal SCC ^[1]^[3]^[4]
Achalasia is listed as a risk factor for SCC alongside smoking, alcohol, hot drinks, nitrosamines, corrosive injury, Plummer-Vinson syndrome, and tylosis ^[4]

Pathophysiology — Detailed

Let's walk through the pathophysiological cascade from the molecular level to the clinical presentation:

Degeneration of inhibitory neurons (NO/VIP) in myenteric (Auerbach's) plexus → unopposed activity of excitatory neurons (ACh) ^[2]

Histology shows: lymphocytic myenteric ganglionitis → progressive ganglion cell loss → eventual fibrosis of the myenteric plexus
The process is progressive: initially presented with uncoordinated peristalsis → eventually aperistalsis ^[2]

Loss of inhibitory neurons in LES → LES smooth muscle cannot relax during swallowing
Basal LES pressure rises because excitatory cholinergic tone is unopposed
The LES becomes a functional obstruction — food piles up above it

Loss of inhibitory innervation in the smooth muscle portion (distal 2/3) → loss of coordinated peristalsis
The oesophagus can no longer generate the sequential contraction waves needed to propel food distally
Three patterns emerge (this is the basis of the Chicago Classification):
- Type I: Minimal oesophageal pressurisation — the oesophageal body is essentially flaccid; no effective contraction ^[2]
- Type II: Pan-oesophageal pressurisation — the entire oesophageal body contracts simultaneously (like squeezing a tube of toothpaste from all sides at once — no net propulsion, but some compression) ^[2]
- Type III: Spastic contractions — premature, vigorous, discoordinated lumen-obliterating spasms ^[2]

With chronic functional obstruction → the oesophagus dilates over months to years
Eventually becomes massively dilated and tortuous — "sigmoid oesophagus"
Retained food undergoes bacterial fermentation → produces lactic acid and gas
Chronic food stasis → mucosal irritation → oesophagitis → risk of squamous cell carcinoma

Aspiration: regurgitated stagnant food/saliva enters the airway → recurrent aspiration pneumonia
Malnutrition/weight loss: inability to eat adequately
Oesophageal cancer: chronically irritated, dilated oesophagus → SCC (estimated 30× increased risk; approximately 3% lifetime risk)

Classification

This is the standard classification used worldwide and is based on oesophageal pressure topography (EPT) patterns on HRM ^[2].

Type	HRM Pattern	Oesophageal Body	Prognosis/Treatment Response
Type I	Achalasia with minimal oesophageal pressurisation ^[2]	Flaccid, dilated, no residual peristalsis; 100% failed swallows with no significant pressurisation	Intermediate response to treatment
Type II	Achalasia with oesophageal compression (pan-oesophageal pressurisation) ^[2]	Simultaneous pan-oesophageal pressurisation in ≥20% of swallows	Best prognosis; best response to all treatments (~95% success with Heller myotomy or POEM)
Type III	Achalasia with oesophageal spasm ^[2]	Premature (spastic) contractions in ≥20% of swallows; retained fragments of distal peristalsis	Worst prognosis; least responsive to treatment; often requires POEM (can extend myotomy onto oesophageal body)

Why Does Classification Matter?

The Chicago Classification is not just academic — it guides treatment decisions:

Type II responds well to almost any intervention (pneumatic dilation, Heller myotomy, POEM)
Type III responds poorly to pneumatic dilation and standard Heller myotomy; POEM is preferred because the myotomy can be extended proximally along the oesophageal body to address the spastic segment
Type I is intermediate

Used to assess symptom severity and treatment response:

Symptom	0	1	2	3
Dysphagia	None	Occasional	Daily	Every meal
Regurgitation	None	Occasional	Daily	Every meal
Chest pain	None	Occasional	Daily	Every meal
Weight loss (kg)	None	< 5	5–10	> 10

Total score 0–12
Score ≤ 3 = remission (treatment success)
Score > 3 = treatment failure; consider re-intervention

Clinical Features

Symptom	Frequency	Pathophysiological Basis
Progressive dysphagia (solid + liquid) ^[2]^[3]	~100%	Loss of peristalsis + failure of LES relaxation → functional obstruction to ALL consistencies. Unlike mechanical obstruction (solids first, then liquids), motility disorders cause simultaneous solid and liquid dysphagia from onset. Patients often describe food "sticking" behind the sternum.
Regurgitation ^[2]^[3]	~70%	Regurgitation of undigested food or saliva immediately after meal ^[3]. Food sits in the dilated oesophagus and is regurgitated (not vomited — no nausea, no bile, no acid). Acidic smell (fermentation of food) ^[2] — retained carbohydrates are fermented by oral bacteria producing lactic acid. Worse when lying down (gravity allows pooling).
Aspiration → recurrent aspiration pneumonia ^[2]^[3]	Variable	Regurgitated food/saliva enters the larynx and trachea, especially during sleep (when protective reflexes are diminished). Aspiration can lead to resultant bronchitis and pneumonia ^[3].
Heartburn ^[3]	40–50%	This is a trap! Patients often initially misdiagnosed with GERD. The "heartburn" in achalasia is NOT from acid reflux — it's from: (1) Direct irritation of oesophageal lining by food, pills, or lactate production by bacterial fermentation of retained carbohydrates ^[3]; (2) Abnormal oesophageal motor activity might trigger the sensation of heartburn ^[3]. True acid reflux is actually reduced in achalasia (the LES is TOO tight, not too loose).
Chest pain ^[2]^[3]	25–50%	Retrosternal non-cardiac chest pain ^[3]; related to oesophageal spasm ^[3]. Vigorous, non-peristaltic contractions of the oesophageal body cause pain. More common in Type III achalasia. Important: treatment is not effective in relieving pain and patient should be counselled about the possible expectations of procedures ^[3].
Difficulty belching ^[3]	Variable	Result of a defect in relaxation of upper oesophageal sphincter ^[3]. The UOS also develops impaired relaxation mechanics due to disrupted vagal reflexes. Patients feel bloated and unable to release swallowed air.
Weight loss ^[2]	Variable	Chronic inability to eat adequate amounts due to dysphagia and regurgitation → progressive weight loss. Significant weight loss (> 10 kg) should raise suspicion for pseudoachalasia/malignancy.

The Dysphagia Pattern is Key

A common exam mistake: confusing achalasia dysphagia with mechanical obstruction dysphagia.

Mechanical (stricture, cancer): progressive dysphagia, solids first → then liquids as lumen narrows further
Motility (achalasia): dysphagia to solids AND liquids from the outset (though may worsen over time)

If a question stem describes simultaneous solid + liquid dysphagia → think motility disorder (achalasia, diffuse oesophageal spasm). If progressive solids → liquids → think mechanical obstruction.

Physical examination is often unremarkable in early achalasia. Signs are typically manifestations of late disease or complications:

Sign	Pathophysiological Basis
Cachexia / wasting	Chronic malnutrition from prolonged dysphagia and regurgitation
Halitosis (bad breath)	Bacterial fermentation of retained food in the dilated oesophagus; the acidic smell described by patients ^[2]
Respiratory signs (crackles, wheeze, signs of consolidation)	Recurrent aspiration pneumonia; may have chronic cough
Epigastric splash (succussion splash)	Rare; massive oesophageal dilation with retained fluid — analogous to gastric outlet obstruction succussion splash but located higher
Cervical lymphadenopathy	If present, raises concern for pseudoachalasia/oesophageal malignancy
No tenderness on abdominal palpation	Achalasia is painless on examination; tenderness suggests perforation or other pathology

If untreated:

Early: intermittent dysphagia, mild symptoms → patients adapt (eat slowly, drink water to "wash food down", adopt upright posture during meals)
Intermediate: progressive dilation, worsening regurgitation, recurrent aspiration events, weight loss
Late: sigmoid-like oesophagus (massively dilated, tortuous, decompensated) ^[2]; aspiration pneumonia; oesophageal SCC (after ~15–20 years of disease; risk ~3%, ~30× general population)

High Yield Summary

Definition: Achalasia = failure of LES relaxation + aperistalsis of oesophageal body due to degeneration of inhibitory neurons (NO/VIP) in the myenteric plexus.

Triad on manometry: (1) Aperistalsis, (2) Elevated basal LES pressure, (3) Impaired LES relaxation on swallowing.

Epidemiology: Equal sex ratio, peak 35–45 years, ~1–3/100,000/year.

Aetiology: Primary (idiopathic, > 90%) vs secondary (Chagas disease, pseudoachalasia from malignancy, infiltrative disorders). Always exclude pseudoachalasia with OGD ± EUS.

Chicago Classification: Type I (minimal pressurisation), Type II (pan-oesophageal pressurisation — best prognosis), Type III (spastic — worst prognosis).

Cardinal symptoms: Progressive dysphagia to solids AND liquids (100%), regurgitation of undigested food (70%), chest pain, heartburn (from fermentation, NOT acid reflux), difficulty belching, weight loss.

Red flags for pseudoachalasia: Age > 60, short symptom duration, rapid weight loss, difficulty passing scope through GOJ.

Complication: Oesophageal SCC (long-term); aspiration pneumonia; malnutrition.

HK relevance: Primary achalasia is dominant; achalasia is a risk factor for oesophageal SCC (most common oesophageal cancer in HK); Chagas disease not relevant locally.

Active Recall - Achalasia (Definition, Epidemiology, Pathophysiology, Clinical Features)

^[1] Lecture slides: GC 189. I can't swallow oesophageal cancer.pdf ^[2] Senior notes: maxim.md (Section 3.4 — Benign diseases of esophagus, Achalasia) ^[3] Senior notes: felixlai.md (Section: Achalasia) ^[4] Senior notes: maxim.md (Section 3.5 — CA esophagus); felixlai.md (Section: Esophageal cancer)

Differential Diagnosis of Achalasia

When a patient walks in with dysphagia ± regurgitation ± chest pain, your job is to systematically work through the differentials. The key clinical reasoning pivot is: Is this a motility (functional) problem or a structural (mechanical) problem? And if it looks like achalasia on manometry, is it true primary achalasia or something mimicking it?

Let's break this down from first principles.

The cardinal symptom of achalasia is progressive dysphagia to both solids and liquids. This immediately narrows your differential because:

Dysphagia to solids only (initially) → progressive to liquids = mechanical/structural obstruction (the lumen is physically narrowing)
Dysphagia to solids AND liquids from the outset = motility/functional disorder (the propulsive mechanism is broken, regardless of bolus consistency)

However, several conditions can overlap in presentation. The differentials fall into three categories:

Conditions that mimic the symptoms of achalasia (dysphagia, regurgitation, heartburn, chest pain)
Conditions that mimic achalasia on manometry (pseudoachalasia)
Other oesophageal motility disorders (similar symptom profile but different manometric findings)

Category 1: Conditions That Mimic Achalasia Symptoms

Feature	GERD	Achalasia
Heartburn	Yes — from acid reflux through a hypotensive LES	Yes — but from fermentation of retained food and direct mucosal irritation, NOT acid ^[3]
Regurgitation	Acidic, partially digested material from stomach	Undigested food/saliva from oesophagus — no bile, no acid (unless fermented)
Dysphagia	Late; due to stricture or oesophagitis	Early and progressive; to solids AND liquids
Response to PPI	Improves	Does NOT improve (this is a key clinical clue)

Why is this a common confusion? Both GERD and achalasia can present with heartburn and regurgitation ^[3]. In early achalasia, patients are frequently misdiagnosed with GERD and started on PPIs. When they don't respond, clinicians should reconsider the diagnosis. The distinguishing investigation is oesophageal manometry, which is diagnostic of achalasia ^[3].

Clinical Pearl

A patient with "refractory GERD" who fails PPI therapy should have oesophageal manometry to exclude achalasia. The heartburn in achalasia is NOT acid-mediated — PPIs are useless. This is one of the most common diagnostic delays in achalasia (average delay from symptom onset to diagnosis is ~5 years).

Painless progressive dysphagia (over weeks to months) is malignancy until proven otherwise ^[5]
Oesophageal cancer typically causes progressive dysphagia to solids → then liquids as the tumour encroaches on the lumen (mechanical pattern)
However, tumours at the EGJ/cardia can invade the myenteric plexus and cause a motility-type picture (pseudoachalasia — see below)
Red flags: age > 60, rapid weight loss, short symptom duration, anaemia, odynophagia (usually due to extra-oesophageal involvement) ^[5]
Key distinguishing features: hoarseness of voice (RLN palsy), haematemesis, Virchow's node, supraclavicular lymphadenopathy ^[5]

Develops as a consequence of chronic oesophagitis → fibrosis → luminal narrowing
Progressive dysphagia to solids in a patient with long-standing GERD/heartburn history
Distinguished from achalasia: the dysphagia is initially to solids only; there is a clear history of preceding heartburn that DID respond to PPIs; manometry shows normal LES relaxation

"Eosinophilic" = eosinophil infiltration; "oesophagitis" = oesophageal inflammation
Typically young, atopic male (history of asthma, eczema, food allergies)
Intermittent dysphagia to solids, food impaction episodes
Distinguished from achalasia: episodic rather than progressive, responds to topical steroids/PPI, manometry shows normal LES relaxation, biopsy shows ≥15 eosinophils/HPF

Pseudoachalasia deserves special attention because it has the same manometric findings as achalasia ^[2]^[3] but is caused by an underlying malignancy or other process.

Malignancy can cause pseudoachalasia by invading the oesophageal neural plexus directly or by release of humoral factors that disrupt oesophageal function as part of a paraneoplastic syndrome ^[3].

Feature	Primary Achalasia	Pseudoachalasia
Age	Any age (peak 35–45)	Typically > 60 years
Symptom duration	Long (months to years)	Short (< 1 year)
Weight loss	Gradual, proportionate	Rapid, disproportionate
Manometry	Elevated IRP, aperistalsis	Same findings ^[2]^[3]
OGD	Scope passes GOJ with gentle pressure; dilated oesophagus, food residue	Scope cannot pass easily; may see mass, mucosal irregularity
Barium swallow	Bird beak sign, smooth tapering	Shouldering / heaping at the distal narrowing ^[2] — irregular, asymmetric
EUS	Thickened muscle layer, no mass	Mass at GOJ / thickened wall with loss of layers
CT	Normal	Mass, lymphadenopathy, metastases

Pseudoachalasia can be differentiated from primary achalasia by upper endoscopy and endoscopic ultrasound ^[2]^[3].

Must-Know: Always OGD Before Diagnosing Primary Achalasia

You should NEVER diagnose primary achalasia based on manometry alone. OGD is mandatory to rule out mechanical causes (e.g. malignancy, stricture) ^[2] and to assess for complications (e.g. oesophagitis, SCC). Up to 4% of patients initially diagnosed with achalasia actually have pseudoachalasia from malignancy. If there is any suspicion, add EUS and CT.

Causes of pseudoachalasia ^[3]:

Direct invasion: adenocarcinoma of gastric cardia/EGJ invading the myenteric plexus
Paraneoplastic: small cell lung cancer, lymphoma (anti-Hu/ANNA-1 antibodies target myenteric neurons)
Infiltrative: amyloidosis, sarcoidosis

This is the key group to differentiate on manometry. Oesophageal manometry can differentiate achalasia from other oesophageal motility disorders since the lower oesophageal sphincter relaxation (integrated relaxation pressure, IRP) is NORMAL in these conditions ^[3].

The fundamental distinction: In achalasia, IRP is elevated (≥ 15 mmHg). In other motility disorders, IRP is normal.

Condition	LES / IRP	Oesophageal Body	Key Distinguishing Feature
Achalasia	Elevated IRP (≥ 15 mmHg)	Aperistalsis	The gold standard triad
Diffuse Oesophageal Spasm (DES) ^[3]	Normal IRP	Premature contractions (≥20% of swallows) with some normal peristalsis preserved	Intermittent dysphagia + chest pain; "corkscrew oesophagus" on barium swallow; normal peristalsis still present between spasms
Jackhammer (Nutcracker) Oesophagus ^[3]	Normal IRP	Hypercontractile peristalsis (DCI > 8000 mmHg·cm·s)	Extreme force of contraction but peristalsis is intact and sequential; predominant symptom is chest pain rather than dysphagia
Absent Contractility (e.g., scleroderma)	Normal or low IRP	100% failed peristalsis	LES is hypotensive (unlike achalasia where LES is hypertensive); associated with GERD (incompetent LES + no peristalsis = worst reflux); look for scleroderma features (CREST, skin thickening, Raynaud's)
Opioid-induced dysmotility	May have elevated IRP	Variable — can mimic achalasia (Type III pattern)	Increasingly recognised; always take a drug history; opioids increase LES tone and disrupt peristalsis via mu-receptor activation in myenteric plexus

Why Does IRP Distinguish These?

The Integrated Relaxation Pressure (IRP) specifically measures the adequacy of EGJ (LES) relaxation during the 10-second window after a swallow. In achalasia, the inhibitory neurons that relax the LES are destroyed → the LES cannot relax → IRP is elevated. In DES and Jackhammer oesophagus, the LES neurons are intact — the problem is in the oesophageal body's contraction pattern, not the sphincter.

These are less commonly confused with achalasia but should be in your differential for any patient presenting with dysphagia ^[5]:

Condition	Mechanism	Key Distinguishing Feature
Oesophageal web/ring (e.g., Schatzki ring)	Thin mucosal fold causing luminal narrowing	Intermittent solid-food dysphagia; Plummer-Vinson syndrome (web + IDA + glossitis) is a risk factor for SCC ^[4]
Extrinsic compression	Extramural causes (4T): tumour/LN, thyroid (retrosternal goitre), thymus, thoracic aortic aneurysm ^[5]	Dysphagia to solids; evident on CT/barium swallow as extrinsic indentation
Corrosive/caustic stricture	Prior ingestion of alkali/acid → fibrotic stricture	History of ingestion; risk factor for SCC ^[4]
Zenker's diverticulum ^[6]	Pulsion diverticulum at Killian's dehiscence (between thyropharyngeus and cricopharyngeus) due to hypertonic cricopharyngeus	Dysphagia with gurgling in throat, food regurgitation, foul breath, aspiration ^[6]; diagnosed by barium swallow; this is an oropharyngeal (transfer) dysphagia, not oesophageal
Foreign body	Physical obstruction of lumen	Acute onset; history of ingestion

Feature	Achalasia	GERD	Pseudoachalasia	DES	Jackhammer	Scleroderma	CA Oesophagus
Dysphagia pattern	S+L from onset	Late, solids	S+L (short Hx)	Intermittent S+L	Mainly chest pain	S+L	Solids → liquids
LES / IRP	↑↑	↓ or normal	↑↑	Normal	Normal	↓	N/A (mechanical)
Regurgitation	Undigested food	Acidic, partially digested	Undigested	Rare	Rare	Acidic (reflux)	Late
Heartburn	Fermentation	Acid reflux	Variable	No	No	Severe (reflux)	No
PPI response	No	Yes	No	No	No	Partial	No
Age	Any (peak 35–45)	Any	> 60	Any	Any	30–50 (F)	> 60
Weight loss	Gradual	No	Rapid	No	No	If systemic	Rapid
OGD	Food residue, tight cardia	Oesophagitis	Mass/irregularity	Normal	Normal	Patulous LES	Tumour

High Yield Summary

Three categories of differentials for achalasia:

Symptom mimics: GERD (heartburn + regurgitation — distinguish by PPI response and manometry), oesophageal cancer (progressive solids → liquids — distinguish by OGD), peptic stricture, EoE
Manometric mimics (pseudoachalasia): Same manometric findings as achalasia. Caused by malignancy invading the neural plexus or paraneoplastic syndrome. Red flags: age > 60, short history, rapid weight loss, shouldering on barium swallow. Always OGD ± EUS before diagnosing primary achalasia.
Other motility disorders: DES and Jackhammer oesophagus have normal IRP on manometry (LES relaxation is preserved) — this is the key distinguishing feature. Scleroderma has absent peristalsis but low LES pressure (opposite of achalasia).

Key investigation: High-resolution manometry (HRM) is the definitive diagnostic tool. IRP ≥ 15 mmHg = achalasia (or pseudoachalasia). Normal IRP = not achalasia, consider DES/Jackhammer/other.

Active Recall - Differential Diagnosis of Achalasia

References

^[1] Lecture slides: GC 189. I can't swallow oesophageal cancer.pdf ^[2] Senior notes: maxim.md (Section 3.4 — Achalasia) ^[3] Senior notes: felixlai.md (Section: Achalasia) ^[4] Senior notes: maxim.md (Section 3.5 — CA esophagus) ^[5] Senior notes: maxim.md (Section 3.2 — Dysphagia) ^[6] Senior notes: maxim.md (Section: Zenker's diverticulum)

Diagnostic Criteria, Algorithm & Investigations for Achalasia

Diagnostic Criteria

There is no single "checklist" diagnostic criterion for achalasia like there is for, say, rheumatic fever. Instead, the diagnosis rests on demonstrating the characteristic manometric triad while excluding mechanical obstruction and pseudoachalasia. Let's build this from first principles.

High-resolution oesophageal manometry (HRM) is the definitive diagnostic investigation ^[2]^[3]. The diagnosis requires demonstrating:

Criterion	What It Means	Why It Occurs
1. Elevated Integrated Relaxation Pressure (IRP) ≥ 15 mmHg ^[3]	The LES fails to adequately relax during swallowing	Loss of inhibitory neurons (NO/VIP) → unopposed excitatory cholinergic tone keeps the LES tonically contracted
2. Absence of normal peristalsis ^[3]	No coordinated sequential contractions in the oesophageal body (100% failed peristalsis in Types I/II; spastic pattern in Type III)	Loss of inhibitory innervation in the smooth muscle oesophageal body → no coordinated "on-off" sequencing needed for peristalsis
3. Elevated resting LES pressure ^[2]^[3]	Basal LES tone is higher than normal ( > 45 mmHg in many cases, though not required for diagnosis)	Same mechanism as criterion 1: unopposed ACh at rest keeps LES contracted

IRP — Understanding the Key Metric

IRP is the median of the maximal relaxation pressures of the EGJ measured across 4 seconds during the 10-second window of EGJ relaxation following a swallow ^[3]. In plain English: after you swallow, the system looks at a 10-second window and picks the 4 consecutive seconds where the EGJ pressure is lowest — the median of those pressures is the IRP.

In simplified continuous form for a single swallow:

\mathrm{IRP}_{4s} = \min_{\tau \in [t_0,\,t_0 + 6s]} \left( \frac{1}{4s} \int_{\tau}^{\tau + 4s} P_{\mathrm{EGJ}}(t)\,dt \right)

\mathrm{IRP} = \operatorname{median}_{i=1,\dots,n} \left(\mathrm{IRP}_{4s,i}\right)

where $P_{\mathrm{EGJ}}(t)$ is the pressure at the EGJ after a swallow at $t_0$ . The integral adds up EGJ pressure over each possible 4-second relaxation window, the division by $4s$ converts it back to an average pressure in mmHg, and the minimum selects the best relaxation achieved after that swallow. HRM software repeats this across the standard series of swallows and reports the median value.

Upper limit of IRP is usually identified as ≥ 15 mmHg ^[3]. If the IRP is ≥ 15 mmHg, the LES is NOT relaxing properly — this is the single most important number in diagnosing achalasia.

Why is IRP better than just measuring "LES relaxation"? Because IRP accounts for the entire EGJ (including the crural diaphragm contribution) and is standardised — it's more reproducible and more specific than older measures.

Manometry alone is insufficient for a complete diagnosis. OGD is mandatory to rule out mechanical causes (e.g. malignancy, stricture) that can produce identical manometric findings ^[2]^[3].

Diagnostic formula: Achalasia = Manometric triad (HRM) + Exclusion of pseudoachalasia (OGD ± EUS/CT)

Once the manometric triad is confirmed, the Chicago Classification (based on oesophageal pressure topography) ^[2] subcategorises achalasia into three types. This matters because it guides treatment selection and predicts outcomes.

Subtype	HRM Pattern	Description	Treatment Implication
Type I: Achalasia with minimal oesophageal pressurisation ^[2]	Elevated IRP + 100% failed peristalsis + no significant pan-oesophageal pressurisation	The oesophageal body is essentially flaccid — it generates no meaningful pressure. Think of it as a floppy, dilated tube above a locked gate	Intermediate response to treatment; Heller myotomy or POEM
Type II: Achalasia with oesophageal compression (pan-oesophageal pressurisation) ^[2]	Elevated IRP + pan-oesophageal pressurisation in ≥ 20% of swallows	The entire oesophagus contracts simultaneously (uniform squeeze), generating > 30 mmHg across the whole length. Not peristalsis (which is sequential), but rather a mass contraction	Best prognosis; ~95% respond to any treatment modality
Type III: Achalasia with oesophageal spasm ^[2]	Elevated IRP + premature (spastic) contractions with DCI > 450 mmHg·cm·s in ≥ 20% of swallows	Vigorous, premature, lumen-obliterating contractions. Some fragments of peristaltic activity remain but are discoordinated	Worst prognosis; POEM preferred (myotomy can be extended along the spastic oesophageal body)

Why Type II Has the Best Prognosis

Type II has pan-oesophageal pressurisation — the oesophagus still has some residual muscular activity (even though it's not coordinated). When you treat the LES obstruction (e.g., myotomy, dilation), this residual pressure helps push food through. In Type I, the oesophagus is completely flaccid — even after LES treatment, there's no propulsive force, so food relies on gravity alone. Type III has spasm, which causes ongoing symptoms (chest pain) even after LES treatment.

The approach follows a logical sequence: clinical suspicion → exclude mechanical cause → confirm with manometry → subtype → plan treatment.

Key reasoning at each step:

OGD first — because you must exclude pseudoachalasia/malignancy before labelling someone with primary achalasia. It's also necessary to assess for complications (oesophagitis, candidiasis, early SCC) ^[2]^[3]
HRM second — the definitive diagnostic test; classifies the subtype
Timed barium swallow — optional but useful as a baseline to objectively assess oesophageal emptying pre- and post-treatment
EUS/CT — reserved for cases where pseudoachalasia is suspected

Investigation Modalities: Detailed Breakdown

What it is: A catheter with closely spaced pressure sensors (typically 36 sensors, 1 cm apart) is passed transnasally into the oesophagus and stomach. The patient performs a series of standardised wet swallows (typically 10 × 5 mL water swallows). Pressure data is displayed as a colour-coded oesophageal pressure topography (EPT) plot (Clouse plot) — essentially a "heat map" of pressure along the oesophagus over time ^[2]^[3].

Why HRM over conventional manometry? Conventional (line-tracing) manometry used fewer sensors and produced simple line graphs. HRM provides a complete spatial-temporal pressure map of the entire oesophagus simultaneously, making it much easier to identify patterns, calculate IRP accurately, and subtype according to the Chicago Classification.

Definitive diagnostic findings ^[2]^[3]:

Parameter	Finding in Achalasia	Normal Value
Integrated Relaxation Pressure (IRP)	≥ 15 mmHg ^[3]	< 15 mmHg
Resting LES pressure	Elevated (often > 45 mmHg) ^[3]	10–45 mmHg
LES relaxation on swallowing	Incomplete / failure to relax ^[2]^[3]	Complete relaxation to near gastric baseline
Peristalsis	Absent normal peristalsis ^[2]^[3]; pattern depends on Chicago subtype	Normal sequential peristaltic contractions

Chicago Classification on HRM ^[2]:

Subtype	EPT Pattern
Type I	IRP ≥ 15 + 100% failed peristalsis + mean integrated relaxation pressure < 30 mmHg across the oesophageal body (minimal pressurisation)
Type II	IRP ≥ 15 + ≥ 20% of swallows show pan-oesophageal pressurisation > 30 mmHg
Type III	IRP ≥ 15 + ≥ 20% of swallows show premature (spastic) contractions (DCI > 450 mmHg·cm·s with shortened distal latency < 4.5 s)

Exam Pearl: Why IRP and Not Just 'LES Pressure'?

Older textbooks describe "elevated resting LES pressure" as a diagnostic criterion, and it IS typically elevated in achalasia. However, the IRP is the criterion used in the Chicago Classification because: (1) some achalasia patients have normal basal LES pressure but still fail to relax on swallowing; (2) IRP specifically measures the dynamic relaxation during swallowing, which is the pathophysiologically relevant event (the LES needs to relax to let food through — it doesn't matter what the resting pressure is if it relaxes properly). A high IRP = failure to relax = diagnostic.

Purpose: To assess complications (e.g. oesophagitis, SCC oesophagus) and rule out mechanical causes (e.g. malignancy, stricture) ^[2].

OGD must be performed in ALL patients with suspected achalasia before the diagnosis of primary achalasia is accepted. This is non-negotiable.

Key findings ^[2]^[3]:

Finding	Significance	Pathophysiological Basis
Dilated oesophagus containing residual material ^[3]	Hallmark of achalasia	Failed peristalsis + non-relaxing LES → food/liquid stasis → oesophageal dilation
Tight cardia (LES) that does not open spontaneously ^[2]	Suggests impaired LES relaxation	Hypertonic LES fails to relax
LES can be traversed with gentle pressure ^[3]	Distinguishes primary achalasia from pseudoachalasia	In primary achalasia, the tight LES is purely due to muscle spasm (functional) — it yields to gentle pressure. In pseudoachalasia from tumour, the obstruction is physical/infiltrative and the scope may NOT pass easily
Food residue, candidiasis, oesophagitis	Complications of chronic stasis	Retained food causes mucosal irritation; stasis predisposes to Candida overgrowth
Mucosal irregularity / nodularity	Raises concern for dysplasia/SCC	Chronic irritation → metaplasia → dysplasia → SCC

Up to 40% of patients with achalasia have a normal OGD ^[3]. This is why manometry is the definitive test — a normal OGD does NOT exclude achalasia.

Critical Point

OGD findings in pseudoachalasia: scope cannot pass through GOJ easily; there may be mucosal irregularity, mass, ulceration, or shouldering/heaping at the narrowing. If you cannot pass the scope or see any suspicious features → proceed to EUS + CT immediately ^[2].

Barium swallow is usually not done now as the primary diagnostic tool ^[2], but it remains useful for:

Assessing oesophageal emptying and EGJ morphology ^[3]
Providing a baseline for post-treatment comparison (timed barium swallow)
Detecting sigmoid oesophagus (end-stage dilation)

Typical findings ^[2]^[3]:

Finding	Stage	Explanation
Bird's beak sign (or "rat-tail" appearance) ^[2]^[3]	Early-moderate	Hold up of contrast with tapering stricture in distal oesophagus and proximal dilation ^[2]. The contrast column tapers smoothly to a point at the non-relaxing LES, resembling a bird's beak. The tapered segment is smooth and symmetric (because it's muscular spasm, not tumour)
Aperistalsis ^[3]	Any stage	No sequential peristaltic waves seen on fluoroscopy; contrast stays in the oesophagus
Delayed emptying ^[3]	Any stage	Contrast does not empty into the stomach in the normal time frame
Dilatation of oesophagus with narrowing of distal oesophagus ^[3]	Moderate-late	Progressive proximal dilation above the functional obstruction
Sigmoid-like appearance ^[2]	Late/end-stage	Massive oesophageal dilatation ^[2] causing the oesophagus to become tortuous and S-shaped, like a sigmoid colon — the "sigmoid oesophagus" or "megaoesophagus". Indicates decompensated, long-standing disease

Red flag on barium swallow: Any shouldering or heaping should lead to suspicion of pseudoachalasia (due to extramural obstruction, e.g. OGJ tumour) ^[2]. In primary achalasia the tapering is smooth; in pseudoachalasia it is irregular, asymmetric, or has a "shelf-like" appearance.

Timed Barium Swallow (TBS): The patient drinks a set volume of barium (e.g., 200 mL); upright films are taken at 1, 2, and 5 minutes. The height of the barium column is measured. This is used:

Pre-treatment: as a baseline
Post-treatment: to objectively assess oesophageal emptying (a reduction in column height indicates treatment success)

Contrast	When to Avoid	Why
Barium	Risk of perforation	Barium peritonitis — barium is inert and non-absorbable; if it leaks into the mediastinum or peritoneum, it causes a severe granulomatous inflammatory reaction
Gastrografin (water-soluble, hyperosmolar)	Risk of aspiration	Chemical pneumonitis — gastrografin is hyperosmolar; if aspirated, it draws fluid into the alveoli via osmosis causing pulmonary oedema and chemical pneumonitis ^[2]^[5]

If high risk of aspiration: use Omnipaque (water-soluble, low-osmolarity contrast medium — lower risk of pulmonary oedema compared to gastrografin) ^[5]

Practical Tip for Achalasia Patients

Achalasia patients are at risk of aspiration (regurgitation of pooled oesophageal contents). If you need contrast imaging, gastrografin is NOT ideal because of the aspiration risk. Use barium (safe from an aspiration standpoint as it is inert in the lungs) or Omnipaque if perforation risk is also a concern. In practice, most achalasia patients undergoing barium swallow can use standard barium safely — perforation is not typically a concern unless there's been prior intervention.

CXR is not diagnostic but may provide clues, especially in advanced disease ^[2]^[3]:

Finding	Explanation
Widening of mediastinum ^[2]^[3]	The massively dilated oesophagus occupies space in the posterior mediastinum, widening the mediastinal silhouette on PA film
Absence of normal gastric bubble ^[3]	Failure of LES relaxation prevents air from entering the stomach ^[3]. Normally, swallowed air passes through the LES into the gastric fundus, producing the gastric air bubble on the left hemidiaphragm. In achalasia, the non-relaxing LES traps air in the oesophagus
Air-fluid level in posterior mediastinum	Retained food/fluid in the dilated oesophagus creates an air-fluid level visible on lateral CXR
Double right heart border	The dilated oesophagus projects over the right heart border, creating a double contour
Aspiration changes	Bilateral lower lobe infiltrates if recurrent aspiration pneumonia

The Absent Gastric Bubble — A Subtle but Classic Sign

This is a favourite exam question. The absence of a gastric bubble on CXR in a patient with dysphagia is a classic clue to achalasia ^[3]. The reasoning: normally you swallow air with every meal and this air passes through the LES into the stomach → gastric bubble on CXR. In achalasia, the LES won't open → air cannot enter the stomach → no gastric bubble.

Not routine in primary achalasia, but critical when pseudoachalasia is suspected.

Purpose: Useful in characterizing tumours of distal oesophagus and gastric cardia ^[3].

Typical findings in primary achalasia ^[3]:

Thickened circular muscle layer at LES and through smooth muscle oesophagus — reflecting smooth muscle hypertrophy from chronic unopposed excitatory stimulation
Normal wall layer architecture preserved

Findings suggesting pseudoachalasia:

Loss of normal wall layer architecture
Hypoechoic mass at the EGJ
Transmural thickening with disrupted layers
Periesophageal lymphadenopathy

EUS-guided FNA can be performed on suspicious lymph nodes or masses for cytological diagnosis.

Not part of the routine diagnostic workup for primary achalasia, but used when:

Pseudoachalasia is suspected (look for EGJ mass, lymphadenopathy, metastases)
Preoperative assessment for advanced/end-stage disease (assess oesophageal diameter, angulation for surgical planning)
Evaluating complications (aspiration pneumonia, mediastinal abnormalities)

CT findings in achalasia:

Dilated, fluid-filled oesophagus
Smooth, concentric thickening of the distal oesophageal wall (in primary achalasia)
Air-fluid level within the oesophagus

CT findings suggesting pseudoachalasia:

Irregular/asymmetric wall thickening at EGJ
Mass lesion
Lymphadenopathy, distant metastases

FLIP is a newer technology that measures the distensibility of the EGJ. A balloon catheter is placed across the LES and inflated with saline; sensors measure cross-sectional area and pressure simultaneously to calculate a distensibility index (DI).

In achalasia: the EGJ distensibility is markedly reduced (the LES won't stretch open)
Used adjunctively when HRM is equivocal or to assess treatment adequacy intraoperatively (e.g., during POEM, the surgeon can check if the LES DI has normalised)
Not yet standard in all centres but increasingly used in tertiary oesophageal centres

Priority	Investigation	Purpose	Key Finding
1st	OGD ^[2]^[3]	Exclude pseudoachalasia and mechanical causes; assess complications	Food residue, tight cardia traversable with gentle pressure; normal in up to 40%
2nd	High-Resolution Manometry (HRM) ^[2]^[3]	Definitive diagnosis + Chicago subtyping	IRP ≥ 15 mmHg, absent peristalsis, elevated basal LES pressure
3rd (optional)	Barium swallow / Timed Barium Swallow ^[2]^[3]	Assess morphology, baseline for post-treatment comparison	Bird's beak sign, dilation, delayed emptying, sigmoid oesophagus
4th (if needed)	CXR ^[2]^[3]	Screening / incidental	Widened mediastinum, absent gastric bubble
5th (if pseudoachalasia suspected)	EUS ± CT ^[2]^[3]	Characterise suspected tumour	Mass, wall thickening, lymphadenopathy
Emerging	FLIP	Measure EGJ distensibility	Reduced distensibility index

High Yield Summary

Definitive diagnosis = High-Resolution Manometry (HRM) showing the triad: (1) IRP ≥ 15 mmHg, (2) absent normal peristalsis, (3) elevated basal LES pressure. Chicago Classification v4.0 subtypes based on oesophageal body pattern: Type I (minimal pressurisation), Type II (pan-oesophageal pressurisation — best prognosis), Type III (spastic — worst prognosis).

OGD is mandatory FIRST to exclude pseudoachalasia and assess complications. Up to 40% of achalasia patients have normal OGD — a normal scope does NOT exclude achalasia. Typical findings: dilated oesophagus with food residue, tight cardia that opens with gentle pressure.

Barium swallow: bird's beak sign (smooth tapering at LES), proximal dilation, sigmoid oesophagus in late disease. Shouldering/heaping = pseudoachalasia red flag. Usually not done now as primary diagnostic tool.

CXR: widened mediastinum + absent gastric bubble (air cannot enter stomach through non-relaxing LES).

EUS: for pseudoachalasia workup — characterise EGJ tumours. In primary achalasia shows thickened circular muscle layer.

Contrast safety: Barium — avoid if perforation risk (barium peritonitis). Gastrografin — avoid if aspiration risk (chemical pneumonitis). Omnipaque — safest if both risks present.

Active Recall - Diagnosis & Investigations for Achalasia

References

^[2] Senior notes: maxim.md (Section 3.4 — Achalasia) ^[3] Senior notes: felixlai.md (Section: Achalasia, Section VI. Diagnosis) ^[5] Senior notes: maxim.md (Section 3.2 — Dysphagia)

Management of Achalasia

Before diving into individual treatments, let's establish the conceptual framework from first principles.

Treatment is aimed at decreasing the resting pressure in the LES to a level which the sphincter no longer impedes the passage of ingested material ^[3].

There are fundamentally only two strategies to achieve this ^[3]:

Pharmacological reduction in LES pressure — using drugs or toxins to relax the sphincter muscle (Botulinum toxin injection / Oral nitrates / CCB)
Mechanical disruption of LES muscle fibres — physically tearing or cutting the circular muscle of the LES (Pneumatic dilation / Surgical myotomy / POEM)

The Uncomfortable Truth About Achalasia Treatment

NO treatment can reverse degeneration of ganglion cells, restore the lost oesophageal neurons, or normalise oesophageal functions ^[3]. The inhibitory neurons are gone and they're not coming back. Available treatments do not normalise swallowing but merely improve it ^[3]. The goal is to remove the obstruction (the hypertonic LES) so that gravity and whatever residual oesophageal function exists can push food into the stomach. Patients must be counselled about realistic expectations.

Key counselling point: Treatment is effective in relieving dysphagia ^[3], but treatment is NOT effective in relieving chest pain — patients should be counselled about the possible expectations of procedures ^[3]. Why? Chest pain in achalasia is caused by oesophageal spasm (disordered contraction of the oesophageal body), which is NOT addressed by LES-directed therapies (except partially by POEM, which can extend the myotomy proximally).

Treatment Modalities — Detailed Breakdown

A. Pharmacological / Temporising Treatments

These are NOT definitive treatments. They provide temporary symptom relief and are reserved for patients who cannot undergo more effective interventions.

Mechanism: Injection of botulinum toxin into LES poisons the excitatory (ACh-releasing) neurons that increase LES smooth muscle tone ^[3]. Botulinum toxin is a neurotoxin produced by Clostridium botulinum. It works by cleaving SNARE proteins (specifically SNAP-25) at the presynaptic nerve terminal, preventing acetylcholine vesicle fusion and release. This chemically denervates the excitatory cholinergic neurons at the LES.

Net effect is a decrease in basal LES pressure which allows emptying of the oesophagus when oesophageal pressures exceed that of the partially paralysed LES ^[3].

Feature	Detail
Route	Endoscopic injection; typically 80–100 units injected in 4 quadrants into the LES muscle at OGD
Onset	Days to 1–2 weeks
Duration	Temporary — effect wears off in 6–12 months as nerve terminals regenerate
Indication	Patients who are not good candidates for more definitive therapy with pneumatic dilation or surgical myotomy ^[3] — e.g., elderly, high surgical risk, severe comorbidities, bridging therapy
Efficacy	~75–90% initial response; diminishes with repeated injections due to antibody formation and fibrosis
Advantages	Minimally invasive; low complication rate; no general anaesthesia required
Disadvantages	Temporary; repeated injections cause submucosal fibrosis → makes subsequent Heller myotomy technically more difficult (harder to find the submucosal plane)
Complications	Transient chest pain; rare mediastinitis; submucosal fibrosis (problematic for future surgery)

Why Not Just Keep Injecting Botox?

Each injection causes progressive fibrosis in the submucosal plane at the LES. This fibrosis makes subsequent surgical myotomy (Heller or POEM) technically much more difficult because the surgeon relies on finding a clean plane between mucosa and muscle. Multiple Botox injections blur this plane, increasing the risk of mucosal perforation during myotomy. Therefore, Botox is a bridge, not a destination — use it only when definitive therapy is not feasible.

Mechanism: Both nitrates and CCBs are smooth muscle relaxants. Nitrates donate nitric oxide (NO) → activates guanylate cyclase → increases cGMP → smooth muscle relaxation. CCBs (particularly nifedipine, a dihydropyridine) block L-type calcium channels → reduce calcium influx into smooth muscle cells → reduce contraction. Both decrease LES tone.

This is the least effective treatment option in patients with achalasia, which relaxes the smooth muscles of LES (decreases the tone of LES) ^[3].

Feature	Detail
Preparations	Sublingual nifedipine (10–20 mg) or sublingual isosorbide dinitrate / nitroglycerin administered before meals ^[3]
Onset	15–30 minutes (sublingual route for rapid absorption)
Duration	Hours; needs repeated dosing before each meal
Indication	Patients who are unwilling or unable to tolerate invasive therapy for achalasia or have failed botulinum toxin injections ^[3]
Efficacy	Poor: only ~10–50% symptom improvement; tachyphylaxis develops with nitrates
Side effects	Headache (very common — nitrate-induced vasodilation), hypotension, dizziness, peripheral oedema (nifedipine), flushing
Clinical role	Transient symptomatic relief only ^[2] — essentially a last-resort temporiser

Why sublingual? The sublingual route bypasses first-pass hepatic metabolism, providing faster onset and higher bioavailability — important when you need the LES relaxed before the meal arrives at the GOJ.

B. Definitive Treatments — Mechanical Disruption of the LES

These are the treatments that actually produce durable symptom relief. The fundamental principle is the same across all three: physically disrupt (tear or cut) the circular muscle fibres of the LES so the sphincter can no longer maintain its hypertonic contraction.

Mechanism: Pneumatic balloon dilation of LES → disrupts muscle fibres ^[2]. A non-compliant (rigid) balloon is positioned across the LES under fluoroscopic or endoscopic guidance, then inflated to a controlled pressure, forcibly tearing the circular muscle fibres. Think of it as a controlled, incomplete myotomy performed from the inside.

Feature	Detail
Technique	Rigiflex balloon (30, 35, or 40 mm diameter); graded protocol — start with 30 mm, escalate to 35 then 40 mm if response is inadequate
Efficacy	Curative in 65–85% of patients ^[2]; best in Type II achalasia
Advantages	Outpatient/day case procedure; no general anaesthesia required (can use sedation); repeatable; no surgical incisions
Disadvantages	Lower long-term efficacy than myotomy; may need repeated dilations; risk of perforation
Complications	Perforation (~2–5% risk — the most feared complication; requires urgent surgical repair) ^[2]; GERD (over-disruption of LES → reflux) ^[2]; haemorrhage; chest pain
Contraindications	Oesophageal perforation risk (prior radiation, eosinophilic oesophagitis with friable mucosa); severe oesophageal dilation/sigmoid oesophagus (poor response); pseudoachalasia
Post-procedure	Water-soluble contrast swallow (e.g., gastrografin) to exclude perforation; observe for 4–6 hours

Why "graded"? Starting with the smallest balloon (30 mm) minimises perforation risk. If symptoms recur, the next size up (35 mm, then 40 mm) progressively disrupts more muscle fibres. This stepwise approach balances efficacy against safety.

Mechanism: Surgical division of the circular (and sometimes longitudinal) muscle fibres of the LES, extending onto the gastric cardia (~2 cm) and proximally onto the oesophageal body (~6 cm). This is called a "myotomy" — "myo" = muscle, "tomy" = cutting. The muscle is divided down to the submucosa, leaving the mucosa intact.

Feature	Detail
Approach	Laparoscopic (minimally invasive); 5-port technique
Myotomy extent	~6 cm on the oesophagus + ~2 cm onto the gastric cardia (beyond the GOJ to ensure complete LES disruption)
Efficacy	Successful in ≥ 90% of cases ^[2]; excellent long-term durability
Indication	Failed endoscopic treatment ^[2]; first-line definitive option (equivalent to POEM and PD for Type I/II); younger patients (better long-term durability)
Anti-reflux procedure	With partial anterior fundoplication (180°) to prevent post-operative GERD (Heller-Dor operation) ^[2]
Why partial (not total) fundoplication?	In achalasia, the oesophageal body has aperistalsis — it cannot generate propulsive force. A total (Nissen 360°) fundoplication creates too much resistance at the GOJ, leading to severe postoperative dysphagia because the aperistaltic oesophagus cannot overcome it. A partial wrap (Dor 180° anterior) provides enough anti-reflux protection without excessive obstruction
Complications	Perforation (mucosal injury during myotomy, ~5%); dysphagia (due to fundoplication) ^[2] — 50% early post-op, 10% long-term; GERD (if myotomy too extensive or wrap too loose); vagus nerve injury; incomplete myotomy

Why Dor (Anterior 180°) and Not Toupet (Posterior 270°)?

Both are partial fundoplications. The Dor procedure wraps the gastric fundus anteriorly over the myotomy site. This has the added advantage of covering the exposed oesophageal mucosa after myotomy — acting as a patch that protects against delayed perforation and helps contain any unrecognised mucosal injury. The Toupet (posterior 270°) does not provide this coverage. In Hong Kong and most centres performing Heller myotomy for achalasia, Dor (anterior 180°) is preferred ^[2]^[7].

Mechanism: Creation of a submucosal tunnel at mid-oesophagus, allowing a long myotomy ^[2]. This is essentially a Heller myotomy performed entirely endoscopically, from within the oesophageal lumen, using the submucosal space as a working tunnel.

Step-by-step concept ^[3]:

Mucosal incision ~10–15 cm above the LES → entry into the submucosal space
Submucosal tunnel created distally towards and beyond the GOJ (using endoscopic dissection)
Selective inner circular muscle myotomy performed within the tunnel — the muscle is divided while the overlying mucosa remains intact
Mucosal entry site closed with endoscopic clips

Feature	Detail
Efficacy	Comparable to Heller myotomy (~90–95%); excellent for Type III achalasia because the myotomy can be extended proximally along the spastic oesophageal body (up to 25 cm)
Advantages	Fewer hospital days ^[2]; no skin incisions; no external scars; ability to perform a LONG myotomy (especially beneficial for Type III); can be performed after prior Heller myotomy
Key disadvantage	More reflux as no fundoplication is done ^[2] — the mucosa tunnel technique does not allow simultaneous fundoplication; patients typically require long-term PPI ^[2]
Preferred indication	Type III achalasia (spastic) — POEM's ability to extend the myotomy along the oesophageal body makes it uniquely suited; also excellent for Types I and II
Complications	Reflux (no fundoplication done → PPI) ^[2]; mediastinitis ^[2]; surgical emphysema (CO₂ used for insufflation can track into the mediastinum/subcutaneous tissues) ^[2]; pneumoperitoneum; bleeding; mucosal perforation

Head-to-Head Comparison of Definitive Treatments

Comparison of treatments ^[2]:

Feature	Pneumatic Dilation	Heller Myotomy + Dor	POEM
Approach	Endoscopic (balloon)	Laparoscopic (surgical)	Endoscopic (submucosal tunnel)
Anaesthesia	Sedation ± GA	General anaesthesia	General anaesthesia
Efficacy (short-term)	65–85%	≥ 90%	90–95%
Efficacy (long-term)	Lower; may need repeat	Excellent; durable	Excellent; still accumulating long-term data
Overall effectiveness	Good	Myotomy (endoscopic/surgical) most effective ^[2]	Most effective ^[2]
Anti-reflux mechanism	None (but less mucosal disruption)	Partial fundoplication (Dor 180°)	None → more reflux ^[2]
Post-op GERD rate	~15–35%	~10–20% (protected by Dor)	Higher (~40–50%) ^[2] → needs PPI
Post-op dysphagia	Rare	More dysphagia ^[2] (from fundoplication)	Less dysphagia
Hospital stay	Day case / overnight	2–3 days	Fewer hospital days ^[2]; 1–2 days
For Type III	Poor response	Moderate (limited myotomy length)	Best option (can extend myotomy)
Repeatability	Yes (graded dilation)	Redo myotomy difficult	Can be done after prior Heller
Perforation risk	2–5%	~5% (mucosal injury)	~2%

How to Choose? A Pragmatic Approach

Type I or II achalasia in a fit patient: All three definitive options are reasonable. Current evidence (2020 POET trial, European Achalasia Trial) suggests Heller myotomy and POEM have similar efficacy; PD is slightly less durable but is less invasive. Shared decision-making with the patient is key.

Type III achalasia: POEM preferred because only POEM can extend the myotomy along the entire spastic oesophageal body.

Elderly or high surgical risk: Graded PD (less invasive) or Botox injection.

Failed PD: Heller myotomy or POEM.

Failed Heller: POEM (can find a new submucosal plane).

End-stage sigmoid oesophagus (decompensated): Oesophagectomy may be the only option — the oesophagus is so dilated and tortuous that myotomy/dilation cannot improve emptying.

These measures apply to all achalasia patients regardless of definitive treatment ^[8]:

Measure	Rationale
IV fluid to correct haemodynamic instability or electrolyte derangements ^[8]	Chronic poor oral intake, regurgitation → dehydration, electrolyte imbalances
NPO if patient cannot tolerate fluid ^[8]	Prevent aspiration from regurgitated oesophageal contents
Total parenteral nutrition (TPN) or feeding tube if patient cannot tolerate fluid ^[8]	Nutritional support in severe cases before definitive treatment
Treatment of aspiration pneumonia with IV antibiotics ^[8]	Aspiration is a common complication; must be treated before elective intervention
Dietary counselling	Eat slowly, chew thoroughly, drink water with meals to aid bolus passage; eat upright; avoid eating close to bedtime
Head-of-bed elevation	Reduce nocturnal aspiration risk (pooled oesophageal contents can reflux into airway when supine)
Long-term PPI	Post-POEM (no fundoplication → reflux); post-PD if GERD develops

Reserved for:

End-stage sigmoid oesophagus that has failed all other treatments
Oesophageal SCC developing on a background of achalasia

This is a last resort — oesophagectomy carries significant morbidity and mortality (~2–5% mortality in high-volume centres). The oesophagus is removed and replaced with a gastric conduit (pulled up through the chest) or colonic interposition.

All achalasia patients require ongoing follow-up:

Aspect	Detail
Symptom monitoring	Eckardt score at follow-up visits; score ≤ 3 = remission
Timed barium swallow	Objective assessment of oesophageal emptying pre- and post-treatment
OGD surveillance	Achalasia increases SCC risk (~30× general population); periodic OGD with biopsies recommended (typically every 3–5 years starting 10–15 years after diagnosis, though guidelines vary)
GERD assessment post-treatment	Especially post-POEM; pH monitoring if symptomatic; long-term PPI if confirmed
Repeat HRM	If symptoms recur — assess for incomplete treatment, re-tightening, or new motility pattern

High Yield Summary

Principle: Treatment reduces LES pressure by pharmacological relaxation or mechanical disruption of muscle fibres. No treatment restores lost neurons or normalises swallowing.

Pharmacological (temporising only):

Botox injection: blocks ACh release → reduces LES tone; for patients unfit for definitive therapy; temporary (6–12 months); causes fibrosis complicating future surgery.
Nitrates/CCB: least effective; sublingual nifedipine or ISDN before meals; last resort.

Definitive treatments:

Graded Pneumatic Dilation: disrupts LES muscle fibres; curative in 65–85%; main risk = perforation (2–5%).
Laparoscopic Heller Myotomy + Dor fundoplication: ≥ 90% success; partial anterior wrap prevents GERD without causing dysphagia in aperistaltic oesophagus; more dysphagia than POEM.
POEM: endoscopic myotomy via submucosal tunnel; ~90–95% success; preferred for Type III achalasia (can extend myotomy along spastic body); shorter hospital stay; higher reflux rate (no fundoplication → needs PPI).

Treatment selection by subtype: Type I/II → any definitive option; Type III → POEM preferred; elderly/unfit → PD or Botox; end-stage → oesophagectomy.

Treatment relieves dysphagia but NOT chest pain — counsel patients accordingly.

Active Recall - Management of Achalasia

References

^[2] Senior notes: maxim.md (Section 3.4 — Achalasia, Management) ^[3] Senior notes: felixlai.md (Section: Achalasia, Section VII. Treatment) ^[7] Senior notes: maxim.md (Section: GERD — Surgical treatment, fundoplication types) ^[8] Senior notes: felixlai.md (Section: Dysphagia, Section V. Treatment — General management)

Complications of Achalasia

Complications of achalasia can be divided into two categories: (A) complications of the disease itself (from chronic oesophageal stasis and dilation) and (B) complications of treatment (from the interventions used to manage it). Let's work through each from first principles, linking every complication back to its pathophysiological basis.

A. Complications of the Disease

The root cause of all disease-related complications is the same: functional obstruction at the LES + aperistalsis → chronic food stasis → progressive oesophageal dilation. Everything else follows.

Pathophysiology: The non-relaxing LES and absent peristalsis cause food, liquid, and saliva to pool in the oesophagus for hours to days. This stagnant material directly irritates the oesophageal mucosa:

Erosive oesophagitis: Retained food particles and pills cause mechanical and chemical irritation to the squamous epithelium. Additionally, bacterial fermentation of retained carbohydrates produces lactic acid, which further erodes the mucosa. This is NOT acid reflux oesophagitis (remember: the LES is too tight for acid to reflux up from the stomach).
Candida oesophagitis: The moist, stagnant, nutrient-rich oesophageal environment is an ideal culture medium for Candida species. The damaged squamous epithelium allows fungal adherence and invasion. Importantly, candida oesophagitis in achalasia can occur even in immunocompetent patients — it's the stasis, not immunosuppression, that drives it. On OGD, you'll see white adherent plaques on erythematous mucosa.

Clinical significance: Candida oesophagitis worsens dysphagia and odynophagia; erosions may cause chronic low-grade blood loss.

Pathophysiology: Regurgitated food, saliva, and fermented material from the dilated oesophagus spills into the airway, particularly during sleep when the patient is supine and protective laryngeal reflexes are diminished. The aspirated material causes:

Chemical pneumonitis: from the acidic (fermented) oesophageal contents
Bacterial pneumonia: oral and oesophageal flora (including anaerobes from fermented food) seed the lungs

Aspiration can lead to resultant bronchitis and pneumonia ^[3]. This is one of the most clinically significant complications and can be the presenting feature of achalasia (patient referred to respiratory medicine for recurrent pneumonia before the oesophageal cause is identified).

Pattern: Typically affects the right lower lobe (the right main bronchus is wider, shorter, and more vertical than the left — aspirated material preferentially enters it) or bilateral lower lobes. Recurrent episodes lead to bronchiectasis.

Clinical Pearl

Any patient with recurrent aspiration pneumonia without an obvious cause (e.g., stroke, neurological disease) should have achalasia considered in the differential. Ask about dysphagia! A simple barium swallow or OGD may reveal the diagnosis.

Pathophysiology: Chronic raised intraluminal pressure in the oesophagus (from aperistalsis + non-relaxing LES creating a closed system during attempted swallowing) causes the oesophageal wall to herniate outward at points of relative weakness. These are pulsion diverticula — "pulsion" because they are pushed out by pressure from within (as opposed to "traction" diverticula pulled out by external adhesions).

Typically epiphrenic (just above the diaphragm) in the distal oesophagus
The diverticula themselves become reservoirs for food stasis, worsening regurgitation and aspiration risk
Rarely, they can perforate or develop mucosal ulceration

This is the most serious long-term complication and the reason for lifelong surveillance.

Pathophysiology: The cascade is: chronic food stasis → chronic mucosal irritation/inflammation → regenerative epithelial proliferation → metaplasia → dysplasia → squamous cell carcinoma.

Estimated ~30× increased risk compared to the general population
Lifetime incidence: approximately 3% of achalasia patients
Typically develops 15–25 years after symptom onset
Location: usually in the mid-oesophagus (the maximally dilated segment, where stasis and mucosal contact with retained food is greatest) — this is different from typical SCC which favours the upper 2/3

Achalasia increases risk of developing oesophageal cancer ^[3]. Achalasia is listed as a risk factor for oesophageal SCC alongside smoking, alcohol, hot drinks, Plummer-Vinson syndrome, and caustic injury ^[4]^[9].

Why SCC and not adenocarcinoma? The oesophagus is lined by squamous epithelium. The chronic irritation is from retained food and fermentation products (not acid reflux). There is no Barrett's metaplasia (which requires acid-mediated columnar metaplasia to progress to adenocarcinoma). The chronic irritation of squamous epithelium → squamous dysplasia → SCC.

Surveillance for SCC

There is no universally agreed protocol, but most guidelines recommend periodic OGD with quadrantic biopsies starting approximately 10–15 years after achalasia diagnosis, repeated every 1–3 years depending on risk factors and local protocols. This is particularly important in Hong Kong where SCC is the most common oesophageal cancer (90%) ^[9].

Pathophysiology: Progressive dysphagia → reduced oral intake → caloric deficit → weight loss → sarcopenia and micronutrient deficiencies. Chronic regurgitation causes further nutrient loss. Patients often self-restrict their diet to soft or liquid foods, which may be calorically insufficient.

Clinical significance: Significant weight loss (> 10 kg) should always prompt re-evaluation — is this from the achalasia itself, or could this be pseudoachalasia/malignancy?

Pathophysiology: Years of chronic dilation → the oesophagus loses all residual tone and becomes massively dilated and tortuous, adopting an S-shaped configuration reminiscent of the sigmoid colon. At this stage:

The oesophageal wall is thinned and atonic
No treatment short of oesophagectomy will restore function
Aspiration risk is extremely high
Nutritional status is severely compromised

B. Complications of Treatment

Each treatment modality carries specific complications, directly related to its mechanism of action.

Complication	Mechanism	Incidence	Management
Perforation ^[2]	The balloon forcibly tears circular muscle — if the tear extends through the full wall thickness, free perforation results	2–5%	Post-procedure water-soluble contrast swallow to detect; if free perforation → urgent surgical repair (thoracotomy + primary repair ± Dor patch)
GERD ^[2]	Over-disruption of LES muscle → LES becomes incompetent → acid reflux	15–35%	PPI therapy; dietary/lifestyle measures
Haemorrhage	Mucosal tear at the dilation site	Rare	Usually self-limiting; endoscopic haemostasis if significant
Chest pain	Muscle fibre disruption; local inflammation	Common (transient)	Analgesics; self-resolving within 24–48 hours

Complication	Mechanism	Management
Perforation (mucosal injury) ^[2]	During myotomy, the surgeon divides muscle fibres down to the submucosa; the thin mucosa can be inadvertently breached	Intraoperative recognition and primary repair; the Dor fundoplication covers the myotomy site as a protective patch
Dysphagia (due to fundoplication) ^[2]	The fundoplication wrap, even a partial one, adds some resistance at the GOJ; in an aperistaltic oesophagus, even modest resistance causes symptoms	50% in early post-op, 10% long-term ^[7]; investigate with water-soluble contrast swallow; treat with endoscopic balloon dilation or revision of fundoplication if persistent
Post-operative GERD	Myotomy disrupts the LES anti-reflux mechanism; if fundoplication wrap is too loose or slips → acid reflux	PPI therapy; if severe, revision fundoplication
Incomplete myotomy	Myotomy does not extend far enough distally onto the gastric cardia or does not fully divide all circular muscle fibres	Persistent dysphagia; treat with redo myotomy (POEM is excellent for salvage after failed Heller) or PD
Vagus nerve injury	Dissection around the GOJ can damage the vagal trunks	Delayed gastric emptying; treat with prokinetics; pyloric intervention if severe

Complication	Mechanism	Management
Reflux (GERD) ^[2]	No fundoplication is performed during POEM → the disrupted LES has no anti-reflux augmentation	Long-term PPI ^[2]; the most common and significant complication (~40–50%)
Mediastinitis ^[2]	Inadvertent full-thickness perforation or contamination of the mediastinum during submucosal tunnel creation	IV antibiotics; drainage; surgical exploration if severe
Surgical emphysema ^[2]	CO₂ used for insufflation during the endoscopic procedure tracks through the submucosal tunnel into the mediastinum and subcutaneous tissues	Usually self-limiting; decompression if causing haemodynamic compromise (tension capnomediastinum/capnopericardium) or respiratory distress
Pneumoperitoneum	CO₂ tracks through the oesophageal hiatus into the peritoneal cavity	Needle decompression if causing abdominal compartment syndrome; usually self-limiting
Mucosal perforation	Breach of mucosa during tunnel creation	Endoscopic clip closure; antibiotics
Bleeding	Injury to submucosal vessels during tunnel dissection	Endoscopic coagulation

Complication	Mechanism
Submucosal fibrosis	Repeated injections cause chronic inflammatory reaction → fibrosis in the submucosal plane; obliterates the surgical plane needed for future myotomy (Heller or POEM)
Transient chest pain	Local tissue reaction at injection site
Rare mediastinitis	Transmural injection or perforation
Diminishing efficacy	Antibody formation against botulinum toxin with repeated injections

Category	Complication	Pathophysiological Link
Disease	Erosions / Candida oesophagitis	Food stasis → mucosal irritation → fungal overgrowth
Disease	Aspiration pneumonia	Regurgitation of stagnant contents → airway contamination
Disease	Lower oesophageal diverticula	Raised intraluminal pressure → pulsion herniation
Disease	Oesophageal SCC	Chronic mucosal irritation → metaplasia → dysplasia → carcinoma
Disease	Malnutrition / weight loss	Chronic dysphagia → reduced oral intake
Disease	Sigmoid megaoesophagus	End-stage dilation and decompensation
Treatment (PD)	Perforation, GERD	Over-disruption of LES
Treatment (Heller)	Perforation, dysphagia, GERD	Mucosal injury; fundoplication resistance
Treatment (POEM)	Reflux, mediastinitis, surgical emphysema	No fundoplication; tunnel contamination; CO₂ tracking
Treatment (Botox)	Submucosal fibrosis	Repeated injection → chronic inflammation

High Yield Summary

Disease complications — all stem from chronic food stasis in a dilated, aperistaltic oesophagus above a non-relaxing LES:

Mucosal: erosions, candida oesophagitis (stasis + irritation)
Respiratory: aspiration pneumonia (regurgitated stagnant food into airway)
Structural: lower oesophageal diverticula (raised intraluminal pressure), sigmoid megaoesophagus (end-stage)
Malignancy: oesophageal SCC (~30× risk; develops after 15–25 years; needs long-term OGD surveillance)

Treatment complications — specific to modality:

PD: perforation (2–5%), GERD
Heller myotomy: mucosal perforation, dysphagia from fundoplication (50% early, 10% long-term), GERD
POEM: GERD (40–50% — the major disadvantage; no fundoplication → needs PPI), mediastinitis, surgical emphysema
Botox: submucosal fibrosis (complicates future myotomy)

Cancer risk: Achalasia is a recognised risk factor for oesophageal SCC. Surveillance with periodic OGD recommended from 10–15 years post-diagnosis.

Active Recall - Complications of Achalasia

References

^[2] Senior notes: maxim.md (Section 3.4 — Achalasia, Complications and Management) ^[3] Senior notes: felixlai.md (Section: Achalasia — Overview, Clinical manifestations) ^[4] Senior notes: maxim.md (Section 3.5 — CA esophagus, Risk factors) ^[7] Senior notes: maxim.md (Section: GERD — Surgical treatment, fundoplication complications) ^[9] Senior notes: maxim.md (Section 3.5 — CA esophagus, Epidemiology)