Achalasia

Detailed Overview

Achalasia manifests progressively with dysphagia to both solids and liquids, regurgitation of undigested food, and weight loss. The loss of inhibitory neurotransmitters (nitric oxide and vasoactive intestinal peptide) leaves unopposed excitatory tone (acetylcholine), causing LES hypertonia. Over time, the esophagus dilates and becomes tortuous (sigmoid esophagus), predisposing to aspiration and squamous cell carcinoma. Timely intervention aims to relieve the outflow obstruction, though peristalsis is rarely restored.

Epidemiology & Demographics

Incidence: 1 to 3 per 100,000 individuals annually. Prevalence: 10 per 100,000. Peak age of onset is between 25 and 60 years. Gender ratio is roughly equal (1:1). Geographically ubiquitous with no specific regional predilection.

Etiological Mechanism

Most cases are idiopathic. The underlying cause is the autoimmune or viral-mediated destruction of the myenteric plexus ganglion cells. Chagas disease (Trypanosoma cruzi infection) can cause secondary achalasia by directly destroying these nerve plexuses.

Primary Causes

Idiopathic immune-mediated destruction

Trypanosoma cruzi (Chagas disease)

Malignancy (pseudoachalasia due to tumor infiltration of GE junction)

Amyloidosis

Sarcoidosis

• Viral infections: Potential link to HSV-1 or measles virus as triggers for autoimmune response.
• Genetic predisposition: Rare familial cases linked to mutations like ALADIN (Allgrove syndrome/Triple A syndrome).

Inflammatory infiltrates (T lymphocytes) target the myenteric plexus, leading to apoptosis of inhibitory neurons. The loss of nitric oxide and VIP-producing neurons eliminates the relaxation reflex of the LES. Concurrently, loss of the intramural neural network abolishes organized peristaltic contractions in the esophageal body. The unopposed cholinergic action maintains the LES in a contracted state, causing dysphagia and subsequent proximal esophageal dilation.

Characteristic Clinical Presentation

• Dysphagia: Difficulty swallowing both solids and liquids, often worsening over months to years.
• Regurgitation: Effortless return of undigested, bland food or saliva, worse when supine.
• Chest pain: Retrosternal discomfort due to esophageal distension or spasms.
• Weight loss: Gradual and significant due to decreased oral intake and fear of eating.

Physical Examination Signs

• Halitosis from putrefaction of retained food
• Signs of aspiration pneumonia (crackles/wheezing on auscultation)
• Malnutrition signs in severe cases (muscle wasting)

• Aspiration pneumonia: Inhalation of retained esophageal contents into the lungs.
• Esophageal squamous cell carcinoma: Risk is increased 10 to 50-fold due to chronic stasis and mucosal inflammation.

Diagnostic Criteria & Guidelines

High-Resolution Manometry (HRM) is the gold standard: defined by an Integrated Relaxation Pressure (IRP) > 15 mmHg and 100% failed peristalsis. Supportive findings on Barium Swallow: 'bird-beak' appearance at the GE junction.

Differential Diagnosis

• Esophageal stricture or web
• Esophageal cancer (Pseudoachalasia)
• Gastroesophageal Reflux Disease (GERD)
• Eosinophilic Esophagitis

Laboratory Tests & Biomarkers

• Trypanosoma cruzi serology: Positive in suspected Chagas-induced achalasia (endemic areas)

Imaging Modalities & Findings

• Barium Esophagram: Dilated esophagus tapering to a smooth 'bird-beak' deformity at the GE junction with delayed emptying.
• Upper Endoscopy (EGD): Retained food/saliva, puckered GE junction that pops open with gentle pressure (rules out pseudoachalasia).

• Type I (Classic)
  Minimal esophageal contractility with no pressurization.
• Type II
  No peristalsis but pan-esophageal pressurization present; best response to treatment.
• Type III (Spastic)
  No normal peristalsis with premature, spastic contractions; hardest to treat.

Second-Line & Adjunctive Therapy

Botulinum toxin A injection (100 units endoscopically into the LES) for patients who are poor surgical candidates, lasting 6-12 months. Pharmacotherapy: Nifedipine 10-20 mg sublingual or Isosorbide dinitrate 5 mg sublingual 15-30 minutes before meals.

Surgical & Procedural Management

Laparoscopic Heller Myotomy (LHM) involving incision of the circular muscle layer of the lower esophagus and proximal stomach. Esophagectomy in end-stage 'sigmoid' esophagus unresponsive to therapy.

Recommended Lifestyle Changes

• Eat slowly and chew food thoroughly.
• Consume ample liquids during meals to assist with gravity-induced esophageal emptying.
• Sleep with the head of the bed elevated by 6-8 inches to prevent nocturnal aspiration.

Patient Counseling & Advice

Inform the patient that treatments aim to palliate symptoms by relieving obstruction, but they do not cure the underlying nerve damage or restore peristalsis. Warn about the increased risk of post-treatment GERD and the necessity of long-term PPI therapy after myotomy.

Follow-Up & Monitoring Schedule

Clinical assessment with the Eckardt Score every 1-2 years. Annual EGD with Lugol chromoendoscopy starting 10-15 years after symptom onset for SCC surveillance is controversial but often recommended in severe retention cases.

Preventive Strategies

No primary prevention strategies exist as the disease is largely idiopathic. Preventing Chagas disease via vector control in endemic areas is the only known preventative measure for secondary cases.

Over 90% of patients achieve significant symptom relief with LHM, PD, or POEM. However, the disease is chronic. Without treatment, severe malnutrition and fatal aspiration can occur.