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Achalasia


Definition

  • Form of esophageal dysmotility characterized by loss of distal esophageal peristalsis and failure of lower esophageal sphincter relaxation 

Etiology & Pathophysiology 

  • Usually idiopathic in origin
    • Degeneration of neurons within the myenteric plexus of the esophageal smooth muscle
  • Neuronal destruction is typically inflammatory in nature
    • Histologically: lymphocytic infiltrate surrounding the plexus
    • Predominantly involves the nitric-oxide producing inhibitory neurons
      • Cause smooth muscle relaxation by inhibiting the acetylcholine producing excitatory neurons
  • Loss of inhibitory input results in unopposed contractile stimulation and aperistalsis
    • Acetylcholine producing neurons (which stimulate smooth muscle contraction) are relatively spared in this degenerative process 

Types

  • Primary achalasia (idiopathic)
    • Unknown cause of inflammatory neuronal degeneration
  • Secondary achalasia (pseudoachalasia)
    • Recognized pathologic causes of esophageal motility disorders often indistinguishable from primary achalasia
      • Malignancy (especially gastric cancer)
      • MEN, Type 2B
      • Chagas’ disease
      • Juvenile Sjögren’s
      • Amyloidosis
      • Chronic idiopathic intestinal
      • Sarcoidosis
      • Pseudo-obstruction
      • Neurofibromatosis
      • Eosinophilic gastroenteritis
      • Fabry’s disease
      • Scleroderma 

Epidemiology

  • Annual incidence of 1 case per 100,000
  • Men and women affected equally
  • Occurs at any age
    • Typically between 25-60 years of age
      • Onset rare before adolescence 

Clinical Findings

  • Dysphagia for solids and liquids predominate (85-95% of patients)
    • Dysphagia for liquids especially should prompt evaluation for achalasia
  • Difficulty belching
  • Hiccups
  • Weight loss
  • Chest pain
    • Usually secondary to failure of LES relaxation
    • More common in younger patients and tends to regress
  • Regurgitation of retained material in esophagus, especially upon lying down
    • May lead to recurrent aspiration
  • Heartburn in 40-60%
    • Tend to have lower LES pressures than those without GERD
  • Increased incidence of esophageal cancer
    • Usually squamous cell
    • Surveillance endoscopy not recommended (usually seen 15-20 years after development of achalasia) 

Imaging Findings

  • Barium studies
    • 95% diagnostic accuracy
    • Early/Stage I
      • Primary peristaltic waves absent with abnormal distal peristalsis
      • Only minimal narrowing of the GE junction
      • Occasionally may see nonpropulsive peristaltic waves in the esophageal body (“vigorous achalasia” secondary to tertiary waves)
    • Progressive disease
      • “Bird’s beak” appearance of GE junction
        • Distal esophagus makes right angle before entering stomach
    • Hurst phenomenon
      • With the patient upright, barium builds up to a point where the hydrostatic pressure of the barium overcomes the LES pressure
        • Occasional “spurt” of barium through the GE junction as it is intermittently  forced open
      • Dilated, aperistaltic esophageal body; may assume a sigmoid shape
    • Severe disease
      • Significant esophageal body dilation with large amounts of fluid/food retention
      • Entire esophagus atonic in late stages 
  • Chest x-ray
    • With severe disease, may readily see the large, dilated esophagus with air fluid level at the aortic arch or above
    • Stomach bubble frequently absent 
  • CT Scan
    • Not typically used for diagnosis
    • Seen as dilated luminal structure with retained debris and narrowing at level where it enters the stomach 
  • Manometry
    • Usually required for confirmation of diagnosis
      • Elevated resting LES pressure
      • Incomplete LES relaxation
      • Absence of peristalsis 
  • Endoscopy
    • Must rule out malignancy
    • Reveals dilated esophagus with normal mucosa
    • Retained fluid/food
    • Possible Candida infection secondary to esophageal stasis
    • Endoscope should pass easily through LES with gentle pressure applied
      • Unlike strictures caused by neoplasms, fibrosis etc 

Differential Diagnosis

  • Reflux esophagitis with stricture
    • Narrowing is usually higher than the EG junction
    • Normal esophageal peristalsis
  • Carcinoma
    • Only minimal dilation with normal peristalsis
  • Scleroderma
    • Barium should empty when patient is upright
    • Other associated GI abnormalities
  • Chagas disease
    • Not distinguishable by x-ray; history needed 

Treatment

  • Medical therapy
    • Nitrates, calcium channel blockers (nifedipine)
      • Cause smooth muscle relaxation but with limited success
  • Pneumatic dilation of the LES
    • Tears muscle fibers of LES, thus weakening it
    • Varying protocols regarding type and diameter of dilator, balloon inflation pressure and rate at which it is inflated, duration of inflation, and number of inflations per session
    • Good short-term results, but many patients require further intervention, with successive dilations adding little benefit
      • Potential complications of esophageal perforation (2-6%) and GERD
  • Surgical myotomy
    • LES muscle fibers cut
    • Laparoscopy becoming more popular
    • Good relief of symptoms in majority of patients with complication rate similar to that of dilation
    • Superior method for achieving better long term results
    • Debate as to whether fundoplication is necessary to prevent longstanding GERD
  • Botulinum toxin injection
    • Inhibits release of excitatory acetylcholine from nerve endings (thus causing lower LES pressures)
    • Good short­-term results, but long term efficacy unknown

Achalasia

Achalasia

Achalasia. Upper: There is a large air-filled tubular structure that represents the dilated esophagus (white arrows). Lower: An esophagram shows a massively dilated esophagus (yellow arrows) down to the esophagogastric junction consistent with achalasia.
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