Achalasia

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. 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.