Introduction
Achalasia is an esophageal disorder of unknown cause characterized by apertistalsis of the esophageal body and non-relaxation of the lower esophageal sphincter (LES). First description is found in 1674, by Sir Thomas Willis. A sponge tipped whale bone was used by a patient to push food down after each meal. The term achalasia was coined by Hurst and Rake (1929) and is Latin for “Failure to relax”, though Von Mikulicz had suggested cardiospasm as the cause in 1981.

Achalasia is an uncommon disease occurring in 5-10 per 100,000 population. Most commonly adults are affected with mean age being 40-50 years. Idiopathic achalasia, found in the northern America closely mimics “Chagas Disease of the esophagus” occurring in South America.




Pathophysiology
Anatomic alterations
Abnormalities in all neuromuscular components of the esophagus and its central nervous connection have been described but a pathogonomic defect remains elusive. Vagal and Doral Motor Nerve Center degeneration is thought to be secondary phenomenon. Most consistently present is the inflammatory reaction with destruction of ganglionic cells in the myenteric plexus in the esophageal wall. There is progressive decrease in number of ganglionic cells with a more advanced disease indicating the loss may later in disease. There is smooth muscle hypertrophy with fibrosis and liquifactive necrosis is thought to be secondary, as is chronic mucosal changes due to irritation by the retained food in the distal esophagus. These changes result in increase incidence of SCC in patients with achalasia.

Physiologic alterations
In healthy esophagus the smooth muscle contraction and resting LES tone is maintained by excitatory cholinergic innervation. To allow peristalsis inhibitory NO/VIP mediated smooth muscle inhibition is generated in response to swallow. The key abnormality in achalasia is impairment of the post- ganglionic neurons to the smooth circular muscle.




Etiology
Genetic theory
86 families have been described but accounts for 1-2% of all patients.

Infectious theory
Possibly a neuro-trophic infectious cause. Herpes virus seems to be most plausible except that they are not uniformly identified. In Chagas disease the cause is Trypanosoma cruzi.

Autoimmune theory
50% patients have anti-bodies and the inflammatory response seen in the esophageal wall is T-cell mediated.

Degenerative theory
some suggestion that in a small percentage of patients, especially the elderly, achalasia is a result of degenerative neurological disorder.




Clinical Presentation
Overview
Mean duration of symptoms is 4.6 Yrs (1mth to 67Yrs)

Patients adapt to slowly worsening symptomatology and present late in the disease progression
Delay in diagnosis due to lack of physician understanding of esophageal motility disorders exacerbates the late presentation
This is frequently confused with GERD and treated as such for a long period of time prior to presentation



Common Symptoms
Dysphagia: This is the most frequent complaint. Liquids are often worse than solids. Usually slowly progressive with weight loss only in advanced disease. Often the patient presents with a history of being the last to finish a meal. Frequently patients report having to use a Valsalva maneuver to force food into the stomach.
Regurgitation: Presents in 75% of patients. Patients can often tell what is regurgitated as the food is undigested. There is a history of chronic saliva, mucous spitting, and drooling on the pillow at night.
Chest pain: Presents in 40% of patients. Patients are often younger with a poor and unpredictable response to dilation or surgical therapy.
Heartburn: Presents in approximately 33% of patients. This is due to undigested food and/or in situ production from fermentation of an uncleared food bolus. This is unresponsive to acid suppression usually hours after eating.
Weight loss: 50-60% of patients show a slight weight loss usually late in the disease progression. If weight loss if significant, malignancy should be suspected.
Megaesophagus: 6 cm dilation of the esophagus with tortuosity.



Diagnostic Testing
Upright Chest X-ray: Widened mediastinum, air-fluid level in the mediastinum, absence of a gastric air bubble
Barium Swallow (with fluoroscopy): this is the single best diagnostic test
No peristalsis, possible simultaneous contractions
Poor clearance (normal < 1 minute)
Bird beak tapering of the LES (smooth narrowing)
Irregular shadow on the top of the barium level: due to food and liquid in the esophagus
Esophageal dilation (sigmoid esophagus in late stages)
Esophageal Manometry: this it the gold standard for diagnosis
Aperistalsis of the esophageal body (especially in the distal 2 channels), also called simultaneous waves/non-propulsive waves
Body pressure usually less than 40 mmHg. If > 40 mmHg then this is called "vigorous achalasia"
Hypertensive non-relaxing LES
Esophageal pressurization (the baseline does not return to below gastric zero level after the catheter has been withdrawn into the esophagus). This is due to retained food and fluid in the esophagus
Inability to advance catheter into the stomach with the possibility of needing an EGD to advance the catheter
Endoscopy: This is always done to rule out other causes of the patients symptomatology (e.g. malignancy)
Dilated fluid-filled esophagus
Tortuosity
Thickened mucosa with friability
Difficult to negotiate LES
Normal LES on retroflexion view
EUS/CT Scan: used to rule out pseudo-achalasia



Treatment Options
The goal of treatment is to improve esophageal clearance.

Medical Therapy
Nitrates and Calcium channel blockers. These are used to relax a hypertensive LES

Botulinum Toxin
BTX administration to the esophagus results in paralysis of the LES with a decreased resistance and increased clearance

Technique: 100 U (4 divided doses) injected intramuscularly in the LES (1 cm above the squamo-columnar junction)
75-90% first time response
50% effect after 6 months
Repeat injections are possible but progressively less helpful
Repeat injections are reserved for those unfit or unwilling to undergo surgery
Use in pseudo-achalasia to differentiate from classical achalasia
Reports of increased risk for mucosal perforation if myotomy is required later
Pneumatic Dilation
This is the oldest known therapy and was first introduced in 1898.

Technique: Rigiflex dilator (3.0, 3.5, 4.0 cm sizes) done under fluoroscopy
2-3% full thickness perforation
50-85% symptom control at 5 years
Frequent need for repeat dilations
Progressive decrease in symptom control over longer periods
Surgical Cardiomyotomy (Heller myotomy)
First described by Heller in 1913 as trans-thoracic double myotomy (anterior and posterior), and subsequently modified to single long anterior-lateral myotomy by Zajjer (1923) has remained the standard of surgical intervention till mid 1990’s.


Pelligrini has been a pioneer in applying minimally invasive technique to the procedure and has evolved the extent of myotomy and need for fundoplication since 1990’s to now.
First reported change was use of left VATS (thoracoscopic) (1992) while maintaining a long esophageal myotomy with only minimal extension (0.5cm) on to the stomach. Reports of 80% relief of dysphagia with 42% GERD symptoms.


To decrease dysphagia the myotomy needed to be extended more on to the stomach. Hence conversion to trans-abdominal (laparoscopic) method. Initially 1.5-2 cm on to the stomach with a Dor fundoplication (1994) to prevent reflux (also the anterior fundoplication helps protect the mucosa). Since then this group has further changed to extend the myotomy 3 cm on to the stomach and use a Toupet fundoplication (1998) for anti-reflux. 95-90% relief with 13% GERD.

If Megaesophagus is encountered, treatment is either via a Heller myotomy (some have reported poor surgical outcomes) or an esophagectomy at experienced centers.

Recurrent Symptoms after previous myotomy
Previous thoracic myotomy
Recurrent dysphagia with or without GERD

Dilated distal esophagus
Perform an extended myotomy onto the stomach with fundoplication if dysphagia is the primary symptom
Esophagectomy a good option, but trans-thoracic mobilization might be needed
Previous Laparoscopic myotomy
Due to either an incomplete myotomy, refibrosis, or obstruction due to fundoplication
Redo Heller myotomy with fundoplication is treatment of choice
If needed a transhiatal esophagectomy is also a good option



References
1. VaeziMF,RichterJE.CurrentTherapiesforAchalasia:Comparisonand efficacy. J Cli Gastroenterolo 1998;27:21-35.
2. Richter JE. Achalasia. The Esophagus 4th ed. Lippincot, Williams and Wilkins. Eds. Castell, Richter.
3, Oelschlager BK, Eubanks TR, Pelligrini CA. Surgery for esophageal motor disorders. The Esophagus 4th ed. Lippincot, Williams and Wilkins. Eds. Castell, Richter.