Achalasia Flashcards
Summarise achalasia
An oesophageal motor disorder characterised by a loss of oesophageal peristalsis and failure of the lower oesophageal sphincter to relax in response to swallowing.
The most common presenting symptoms are dysphagia to solids and liquids, regurgitation, and retrosternal pain. These can be slowly progressive over months or years.
The first investigation for any patient with dysphagia is usually endoscopy to exclude malignancy. Subsequent barium swallow studies and oesophageal manometry are often required to establish the diagnosis of achalasia.
Treatment is symptomatic, not curative, and is primarily aimed at relieving dysphagia; options include pharmacological, endoscopic, and surgical procedures.
Define achalasia
Achalasia is an oesophageal motor disorder of unknown aetiology, characterised by oesophageal aperistalsis and insufficient lower oesophageal sphincter relaxation in response to swallowing. This results from loss of inhibitory nitrinergic neurons in the oesophageal myenteric plexus.
What is the median age of diagnosis for achalasia
Achalasia may occur at any age; however, incidence increases with age. The median age at diagnosis is 53 years.[1] Achalasia affects both sexes equally.
Describe the geographical, racial and temporal trend in achalasia
Geographical, ethnic, and temporal differences have been reported for the prevalence and incidence of achalasia. Incidence rates of 2.92/100,000 and 2.3-2.8/100,000 per year have been reported in North America and South Australia.[3][4] The incidence in Korea is 0.39/100,000 per year, 0.03/100,000 per year in Zimbabwe, and 0.3/100,000 per year in Singapore.[5][6][7]
Estimates of prevalence range from 8.0/100,000 to 27.1/100,000.[1][8][9][2]
Some studies demonstrate increasing incidence and prevalence over time.[1][10][2] In the United States, there has been an increase in the number of Heller myotomies performed, with a concomitant increase in utilisation of the laparoscopic rather than the open approach.[11] The study authors concluded that these findings probably reflect increased disease prevalence alongside improving surgical technique (and, therefore, a concomitant growth in the number of surgical candidates)
Describe the ethnic variation in achalasia
Racial differences have been highlighted in some studies, with a study from New Zealand showing a higher incidence of achalasia in Pacific Islanders and people of Maori descent than in white people.[12] In Singapore, one study found that achalasia was more common in Chinese and Indian people compared with Malay people.[7] In the US, achalasia occurs at a similar rate in people of all races.[13]
Regional and ethnic variations in the incidence of achalasia suggest a role for both environmental and genetic factors in its aetiology.
Summarise the aetiology of achalasia
Inflammatory destruction of inhibitory nitrinergic neurons in the oesophageal myenteric (Auerbach) plexus results in loss of peristalsis and incomplete lower oesophageal sphincter relaxation. The exact cause of this inflammatory process is unknown, but possible triggers include infection, autoimmunity, and genetic factors.
Describe the infectious aetiology of achalasia
Infectious diseases such as Chagas disease can manifest in a similar way to achalasia. Herpes and measles viruses have been associated with achalasia, and increased antibody titres against these viruses have been found in patients with achalasia, compared with healthy controls.[14] However, a causal relationship has not been established.
Describe the autoimmune aetiology of achalasia
Patients with achalasia are more likely to suffer from autoimmune conditions.[15] This association is supported by the presence of myenteric plexus antibodies in many patients with achalasia, a T-cell infiltrate in the inflamed myenteric plexus, and increased prevalence of human leukocyte antigen class II antigens.
Describe the genetic factors in the aetiology of achalasia
Familial achalasia is rare. However, a number of cases of achalasia have been reported among children of consanguineous couples.[16]
The triple-A (Allgrove) syndrome, characterised by achalasia, alacrima, and adrenocorticotrophic hormone-resistant adrenal insufficiency, is an autosomal recessive disorder that has been mapped to chromosome 12.[17][18]
The rs1799724 single nucleotide polymorphism (SNP) has been shown to be associated with the development of achalasia. This SNP is located between the lymphotoxin-alpha and tumour necrosis factor-alpha genes
Describe the innervation of the smooth muscle in the distal oesophageal wall
The smooth muscle of the distal oesophageal wall and lower oesophageal sphincter are innervated by vagal pre-ganglionic fibres arising in the dorsal motor nucleus. These form synapses in the myenteric plexus ganglia with post-ganglionic fibres, consisting of cholinergic excitatory neurons, and inhibitory neurons releasing nitric oxide (NO) and vasoactive intestinal peptide
What happens in the pathophysiology of achalasia
In achalasia, the loss of ganglion cells in the myenteric (Auerbach) plexus is accompanied by an inflammatory response, consisting of T lymphocytes, eosinophils, and mast cells, with neural fibrosis. The end result of these changes is a selective loss of post-ganglionic inhibitory neurons containing NO and vasoactive intestinal peptide. Stimulatory cholinergic neurons remain intact, resulting in a high basal lower oesophageal sphincter pressure and insufficient relaxation
Describe Aperistalsis in achalasia
Aperistalsis is caused by loss of the latency gradient that normally permits sequential contractions along the oesophageal body, a process that is mediated by NO. Studies measuring NO synthase activity have confirmed loss of NO innervation in patients with achalasia, as have histological studies of oesophagectomy specimens from patients with achalasia
Describe a typical case history for a patient with achalasia
A 52-year-old man presents with a 6-month history of heartburn and atypical chest pain, both unrelated to food. He also described ‘gurgling’ sounds in his chest. A month before presentation he developed intermittent dysphagia to both solids and liquids, regurgitation, and weight loss of 3 kg.
Describe some other presentations for achalasia
Patients may need to adopt certain positions or manoeuvres to ease swallowing. Atypical symptoms include nocturnal cough, recurrent chest infections, and a globus sensation.
Summarise a basic approach to the history and investigations in a patient with achalasia
Achalasia cannot be diagnosed on the basis of history alone. Symptoms are often slowly progressive, during which time many patients may adapt to significant symptoms by slowly altering their diet or eating habits. A minority of patients present with heartburn, regurgitation, or slow eating compared with other family members, rather than dysphagia.[22]
Barium swallow or endoscopy can appear normal in patients with early disease. Therefore, many patients with achalasia may be symptomatic for months or years before the correct diagnosis is made.
Describe dysphagia in achalasia
Dysphagia to solids and liquids is the key symptom of achalasia. Dysphagia to liquids is uncommon in structural causes of oesophageal obstruction, except in advanced disease. Therefore, its occurrence at presentation suggests an oesophageal motility disorder.[22]
Individual patients often develop a range of strategies to live with their dysphagia, such as arching the neck and shoulders, raising the arms, standing or sitting up straight during the meal, and walking around after a meal.[22] These manoeuvres increase intrathoracic pressure to overcome the increased lower oesophageal sphincter pressure, allowing oesophageal contents to empty into the stomach. Patients may eat slowly and take longer than others to finish their meal.
Describe the retrosternal pressure in achalasia
Drinking fluid may initially cause a sensation of retrosternal pressure, which is relieved by continued drinking.
Retrosternal pain typically affects younger patients and may be relieved by drinking cold water.[24] It is often described as cramp-like in nature and may wake the patient from sleep. This may persist even when dysphagia has improved following successful dilatation.
