Achalasia

Achalasia is characterized by oesophageal aperistalsis and impaired relaxation of the lower oesophageal sphincter.

Clinical features

Achalasia incidence is 1 : 100 000 equally in males and females. It occurs at all ages but is rare in childhood. Patients usually have a long history of intermittent dysphagia, characteristically for both liquids and solids from the onset. Regurgitation of food from the dilated oesophagus occurs, particularly at night, and aspiration pneumonia is a complication. Spontaneous chest pain occurs, said to be due to oesophageal ‘spasm’. Dysphagia may be mild and accepted by the patient as normal. The pain may be misdiagnosed as cardiac. Weight loss is usually not marked.

Pathogenesis

The aetiology is unknown. Autoimmune, neurodegenerative and viral aetiologies have been implicated. A similar clinical picture is seen in chronic Chagas’ disease (American trypanosomiasis) where there is damage to the neural plexus of the gut. Histopathology shows inflammation of the myenteric plexus of the oesophagus with reduction of ganglion cell numbers. Cholinergic innervation appears to be preserved. Reduction in nitric oxide synthase-containing neurones has been shown by immunohistochemical staining. Pharmacological studies in patients with achalasia support the selective loss of inhibitory, nitrergic neurones. The differential diagnosis of achalasia worldwide includes genetic syndromes, infectious diseases, neoplasms and chronic inflammatory conditions.

Investigations

Chest X-ray shows a dilated oesophagus, sometimes with a fluid level seen behind the heart. The fundal gas shadow is absent.
Barium swallow shows lack of peristalsis and often synchronous contractions in the body of the oesophagus, sometimes with dilatation. The lower end shows a ‘bird’s beak’ due to failure of the sphincter to relax.
Oesophagoscopy is performed to exclude a carcinoma at the lower end of the oesophagus, which can produce a similar X-ray appearance. When there is marked dilatation, a 24-hour liquid-only diet and a washout prior to endoscopy is useful to remove food debris. In true achalasia the endoscope passes through the lower oesophageal sphincter with little resistance.
CT scan excludes distal oesophageal cancer.
Manometry shows aperistalsis of the oesophagus and failure of relaxation of the lower oesophageal sphincter.

Treatment

All current forms of treatment for achalasia are palliative. Drug therapy rarely produces satisfactory or durable relief; nifedipine (20 mg sublingually) or sildenafil can be tried initially.

Endoscopic and surgical therapies are equally effective.
Endoscopic dilatation of the LOS using a hydrostatic balloon under X-ray control weakens the sphincter and is successful initially in 80% of cases. About 50% of patients require a second or third dilatation in the first 5 years. There is a low but significant risk of perforation. Intrasphincteric injection of botulinum toxin A produces satisfactory initial results but the effects wear off within months. Further injections can be given. It is safer and simpler than dilatation, so may be valuable in patients at risk of death if a perforation occurs. Neither pneumatic dilatation nor botulinum toxin works as well in younger patients.
Surgical division of the LOS, Heller’s operation, usually performed laparoscopically is the surgical treatment of choice. This can now be performed endoscopically. Reflux oesophagitis complicates all procedures and the aperistalsis of the oesophagus remains.

Complications

There is a slight increase in the incidence of squamous carcinoma
of the oesophagus in both treated and untreated cases (7% after 25 years).