Esophageal motility disorders are relatively uncommon conditions that are thought to cause chest pain or dysphagia in some patients. They are diagnosed not by specific symptoms or imaging studies, but on the basis of specific patterns seen on esophageal manometry, ranging from the complete absence of contractility in patients with achalasia to unusually forceful or disordered contractions in those with hypercontractile motility or “esophageal spasm” disorders.¹

Achalasia has well-defined and objective diagnostic criteria, as well as effective evidence-based treatment options, but its diagnosis is often delayed. Conversely, recent research suggests that hypercontractile motility disorders may be overdiagnosed,² leading to unnecessary and irreversible interventions. Although gastroesophageal reflux disease (GERD) and unrecognized functional esophageal disorders are more likely than achalasia or hypercontractile motility disorders to cause chronic symptoms,^3,4 family physicians should also be familiar with the current understanding and terminology of these less common conditions to ensure timely and appropriate referral for testing and intervention.

Classification and Epidemiology

When normal swallowing (deglutition) is initiated, the upper esophageal sphincter relaxes, followed within one to two seconds by the lower esophageal sphincter, allowing a food bolus from the oropharynx to be propelled by peristalsis through the esophagus and into the stomach. In normal peristalsis, excitatory neurons cause contraction of one segment of smooth muscle as inhibitory neurons relax the segment below.

Achalasia is the esophageal motility disorder of greatest clinical significance. Hypercontractile motility disorders, although seemingly well-defined, may overlap with functional esophageal disorders to a greater degree than previously recognized. Several other conditions are classified among the esophageal motility disorders but are much less relevant (Table 1).^1,4–7

ACHALASIA

Achalasia is a progressive disorder that may not be recognized in its early stages, but that causes increasingly troublesome dysphagia and chest pain over time.⁸ It is present in less than 5% of patients referred to specialized centers.⁹ Achalasia can occur at any age but is more common in older adults. In this degenerative disorder, chronic esophageal smooth muscle denervation causes a deficiency of nitric oxide in tissues and a progressive loss of inhibitory neurons, ultimately resulting in impaired relaxation of the lower esophageal sphincter and absence of normal peristalsis. Although delayed diagnosis of achalasia does not increase the risk of esophageal cancer,¹⁰ it can cause significant esophageal dilatation over time, which may make surgical treatment less successful.¹¹

HYPERCONTRACTILE MOTILITY DISORDERS

Distal esophageal spasm and hypercontractile (jackhammer) esophagus are the major hypercontractile motility disorders. These disorders are rare, even in referral populations, and occur primarily in people 60 years and older.^5,6 They are also thought to result from the loss of inhibitory neuronal function. Distal esophageal spasm is characterized by premature contractions that are more forceful than normal. Jackhammer esophagus is characterized by appropriately timed but abnormally forceful hypercontractile peristalsis. Some patients with early achalasia have abnormal contractions similar to those occurring in distal esophageal spasm or jackhammer esophagus; however, these disorders themselves rarely progress to achalasia.¹²

Although the general term “esophageal spasm” is often used to refer to chest pain or dysphagia not explained by other causes, it should be used only in the context of hypercontractile motility disorders.

FUNCTIONAL ESOPHAGEAL DISORDERS

Like irritable bowel syndrome or functional dyspepsia, functional esophageal disorders involve abnorma lities of gut–brain interaction and central nervous system processing.^4,13 Patients may report chest pain, heartburn, or dysphagia, and they may be hypervigilant about minor symptoms or hypersensitive to even physiologic amounts of acid. These disorders usually have a benign and self-limited course.