Longitudinal Muscle Dysfunction in Achalasia Esophagus and Its Relevance

Abstract

Muscularis propria of the esophagus is organized into circular and longitudinal muscle layers. Goal of this review is to summarize the role of longitudinal muscle in physiology and pathophysiology of esophageal sensory and motor function. Simultaneous manometry and ultrasound imaging that measure circular and longitudinal muscle contraction respectively reveal that during peristalsis 2 layers of the esophagus contract in perfect synchrony. On the other hand, during transient relaxation of the lower esophageal sphincter (LES), longitudinal muscle contracts independently of circular muscle. Recent studies provide novel insights, i.e., longitudinal muscle contraction of the esophagus induces LES relaxation and possibly descending relaxation of the esophagus. In achalasia esophagus and other motility disorders there is discoordination between the 2 muscle layers. Longitudinal muscle contraction patterns are different in the recently described three types of achalasia identified by high-resolution manometry. Robust contraction of the longitudinal muscle in type II achalasia causes pan-esophageal pressurization and is the mechanism of whatever little esophageal emptying that take place in the absence of peristalsis and impaired LES relaxation. It may be that preserved longitudinal muscle contraction is also the reason for superior outcome to medical/surgical therapy in type II achalasia esophagus. Prolonged contractions of longitudinal muscles of the esophagus is a possible mechanism of heartburn and "angina like" pain seen in esophageal motility disorders and possibly achalasia esophagus. Novel techniques to record longitudinal muscle contraction are on the horizon. Neuro-pharmacologic control of circular and longitudinal muscles is different, which provides an important opportunity for the development of novel pharmacological therapies to treat sensory and motor disorders of the esophagus.

Long-term Outcomes of Patients With Normal or Minor Motor Function Abnormalities Detected by High-resolution Esophageal Manometry

“…The existence of diminished compliance, increased muscle thickness, and asynchrony of circular and longitudinal muscle contraction have all been associated with chest pain and heartburn in these patients. 16–19 However, it should be noted that the actual relationship of symptoms with nutcracker esophagus is unclear. As seen in our study, a large proportion of patients with nutcracker esophagus are asymptomatic and the persistence or remittance of symptoms is independent of whether manometric evidence of nutcracker esophagus persists in these patients.…”

The Spectrum of Achalasia: Lessons From Studies of Pathophysiology and High-Resolution Manometry

“…The panesophageal pressurization pattern itself is likely the consequence of some preserved contraction of proximal striated muscle, longitudinal muscle, and even nonocclusive circular muscle contraction in the distal esophagus against augmented EGJ outflow obstruction. 104,105 …”

“…However, Mittal et al reported analogous observations using intraluminal ultrasonography and suggested that longitudinal muscle function was vastly attenuated or absent in patients with type I achalasia. 104,105 …”

Achalasia Is Associated With eNOS4a4a, iNOS22GA, and nNOS29TT Genotypes: A Case-control Study

“…1 Its pathogenesis is still enigmatic. [2][3][4] Genetic factors are likely to be important in its pathogenesis as supported by occasional familial aggregation, concordance among monozygotic twins and reports on association between achalasia and Hirshsprung's disease, a similar condition with genetic basis. [5][6][7] Esophageal aperistalsis and incomplete lower esophageal sphincter (LES) relaxation, the characteristic features of achalasia, result from degeneration of the ganglion cells in the myenteric plexus.…”