The question asked where th degeneration of inhibitory neurons is located. I know Auerbach’s plexus is between the circular and longitudinal smooth muscle layers. But I still got it wrong. :( The inhibitory neurons (Auerbach’s plexus) are in the muscularis externa. Inhibitory neurons release VIP and NO to relax the LES. In pts who have achalasia, these neurons are missing, so they can’t relax their LES.
This patient has achalasia, as confirmed by the narrowing of the gastroesophageal junction (“bird’s beak” appearance) seen on barium swallow test, i.e., the upper gastrointestinal series. This disease presents with difficulty swallowing, regurgitation of non-digested food, chest pain and weight loss. Manometry can be used to confirm the diagnosis and will show abnormal contractions of esophageal muscles, absence of peristalsis, and absence of relaxation of the lower esophageal sphincter (LES) upon swallowing. Failure of relaxation of the lower sphincter is due to a loss of function of the myenteric (Auerbach’s) plexus, which is composed of non-adrenergic, non-cholinergic, inhibitory ganglion cells. These cells are located between the longitudinal and circular layers of muscularis externa in the gastrointestinal tract and are responsible for coordinating motility of the entire alimentary canal. In patients with achalasia, there is a decrease in ganglion cell density in Auerbach’s plexus resulting in aperistalsis of the esophagus and incomplete relaxation of the LES. The majority of cases are idiopathic, however, secondary causes include malignancies (most commonly adenocarcinoma of proximal stomach) and Chagas’ disease. There is no cure for achalasia. Management includes lifestyle modifications (excessive chewing of food, sleep with trunk elevated, avoid eating before bed), medical therapy (anti-muscarinics, sublingual nitroglycerin, long acting nitrates, calcium channel blockers), botulinum toxin injections, and surgical intervention (balloon dilatation, myometry).
Bottom Line: Intrinsic innervation is fundamental to coordinating gastrointestinal motor activity. Auerbach’s plexus, also called the myenteric plexus, is a neural network branching between longitudinal and circular muscle layers of the gastrointestinal tract and allows for coordinated movement along the tract. Loss of these neural cells results in achalasia, which commonly presents with chest pain, heart burn, dysphagia, and regurgitation.