A 52-year-old woman presents with a 6-month history of intermittent dysphagia to both solids and liquids, accompanied by retrosternal chest pain that prompted cardiac workup (ECG and troponin normal). Upper endoscopy was unremarkable. A barium esophagram shows the appearance marked **A** in the diagram—a tortuous, corkscrew-like esophageal lumen with multiple simultaneous segmental contractions. High-resolution esophageal manometry confirms normal lower esophageal sphincter relaxation (IRP 12 mmHg) with ≥20% premature distal contractions (distal latency 3.8 seconds). Which of the following best explains the underlying pathophysiology of the disorder demonstrated by structure **A**?
A. Impaired lower esophageal sphincter relaxation due to increased resting pressure and failure of normal accommodation
B. Relative loss of nitric oxide synthase activity with imbalance between inhibitory and excitatory neural pathways in the distal esophagus
C. Mechanical obstruction from a mucosal ring with concentric narrowing of the esophageal lumen
D. Eosinophilic infiltration of the esophageal mucosa with chronic inflammation and stricture formation
Explanation
Why "Relative loss of nitric oxide synthase activity with imbalance between inhibitory and excitatory neural pathways in the distal esophagus" is right
The clinical presentation—intermittent dysphagia to solids and liquids, retrosternal chest pain, normal LES relaxation, and manometric evidence of premature distal contractions (DL <4.5 seconds) with ≥20% spastic events—is pathognomonic for diffuse esophageal spasm (now reclassified as distal esophageal spasm by Chicago Classification v4.0). The corkscrew/rosary bead appearance on barium esophagram (structure A) reflects simultaneous, uncoordinated contractions rather than orderly peristalsis. The fundamental pathophysiology is an imbalance between inhibitory nitric oxide (NO)-mediated pathways and excitatory cholinergic pathways in the smooth muscle of the distal esophagus. Relative loss of nitric oxide synthase activity produces this loss of coordinated relaxation, resulting in spastic, premature contractions (Chicago Classification v4.0; ACG Esophageal Motility Guideline).
Why each distractor is wrong
Impaired lower esophageal sphincter relaxation due to increased resting pressure and failure of normal accommodation: This describes achalasia (Type I) or Type III achalasia with impaired IRP. The manometry in this case shows normal LES relaxation (IRP 12 mmHg), which explicitly excludes achalasia and is a defining criterion for distal esophageal spasm.
Eosinophilic infiltration of the esophageal mucosa with chronic inflammation and stricture formation: This describes eosinophilic esophagitis (structure D in the diagram), which presents with dysphagia and may show rings and furrows on endoscopy. Upper endoscopy in this case was unremarkable, and the manometric pattern is characteristic of spasm, not inflammation.
Mechanical obstruction from a mucosal ring with concentric narrowing of the esophageal lumen: This describes a Schatzki ring (structure C in the diagram), which causes mechanical obstruction and typically presents with dysphagia to solids more than liquids. The manometric findings and corkscrew appearance are inconsistent with a fixed structural lesion.
High-YieldNEET PG
Distal esophageal spasm = premature spastic contractions + normal LES relaxation + NO-mediated inhibitory pathway dysfunction; always exclude cardiac causes and achalasia first.
Chicago Classification v4.0; ACG Esophageal Motility Guideline
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