Título De Especialista Em Gastroenterologia (FBG) Practice Questions - Título De Especialista Em Gastroenterologia - Federação Brasileira De Gastroenterologia (FBG AMB) Exam

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A 62-year-old patient born in a rural area of Minas Gerais, Brazil, presents with a 5-year history of worsening dysphagia, regurgitation, and weight loss. A barium esophagogram demonstrates an esophageal diameter of 6.5 cm with marked distal tapering ('bird-beak' sign), tortuosity, and significant barium retention (Rezende Classification Group III). Serology for Trypanosoma cruzi (ELISA and indirect immunofluorescence) is positive. What is the underlying pathophysiology of Chagasic megaesophagus?

Parasite-mediated destruction of the myenteric (Auerbach's) nerve plexus leading to loss of inhibitory nitrergic neurons and aperistalsis. Direct autoimmune destruction of the circular smooth muscle layers sparing the intramural neural plexus. Hypertrophy of the vagal motor nucleus in the brainstem causing secondary lower esophageal sphincter hypertonia. Deposition of IgA immune complexes in the esophageal submucosa causing severe fibrostenosis.

Correct Answer:

Parasite-mediated destruction of the myenteric (Auerbach's) nerve plexus leading to loss of inhibitory nitrergic neurons and aperistalsis.

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