**6. Chagasic megaesophagus**

The most common gastrointestinal affectation due to Chagas disease is the megaesophagus, it affects any age, sex, and stage of the disease. The initial symptoms can be quite nonspecific, such as hypersalivation, nocturnal cough, a sensation of coughing after eating, and weight loss that further complicates the diagnosis [13], is characterized by the inability of the esophagus lower esophageal sphincter (LES) to relax in response to swallowing and absence of peristalsis in the esophageal body and; both motor abnormalities determine esophageal dilation with food stasis that will produce most of the symptoms and complications of the disease [13].

In the acute phase of the disease, parasites cause invasion of muscle tissue of the heart and digestive system, causing ganglionitis and lymphocytic infiltration, which leads to neuronal degeneration in these organs. It has been observed a massive loss of myenteric neurons, while the loss of submucosal neurons is moderate [14]. The asymptomatic or indeterminate chronic phase is clinically silent and with very low parasitemia, the duration varies between 5, 10, and up to 20 years; during this stage, the diagnostic methods of choice are serological tests. After this phase, the chronic symptomatic period occurs in which approximately 27% of patients present cardiac lesions, 6% damage to the digestive system (mainly in the esophagus and colon), and 3% to the peripheral nervous system [13].

The myenteric and submucosal plexus make up the enteric nervous system in humans, where the ganglionic nerve networks are located. The myenteric or Auerbach's plexus is located between the muscular layer and the longitudinal layer (**Figure 3**) and extends from the upper part of the esophagus to the internal anal sphincter. Additionally, the human submucosa contains two ganglion plexuses, the inner one is called Meissner's plexus and is localized in the submucosal plexus, while the Schabadasch's plexus is outer [15].

The progressive and irreversible deterioration in the enteric nervous system caused by the *T. cruzi* parasite is responsible for most of the gastrointestinal symptoms. Although any organ of the digestive system can be affected by Chagas disease, the esophagus and the colon are the ones that are most frequently damaged. The symptoms associated with Chagasic megaesophagus generally do not put the patient's pathway at risk, however, they considerably reduce their quality of life, since they generate eating disorders secondary to dysphagia, odynophagia, or esophageal insufficiency [16].

Hypocontractibility, motor dyskinesia, and incomplete or absent relaxation of the lower esophageal sphincter are results of this destruction of the myenteric plexuses,

*Digestive Disorders in Chagas Disease: Megaesophagus and Chagasic Megacolon DOI: http://dx.doi.org/10.5772/intechopen.102871*

### **Figure 3.**

*Amastigote without flagellum responsible for cell invasion.*

which lead to the classic presentation of achalasia. In esophageal symptoms and altered motility, an increase in the diameter of the esophagus is observed in 7–10% of infected subjects (Nisimura et al., 2020). Despite the findings that have been made in relation to the loss of esophageal motility secondary to damage to nerve structures, it has been proposed that the condition in other cell groups is necessary to explain more broadly the damage caused by the parasite. Therefore, it has been proposed that the damage caused to the muscle and nerve layers is also associated with immunomodulatory mechanisms and the local inflammatory response [14].

The biomechanics of swallowing is directly related to the contraction of the suprahyoid muscles. This contraction promotes the elevation and stabilization of the laryngeal complex during swallowing. Analysis of the suprahyoid musculature by electromyography has generally included the end of the oral phase, the pharyngeal

**Figure 4.** *Unilateral eyelid edema, Romaña-Mazza sign.*

phase, and the beginning of the esophageal phase. In the oral and pharyngeal phases of swallowing in patients with Chagas disease, there is an increase in oral residues, a longer pharyngeal clearance and upper esophageal transit, and a longer opening of the upper esophageal sphincter. It has been observed that the contractile activity in the electromyography of patients with Chagas disease is lower than that of those who present motor esophageal disorders without this disease. This may be explained by decreased muscle recruitment of the suprahyoid muscles in patients with Chagasic megaesophagus and symptoms of dysphagia [16].

The diagnosis of Chagas megaesophagus is based mainly on the clinical history, symptoms, barium esophagram (**Figure 4**), manometry, and endoscopy [17], which could be classified as follows.


An objective way to assess the severity of symptoms, as well as the effectiveness of treatment, is the Eckardt score, which ranges from 0 to 12 points, which classifies the stages of the disease. The score assigns from 0 to 3 for weight loss, dysphagia, chest pain, and regurgitation, the final value consisting of the sum of these elements—stage 0 (0–1 points), stage I (2–3 points), stage II (4–6 points), and stage III (> 6 points) [18].


The goal of treatment is to restore the ability to feed orally and alleviate all these symptoms, which can be achieved by various modalities, such as endoscopic dilation, peri-oral endoscopic myotomy, and Heller Pinotti laparoscopic cardiomyotomy, which is currently considered the standard treatment for non-advanced megaesophagus patients. These modalities eliminate resistance to the outflow of food, improving esophageal emptying [18].

Recurrence of dysphagia after cardiomyotomy is associated with gastroesophageal reflux with esophagitis, incomplete myotomy, fibrosis at the site of the gastroesophageal junction, an inappropriate indication of technique for patients with advanced megaesophagus, and intrathoracic migration of the gastric fundus. The reoperation is usually not very successful in relation to the first procedure and many patients require

### *Digestive Disorders in Chagas Disease: Megaesophagus and Chagasic Megacolon DOI: http://dx.doi.org/10.5772/intechopen.102871*

esophagectomy treatment, which is the option of choice when symptoms reappear or the stage is advanced but adds greater morbidity and mortality associated with thoracic esophageal dissection. An alternative to esophagectomy is esophageal mucosectomy, with less morbidity due to preservation of the esophageal muscle tunica and an intraluminal dissection of the esophageal mucosa with subsequent transposition of the gastric tube without violation of the mediastinum [18].

The appropriate choice of surgical treatment for recurrent achalasia depends on the pathophysiology of the recurrence. Therefore, for patients with incomplete myotomy or fibrosis at the esophagogastric junction, a new myotomy with partial fundoplication is still indicated, as long as the esophageal wall has not been damaged during dissection. For patients with significant reflux or dolichomegaesophagus, the indication is esophagectomy with transposition of a stomach or colonic tube [18].
