Achalasia – Top USMLE Diseases

Megacolon is a severe, abnormal dilatation of the colon and is classified as acute or chronic. There are many etiologies of megacolon, including neuropathic and dysmotility conditions, severe infections, ischemia, and inflammatory bowel disease. Toxic megacolon is an acute form of megacolon with systemic toxicity and carries the highest morbidity and mortality. Common symptoms include abdominal distention, pain, bloody diarrhea, or obstipation. Diagnosis depends on the underlying cause and is usually established with a combination of the patient’s history, laboratory findings, and imaging studies. Patients with chronic megacolon may require laxatives, enemas, and bowel training. Management for acute megacolon includes supportive care, decompression, and potential surgery.

Gastritis is inflammation of the gastric mucosa and can be classified by time course (acute or chronic), histologic features, and etiology. It is usually due to an infection (usually by Helicobacter pylori) or an immune-mediated process, but it can also be caused by substances that are direct gastric irritants. Chronic, metaplastic atrophic gastritis may be due to autoimmune or environmental causes and is a risk factor for gastric cancer. Individuals with gastritis may be asymptomatic or may have abdominal pain, dyspepsia, and nausea. Treatment of acute and chronic gastritis due to H. pylori infection involves acid suppression and antibiotics. Other causes are managed by avoiding offending agents and replacing associated deficiencies.

Achalasia is an esophageal motility disorder that is due to degeneration of the myenteric plexus; it results in failure of the lower esophageal sphincter to relax and a lack of normal esophageal peristalsis. Patients typically present with dysphagia to solids and liquids, along with regurgitation. Diagnosis is established by high-resolution manometry. Upper endoscopy is performed to rule out malignancy as a cause. Barium swallow study helps evaluate the esophageal morphology. Management options include pneumatic balloon dilation, surgical myotomy, and botulinum toxin injection. Choice of treatment is dependent on the type of achalasia and surgical risk. Medications are available for those for whom initial intervention fails but provide the least benefit.

Dysphagia is the subjective sensation of difficulty swallowing. Symptoms can range from a complete inability to swallow, to the sensation of solids or liquids becoming “stuck.” Dysphagia is classified as either oropharyngeal or esophageal, with esophageal dysphagia having 2 sub-types: functional and mechanical. Common causes of functional dysphagia include achalasia, scleroderma, and diffuse esophageal spasm (DES). Mechanical causes of dysphagia include esophageal rings, webs, strictures, and cancer. Oropharyngeal dysphagia may be due to structural abnormalities or abnormal neuromuscular function and coordination. The diagnostic workup depends on the patient’s presenting symptoms, but may include manometry, barium esophagram, or direct visualization with nasopharyngeal laryngoscopy or endoscopy. Treatment varies depending on the underlying cause.

Basic surgical intervention in the thoracic cavity has the primary goal of alleviating any malady that mechanically affects the function of the heart and lungs, which can be secondary to underlying pathologies or, most commonly, trauma. Interventions such as tube thoracostomy and thoracentesis are performed to evacuate fluid, blood, or air that is occupying the thoracic cavity in order to restore thoracic negative pressure. When direct intervention to the heart and mediastinum is required, an emergency thoracotomy is performed. Once the immediate mechanical problems are addressed, more advanced reparative surgery involving heart, lungs, or mediastinal structures can then be performed as necessary.

The esophagus is a muscular tube-shaped organ of around 25 centimeters in length that connects the pharynx to the stomach. The organ extends from approximately the 6th cervical vertebra to the 11th thoracic vertebra and can be divided grossly into 3 parts: the cervical part, the thoracic part, and the abdominal part. The wall of the esophagus is made up of 4 primary layers: mucosa (lined with squamous epithelium), submucosa, a thicker muscularis layer, and an outer layer of connective tissue. The esophagus also has a sphincter at each end, which allows it to help control the passage of food into the stomach.

Megacolon is a severe, abnormal dilatation of the colon, and is classified as acute or chronic. There are many etiologies of megacolon, including neuropathic and dysmotility conditions, severe infections, ischemia, and inflammatory bowel disease. Toxic megacolon is an acute form of megacolon with systemic toxicity, and carries the highest morbidity and mortality. Common symptoms include abdominal distention, pain, bloody diarrhea, or obstipation. Diagnosis depends on the underlying cause, and is usually established with a combination of the patient’s history, laboratory findings, and imaging studies. Patients with chronic megacolon may require laxatives, enemas, and bowel training. Management for acute megacolon includes supportive care, decompression, and potential surgery.

Gastritis refers to inflammation of the gastric mucosa. Gastritis may occur suddenly (acute gastritis) or slowly over time (chronic gastritis). Gastritis may be asymptomatic or with symptoms, including burning abdominal pain (which either worsens or improves with eating), dyspepsia, nausea, and vomiting. The most common etiologies for gastritis are Helicobacter pylori infection and autoimmune disease. Chronic gastritis is a risk factor for gastric cancer. Management involves the use of proton pump inhibitors with antibiotics (in case of H. pylori infection), avoidance of offending agents, and replacement of associated deficiencies.

Achalasia is a primary esophageal motility disorder that develops from the degeneration of the myenteric plexus. This condition results in impaired lower esophageal sphincter relaxation and absence of normal esophageal peristalsis. Patients typically present with dysphagia to solids and liquids along with regurgitation. Diagnosis is established by high-resolution manometry. To rule out malignancy as a cause of achalasia, upper endoscopy is performed. Barium swallow study helps evaluate the esophageal morphology. Management options include pneumatic balloon dilation, surgical myotomy, and botulinum toxin injection. Choice of treatment is dependent on the type of achalasia and surgical risk. Medications are available for those who fail initial intervention; however, they provide the least benefit.