Internal Medicine Correlations and Clinical Scenarios (CCS) USMLE Step 3

CASE 2: Achalasia

Setting: ambulatory care center

CC: “Food gets stuck when I eat.”

HPI: A 37-year-old woman with difficulty swallowing over the past few months comes to the ambulatory care center. She says that the difficulty has been with solid food as well as liquids. It has continued to worsen. She now wakes up with undigested food particles on her pillow. There is no pain on swallowing.

ROS:

Image No tobacco use

Image Minimal alcohol consumption

Image Twelve-pound weight loss over 3 months

PMHX/Medications: none

PE:

Image General: no visible distress

Image Abdomen: normal

Image Chest: normal

Image Rectal: stool heme negative

Initial Orders:

Image Comprehensive metabolic panel (CHEM-20)

Image Chest x-ray

Barium is okay to start with for dysphagia cases.

Esophagus: Barium is useful.

Stomach: Barium is not useful.

Ambulatory cases should be moved forward a week at a time if there is a new diagnosis to make. Chronic, long-term disease is moved forward at 1-month to 3-month intervals. Any patient with GI tract bleeding should have a GI consultation ordered.

A week later, the patient feels the same. Dysphagia for solid food and liquid continues. Food particles continue to be found on her pillow in the morning.

Reports:

Image CHEM-20: BUN 4 g/dL (slightly low); albumin 3.6 g/dL

Image Chest x-ray: widening at the top of the mediastinum

Wide Mediastinum

+ Chest pain = Dissection

+ Dysphagia = Esophagus

Dysphagia with pain on swallowing is odynophagia. In a person with acquired immunodeficiency syndrome (AIDS) and a CD4 cell count <100 cells/mm3, what is the first step?

a. Endoscopy

b. Fluconazole

c. Stool candida culture

d. Serum candida antigen

e. Chest computed tomography (CT)

Answer b. Fluconazole

AIDS with a CD4 cell count <100 cells/mm3 plus odynophagia indicates esophageal candidiasis in 90% of patients. Because there is such a high likelihood of candida in AIDS, this is one of the few times you can use empiric therapy to confirm a diagnosis. There is no such test as serum candida antigen. If there is no response, then do an endoscopy.

Never culture stool for yeast! Everyone has yeast in their stool.

Schedule the patient to see a gastroenterologist and order a barium esophagram. There is no blood test for any form of dysphagia.

Report:

Image Barium esophagram: wide at top, narrow at bottom (Figure 5-1)

Image Gastroenterologist: no specific recommendations; order what you think is necessary

Image

Figure 5-1. Esophageal achalasia. Note dilation of the esophageal body, retained barium, and distal esophageal narrowing (bird’s beak). (Reproduced with permission from Doherty GM. Current Diagnosis & Treatment: Surgery, 13th ed. New York: McGraw-Hill; 2010.)

What is the most accurate diagnostic test?

a. Endoscopy

b. Manometry

c. Biopsy

d. Secretin stimulation test

Answer b. Manometry

The single most accurate test for achalasia is manometry. This is never a test that is done first. Manometry is the right answer when a patient has a swallowing disorder and no clear diagnosis after barium and endoscopy.

Proximal esophagus: skeletal muscle.

Distal esophagus: smooth muscle.

Smooth muscle is connected by gap junctions. When stretched, it contracts as a syncytium.

Now consider the occurrence of intermittent chest pain in a man whose ECG and stress test are normal. The chest pain is brought on by cold drinks. It is prevented by calcium channel blockers and nitrates. What is the most accurate test?

a. Barium

b. Manometry

c. Endoscopy

Answer b. Manometry

Esophageal spasm is characterized by intermittent severe contraction of the smooth muscle of the esophagus. Manometry is most accurate. Calcium channel blockers and nitrates relax smooth muscle.

Consultations on CCS will not tell you what to order. In this case, order the upper endoscopy yourself. If consultants told you what to order, then the Step 3 examination could not test your knowledge level.

Move the clock ahead until you see “Report Available” on the upper endoscopy. The report shows smooth mucosa with no lesions and narrowing at the distal esophagus.

Plummer-Vinson Syndrome

• Iron deficiency without bleeding

• Some transform to squamous cell cancer

Barrett Esophagus Histology

• Columnar metaplasia

• Becomes adenocarcinoma, not squamous

Why does the lower esophageal sphincter (LES) tighten in achalasia?

a. Loss of myenteric plexus

b. Loss of Auerbach plexus

c. Decrease in vasoactive intestinal peptide (VIP)

d. Excess vagal tone

Answer a. Loss of myenteric plexus

Achalasia is the loss or degeneration of the inhibitory neurons of the esophageal wall. There is incomplete peristalsis. Auerbach plexus is what is lost in Hirschsprung disease.

It is not known why the neurons degenerate in achalasia.

What causes the receptive relaxation that opens the stomach from 50 mL to 2000 mL on eating?

a. Epinephrine

b. VIP

c. Dopamine

d. Norepinephrine

e. Serotonin

Answer b. VIP

Stretch receptors in the stomach detect increased volume and through vagal stimulation release VIP. VIP is what opens the stomach for receptive relaxation.

VIP opens GI tract sphincters.

Now that achalasia is confirmed, a dilation procedure with an endoscope or surgical myotomy can be performed. Dilation procedures are less invasive, but also have a higher risk of perforation.

For those declining either procedure, botulinum toxin, or Botox, can be injected into the LES. These injections have less complications, but they also wear off after a few months or a year.

What is the mechanism of botulinum toxin?

a. Decreased release of acetylcholine from the presynaptic terminal

b. Blockade of acetylcholine receptor

c. Increased acetylcholine esterase

d. Blockage of the sodium channels

Answer a. Decreased release of acetylcholine from the presynaptic terminal

Botulinum toxin prevents the release of vesicles of acetylcholine in response to depolarization of the nerve. The nerve impulse hits the neuromuscular junction, but no neurotransmitter is released and the muscle relaxes.

Most people choose endoscopic dilation. This can be curative. See the patient immediately after the procedure to check for perforation. Then ask her to return several times over the next month to be sure the procedure is effective. If successful, it should be fully curative.



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