[git] Achalasia

THE GASTROINTESTINAL SYSTEM

Achalasia

A 42-year-old woman is admitted to the hospital because of difficulty in swallowing solid foods; liquids are less difficult to swallow. Chest pain follows eating, and the patient frequently regurgitates swallowed food after a meal. When the recumbent patient is observed by fluoroscopy after a barium swallow, her lower esophagus is seen to be somewhat dilated, but her upper esophagus is of normal caliber. Subsequent swallows initiated by the patient do not cause the barium to be cleared from the esophagus as rapidly as in a normal individual. Rather, it appears that the lower esophageal sphincter (LES) relaxes very transiently, allowing small amounts of barium to empty into the stomach. Administration of amyl nitrate accelerates clearance of barium from the esophagus. The transient openings of the LES do not bear any simple temporal relationship to the swallows initiated by the patient. Esophageal manometric studies of the patient are then undertaken. The coordinated peristaltic wave that is observed in the esophagus of a normal individual after a swallow does not occur in this patient. Rather, each swallow elicits a low pressure increase in the esophagus; the pressure increase occurs almost simultaneously at various places along the length of the esophagus. The resting pressure in the LES is about 60 mm Hg, and the LES pressure decreases to about 45 mm Hg after a swallow. The patient is treated by dilating the LES by brief, forceful inflations of a pneumatic device. After this procedure, the patient's ability to swallow solid food is dramatically improved. Fifteen months after the dilation, the patient returns with the complaint that swallowing has again become difficult.

l. What appears abnormal on fluoroscopic examination after a barium swallow?

2. What esophageal malfunctions might account for these observations?

3. What is learned from the patient's response to amyl nitrate administration?

4. What abnormalities are revealed by manometric studies?

5. What physiologic malfunctions are suggested by the manometric studies?

6. Why does the increase in pressure after a swallow occur at the same time at different locations along the esophagus?

7. Why did the forceful dilation of the LES enhance the ability of the patient to swallow solid food?

8. Why did the patient's symptoms recur?

9. What therapeutic options remain when the patient's symptoms reappear?

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1. The lower part of the patient's esophagus is abnormally dilated. After subsequent swallows, the barium is mostly retained in the esophagus. In a normal individual, subsequent swallows would readily clear the barium into the stomach.

2. The most likely explanation for the fluoroscopic observations is that the patient's LES fails to relax appropriately after a swallow.

3. The increased rate of emptying barium after amyl nitrate administration suggests that the patient's LES is capable of relaxing and that no structural abnormality of the LES prevents emptying of the esophagus.

4. Esophageal manometry revealed the following abnormalities in this patient: (a) a smaller than usual increase in esophageal pressure after a swallow, (b) the failure of this pressure increase to propagate in a peristaltic fashion, (c) a higher than normal resting pressure in the LES, and (d) the failure of the LES pressure to fall as much as normal after a swallow.

5. The small increases in pressure that are observed after each swallow and the absence of detectable esophageal peristalsis suggest deficits of esophageal contractility and deficits in the propagation of the esophageal wave of contraction. This finding is consistent with dysfunction of the intramural plexuses of the esophagus or of the vagal motor innervation. The resting pressure in the LES is about double the normal resting LES pressure. More important, the LES fails to relax very much after a normal swallow; this might result from hypertrophy of the LES or from a deficit or malfunction in the neuronal circuitry that mediates LES relaxation. In the normal individual, the LES relaxes essentially completely after a swallow to allow esophageal propulsion to proceed. This dysfunction of the LES is the major problem in the patient's disorder, which is known as achalasia.

6. Because the esophageal sphincter remains closed, when the upper part of the esophagus (which appears to be close to normal in this disorder) contracts, the pressure is transmitted down the esophagus with essentially no time delay, because water is incompressible.

7. Forceful dilation of the LES tears some of the esophageal muscle fibers. This makes it possible for the LES to relax sufficiently after a swallow to allow swallowing to be almost normal.

8. With time the damage done to the LES is repaired, and the original problems with swallowing, caused by failure of the LES to relax sufficiently, recur.

9. The therapeutic options at this point are the same as those available when the disorder was first diagnosed: (a) to treat the patient with drugs (calcium channel blockers such as nifedipine taken by mouth just before eating), (b) to repeat the abrupt mechanical dilation of the LES, (c) to make a longitudinal incision in the LES through the entire thickness of the musculature, which markedly weakens the LES.

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