Achalasia other diagnostic studies
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Other Diagnostic Studies
Manometry
Manometry is the key test for establishing the diagnosis.
Conventional Manometry
A probe measures the pressure waves in different parts of the esophagus and stomach during the act of swallowing. A thin tube is inserted through the nose, and the patient is instructed to swallow several times. Pressure sensors are placed by means of conventional catheters in esophagus at a distance ranging from 3-5 cm. On conventional manometry following findings characterize achalasia:
- Residual pressure of LES > 10 mmHg.
- Incomplete relaxation of the LES.
- Increased resting tone of LES
- Aperistalsis – contractions may be absent, diffuse and not coordinated, and / or ‘vigorous’ (> 60 mmHg).
- Raised intraoesophageal pressure (due to stasis of food)
High Resolution Manometry
High resolution manometry (HRM) provides more detailed information about esophageal pressures. It is the gold standard investigation for diagnosing achalasia. In HRM 36 or more pressure sensors are placed at a distance of not more than 1 cm from each other. Following table depicts characteristics of achalasia on conventional and high resolution manometry:
| Conventional manometry | High resolution manometry |
| LES | |
| Mean fall in post deglutitive LES pressure > 8mmHg above gastric pressure Basal LES pressure > 45 mmHg |
Impaired EJG relaxation Mean 4s IRP > 10 mmHg over test swallows |
| Peristalsis | |
| No contractions and/or Simultaneous contractions with amplitudes <40 mmHg |
Absent peristalsis (Type 1 achalasia) Pan esophageal pressurization (Type II achalasia) |
| Vigorous achalasia | |
| Peristalsis present with esophageal contractions > 40 mmHg OR Simulataneous contractions > 40 mmHg |
Spastic achalasia (Type III achalasia) |
Cholecystokinin (CCK) stimulation test
Cholecystokinin (CCK) stimulation test: CCK causes mild contraction of the LES and a more pronounced release of inhibitory neurotransmitters in the wall of the esophagus. In normal people, LES tone will decrease due to the predominant effect of the inhibitory neurotransmitters. In patients with achalasia, however, the stimulatory effect on the LES is unopposed, and LES pressure increases.
Endoscopy
Endoscopy, which provides a view inside the esophagus and stomach. A small camera is inserted through the mouth while the patient is under sedation. The endoscopist observes a "pop" as the scope passes through the non-relaxing lower esophageal sphincter.