Animal studies continue to show the importance of nitric oxide as a mediator of lower esophageal tone. It may act directly on or in conjunction with vasoactive intestinal polypeptide. Human studies show little evidence that would support the notion that swallowing function is significantly affected by age. Esophageal motility studies differ between swallowing liquids versus solids. The findings of 'nutcracker' esophagus may simply be a marker for gastroesophageal reflux, as symptoms can resolve with treatment of the latter, although a nutcracker esophagus motility pattern may persist. Using a graded pneumatic regimen, dilation in achalasia can be performed safely and successfully in the majority of patients on an outpatient basis. Nonspecific motor disorder is associated with selective impairment of semisolid emptying and is thus a 'real' clinical disorder of motility. Esophageal manometry is a useful and cost-effective test leading to diagnostic and management decisions in more than half of patients.
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