The finding of esophageal spasm is considered separately from hypercontractility, although it can have similarities with outflow obstruction. Esophageal spasm is defined as premature contractions of normal contraction vigor in more than 20% of test swallows. A premature contraction is defined by the rapidity by which the wave front moves from the initiation of a swallow to the distal esophagus. More precisely, it is the time interval between the relaxation of the upper esophageal sphincter to the inflection point of the contractile front of the propagated swallow within 3 cm of the lower esophageal sphincter (contractile deceleration point) known as distal latency. A normal distal latency is >4.5 s. Anything less than that is considered premature, rapid, or spastic. Importantly, the contractile deceleration point needs to be measured along the pressure wave created from the esophageal contraction not to be confused with the potentially elevated intrabolus pressure that precedes the waveform. Many automated computer-generated interpretations make this mistake and over-call esophageal spasm when it really represents isolated gastroesophageal outflow obstruction. Patients with esophageal spasm are generally differentiated from spastic achalasia by the presence of an elevated integrated relaxation pressure. However, on occasion, some gray areas will be encountered when patients exhibit characteristics across categories. For example, achalasia should still be considered in patients with normal integrated relaxation pressures but 100% failed peristalsis, particularly if there is evidence of esophageal body pressurization. The point is, there is not a specific category for which myotomy could be applicable. The precise name applied to the disorder is less important than understanding the underlying pathophysiology that may be causing the symptoms one is trying to alleviate (Fig. 11.2).