 It has been incorporated into a number of clinical guidelines for the evaluation of dysphagia.The Achem criteria are more stringent, and are an extension of the study of 93 patients used by Richter and Castell in the development of their criteria, and require amplitudes of greater than 199 mm Hg at 3 cm above the lower esophageal sphincter (LES), greater than 172 mm Hg at 8 cm above the LES, or greater than 102 mm Hg at 13 cm above the LES.Pathology specimens of the esophagus in patients with nutcracker esophagus show no significant abnormality, unlike patients with achalasia, where destruction of the Auerbach's plexus is seen.