Reevaluation of manometric criteria for vigorous achalasia. Is this a distinct clinical disorder? Clinical and manometric data from 97 consecutive patients with idiopathic achalasia were analyzed to see if a distinct subset with vigorous achalasia could be identified. Statistical analyses failed to detect a unique group of subjects based on the distribution of contraction wave amplitudes alone. Because of this, patients falling above the 95th percentile (N = 4, mean wave amplitude greater than 100 mm Hg for each) were compared with those having mean amplitudes above the conventional threshold for the diagnosis of vigorous achalasia (mean amplitude 60-100 mm Hg, N = 4), and with the remainder (N = 89, mean amplitude less than 60 mm Hg). Subjects with mean amplitudes less than 60 mm Hg and with mean amplitudes 60-100 mm Hg closely resembled each other in all measured clinical features, whereas subjects with mean amplitudes greater than 100 mm Hg were all male, were older (67 +/- 4 years vs 47 +/- 2 years; P less than 0.01), and appeared to have somewhat longer duration of symptoms when compared with the remainder (82 +/- 41 vs 44 +/- 10 months; P = 0.4). Chest pain and other esophageal symptoms, basal and residual lower sphincter pressures, and response to first treatment did not differ among the three groups. These data indicate that high-fidelity manometry techniques identify a rare subset of achalasia patients with mean contraction amplitudes exceeding 100 mm Hg that, although older and possibly with greater duration of symptoms, presents similarly to others with idiopathic achalasia. Outcome from conventional treatment is also similar for the "vigorous" and "nonvigorous" patients, making the distinction of questionable value. 