[Standardization of the electromyographic tetany test in the diagnosis of normocalcemic tetany: the 10-minute Trousseau test in patients and healthy humans].

Eighteen adult patients with typical history and signs of normocalcemic tetany (hyperventilation syndrome) and 18 age- and sex-matched controls were submitted to a provocation test for tetany. This consisted of 10-min ischemia of the right arm produced by suprasystolic cuff compression at the upper arm (Trousseau test) and a postischemic electromyographic recording from the right interosseous I muscle. Postischemic repetitive discharges were found in all patients and predominantly consisted of multiples of 5 times and more. These discharges lasted 8 min on the average. Of the normal controls, as many as 16 subjects (88.8%) also exhibited tetanic discharges. However, these preferred a lower number of repetitions, such as doublets or triplets. Both number of repetition and duration of postischemic tetanic activity were significant parameters discriminating between patients and controls (2P less than 0.001), as was the cumulative total number of spontaneous potentials, amounting, on the average, to 10,266 in the group of patients and to only 320 in the controls (2P less than 0.001). The investigation has shown that the occurrence of postischemic tetanic spontaneous activity per se does not help to discriminate between cases of latent tetany and healthy controls. However, a normocalcemic tetanic condition may be assumed if multiples occur with a complexity of quadruplets or more, if these multiples last at least 2 min, and if they appear in a rhythmic order and in groups.