A method for evaluating the thermal threshold in patients with Raynaud's syndrome living in temperate area - A report of three cases

Background. The concept of "thermal threshold" in Raynaud's syndrome was th eorized in 1990 by Pratesi as the ambient temperature below which an attack of vasospasm is more likely to be provoked, though so far it has not yet b een proved to be a reality. Our preliminary report of two cases, whose atta cks were compared with the daily maximum temperatures, showed results sugge stive of the existence of this parameter. Methods. We asked a third female patient with Raynaud's syndrome of the han ds and feet to keep note of the time, days and modalities of the phenomena, for at least three months including the summer. Data of six and five month s from Cases 1 and 2 respectively, not including the times at onset, were r econsidered. The data available from all cases were compared to the true da ily mean temperature. The data of the new Case 3 were also compared with th e hourly temperatures on each day over the period of study. All calculation s referred to the estimated temperature to be expected from the difference in altitude between the weather stations and the usual and temporary reside nces. Results. The mean thermal threshold was 17.166 degreesC in the less severe Case 1 and 28.438 degreesC in Case 2 (complicated by gangrene). In Case 3, the mean and hourly thresholds were 26.740 and 26.807 degreesC for the hand s, and 25.092 and 23.807 degreesC for the feet, respectively. Conclusions. This report is suggestive, although not conclusively, of the e xistence of a thermal threshold, which is higher in the more severe cases. Further research is required.