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

BACKGROUND

The concept of "thermal threshold" in Raynaud's syndrome was theorized 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 been proved to be a reality. Our preliminary report of two cases, whose attacks were compared with the daily maximum temperatures, showed results suggestive of the existence of this parameter.

METHODS

We asked a third female patient with Raynaud's syndrome of the hands 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 months from Cases 1 and 2 respectively, not including the times at onset, were reconsidered. The data available from all cases were compared to the true daily mean temperature. The data of the new Case 3 were also compared with the hourly temperatures on each day over the period of study. All calculations referred to the estimated temperature to be expected from the difference in altitude between the weather stations and the usual and temporary residences.

RESULTS

The mean thermal threshold was 17.166 degrees C in the less severe Case 1 and 28.438 degrees C in Case 2 (complicated by gangrene). In Case 3, the mean and hourly thresholds were 26.740 and 26.807 degrees C for the hands, and 25.092 and 23.807 degrees C for the feet, respectively.

CONCLUSIONS

This report is suggestive, although not conclusively, of the existence of a thermal threshold, which is higher in the more severe cases. Further research is required.