ABC of vascular diseases. Raynaud's syndrome and similar conditions.

Baseline temperature 23-2°C Initial temperature 20 50C Temperature at 7 min 21 °OC Latent period >8 min Maximum rewarming time 0 20C/min The circulation of the extremities can be regulated by temperature-for example, exposure to cold in a normal person will cause vasoconstriction and a decrease in blood flow to the skin. Abnormalities of this apparently simple response have been of interest since Maurice Raynaud described the syndrome that bears his name in 1862. He attributed the clinical signs that he observed to overactivity ofthe sympathetic nervous system, and so began a series of controversies that persist today.