The cold hand sign in multiple system atrophy: skin perfusion revisited.

The cold hand sign (CHS) is a distinct feature of multiple system atrophy (MSA), but its pathophysiology is poorly understood. We, therefore, conducted a study to examine the skin temperature and the skin blood flow at rest and after local heating in 6 age-matched MSA patients with CHS (MSA + CHS), 18 MSA patients without CHS (MSA - CHS) and 13 patients with idiopathic Parkinson's disease (PD). Basal skin temperature and blood flow were significantly lower in MSA + CHS patients than in MSA - CHS or PD patients. Local heating induced a greater response in terms of amplitude in MSA + CHS compared to MSA - CHS and PD. Considering kinetics, skin blood flow increment per 1 degrees C was higher in MSA + CHS than MSA - CHS but was similar when compared to PD patients. Skin blood flow rate (change per second) did not differ among the groups. Our findings suggest that despite impaired basal skin perfusion, the skin vasomotor response to local heating is intact in MSA + CHS but disturbed in MSA - CHS. By measuring skin temperature and blood flow, the presence of CHS can be diagnosed in MSA patients. Further studies are necessary to understand regulation of skin perfusion in patients with extrapyramidal disease.