Cold caloric microcirculatory reflex disturbance in patients with Parkinson's disease.

The basal skin microcirculatory blood flow and its change in response to a cold caloric stimulus (cold water, 5 degrees C, exposure of one foot for 30 s) were investigated in nine patients with Parkinson's disease (PD) and nine normal subjects (controls). The results revealed a significant (p < 0.001) difference between the groups. In the controls there was a strong decrease in the red cell flux (RCF) on cold water exposure, while eight of the nine PD patients revealed no detectable change in RCF; in one patient only there was a less pronounced reaction. It was concluded that the regulation of the microcirculatory blood flow was affected in PD patients; the cold caloric reflex was attenuated or absent but there was no difference in the basal microcirculatory blood flow compared to normal subjects.