Digital laser doppler flowmetry may discriminate "limited" from "diffuse" systemic sclerosis

To investigate skin blood flux and microvascular functional changes by laser Doppler flowmetry (LD) in patients with systemic sclerosis (SSc) at baseline and following dynamic stimulations.

Skin blood flux of the dorsal hands was recorded by LD at baseline and after the cold test and the post-occlusive hyperemia test in 59 SSc patients (49 limited cutaneous, 10 diffuse cutaneous). Twenty-five patients with primary Raynaud's phenomenon (PRP), and 31 healthy donors (HD) were studied as controls.

After the cold test, SSc patients had a significantly higher reduction of the blood flux (-38.4%+/-28) than PRP (-21.1%+/-37) and HD (-22.1%+/-23) subjects (p<0.05). Within the SSc group, the cold test flux was significantly reduced in limited-SSc (-399%+/-28, p<0.05), but not in diffuse-SSc (-31.2%+/-29), whereas, the time needed to recover the basal flux after the occlusive/ischemic test was significantly longer in diffuse-SSc (18.8s+/-21)than in limited-SSc (4.5s+/-4, p<0.01) or HD (2.2s+/-2, p<0.01) or PRP (0.4s+/-0.7, p<0.01).

These data clearly indicate an impairment of vascular tone regulatory mechanisms in SSc and suggest that a peculiar pathogenic mechanism may be involved in different SSc subset. Nevertheless, it has clear that PRP and SSc-associated RP have a distinct pattern at LD evaluation, and monitoring patients with PRP could be helpful to understand whether a change in the LD pattern might predict the development of SSc.