Abnormal digital neurovascular response to local heating in systemic sclerosis.
OBJECTIVE
To investigate neurovascular dysfunction using the axon reflex-dependent hyperaemia (initial peak of skin local heating response) in fingers of patients with SSc or primary RP.


METHODS
Ten healthy subjects were initially enrolled to compare axon reflex-dependent thermal hyperaemia between the finger and forearm cutaneous circulations. Then, 10 patients with primary RP and 16 patients with SSc participated in a similar protocol focusing on the finger circulation only. Lidocaine/prilocaine cream was applied for 1 h to produce local blockade of cutaneous sensory nerves. After lidocaine/prilocaine pre-treatment, laser Doppler probes were heated from skin temperature to 42 degrees C for 30 min, and 44 degrees C for 5 min to achieve maximal skin blood flow. Data were expressed as a percentage of maximal cutaneous vascular conductance.


RESULTS
In healthy volunteers, we observed a significantly higher initial peak on the finger compared with the forearm, with both responses blunted following topical anaesthesia. In primary RP patients, we observed a decreased initial peak following lidocaine/prilocaine pre-treatment in the finger circulation [96.7% (33.4) vs 75.9% (29.5) with anaesthesia, P = 0.02]. In contrast, pre-treatment did not alter the initial peak in patients with SSc. A minute-by-minute analysis showed no delay of the initial peak.


CONCLUSIONS
We show an abnormal digital neurovascular response to local heating in SSc. Thermal hyperaemia could be monitored as a clinical test for neurovascular function in SSc. Further studies are required to test whether the abnormal digital neurovascular response correlates to the degree of peripheral vascular involvement.
Roustit
M
M
Inserm CIC03 - Centre d'Investigation Clinique, CHU de Grenoble, 38043 Grenoble Cedex 09, France.
Simmons
G H
GH
Carpentier
P
P
Cracowski
J L
JL
D000293:Adolescent; D000328:Adult; D000368:Aged; D000779:Anesthetics, Local; D001369:Axons / Q000187:drug effects / Q000502:physiology; D005260:Female; D005385:Fingers / Q000098:blood supply* / Q000294:innervation*; D005542:Forearm / Q000098:blood supply / Q000294:innervation; D006358:Hot Temperature; D006801:Humans; D006940:Hyperemia / Q000503:physiopathology; D017078:Laser-Doppler Flowmetry / Q000379:methods; D008012:Lidocaine; D008297:Male; D008833:Microcirculation / Q000187:drug effects / Q000503:physiopathology; D008875:Middle Aged; D011318:Prilocaine; D012595:Scleroderma, Systemic / Q000503:physiopathology*; D012881:Skin Temperature
D000779:Anesthetics, Local; D011318:Prilocaine; D008012:Lidocaine