Evidence of a selective nociceptive impairment in systemic sclerosis

To test for the autonomic neuropathy in systemic sclerosis (SSc) using cardiovascular reflex evaluation including the "cold face test", which elicits forehead cold receptors (C-fibres). These tests examine the induced bradycardia-hypertensive response and the integrity of nociceptive afferent and parasympathetic-sympathetic efferent pathways.

Twelve SSc patients were studied; including 5 with the limited cutaneous (lcSSc) involvement, and 7 with diffuse cutaneous involvement (dcSSc). All patients were matched with healthy controls. We performed cardiovascular autonomic tests (tilt-test, Valsalva manoeuver, deep breathing, sustained handgrip and cold face) with continuous monitoring of beat-to-beat blood pressure (BP) and heart rate (HR). Baroreceptor sensitivity index (BRSI) and power spectral analysis (PSA) of heart rate variability (HRV) were also evaluated.

SSc patients showed a statistically significant higher HR at rest (p<0.01), a lower increase of diastolic BP during tilt test (p<0.01). They had suboptimal hypertensive and bradycardic response to the cold face test (Systolic BP: p<0.05; Diastolic BP: p<0.01; HR: p=0.08). The Valsalva manoeuver, deep breathing, isometric handgrip, BRSI and PSA of HRV results were within normal limits in the majority of SSc patients.

In this group of SSc patients cardiovascular reflexes were normal, whereas the cold face test which acts through cutaneous nociceptive sensory fibres was abnormal in almost all patients. These results suggest that insufficiency of epidermal small fibres (C-fibres) is involved in SSc.