Indices of Sympathetic Vascular Innervation in Scleroderma Patients Treated by Epidural Spinal Cord Electrical Stimulation (ESES)

Abstract

In an attempt to explain the epidural spinal cord electrical stimulation (ESES) mechanism of action on microcirculation, the authors measured arterial and venous plasma concentration of norepinephrine (NE), by chromatography, in 17 patients (16 women - 1 man, mean age forty-seven years, range: twenty- four to sixty-four years) affected by scleroderma (15 patients) and Raynaud's disease (2 patients), treated by ESES (mean follow-up 29.3 months, range: one to forty-nine months).

Blood was sampled with the patient in the supine position, resting at least for thirty minutes, in environmental standard conditions, from a brachial vein (without tourniquet) and a radial artery, with pacemaker off for twelve hours and pacemaker on for thirty minutes. Microcirculatory modifications induced by ESES were also evaluated in all patients by transcutaneous oxygen tension (TcPO₂) and laser Doppler flow (LDF), simultaneously measured with the pa tient in the supine position, on the palm (thenar and hypothenar eminences) during three thirty-minute consecutive phases at 42 ° C and 45°C (phase I: pace maker off for twelve hours; phase II: pacemaker on; phase III: pacemaker off).

For technical reasons, NE dosages were available in only 12 patients. Cate gorizing the patients on the basis of clinical results (group A, excellent-good, 9 patients; group B, poor-null, 3 patients) the authors noted after the ESES stim ulation:

1. The vasodilatation index (TcPO₂ 42°C/TcPO₂ 45 ° C) increased in phase II and phase III (phase I vs phase II, p < 0.001; phase I vs phase III, p < 0.01).

2. The LDF flow differences between 42°C and 45°C were statistically sig nificant in responders between phase I and phase III (p < 0.01).

3. The physiologic norepinephrine arteriovenous ratio was inverted in 7 of 9 patients of group A and in none of group B (p < 0.05).

TcPO₂ and LDF are useful noninvasive techniques to evaluate microcircula tory modifications induced by ESES. Moreover, the arteriovenous ratio de crease in plasma norepinephrine may explain the ESES effect on microcircula tion and the reduced vasomotor tone.