The influence of isolated small nerve fibre dysfunction on microvascular control in patients with diabetes mellitus

Aim The aim of the study was to investigate the influence of isolated small nerve fibre dysfunction on microvascular skin blood flow and transcutaneou s oxygen tension in patients with diabetes mellitus. Methods Small nerve fibre dysfunction was assessed by the measurement of th ermal and pain perception thresholds. Patients with evidence of large fibre disturbances as evaluated by means of vibration perception threshold were excluded from the study. Microvascular blood flow was investigated with las er-Doppler-fluxmetry (LDF) following stimulation with acetylcholine and mil d thermal injury. Results Diabetic patients with small nerve fibre injury showed a significan tly reduced increase in the laser-Doppler-flux signal following the applica tion of acetylcholine compared with patients without neuropathy or healthy control subjects (2.8 arbitrary units (AU) (1.3-5.5) vs. 7.2 AU (4.1-25.5); P = 0.007 and vs. 8.5 AU (3.0-17.0), P = 0.02, respectively). The increase in LDF following thermal injury was also diminished in patients with small nerve fibre dysfunction compared with patients without neuropathy or the c ontrol group (29.8 AU (17.2-46.5) vs. 51.2 AU (29.5-93.5); P = 0.02 and vs. 54.6 AU (39.7-97.7); P = 0.004, respectively). In addition, they showed a significantly reduced transcutaneous oxygen tension compared with the other groups (42.9 mmHg (41.6-55.5) vs. 56.1 mmHg (49.2-60.8); P = 0.04 and vs. 59.0 mmHg (54.6-80.3), P = 0.03, respectively). Conclusions Our study confirms an association between small nerve fibre inj ury and skin microvascular dysfunction. It further underlines the concept o f neurovascular disturbances in the pathogenesis of neurotrophic foot ulcer ation.