[Correlations between cardiorespiratory reflex impairment and distal neuropathy in diabetics free of clinical symptoms of autonomic neuropathy]

Abstract

Signs of autonomic cardiac neuropathy and its association with distal symmetrical polyneuropathy were investigated in adult diabetic patients free from clinical symptoms of autonomic neuropathy. Cardiorespiratory reflexes were assessed by non-invasive tests (deep-breathing, Valsalva manoeuvre and lying-to-standing) evaluating parasympathetic function of cardiac innervation. Measurement of motor nerve conduction velocity in both peroneal nerves and neurological physical examination were carried out for assessment of distal somatic neuropathy. Among 64 diabetics, definitive signs of cardiac autonomic neuropathy were found in 28 patients (44%), early signs of cardiac autonomic neuropathy were observed in 19 patients (30%) while no alterations were documented in 17 patients (26%). The values of motor nerve conduction velocity in peroneal nerves (41.8 +/- 0.7 m/s) were significantly (p less than 0.01) lower in patients with definitive cardiac autonomic neuropathy (n = 28) than those (45.8 +/- 1.1 m/s) of patients without any signs of cardiac autonomic neuropathy (n = 17). These latter values were, however, significantly (p less than 0.001) lower than those (53.7 +/- 0.7 m/s) of control subjects (n = 50). Abnormal results of non-invasive tests for autonomic neuropathy, i.e. alterations of cardiorespiratory reflexes indicating parasympathetic impairment in cardiac innervation could be often found in diabetics without clinical signs of autonomic neuropathy. These alterations could be frequently observed in diabetics with distal symmetrical neuropathy as well as in diabetic patients with one or more late specific complications.