COMPARISON OF CLINICAL EXAMINATION, CURRENT AND VIBRATORY PERCEPTION THRESHOLD IN DIABETIC POLYNEUROPATHY

The study of diabetic polyneuropathy is complicated by a lack of clear definitions and the absence of a simple reliable test procedure. Rece ntly, a new sensory perception testing device has been introduced for detection of thresholds for electrical stimuli (current perception: CP T) at different frequencies (Neurometer(R)). We compared standardized clinical examination scores with measurements of vibratory perception threshold (VPT) and CPT (foot) and obtained reproducibility figures. P articipants in the study were healthy controls (H, n = 33), diabetic p atients without clinical signs of neuropathy (DN - , n = 23), diabetic s with overt diabetic neuropathy (DN + , n = 22), and patients with a diabetes duration of over 20 years (D20, n = 38). As expected, there w ere highly significant differences (Wilcoxon) in CPT, VPT and neurolog ical scores between H/DN - and DN + (p < 0.001), but not between H and DN - . Correlation between CPT and total as well as partial (reflecti ng small and large fibre functions) neurological examination score wer e highest at 2000 Hz (r = 0.88); no advantage of lower frequency CPT c ould be identified. CPT seemed rather insensitive in detecting neuropa thy. Correlations between CPT and VPT were only moderate and maximal a t 2000 Hz (r = 0.61). Reproducibility of CPT was good at 2000 Hz (coef ficient of variation 13.3-20.2%), but moderate to poor at lower freque ncies (ranging to 62%). We conclude that CPT and VPT quantitative sens ory testing is only of limited value, mainly because of high variabili ty and poor reproducibility.