quantitative sensory testing in type-1 diabetic patients with mild to severe diabetic neuropathy

Background: Small nerve fibre damage has been shown to precede large fibre damage and represents the early stage for diabetic neuropathy (DPN). Aims: To assess small nerve fibre deficit in patients with mild to severe DPN using quantitative sensory testing (QST) and to correlate QST findings with other neuropathy assessment measures in patients with DPN. Materials and Methods: Seventy-nine diabetic patients (49 with and 30 without diabetic neuropathy) and 35 healthy volunteers underwent neuropathy assessment. The evaluation comprised neuropathy symptoms profile, modified neuropathy disability score (NDS), quantitative sensory testing (QST) in form of cold and warm thresholds, vibration pressure threshold (VPT), nerve conduction studies (NCS), deep breathing heart rate variability (DB-HRV), and Neuropad staining scores. Patients were also stratified by their NDS scores into mild, moderate and severe DPN. Measures of QST were compared among various grades of DPN severity and correlated with other clinical and neurophysiological tests. Results: Patients with DPN demonstrated higher vibration perception (P<0.001) and warm (P<0.001) thresholds and lower cold threshold (P<0.001) and these QST abnormalities related directly to the grade of DPN severity. Measures of QST also correlated with those of nerve conduction studies (r range 0.54-0.68) and autonomic function assessment(r range 0.33-0.48). Conclusion: Quantitative sensory testing can identify small nerve fibres impairment which could represent the early stage of diabetic neuropathy and hence the optimal period for intervention.