The use of Quantitative sensory testing for sensible diabetic neuropathy in children and adults

Introduction: Children with diabetes mellitus type 1 (DM1) need sensory nerve fibre function tests to prevent later consequences of sensory diabetic neuropathy (SDN). Nerve conduction and vibration detection assess only large fibres function whereas small fibre involvement may be earlier and more pronounced in SDN. Quantitative sensory testing (QST) detects all peripheral nerve fibre functions. Thus, the aim of our study was 1. to assess small and large nerve fibre function in juvenile DM1 patients using QST and nerve conduction tests, 2. to evaluate QST for the most sensible parameter for SDN and 3. to elucidate if sensory testing abnormalities correlated with disease parameters.

Patients and Methods: Within 3 month all consecutive patients with DM1 lasting ≥3 years from our diabetes outpatient department who agreed, received nerve fiber function on the foot with the QST protocol of the German research network on neuropathic pain (DFNS), suralis nerve conduction and neurological examinations and pain questionnaires. Results were compared with healthy age and gender matched controls and reference data (Blankenburg et al., 2010) and clinical parameters.

Results: Of 45 patients (22 boys, 23 girls) aged 13.2±2.5 years who suffered from DM1 since 6.6±2.5 years with normal clinical examination, half had loss of mechanical detection (38%; p<0.001) and sensory nerve conduction (24%) and/or increase of pressure pain (40%) and/or mechanical pain sensitivity (22%) and/or paradoxical heat sensation (24%; p<0.001 each). Mechanical detection thresholds had the highest positive predictive value (0.96), sensitivity (0.96) and specificity (0.84) of al tests. Validity was given by high correlation between nerve conduction tests and mechanical detection thresholds. Vibration detection loss was only present in 3 patients with long (≥6 years) DM1 duration. Beside there were minimal differences between patients with long vs. short (<6 years) DM1 duration and good (<8%) vs. bad (≥8%) hbA1c long-term.

Conclusions: Results indicate sub clinical small and large fibre dysfunction in half of DM1 patients at all stages. Mechanical detection thresholds may be most useful for nerve fibre function testing in children with DM1. Their sensitivity and specificity for SDN has to be verified in further studies.