THE USE OF BIOTHESIOMETRY TO DETECT NEUROPATHY IN CHILDREN AND ADOLESCENTS WITH IDDM

OBJECTIVE - To develop clinically useful reference ranges for vibratio n perception thresholds (VPTs), using biothesiometry in children and a dolescents and to assess the reliability of the technique to identify subclinical neuropathy in subjects with IDDM at this age and to examin e a large population-based sample of pediatric patients. RESEARCH DESI GN AND METHODS - VPTs were measured using a handheld biothesiometer at the medial malleolus and hallux in 232 nondiabetic children and adole scents aged 7-18 years (12.9 +/- 4.2 years) and a population-based sam ple of 307 young IDDM patients (13.3 +/- 4.6 years of age). The mean o f three readings at each site was correlated with height, pubertal sta tus, and age for all subjects and, in addition for the IDDM sample, wi th the duration of IDDM, ambient blood glucose, and mean HbA(1c) from diagnosis. Those IDDM subjects found to have elevated VPTs (>97th perc entile), and a control group of patients with IDDM underwent nerve con duction studies to determine the sensitivity and specificity of biothe siometry to detect abnormal neural function in children. Interoperator reliability was assessed in a separate trial in which two operators m easured VPTs independently in the same 11 children. RESULTS - In the n ondiabetic control subjects, height demonstrated the best correlation with VPT measures, and a reference range was thus established with per centile charts, using mean VPT and height. VPTs were higher in the dia betic sample, compared with the nondiabetic sample (P < 0.05). Of the children, 28 (9.1%) had VPT values >97th percentile developed from stu dies of the nondiabetic subjects; of these, 11 were younger than 11 ye ars and 8 were prepubertal. Nerve conduction studies confirmed reduced conduction velocity and prolonged distal latencies in those with abno rmal VPTs, compared with normal control subjects and IDDM patients wit h normal VPTs. Sensitivity of biothesiometry to reflect abnormal nerve function was estimated as 82% and specificity as 75% at this age. Int eroperator variation was small (7.25% of total variance). CONCLUSIONS - Biothesiometry is a useful noninvasive tool for the detection of sub clinical neuropathy in children and adolescents. The use of height-rel ated reference ranges may make screening for neuropathy more feasible in younger patients and allow large-scale longitudinal analysis of its development.