Back to basics in diagnosing diabetic polyneuropathy with the tuning fork!

Several national and international scoring systems are used to diagnose diabetic polyneuropathy (PNP). The variety in these scores and the lack of data on validity and predictive value has led to a comparison and validation of the scores with clinical standards for PNP to determine the most powerful measurement for screening.

Three matched groups were selected: 24 diabetic patients with neuropathic foot ulcers, 24 diabetic patients without PNP or ulcers, and 21 control subjects without diabetes. In all participants the scores from the International Consensus on the Diabetic Foot (ICDF) and the Dutch Nederlandse Diabetes Federatie-Centraal Beleids Orgaan (NDF/CBO) were tested. The Diabetic Neuropathy Symptom score, the Diabetic Neuropathy Examination score, Heart Rate Variability, the Nerve Conduction Sum score, and a San Antonio Consensus sum score were obtained as clinical standards. Reproducibility was tested in a separate study (13 patients).

The construct validity and discriminative power of the ICDF and NDF/CBO scores were comparable, although monofilaments (NDF/CBO) scored lower. The predictive value was good for all scores, with the best results being obtained for the tuning fork (NDF/CBO). Reproducibility of the NDF/CBO scores (monofilaments and tuning fork) was high.

The characteristics of the scores of tests recommended by ICDF and NDF/CBO are comparable. The single use of the 128-Hz tuning fork produces results similar to the extended scores of the ICDF and much better than those of monofilaments on validation and for predictive value. For screening we therefore advise the use of the tuning fork alone.