Correlation of Neurologic Disability Score and Nerve ConductionParameters in Diabetic Polyneuropathy

ABSTRACT

BACKGROUND: The neuropathy disability score (NDS) is a type of clinical grading method for diabetic polyneuropathy. In clinical practice, a nerve conduction study (NCS) is routinely employed as a non-invasive test for the evaluation of polyneuropathy. However, the consensus regarding the degree of abnormalities in NCS as a parameter for the severity of the disease is lacking. The objective of our study is to assess the relation between NDS and NCS parameters and thus verifying the reliability of our new NCS grading method in the representation of objective neurological defects. METHODS: Seventy three patients (man 31, women 42) with diabetes mellitus were included in the study. The NDS was scored in each patient by a single examiner and a NCS was performed on one side of extremities by an experiencedtechnician. Also, the gastrocnemius-soleus H-reflex was performed and analysed for the representation of a deep tendon reflex. The observed values of CMAP and CNAP were transformed into square root and log values. The transformed individual amplitudes and nerve conduction velocities were graded in relation to the mean normal values and standard deviations of our control group study. Then, the sum of the graded score was calculated in each individual and was correlated to the NDS using correlational analysis. RESULTS: There has been a significant linear relationship between NDS and our new NCS scoring system (Pearson's correlation coefficient r=0.703, p<0.01) CONCLUSIONS: The study showed significant correlations between NDS and our new grading system for NCS. Thus, NCS appears to reliably represent theobjective neurologic findings. In asddition, the quantititive grading of NCS would be useful in determining the grade of peripheral polyneuropathy in diabetic patients.