Diagnostic Usefulness of Quantitative Sensory Test in Diabetic Polyneuropathy: Comparison with Nerve Conduction Study

ABSTRACT

BACKGROUND: Although nerve conduction study(NCS) is useful to diagnose diabetic neuropathy, it is still difficult to define objectively the presence or absence of neuropathy in patients with diabetes mellitus. Results of NCS mainly reflect the function of large myelinated nerve fibers, and sometimes reveal no abnormality even in patients with objective signs or subjective sensory symptoms. Recently, a new diagnostic approach, quantitative sensory test (QST) was introduced and exploited for diagnosis of diabetic neuropathy. The objective of this study is to compare the sensitivities of two tests, QST and NCS. METHODS: We evaluated the sensory thresholds of QST in 22 normal controls (group 1) and 26 diabetic patients. The diabetic patients were divided into two groups, 11 patients without symptomatic diabetic polyneuropathy(group 2) and 15 patients with symptomatic diabetic polyneuropathy(group 3). We evaluated warm (WDT), cooling (CDT), heat-pain (HPDT) and vibration (VDT) detection thresholds in all three groups with computer-assisted sensory examination system (CASE IV). We also did NCS in group 2 and 3. The diagnostic value of QST was compared with NCS. RESULTS: In group 1, the CDT, WDT, VDT and HPDT were 7.3, 9.9, 8.7, and 17.2 JND on hand, and 11.6, 15.3, 13.9 and 17.8 JND on foot respectively. On foot, the CDT and WDT of group 3 were different from that of group 1 and 2, and the VDT of group 3 was different from that of group 1. However, no other sensory thresholds on hand and foot were different significantly among three groups. The diagnostic specificity of QST was similar to NCS and the diagnostic sensitivity was slightly lower than NCS without statistical significance. CONCLUSIONS: We measured sensory thresholds in normal and diabetic patients, and concluded that the QST might be complement to NCS for early detection of diabetic polyneuropathy.