Validation of a Novel Screening Device (NeuroQuick) for Quantitative Assessment of Small Nerve Fiber Dysfunction as an Early Feature of Diabetic Polyneuropathy

Abstract

OBJECTIVE—To validate a handheld screening device (NeuroQuick) for an early detection of diabetic distal symmetric polyneuropathy (DSP) by quantitative testing of cold sensation based on the wind chill factor (NeuroQuick threshold [NQT]). RESEARCH DESIGN AND METHODS—NQT was measured on the dorsum of the foot in 160 healthy subjects as well as 60 and 128 diabetic patients without and with DSP, respectively. DSP was diagnosed by a neurological examination, motor and sensory nerve conduction velocity, vibration perception threshold, and warm and cold thermal perception threshold (TPT) (TPT Medoc). In addition, a C-64 Hz tuning fork and TipTherm device were used as screening instruments. RESULTS—In the diabetic cohort, NQT correlated significantly with all nerve function tests, with the highest correlation coefficients being found on the foot versus Medoc warm TPT (r = 0.618, P < 0.001) and cold TPT (r = 0.529, P < 0.001). Among patients with DSP, NQT was abnormal, whereas Medoc warm TPT was normal in 34%, whereas only 5% showed the opposite constellation (P < 0.05). Likewise, the corresponding percentages for Medoc cold TPT were 32 and 11%, for TipTherm 47 and 2%, and for the tuning fork 29 and 10% (all P < 0.05), whereas no significant differences were noted when comparing NQT with peroneal motor nerve conduction velocity, sural sensory nerve conduction velocity, and malleolar vibration perception threshold. The coefficients of variation for repeated NQT measurements in 41 control and 41 diabetic subjects were 20.4 and 8.5%, respectively. CONCLUSIONS—The NeuroQuick is a valid and reliable screening tool for quantitative assessment of small nerve fiber dysfunction. This device appears to be more sensitive in detecting early diabetic polyneuropathy than both elaborate thermal testing and screening tests such as the tuning fork.