Applicability of High-Frequency Ultrasound to the Early Diagnosis of Diabetic Peripheral Neuropathy

This study investigated the applicability of high-frequency ultrasound (HFU) to the early diagnosis of diabetic peripheral neuropathy (DPN). Patients with type 2 diabetes (N = 60) were divided into diabetic nonperipheral neuropathy and DPN groups (group A and group B, respectively; n = 30 each) based on electroneurophysiologic findings. Additionally, 30 nondiabetic patients were included as the healthy control group (group C). We calculated the cross-sectional area (CSA) of the median nerve (MN) of the right upper limb at 7 different sites (MN1-7) based on measured width (W) and thickness (T). Ultrasound imaging characteristics of the MN including internal echo, internal structure, boundary, epineurium, and blood flow were recorded. The 90 subjects (51 male and 39 female) had an average age of 56.09 ± 12.66 years. W, T, and CSA of the MN were increased in group A compared to group C (with significant differences at MN1, MN4, and MN7 (P < 0.05)) and in group B compared to group C (with significant differences at all 7 levels, especially MN6 and MN7 (P < 0.05)). Receiver operating characteristic curve analysis showed that CSA at the MN7 level had the highest diagnostic accuracy for DPN in group B, with a threshold value of 12.42 mm2. Ultrasound examination revealed that the MN had lost the internal sieve mesh structure and showed reduced echo, a partial blood flow signal, and thickened epineurium in patients with DPN; these findings were particularly obvious at MN6 and MN7, corresponding to the carpal tunnel. CSA was positively correlated with motor latency and F wave average latency and negatively correlated with motor conduction velocity, motor amplitude, and sensory conduction velocity in group B. Thus, HFU may be useful for the early diagnosis of DPN, which can improve clinical outcomes.