Preliminary evaluation of median nerve by high-frequency ultrasound in patients with diabetic polyneuropathy

Abstract

Objective To explore the feasibility of high-frequency ultrasound detecting median nerve(MN) in type 2 diabetes mellitus(T2DM) with diabetic peripheral neuropathy(DPN). Methods Forty-two healthy volunteers were included as control group(Group A). Eighty-eight T2DM patients were divided into two groups according to symptoms, signs and electrophysiological results: with DPN (group C, 46 patients) and without DPN (Group B, 42 patients). The width(W), thickness(T) and cross-sectional area(CSA) of MN at 6 points [the wrist crease, pisiform bone, hamate bone, the 6 cm proximal to the wrist crease, the 4 cm proximal to tip of the medial epicondyle(ME) and the midpoint of the humerus] were evaluated.ROC curve was plotted to determine clinical diagnostic value of three lines on six points in diagnosis of DPN. Results ①Comparing with Group A, the width(P<0.05) except for the 4 cm proximal to tip of ME and the midpoint of the humerus, the thickness (P<0.05) except for the 4 cm distal to ME and CSAs of all points were enlarged in DPN patients (P<0.001). The width( P<0.05) at the wrist crease, hamate bone and the midpoint of the humerus, the thickness ( P<0.01) at the wrist crease and pisiform bone, CSAs (P<0.01) of all sites except for the wrist crease were increased in Group B. Comparing Group B with C, the width at the wrist crease, the thickness in the midpoint of the humerus, CSAs except for the 4 cm proximal to ME and the midpoint of the humerus were dramaticlly increased in Group C (P<0.001). ②A diagnostic value comparison: when diagnostic value of W, T and CSA at six points is the most predictive, the sensitivity is 80.4%, 84.8%, 84.8% respectively and specificities are all 54.8%. Diagnostic value of CSA and T is superior to the width. The CSA and T of the hamate bone level were the most predictive of DPN. The corresponding optimal cut-off value was 0.097 cm2, 0.233 cm respectively. Conclusions The backbone and the abnormal changes of different lines of the MN in DPN can be observed by high-frequency ultrasound. The width and thickness of the MN at six points are increased in different degree, but CSAs of all levels can enlarge. When diagnostic value of W, T and CSA at six points is the most predictive for DPN, the sensitivity is superior to specificity respectively. The CSA and T of the hamate bone levelare the most predictive for the evaluation of DPN. Key words: Ultrasonography; Diabetes mellitus, type 2; Diabetic neuropathies; Median nerve