Evaluation of sural nerve automated nerve conduction study in the diagnosis of peripheral neuropathy in patients with type 2 diabetes mellitus

Abstract

IntroductionNew tests for improved diagnosis of diabetic peripheral neuropathy (DPN) are useful.Material and methodsWe evaluated the utility of automated nerve conduction study (NCS) of the sural nerve with a new portable device for the diagnosis of DPN in patients with type 2 diabetes mellitus (T2DM). This study included 114 T2DM patients (58 men) with mean age 64.60 ±8.61 years. Exclusion criteria were B12 depletion, alcohol abuse and other causes of peripheral neuropathy. The reference method was the Neuropathy Disability Score (NDS) with a threshold NDS ≥ 3. Sural nerve automated NCS was carried out with the portable NC-stat DPNCheck device. Sensory nerve conduction velocity and sensory nerve action potential amplitude were measured bilaterally. Automated NCS was considered abnormal when ≥ 1 of the two aforementioned neurophysiological parameters was abnormal in at least one leg.ResultsExamination with NC-stat DPNCheck exhibited 90.48% sensitivity, 86.11% specificity, 79.17% positive predictive value (PPV) and 93.94% negative predictive value (NPV). The positive likelihood ratio (LR+) was 6.51 and the negative likelihood ratio (LR–) was 0.11.ConclusionsSural nerve automated NCS with the NC-stat DPNCheck device exhibits high sensitivity and specificity for the diagnosis of DPN in T2DM.

NC-stat for the diagnosis of diabetic polyneuropathy

“…DPN was defined as NDS ≥3 [15]. NC-stat ®/DPNCheck™ yielded excellent sensitivity (90.48%) and NPV (93.94%) along with high specificity (86.11%) and PPV (79.17%), Youden's J being as high as 0.77 [15]. A very good negative likelihood ratio of 0.11 was also demonstrated [15].…”

“…We have also provided evidence of the diagnostic accuracy of NC-stat®/DPNCheck™, especially in exclusion of DPN [15]. We compared the NC-stat®/DPNCheck™ device with the standardized clinical examination score Neuropathy Disability Score (NDS), in 114 type 2 DM patients and 46 age-and sexmatched controls.…”

“…Hence, NC-stat®/DPNCheck™ harbors very useful characteristics: (1) it exhibits high reproducibility [7]; (2) its results in confirming vs. excluding DPN correlate well with conventional NCS [7,12,13] and clinical NDS [15]; (3) it additionally detects DPN in up to 60% of patients with a negative monofilament test [14]; (4) its application is not restricted by physician's subjective interpretation or by inadequate patient cooperation [15]; (5) it can be easily performed by nontechnical personnel after very brief training [7,20]. Nonetheless, impaired sural nerve function is not always by definition attributable to DM, and other causes of sensory polyneuropathy may have to be excluded, as, indeed, with any other diagnostic tool of DPN.…”

“…We compared the NC-stat®/DPNCheck™ device with the standardized clinical examination score Neuropathy Disability Score (NDS), in 114 type 2 DM patients and 46 age-and sexmatched controls. DPN was defined as NDS ≥3 [15]. NC-stat ®/DPNCheck™ yielded excellent sensitivity (90.48%) and NPV (93.94%) along with high specificity (86.11%) and PPV (79.17%), Youden's J being as high as 0.77 [15].…”

“…Furthermore, national institute for clinical excellence (NICE) recommendations for lower limb neuropathy of T2DM patients in the primary care setting implicate the two aforementioned tools alongside with palpation of foot pulses and inspection for foot deformity and of footwear, whereas there is currently no standardized test in the primary care setting to test for early stages of peripheral neuropathy [19]. Additionally, clinical examination relies importantly on patient feedback [7], whereas application of the gold standard NCS is limited by restricted availability and device complexity [14,15].…”