The utility of a point-of-care sural nerve conduction device for detection of diabetic polyneuropathy: A cross-sectional study.

INTRODUCTION: Rapid and accessible methods for diagnosing diabetic polyneuropathy (DPN) have been developed, but not validated, in large cohorts of people with diabetes. METHODS: The performance of a point-of-care device (POCD) was studied in 168 patients with type 2 diabetes, estimating the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) compared with conventional sural nerve conduction studies (NCS). RESULTS: A POCD amplitude limit of 6 µV increased the sensitivity (96%) and NPV (98%), but decreased the specificity (71%) and PPV (54%) compared with the 4-µV limit, which had values of 78%, 92%, 89%, and 71%, respectively. POCD on both legs showed better performance than on 1 leg. POCD amplitudes and conduction velocities correlated significantly with conventional sural NCS, but POCD values were underestimated compared with NCS. DISCUSSION: The POCD may be used as a suitable screening tool for detection of DPN. Patients with abnormal and borderline results should undergo conventional NCS. Muscle Nerve 59:187-193, 2019.

Longitudinal Change in Serum Neurofilament Light Chain in Type 2 Diabetes and Early Diabetic Polyneuropathy: ADDITION-Denmark.

OBJECTIVE: To investigate the longitudinal development of neurofilament light chain (NfL) levels in type 2 diabetes with and without diabetic polyneuropathy (+/-DPN) and to explore the predictive potential of NfL as a biomarker for DPN. RESEARCH DESIGN AND METHODS: We performed retrospective longitudinal case-control analysis of data from 178 participants of the Anglo-Danish-Dutch Study of Intensive Treatment in People with Screen-Detected Diabetes in Primary Care-Denmark (ADDITION-Denmark) cohort of people with screen-detected type 2 diabetes. Biobank samples acquired at the ADDITION-Denmark 5- and 10-year follow-ups were analyzed for serum NfL (s-NfL) using single-molecule array, and the results were compared with established reference material to obtain NfL z-scores. DPN was diagnosed according to Toronto criteria for confirmed DPN at the 10-year follow-up. RESULTS: s-NfL increased over time in +DPN (N = 39) and -DPN participants (N = 139) at levels above normal age-induced s-NfL increase. Longitudinal s-NfL change was greater in +DPN than in -DPN participants (17.4% [95% CI 4.3; 32.2] or 0.31 SD [95% CI 0.03; 0.60] higher s-NfL or NfL z-score increase in +DPN compared with -DPN). s-NfL at the 5-year follow-up was positively associated with nerve conduction studies at the 10-year follow-up (P = 0.02 to <0.001), but not with DPN risk. Areas under the curve (AUCs) for s-NfL were not inferior to AUCs for the Michigan Neuropathy Screening Instrument questionnaire score or vibration detection thresholds. Higher yearly s-NfL increase was associated with higher DPN risk (odds ratio 1.36 [95% CI 1.08; 1.71] per 1 ng/L/year). CONCLUSIONS: Our findings suggest that preceding s-NfL trajectories differ slightly between those with and without DPN and imply a possible biomarker value of s-NfL trajectories in DPN.

Serum neurofilament light chain - A potential biomarker for polyneuropathy in type 2 diabetes?

AIMS: To investigate the relationship between neurofilament light chain (NfL) and the presence and severity of diabetic polyneuropathy (DPN). METHODS: We performed cross-sectional analysis of data from 178 participants of the ADDITION-Denmark cohort of people with screen-detected type 2 diabetes and 32 healthy controls. Biobank serum samples were analyzed for NfL using single-molecule array. DPN was defined by Toronto criteria for confirmed DPN. Original and axonal nerve conduction study (NCS) sum z-scores were used as indicators of the severity of DPN and peripheral nerve damage. RESULTS: 39 (21.9%) participants had DPN. Serum NfL (s-NfL) was significantly higher in participants with DPN (18.8 ng/L [IQR 14.4; 27.9]) than in participants without DPN (15.4 ng/L [IQR 11.7; 20.1]). There were no unadjusted s-NfL differences between controls (17.6 ng/L [IQR 12.7; 19.8]) and participants with or without DPN. Higher original and axonal NCS sum z-scores were associated with 10% higher s-NfL (10.2 and 12.1% [95% CI's 4.0; 16.8 and 6.6; 17.9] per 1 SD). The AUC of s-NfL for DPN was 0.63 (95% CI 0.52; 0.73). CONCLUSIONS: S-NfL is unlikely to be a reliable biomarker for the presence of DPN. S-NfL is however associated tothe severity of the nerve damage underlying DPN.

Relative Source Power: A novel method for localizing epileptiform EEG discharges.

OBJECTIVE: To validate relative source power (RSP) imaging of extratemporal interictal epileptiform discharges (IEDs). METHODS: The accuracy of RSP was validated in a cohort of patients with extratemporal focal epilepsy and a confined epileptogenic lesion (<19 cm3) using distance to the lesion, concordance with resected area and postoperative outcome. Performance was compared with three conventional methods: voltage maps, equivalent current dipole and a distributed source model. RESULTS: Thirty-three of 41 consecutive patients (80%) had IED averages suitable for analysis. While the peak negativity in voltage maps localized above the epileptogenic lesion only in 18 cases, RSP-maps matched in 29 cases (88%, p < 0.0026). Source localization showed a median distance of 9.8 mm from the lesion. Source-regions with 20 mm radius included 98% of all source-to-lesion distances. In the 21 surgical cases, outcome showed a sensitivity of 82.35% and specificity of 50% without significant differences between the three source imaging methods. CONCLUSIONS: RSP-maps provide a rapid, intuitive and more accurate source estimation than voltage maps. At sublobar level, RSP localizes with an accuracy similar to conventional methods and results of previous studies. SIGNIFICANCE: The definition of a source region with 20 mm radius helps in guiding further exploration in extratemporal focal epilepsy.

Near-Nerve Needle Technique Versus Surface Electrode Recordings in Electrodiagnosis of Diabetic Polyneuropathy.

PURPOSE: The sural nerve can be examined by either surface electrode recording or near-nerve technique (NNT) for electrodiagnosis of polyneuropathy. This study compared the sensitivity of these two methods and correlated nerve conduction studies to "The Utah Early Neuropathy Scale" (UENS) and HbA1c levels. METHODS: In 29 diabetic patients, 55 sural nerves were examined with both antidromic surface recording and orthodromic NNT. The sensitivities were compared with chi-square statistics. Nerve conduction study parameters were correlated with UENS and HbA1c levels using regression analysis. RESULTS: More often absent responses were seen with surface electrodes than NNT (15 vs. 0) (P < 0.001). A higher number of normal nerves were found with surface recording (27) than with NNT (15) (P < 0.001). The decrease in sensory nerve action potential amplitude correlated significantly to total UENS scores and UENS subscores for both surface recordings and NNT. However, decrease in conduction velocity and sensory nerve action potential duration correlated to UENS scores and subscores more often for NNT than for surface recording. Similarly, there was significant correlation between HbA1c levels and sensory nerve action potential amplitude and duration for NNT, but not for surface electrode recordings. CONCLUSIONS: Near-nerve technique is recommended for better and more sensitive electrodiagnosis of polyneuropathy, and clinical scoring with UENS is of importance for diabetic neuropathy diagnosis.