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Introduction/Aims: Nerve conduction studies (NCSs) are widely used to support the clinical diagnosis of neuromuscular disorders. The aims of this study were to obtain reference values for peroneal, tibial, and sural NCSs and to examine the associations with demographic and anthropometric factors. Methods: In 5099 participants (aged 40–79 years) without type 2 diabetes of The Maastricht Study, NCSs of peroneal, tibial, and sural nerves were performed. Values for compound muscle action potential (CMAP) and sensory nerve action potential amplitude, nerve conduction velocity (NCV), and distal latency were acquired. The association of age, sex, body mass index (BMI), and height with NCS values was determined using uni‐ and multivariate linear regression analyses. Results: Detailed reference values are reported per decade for men and women. Significantly lower NCVs and longer distal latencies were observed in all nerves in older and taller individuals as well as in men. In these groups, amplitudes of the tibial and sural nerves were significantly lower, whereas a lower peroneal nerve CMAP was only significantly associated with age. BMI showed a multidirectional association. After correction for anthropometric factors in the multivariate analysis, the association between sex and NCS values was less straightforward. Discussion: These values from a population‐based dataset could be used as a reference for generating normative values. Our findings show the association of NCS values with anthropometric factors. In clinical practice, these factors can be considered when interpreting NCS values. [ABSTRACT FROM AUTHOR]

Cerebrovascular dysfunction plays a role not only in vascular causes of cognitive impairment but also in Alzheimer's disease (AD). We hypothesized that cerebral autoregulation is impaired in patients with AD compared to subjects with mild cognitive impairment (MCI) and controls. Dynamic cerebral autoregulation (dCA) was investigated in 17 AD patients, 19 MCI subjects, and 20 controls (C). Groups were matched for age, gender, and level of education. Electrocardiogram and non-invasive finger arterial blood pressure were measured and transcranial doppler ultrasonography was used to measure cerebral blood flow velocity in right and left middle cerebral artery (MCA). Cerebrovascular resistance index (CVRi) was also computed. dCA in supine position was quantified based on spontaneous blood pressure variations by computation of the linear transfer function between arterial blood pressure and MCA cerebral blood flow velocity. dCA gain and phase were evaluated for different frequency bands. Results were also evaluated using a 3-parameter windkessel model (WKM). CVRi was significantly higher in AD (2.9 ± 0.2) compared to both MCI (2.3 ± 0.1, p = 0.02) and C (2.1 ± 0.1 mmHgs/cm, p = 0.002). Five MCI patients who converted to AD during the course of the study also had higher CVRi compared to non-converters (2.8 ± 0.6 versus 2.1 ± 0.5 mmHgs/cm, p < 0.05). No significant differences in dCA gain and phase were found. In terms of the WKM approach, in the order C→MCI→AD groups showed about equal arterial resistance and peripheral compliance, but increased peripheral vasculature resistance (26 ± 2 versus 36 ± 3 mmHgs/ml in C resp. AD, p = 0.004). In conclusion, AD patients compared to MCI patients and controls have increased CVRi, whereas dCA parameters do not seem to differentiate AD patients. For MCI patients, CVRi might have predictive value in developing AD. [ABSTRACT FROM AUTHOR]

Objective: Low baroreflex sensitivity (BRS) has been hypothesized to underlie high blood pressure (BP) and greater BP variability on the longer term, but evidence is scarce. In addition, these associations may differ by sex and (pre)diabetes. Therefore, we investigated whether cardiovagal BRS is associated with short- to mid-term mean BP and BP variability, and differs according to sex and (pre)diabetes., Methods: Cross-sectional data from the population-based Maastricht study (age 60 ± 8 years, 52% men), where office ( n  = 2846), 24-h ( n  = 2404) and 7-day BP measurements ( n  = 2006) were performed. Spontaneous BRS was assessed by cross-correlating systolic BP and instantaneous heart rate. We used linear regression with adjustments for age, sex, BP or BP variability, and cardiovascular risk factors., Results: With regard to BP, 1-SD (standard deviation) lower BRS (-5.75 ms/mmHg) was associated with higher office, 24-h and 7-day systolic BP (2.22 mmHg [95% confidence interval [CI]: 1.59; 2.80], 0.95 mmHg [0.54; 1.36], and 1.48 mmHg [0.99; 1.97], respectively) and diastolic BP (1.31 mmHg [0.97; 1.66], 0.57 mmHg [0.30; 0.84], and 0.86 mmHg [0.54; 1.17], respectively). Per 1-SD lower BRS, these associations were stronger in women (0.5-1.5 mmHg higher compared to men), and weaker in those with type 2 diabetes (1-1.5 mmHg lower compared to normal glucose metabolism). With regard to BP variability, BRS was not consistently associated with lower BP variability., Conclusions: Lower cardiovagal BRS is associated with higher mean BP from the short- to mid-term range, and not consistently with BP variability. The associations with mean BP are stronger in women and weaker in those with type 2 diabetes., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Introduction: We examined optimization of a temperature threshold testing (TTT) protocol for patients with suspected small-fiber neuropathy (SFN) to lessen the burden for both patients and technicians, without sacrificing accuracy., Methods: Data from 81 patients with SFN (skin biopsy and TTT abnormal) and 81 without SFN (skin biopsy and TTT normal) were used. Warm, cold, and heat pain sensation thresholds were determined bilaterally on the thenar eminence and foot dorsum by methods of limits and levels. Diagnostic accuracy was determined for various sensory modality combinations through comparative corresponding area under the receiver-operator characteristic curves., Results: Assessment of warm and cold thresholds in all extremities by the method of levels showed the best discriminatory ability (area under the curve 0.95, sensitivity 84.2%, specificity 93.8%)., Conclusions: These assessments are suggested for TTT examination in possible SFN patients. By applying this combination, the time needed for TTT can be reduced, maintaining diagnostic accuracy., (© 2014 Wiley Periodicals, Inc.)

Introduction: Contact heat evoked potentials (CHEPs) may be an objective, non-invasive diagnostic tool in small-fiber neuropathy (SFN). This study establishes normal CHEP values and examines their applicability in SFN patients., Methods: Standardized CHEPs were administered at the wrist and ankle. The N2 and P2 latencies and N2 -P2 peak-peak amplitude were recorded by electroencephalography. We examined healthy subjects (n = 97), stratified by age and gender, and SFN patients with abnormal intraepidermal nerve fiber density (n = 42). CHEP reproducibility and interobserver values were also investigated., Results: CHEP normative values were determined. There was a 9-16% increase in latency per centimeter of height with increasing age. Amplitudes were higher in women than men, and decreased (17-71%) with aging. Test-retest reproducibility and interobserver values were >0.61 and >0.96, respectively. CHEPs were abnormal in 73.8% of the patients., Conclusion: In this study we have established normal values, reliability, and clinical applicability of CHEPs in SFN., (© 2014 Wiley Periodicals, Inc.)

Objectives: To analyze sensory characteristics and small nerve fiber function in patients suffering from painful diabetic polyneuropathy (PDP) and compare outcomes in responders and nonresponders to SCS treatment., Methods: Fifteen patients with intractable PDP in the legs were recruited. If trial stimulation resulted in clinically relevant pain relief, a pulse generator was implanted and pain scores were measured after 12 months. Sensory characteristics (modified Inflammatory Neuropathy Cause and Treatment [md-INCAT] sum score) and small nerve fiber function (contact heat evoked potentials, CHEPs) were measured before implantation (D1), and CHEP measurement was repeated after two weeks of trial stimulation (D2). Outcomes in responders (N = 10) and nonresponders (N = 5) to SCS treatment were compared. Data were analyzed using nonparametric statistics., Results: At one year, clinically relevant pain relief was achieved in 10 out of 15 patients. The md-INCAT score did not differ between SCS responders and nonresponders (8.0 vs. 5.0; p = 0.59). No differences were found in CHEP outcomes at D1 vs. D2, except for dorsal forearm P2 latency, and the correlation between D1 and D2 CHEP outcomes was high. Volar N2 forearm latency (0.492 vs. 0.434; p < 0.01), dorsal forearm N2 latency (0.518 vs. 0.453; p = 0.04), and dorsal forearm P2 latency (0.660 vs. 0.589; p = 0.04) were increased in SCS responders as compared with SCS nonresponders., Conclusions: From this small-scale clinical pilot study we conclude that forearm CHEP latencies are increased in PDP patients who respond to SCS therapy as compared with SCS nonresponders. Before the CHEP latency can be used as a predictor of SCS outcome in PDP patients, a large-scale study is needed., (© 2014 Maastricht University Medical Center.)

Visually evoked flow responses recorded using transcranial Doppler ultrasonography are often quantified using a dynamic model of neurovascular coupling. The evoked flow response is seen as the model's response to a visual step input stimulus. However, the continuously active process of dynamic cerebral autoregulation (dCA) compensating cerebral blood flow for blood pressure fluctuations may induce changes of cerebral blood flow velocity (CBFV) as well. The effect of blood pressure variability on the flow response is evaluated by separately modeling the dCA-induced effects of beat-to-beat measured blood pressure related CBFV changes. Parameters of 71 subjects are estimated using an existing, well-known second order dynamic neurovascular coupling model proposed by Rosengarten et al., and a new model extending the existing model with a CBFV contributing component as the output of a dCA model driven by blood pressure as input. Both models were evaluated for mean and systolic CBFV responses. The model-to-data fit errors of mean and systolic blood pressure for the new model were significantly lower compared to the existing model: mean: 0.8%±0.6 vs. 2.4%±2.8, p<0.001; systolic: 1.5%±1.2 vs. 2.2%±2.6, p<0.001. The confidence bounds of all estimated neurovascular coupling model parameters were significantly (p<0.005) narrowed for the new model. In conclusion, blood pressure correction of visual evoked flow responses by including cerebral autoregulation in model fitting of averaged responses results in significantly lower fit errors and by that in more reliable model parameter estimation. Blood pressure correction is more effective when mean instead of systolic CBFV responses are used. Measurement and quantification of neurovascular coupling should include beat-to-beat blood pressure measurement., (Copyright © 2014 IPEM. Published by Elsevier Ltd. All rights reserved.)

The baroreflex (BR) reflects autonomic blood pressure control. Alzheimer's disease (AD) affects the autonomic system. Detailed properties of BR in AD are unknown. We hypothesized that BR is reduced in AD, and is influenced by autonomic effects of cholinesterase inhibitors (ChEI). BR was determined in 18 AD patients, 11 patients with mild cognitive impairment (MCI) and 19 healthy control subjects. In AD, BR was measured again after ChEI treatment. Receiver operating characteristic analysis was used to define a BR cutoff value, which was then tested in an independent validation sample of 16 AD, 18 MCI, and 18 control subjects. BR was lower in AD compared with MCI (p < 0.05) and in MCI compared with healthy control subjects (p < 0.01). Receiver operating characteristic analysis between AD and healthy control subjects yielded a sensitivity of 89% and a specificity of 94%. ChEI treatment increased BR with 66% (p < 0.01). BR was reduced in AD and increased after treatment with ChEI. BR might be a good biomarker to further explore the link between cardiovascular disease and AD., (Copyright © 2013 Elsevier Inc. All rights reserved.)

We describe a patient with severe small fiber neuropathy (SFN) accompanied by autonomic involvement, who was experimentally treated with infliximab, an anti-tumour necrosis factor-alpha (TNF-alpha) therapy. Six months after this treatment was started his symptoms completely resolved. Until now they did not return. Repeated temperature threshold testing (TTT) as well as cardiovascular autonomic function test clearly improved after one year therapy. This case reveals two important issues. First, it shows that SFN seems not an irreversible disorder, even in severe cases. Second, TNF-alpha may be a crucial cytokine in the pathogenesis of SFN in sarcoidosis and eventually also in other immune mediated inflammatory diseases.

Background and Aim: Recently we found that small fiber neuropathy (SFN) occurs frequently in sarcoidosis. Autonomic dysfunction may be a feature of SFN. Since cardiac autonomic dysfunction has been identified as a strong predictor of morbidity and mortality, recognition of cardiac autonomic involvement is of clinical relevance. It was hypothesised that SFN might be related to cardiac sympathetic denervation in sarcoidosis., Methods: In the present study 45 consecutive sarcoidosis patients (13 without SFN assessed by thermal threshold testing (TTT), 32 with SFN (abnormal TTT) were enrolled. To rule out bias due to myocardial ischemia, cases with abnormal Thallium (201Tl) perfusion scintigraphy were excluded (n = 2). Cardiovascular autonomic function testing (Ewing tests) and 123I-MIBG (metaiodobenzylguanidine) scintigraphy were used to assess cardiac autonomic function. Further cardiac diagnostic work-up included ECG, Holter recording and echo Doppler cardiography., Results: Mild to moderate heterogeneity of 123I-MIBG uptake regional in the myocardium was demonstrated in a substantial number of the studied sarcoidosis population, especially in those with SFN (abnormal TTT). Mean inferior-anterior ratios were 0.85+/-0.17 (SFN) and 1.0+/-0.17 (no SFN; p = 0.003), respectively. Four out of the 14 cases with abnormal MIBG scintigraphy and SFN showed an abnormal Ewing test., Conclusion: Cardiac sympathetic dysfunction assessed by use of 123I-MIBG myocardial scanning appeared to be heterogeneous in sarcoidosis patients and dependent on the presence or absence of SFN. MIBG scintigraphy may be of additional value in the management and follow-up of sarcoidosis patients. Future study is warranted to explore possible prognostic and therapeutic implications of these findings in sarcoidosis.