University of Twente Student Theses


Observing small fiber dysfunction using nociceptive stimulus detection and evoked potentials

Gefferie, S.R. (2020) Observing small fiber dysfunction using nociceptive stimulus detection and evoked potentials.

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Abstract:Introduction. Besides invasive and labor-intensive nerve biopsies, there is a lack of objective measures for small-diameter epidermal nerve fiber function. A novel measurement method (‘NDT-EP’), which allows evaluation of tracked responses and evoked potentials (EP) following intraepidermal electrical stimuli, constitutes a potential candidate for this purpose. Therefore, practicality and outcomes of this method were explored in a lidocaine model of small fiber neuropathy (SFN) and diabetes mellitus (DM) patients. Methods. Three groups of participants were included. The first comprised healthy, pain-free individualsthat received 2 hours of lidocaine and placebo patch treatment before measurements (‘lidocaine experiment’). The second and the third group involved DM patients with chronic painful diabetic peripheral neuropathy (PDPN) and without pain complaints, respectively. By stimulating dorsa of the hands, stimulus detection probabilities and EPs were obtained. Data from healthy participants in an earlier study, without patches, were included as control data. (Generalized) linear mixed regression was used to compare measurement outcomes between interventions (lidocaine experiment) and between study groups. Results. 19 healthy participants (average age: 38.9 ± 10.9 years, 12 females), 13 DM patients with chronic PDPN (median age: 68.0 years, two females), and 20 pain-free DM patients (median age: 58.5 years, 11 females) were included. Control data originated from 17 participants in the previous study (average age: 35.9 ± 12.3 years, 14 females). There were no differences in detection probabilities between lidocaine, placebo, and control measurements. Still, EP amplitudes were significantly smaller for lidocaine compared to placebo (P = 0.049) and no patch (P < 0.001) treatments. DM patients with chronic PDPN demonstrated detection probabilities different from patients without pain (P < 0.05), and both groups of DM patients showed different detection probabilities compared to healthy control data (P < 0.05). Outcomes for EPs were similar, with lowered amplitudes for PDPN in the DM sample and DM in general (P < 0.05). Finally, there were no differences in detection probabilities between lidocaine measurements and pain-free DM patients, nor in EP amplitudes between lidocaine measurements and both groups of DM patients. Conclusions. The results of this study suggest the general feasibility of NDT-EP measurements in DM patients and that decreased EP amplitudes in these patients resemble experimentally induced small fiber dysfunction. Contrastingly, current evidence that altered detection probabilities mirror the same condition is limited. Differences between DM patients and healthy controls may have first resulted from other group dissimilarities, such as in attentional levels. Continued investigations are advised to further examine demographic influences, experiment with alternative measurement set-ups, and explore the method in other diseases marked by SFN and chronic pain conditions.
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:02 science and culture in general, 42 biology, 44 medicine, 50 technical science in general
Programme:Technical Medicine MSc (60033)
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