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Session: Neurophysiology & Sleep
Session starts: Thursday 26 January, 10:30
Presentation starts: 11:00
Room: Room 530

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Tom Berfelo (University of Twente)
Imre P. Krabbenbos (St. Antonius Hospital)
Boudewijn van den Berg (University of Twente)
Eva Kleinveld ()
Jan R. Buitenweg (University of Twente)

Abstract:
For improved observation of nociceptive dysfunction, we are developing a novel measurement technique that combines the nociceptive detection threshold (NDT) with brain evoked potentials (EP) using intra-epidermal electrical stimulation. To validate the applicability of the NDT-EP method in patients with higher body mass index (BMI) values, we explored the feasibility of the NDT-EP method in pain-free patients with morbid obesity (MO). Subsequently, we compared the NDT-EP outcomes in MO with those of healthy controls (HC) at the various stimulus types used. Seventeen pain-free MO patients (BMI: 45.9 ± 4.6) and sixteen HC (BMI: 22.0 ± 2.0) were measured at the St. Antonius hospital. Three stimulus types (i.e., single- and double-pulse stimuli with 10 and 40 ms inter-pulse interval) consisting of a total of 450 trials were applied to each subject during two measurements. Subsequently, NDT-EP outcomes related to stimulus properties were calculated using (generalized) linear mixed regression models. The NDT-EP method was completed successfully in all MO patients. NDT results demonstrated that the detection probability was significantly (p=0.014) associated with the effect of MO diagnosis. The detection probability was significantly (p=0.020) decreased by the interaction of diagnosis with the amplitude of the first pulse. Furthermore, EP results showed that the positive peak of the EP amplitude at 485 ms post-stimulus was significantly (p=0.031) decreased by the interaction of diagnosis with the amplitude of a second pulse after 10 ms. The NDT-EP method was feasible to use in pain-free MO patients. Different NDT-EP outcomes were seen in MO compared to HC, which may indicate altered nociceptive function. Therefore, we need future research into clinical features, e.g., BMI, related to nociceptive dysfunction.