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Background: Virtual reality (VR) and serious games (SGs) are widespread in rehabilitation for many orthopedic and neurological diseases. However, few studies have addressed the effects of rehabilitation with VR-based SGs on clinical, gait, and postural outcomes in individuals with total knee replacement (TKR). Objective: The primary objective was the efficacy of balance training using non-immersive VR-based SGs compared to conventional therapy in TKR patients on the Time Up and Go test. Secondary objectives included the efficacy on clinical, gait, and postural outcomes. Methods: We randomly allocated 56 individuals with unilateral TKR to the experimental group (EG) or control group (CG) for 15 sessions (45 min; 5 times per week) of non-immersive VR-based SGs or conventional balance training, respectively. The primary outcome was functional mobility measured by the Timed Up and Go test; secondary outcomes were walking speed, pain intensity, lower-limb muscular strength, independence in activities of daily living as well as gait and postural parameters. Results: We found significant within-group differences in all clinical outcomes and in a subset of gait (p<0.0001) and postural (p ≤ 0.05) parameters. Analysis of the stance time of the affected limb revealed significant between-group differences (p = 0.022): post-hoc analysis revealed within-group differences in the EG (p = 0.002) but not CG (p = 0.834). We found no significant between-group differences in other outcomes. Conclusions: Balance training with non-immersive VR-based SGs can improve clinical, gait, and postural outcomes in TKR patients. It was not superior to the CG findings but could be considered an alternative to the conventional approach and can be added to a regular rehabilitation program in TKR patients. The EG had a more physiological duration of the gait stance phase at the end of the treatment than the CG. ClinicalTrials.gov: NCT03454256

Although the inhibitory action that tactile stimuli can have on pain is well documented, the precise timing of the interaction between the painful and non-painful stimuli in the central nervous system is unclear. The aim of this study was to investigate this issue by measuring the timing of the amplitude modulation of laser evoked potentials (LEPs) due to conditioning non-painful stimuli. LEPs were recorded from 31 scalp electrodes in 10 healthy subjects after painful stimulation of the right arm (C6-C7 dermatomes). Non-painful electrical stimuli were applied by ring electrodes on the second and third finger of the right hand. Electrical stimuli were delivered at +50, +150, +200 and +250 ms interstimulus intervals (ISIs) after the laser pulses. LEPs obtained without any conditioning stimulation were used as a baseline. As compared to the baseline, non-painful electrical stimulation reduced the amplitude of the vertex N2/P2 LEP component and the laser pain rating when electrical stimuli followed the laser pulses only at +150 and +200 ms ISIs. As at these ISIs the collision between the non-painful and painful input is likely to take place at the cortical level, we can conclude that the late processing of painful (thermal) stimuli is partially inhibited by the processing of non-painful (cutaneous) stimuli within the cerebral cortex. Moreover, our results do not provide evidence that non-painful inputs can inhibit pain at a lower level, including the spinal cord.

Charcot-Marie-Tooth (CMT) disease is the most common inherited neuropathy. The CMT1A type can be considered the typical phenotype of this disease. Although pain is not considered a relevant symptom in CMT patients by physicians and no study assessed it comprehensively, this symptom is frequently complained by patients. The objective of the present study was to investigate the nociceptive system in a sample of CMT1A patients suffering from pain by laser-evoked potentials (LEPs). Moreover, we also used a pain specific questionnaire in order to obtain patient-oriented data about their painful symptoms, the Neuropathic Pain Diagnostic Questionnaire (DN4). We evaluated 16 patients affected by CMT1A and 14 controls. All subjects underwent a standard LEP recording session (foot, hand, and face stimulation) and filled in the DN4. While the N2/P2 amplitude to foot stimulation was lower in CMT patients than in controls (p=0.003), no difference in LEP amplitude to both hand and face stimulation was found between patients and healthy subjects (p>0.05). This result is probably due to a length-dependent Adelta-fiber loss which involves mostly the longer fibers coming from the lower limb. In our patients, there was a significant association between a reduced N2/P2 amplitude to foot stimulation and a high DN4 score (p=0.03), meaning that patients with highly probable neuropathic pain had also low N2/P2 amplitude values to painful foot stimulation. This suggests that in our CMT1A patients neuropathic pain is probably related to a reduction of the Adelta afferents. Copyright 2010 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

Cardiac syndrome X (CSX) is characterized by effort angina, ST-segment depression during stress tests and normal coronary arteries. Abnormal nociception was suggested in these patients by studies showing a reduced cardiac pain threshold; furthermore, we recently found a lack of habituation to pain stimuli using recording of laser evoked potentials (LEPs). In CSX patients with severe angina, spinal cord stimulation (SCS) was shown to improve symptoms. In this study we investigated whether, in these patients, SCS has any effects on the excitability of the nociceptive system, assessed by LEPs recording. We studied 16 CSX patients (61.6+/-7 years; 4 men) who underwent SCS for refractory angina. Cortical LEPs were recorded during stimulation of the chest and right-hand during active SCS (SCS-ON) and in the absence of SCS (SCS-OFF), using a randomized cross-over design. Three sequences of painful stimuli were applied at each site during each test. During the first sequence of chest stimuli, the N2/P2 LEP amplitude was higher during the SCS-ON, compared to the SCS-OFF phase (18.2+/-7.8 vs. 11.5+/-4.4 microV, P=0.006). The N2/P2 amplitude did not change significantly across the three stimulation sequences during the SCS-OFF phase (P=0.22), whereas it decreased progressively during the second and third sequence (to 87.1+/-29.5% and 76.4+/-24.1%, respectively) compared with the first sequence, during the SCS-ON phase (P=0.014). Similar results were observed during right-hand stimulation. Our study shows that in CSX patients SCS is able to restore habituation to peripheral pain stimuli. This effect might contribute to restore the ability of CSX patients to better tolerate cardiac pain.

To investigate the possible contribution of the primary somatosensory area (SI) to pain sensation.