In Canada, many veterans suffer from chronic pain, with a prevalence twice that of the general population. Chronic pain is often linked to post-traumatic stress disorder (PTSD), and both conditions impact the functioning and quality of life of veterans. Recent studies suggest that the autonomic nervous system (ANS) plays an important role in the pathophysiology of chronic pain and PTSD, making it a therapeutic target of choice.
Virtual reality (VR) is an approach already used with this population, and its effectiveness in relieving pain and PTSD is well documented in veterans, mainly through modulation of ANS activity. Two VR approaches are commonly used: prolonged exposure VR (desensitization) and calming VR (aimed at normalizing the stress response and ANS activity). Calming VR is better tolerated than prolonged exposure VR and remains better suited to rebalancing ANS activity and relieving symptoms. It helps calm the ANS and relieve pain (acute and chronic) when combined with traditional rehabilitation, but its effects on pain intensity remain modest and limited in time.
To enhance the benefits of VR, the investigators suggest combining VR with a non-pharmacological approach, as recommended by experts. This approach is known as non-invasive cranial nerve neuromodulation (CN-NINM). CN-NINM is an innovative approach that stimulates the cranial nerves via electrodes placed directly on the tongue; the impulses reach and modulate the activity of the ANS structures located in the brainstem. These structures are linked to autonomic functions and pain modulation. This combination could reinforce and prolong the positive effects of VR on pain in veterans.
Primary objective: To document the feasibility of an intervention combining virtual reality (VR) with real and sham non-invasive cranial nerve neuromodulation (CN-NINM) in veterans with post-traumatic stress disorder and chronic pain.
Secondary objectives : 1) to explore and compare the effect of the two interventions (VR + real CN-NINM vs. VR + sham CN-NINM) on the following clinical measures: i) quality of life, ii) pain (e.g., intensity, impact on physical function), and iii) PTSD-related symptoms, 2) to explore and compare the effect of these two interventions on autonomic nervous system (ANS) activity, and 3) to determine whether there are associations between changes in quality of life and clinical changes on the one hand, and physiological changes (autonomic nervous system activity) on the other.
Methods: To do this, the investigators propose a feasibility study with two groups (experimental group vs. control group) with 30 participants. Participants will take part in an assessment of their pain condition (diagnosed or undiagnosed pain condition, type, location, intensity, and unpleasant aspects of pain) and their PTSD-related symptoms. The participants will also complete clinical questionnaires assessing their pain, PTSD-related symptoms, and their impact on physical function and quality of life. The investigators will also take various autonomic measurements (blood pressure, heart rate variability \[HRV\], electrodermal response) to characterize autonomic nervous system activity. Sociodemographic, pain and PTSD-related variables will be collected to confirm participant eligibility.
Participants will come to the laboratory eight times to receive the interventions (VR + real CN-NINM or VR + sham CN-NINM) and will complete online questionnaires at four measurement points (T0, T1, T2, and T3). Participants will be seated and wearing a virtual reality headset equipped with an audio device that plays sounds. The VR headset will broadcast calming images designed by our team specifically for veterans for 20 minutes. CN-NINM will be applied using a portable stimulator directly to participants' tongues for 20 minutes, at the same time as the VR. For the control group, participants will apply CN-NINM to their tongues without any perceptible stimulus.
