Percutaneous Auricular Vagus Nerve Stimulation With Conventional Rehabilitation Training in Chronic Back Pain Patients

The therapeutic action of aVNS in pain treatment is based on the masking of pain by the electrical stimulation pulses, the activation of inhibiting pain control systems, and the release of neurotransmitters, such as endorphins. Pairing VNS stimulation with exercise and physiotherapy has yielded beneficial results in stroke patients as well as in smaller studies with back pain patients, already in short periods of time (2-4 weeks). The current study is intended to evaluate the performance of percutaneous auricular Vagus Nerve Stimulation (pVNS) in combination with Standard-of-Care (SoC) in a 3-week in-patient rehabilitation setting, in patients with chronic musculoskeletal/myofascial back pain. This will be a prospective, open, randomized, controlled pilot study to evaluate pVNS using the VIVO® wearable medical device for personalized pain treatment, in terms of feasibility, efficacy, and safety in combination with rehabilitation training. Patients will be randomized into one of the following treatment groups: * Group A: VIVO® (pVNS) + SoC (treatment group) * Group B: SoC (control/comparator group) Patients will remain on treatment for 3 weeks. This is comparable to other studies performed earlier, which showed safe and effective use of pVNS in chronic pain patients. The additional follow-up period of 3 weeks (optional 3 months and 6 months) allows to evaluate sustainable effects of treatment and late time effects, as previously shown in other studies. Patients in the treatment group (VIVO® + SoC) will receive personalized aVNS therapy in combination with SoC. Personalization of VIVO® treatment is performed based on the individual perception level of the stimulation at the ear with regards to the stimulation amplitude (in Group A). Amplitude is adjusted (range 0-5 V) to reach a distinct but comfortable tingling sensation to reach activation of Aβ-fibers of the auricular vagus nerve but not Aδ-fibers producing a sensation of pain. Not only the Investigator is able to adjust the amplitude at the trial visit (via VIVO® Pen) but also the patient is able to adjust the amplitude according to his/her perception. Patients will be randomized in this pilot study to receive either aVNS with the VIVO® system in addition to SoC vs. SoC alone as comparator group. Estimates of performance endpoints will thus be contrasted between aVNS and an established treatment option in this indication and controlled for regression to the mean and other forms of sampling bias. All concomitant medication and therapies will be thoroughly documented and taken into account in the final analysis.