Could a gentle zap to the ear ease stubborn back pain?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Male or female patients aged ≥ 30 and ≤ 60 years; * High impact lumbar or lumbosacral myofascial/musculoskeletal chronic (\> 6 months) low back pain that is moderate to severe (defined as average pain over the last 4 weeks ≥ 5 on the NRS at baseline); * Normal function of lumbosacral nerves based on clinical assessment; * Unresponsive/intolerance (meaning insufficient pain reduction or intolerance) to oral pharmacotherapy (World Health Organization (WHO) grade II); * ODI 21-80 at baseline; * Patient understands the therapy and procedures, agrees to its provisions, and gives written informed consent prior to any procedures Exclusion Criteria: * Organic low back pain (trauma, fracture, tumor, infection, documented severe degenerative spine, documented high-grade spinal stenosis, rheumatologic conditions); * Indication for back surgery; * Radicular pain; * New analgesics 2 weeks before baseline (paracetamol, NSAIDs, etc.); * Opioid analgesic therapy; * Underwent other physical therapy modalities, including TENS, ultrasound, infiltration, RF-treatment, 2 weeks before screening; * History of Vagus Nerve Stimulation or ear stimulation; * History of vasovagal syncope; * BMI \> 35 kg/m² (Obesity Class 2 or higher); * Hemophilia; * Documented autonomic disorders; * Advanced stage or poorly controlled diabetes mellitus type I or II * Poorly controlled high blood pressure at baseline (systolic blood pressure (SBP) \> 160 mmHg); * Major psychiatric comorbidity (HADS ≥ 10 on each subscale at baseline); * Other serious clinically relevant co-morbidity, florid malignant conditions or neurological diseases; * History of arrhythmia, bradycardia, other rhythm disorders or any other clinically significant cardiac anomalies; * Use of prescription blood thinners, e.g., oral anticoagulants (marevan, sintrom, marcoumar), noval oral anticoagulants (pradaxa, xarelto, eliquis, lixiana), anti-platelet medication (asaflow); * Infection, eczema, or psoriasis at application site (ear and neck); * Numbed and desensitized skin at the application site (ear and neck); * Serious drug-related behavioral issues (e.g., alcohol dependency, illegal substance abuse) in the last 6 months; * Pregnant, parturient or breast-feeding women; * Active implantable device (e.g. cardiac pacemaker, defibrillator, cochlear implant, neurostimulator like Spinal Cord Stimulation or Peripheral Nerve Stimulation) ; * Currently participating in another interventional clinical trial or participated over the last 3 months; * Patients who are unable to sufficiently speak and write in the Dutch language; * Mental and physical impairments that represent a source of risk for handling the device; * Patients under legal protection (curatorship, guardianship); * Patients subject to a legal protection measure; * An adult who is incapable or unable to give consent.