Non-suicidal self-injury (NSSI) are acts defined by the DSM-5 (Diagnostic and Statistical Manual of Mental Disorders 5) as intentional and deliberate, occurring outside a psychotic state and directly causing moderate injury.

Their international prevalence is between 13 and 17% in adolescents and young adults, and has recently increased with the COVID-19 health crisis, with the prevalence of NSSI rising to 40% in adolescents. Access to psychiatrists is declining. Drug solutions, meanwhile, lack scientific proof in this indication.

The autonomic nervous system and the hypothalamo-hypophyseal axis are involved in the human response to experimentally-induced pain, as well as in stress regulation, notably via control of cortisol secretion.

Abnormally low levels of the latter hormone have been detected in persons with NSSI disorder.

Transcutaneous neurostimulation of the atrial vagus nerve (taVNS) has been studied for some ten years. The afferent branches of the vagus nerve stimulate the hypothalamic-pituitary axis, leading to the production of cortisol by the adrenals.

The hypothesis of this research is that stimulation of the vagus nerve by taVNS would improve the functioning of the hypothalamic-pituitary axis in patients with NSSI, and thus reduce the frequency of acting out.

Although taVNS is an easy-to-access technique that patients can implement at home, the question of adherence to this treatment in adolescents has not yet been evaluated. The aim of this pilot study is to assess whether adolescents with NSSI will adhere to taVNS treatment.

Inclusion Criteria:

• Adolescents aged between 13 and 17 years old
• Patients with NSSI disorder as defined by DSM-5
• Patient affiliated to a social security scheme
• Patient who parents or guardians have signed a free and informed consent form
• Patient able to understand neurostimulation instructions

Exclusion Criteria:

• Contraindication to taVNS:
• Malformation, skin pathology of the external ear. (piercings in the area concerned must be removed during the neurostimulation session).
• Children with sleep apnea syndrome treated with NIV (non-invasive ventilation)
• Presence of epileptic seizures
• Proven cardiac pathology on the advice of the attending cardiologist
• History of venous or arterial thrombosis
• Adolescent with pacemaker or defibrillator
• Adolescent with an active implantable device
• Pregnancy (based on anamnestic criteria, checked by blood test if necessary)
• Patients with psychotic episodes, confusional states or severe neurodevelopmental disorders
• Patients with an allergic skin reaction to silicone (component of the ear electrode)
• Patients with a cochlear implant on the stimulation side
• Pregnant or breast-feeding women
• Minor under guardianship
• Minor under judicial measure or sanction