Efficacy of Home-delivered Transcranial Direct Electrical Stimulation or Chronic Pain

Inclusion Criteria: Chronic pain for at least 6 months Pain intensity ≥ 4/10 on 0-10 NRS Pain present every day or nearly every day Neuropathic pain (DN4 score ≥ 4/10) or nociplastic pain (Kosek et al Pain 2021) Patients previously treated with rTMS of the motor cortex in routine in our pain center but with only transient efficacy (ie, efficacy for less than one month, defined as pain intensity improved by at least 30 %) Affilitated to social security Exclusion Criteria: Contraindications to tDCS as stated in the manufacturer brochure (ie, implantable device , severe cognitive disorders, epilepsia, skin problems where will placed the electrodes, arterial or venous thrombosis, thrombophlebitis, metallic intracranial implant, cranioth-omy, incracranial aneuvrysm, cerebral tumor, severel sleep disorders such as narcolepsia) Conciomitant treatment which might increase the risk of epilepsia such as high doses opioids (≥ 140 mg morphine equivalent) or high. doses tricyclic antidepressants (≥ 150 mg per day) Pregnancy or lactation Age below 18 or \> 80 years Pending litigation related to pain Pain more severe than neuropathic or nociplastic pain requiring treatment Severe disease such as cancer Severe psychiatric condition (psychosis) Impossible to be followed for up to 3 months Participation in a recent protocol (less than 3 months) Psychoactive drug abuse