Treatment of Erosive Digital Osteoarthritis by Transcutaneous Auricular Nerve Stimulation

Transcutaneous Auricular Vagus Nerve Stimulation in Erosive Hand Osteoarthritis

Erosive hand osteoarthritis (EHOA) is a subtype of had osteoarthritis characterized by inflammation and pain, with subsequent burden. Few symptomatic treatments are available in EHOA, while this population with EHOA has frequently comorbidities.

Stimulation of the vagus nerve (VN), belonging to parasympathetic system, dampens pro-inflammatory cytokines production by splenic macrophages, through to the binding of acetylcholine neurotransmitter to α7nicotinic receptor on macrophages: this is the cholinergic anti-inflammatory pathway (CAP). Beyond its anti-inflammatory effects, VNS is analgesic in chronic pain disorders (headache, fibromyalgia). Beside implantable devices, VNS may be performed using transcutaneous stimulation of the ascendant auricular branch of the VN (tVNS) at the left ear localized on the cymba conchae tVNS is well-tolerated therapy avoiding invasive neurosurgery.

The investigator do the hypothesis that auricular tVNS using a transcutaneous electrical nerve stimulation (TENS) device could be a novel, simple and well-tolerated analgesic and anti-inflammatory treatment of symptomatic EHOA.

In symptomatic and inflammatory EHOA patients, we will apply tNVNS using device from Schwa-Medico (TENSeco2 + auricular electrode + conductive gel) 25 Hz stimulation will be applied, intensity escalated up to 15 mA or below if tingling sensation.

tVNS will be performed 1 hour daily for 1 month and we will assess EHOA symptoms (pain and function) at 1 month (end of the study)

Inclusion Criteria:

• Age≥18 years

• Symptomatic HOA (1990 American College of Rheumatology criteria)

• EHOA according to hand radiographs with ≥1 erosive digital joints of proximal or distal interphalangeal joint (phases "E" or "R" of Verbruggen-Veys score)

• Visual Analogic Scale (VAS) for hand pain ≥ 40/100 at inclusion

  -≥1 interphalangeal joints symptomatic ≥ 3 months despite analgesics or non-steroidal anti-inflammatory drugs (NSAIDs) (or contraindicated)

• ≥1 symptomatic interphalangeal joint with clinical palpable synovitis at inclusion

• Informed written consent

Exclusion Criteria:

• Isolated thumb-base OA (ie, rhizarthrosis)
• Hand osteoarthritis secondary to other known causes (eg gout, psoriatic arthritis)
• Psoriasis
• Current skin disease of the ear
• Ear canal not adapted to apply the auricular electrode
• History of severe cardiac disease (coronary artery disease, rhythm disturbance, heart failure, valvulopathy)
• Conduction or rhythm disturbances on electrocardiogram
• Symptomatic orthostatic hypotension or vasovagal syncope history
• History of vagotomy
• Pregnancy
• Fibromyalgia
• Use of other electrically active medical devices (eg pacemaker)
• Documented sleep apnea
• Use of corticosteroid (oral, intramuscular, intra-articular or intravenous), immunosuppressive agents, hyaluronic acid injection in interphalangeal joint within the last 3 months
• Hand surgery planned during the study period
• Pregnancy or breastfeeding if applicable
• Oral NSAIDs consumption during the last 48 hours before inclusion