External peripheral neuromodulation for the relief of chronic pain

INTERVENTION: Three 5‐minute treatment sessions of external peripheral neuromodulation at 2 Hz (or sham stimulation) at weekly intervals. Follow‐up to 7 days after the last session, i.e. 21 days. CONDITION: Chronic neuropathic pain ; Nervous System Diseases ; Disorders of autonomic nervous system PRIMARY OUTCOME: Visual Analogue Score (VAS) of pain severity one week following third (final) neuromodulation session. SECONDARY OUTCOME: 1. VAS of pain severity immediately after treatment and at 7 day intervals to end of study (i.e., days 7, 14 and 21); 2. VAS of pain severity at shorter intervals of less than a week; 3. Numerical rating scores (NRS) of:; 3.1. Sleep quality; 3.2. Functional impact; 3.3. Emotional impact ; Measured at 7 days following third (final) neuromodulation session.; 4. Numerical rating scores on Pain Self‐Efficacy Questionnaire (PSEQ) at 7 days following third (final) neuromodulation session; 5. Changes in medication usage; 6. Change in size of painful area on pain/paraesthesiae map INCLUSION CRITERIA: 1. Patient age is 18 years or older, either sex 2. Patient has chronic neuropathic (or predominantly neuropathic) intractable pain 3. Patient has an area of pain with a typical dermatomal distribution that can be expected to be covered with a single episode of local stimulation 5. In the opinion of the Investigator and the patient's consultant, all standard medical options have been tried without sufficient improvement in pain control (including opioids, nerve blocks, etc.) 6. Patient has a Visual Analogue Scale (VAS) pain score of 5 cm (or greater) on a 10 cm line