Depolarising Electrical Skin Stimulation in Neuropathic and Postoperative Pain

Selective Activation of Unmyelinated Skin Nerve Fibres Using Slow Depolarising Transcutaneous Electrical Stimulation in Patients With Neuropathic Pain or Chronic Postoperative Pain

The aim of the study is to evaluate voltage gated sodium channel (NaV1.7) dependent pain phenomena in neuropathic pain and chronic postoperative pain.

Sinus-like electrical stimulation may depolarize unmyelinated skin nociceptors involving NaV1.7 channels. In this case electrical stimulation may provoke pain already with very low currency intensity which normally not provoke pain in healthy subjects. This may be predictive for pain relief due to the sodium channel blocker lidocaine 5% patch.

The study will characterize pain states in peripheral neuropathic pain as well as within the painful scar in chronic postoperative pain with regard to the involvement of NaV1.7 channels.

In addition, the pain site in chronic postoperative pain (scar) will be characterized by laser-evoked potentials (LEP) and quantitative sensory testing (QST).

Pain related questionnaires will be obtained.

Inclusion Criteria:

• Group (1) patients with neuropathic pain
• Group (2) patients with chronic postoperative pain

Exclusion Criteria (both Groups):

• severe psychiatric disorder requiring hospitalisation in the past
• any neurological disease other than the pain diagnosis