Following a nerve infection with the herpes virus (we are not talking about cold sores), severe pain in the trunk or limbs that does not respond to medication may linger. In such a case, a test electrode can be implanted under the skin or in the back and low-intensity electrical stimulation can be injected. This way, 50-60% of the pain will be eliminated. If the test is successful, the electrode can be permanently implanted in the patient’s body, by means of a simple surgery.