Percutaneous Electrical Nerve Stimulation (PENS)
Pain is transmitted by nerves so it is often possible to reduce pain by blocking signals from affected nerves.
What is percutaneous electrical nerve stimulation (PENS)?
PENS therapy does not destroy the affected nerves but makes them less sensitive to pain. A low voltage electrical current is delivered through a specially designed needle/electrode to the fatty layer just below the surface of the skin close to the specific nerve, or to the nerve endings situated in the local area. This stimulation is intended to induce a pain-relieving effect by altering the state of the nerves. The electrode is activated so that the current flows through the suffering area. The current intensity is variable but it is crucial the detection of activation of the nervous structures by manifest as paresthesias.
What are main indications?
PENS therapy is used to treat chronic nerve pain including areas of hypersensitivity, headache and chronic post-surgical pain. Occasionally PENS is used as a diagnostic tool.
How is the procedure done?
The patient is escorted to the operating theatre. The procedure is carried out whilst the patient is lying on a theatre trolley, either on their back, side or front depending on the area to be treated. During the procedure, the doctor will mark the area to be treated. He will inject local anaesthetic to numb the area before inserting one or two thin probes under their skin. A grounding plate (a sticky patch) will be applied to an area of skin near to the treatment site. A very low voltage electrical current will be delivered through the probe/s for between 20 and 30 minutes. When the treatment is complete, the probes and grounding pad will be removed and a small sterile dressing placed over the probe insertion sites for 24 hours. The patient will be allowed to go home shortly after the procedure. They can eat and drink as normal.
What are the beneficial effects?
The most obvious benefit of PENS is the significant reduction in pain levels associated with peripheral neuropathic pain. But there are other "hidden" advantages to using the PENS system.
It is a relatively non-invasive procedure. Many patients who have peripheral neuropathic pain may have experienced several procedures and may be reluctant to undergo further invasive procedures or they may have underlying conditions that preclude an invasive procedure being the initial course of action. The risks associated with the procedure are relatively low, since it is administered through the skin by a physician and there is no device implanted in the patient. For individuals experiencing chronic levels of peripheral neuropathic pain, their quality of life can be adversely affected to such a degree that they can often find “normal” daily life difficult. Chronic depression can also be associated with pain that cannot be controlled, so PENS can offer patients the chance to enjoy life again!
Can the patient has further PENS therapy?
PENS can be repeated at intervals if the patient and the doctor feels this is appropriate and effective for you.
What are the side effects?
The contraindications presented by the Pens system are minimal. As with any other electrical stimulation procedure, PENS should not be used on patients who have epilepsy, heart disease, who are (or may be) pregnant and it has not been validated as being safe for use with children. Patients on anticoagulants should also not be treated using a PENS system: but for everyone else with peripheral neuropathic pain, it is an effective and safe procedure.
Advice and precautions
- The patient can go home immediately after the PENS therapy and he/she can drive;
- The patient can resume her/his normal daily activities;
- If the probe insertion site/s is sore take regular painkillers as needed;
- Keep the dressing/plaster in place for 24 hours.
It is very important to tell to physician, before the treatment if:
- The patient is allergic to any medications;
- The patient is on blood thinning medication such as Warfarin, Fondaparinux, Nicoumalone (Sinthrome®), Aspirin, Clopidogrel (Plavix®);
- The patient has an infection at the treatment site;
- The patient thinks she might be pregnant;
- The patient has a demand type cardiac pacemaker;
- The patient has epilepsy;
- The patient has had a recent vaccination;
- The patient has had a recent heart attack.
Sources: NHS Fundation UK, London Pain Clinic UK