Many patients who deal with chronic or recurrent sciatic pain are often prescribed a tens unit, transcutaneous electronic nerve stimulator, or go to a clinic for an interferential treatment. Both of these devices require the placement of what are called "reusable electrode patches" on the body to modify or eliminate the pain impulse. In the clinical setting the placement is not as important to the patient since a physical therapist, Doctor, Chiropractor or a clinical person places the electrodes in the most appropriate location depending upon the input from the patient.
Today with the advent of self treatments with interferential, as well as tens, it is becoming imperative that any patient suffering from sciatica that is using a tens or portable interferential unit be properly educated on what the goals are and how to achieve the treatment objectives. No portable pain machine is any good whatsoever unless the patient has been shown how to use the device properly and were properly educated on the reasons for the electrode placements.
Generally speaking sciatica is a secondary pain meaning the sciatic pain was caused by posturing, guarding due to the primary pain diagnosis which would normally be some form of chronic low back pain. The sciatic pain evolved over time due to the primary pain diagnosis.
With interferential therapy the treatment of a secondary pain issue is almost always effective. Once the secondary pain issues are resolved, then the patient can self treat and prevent the recurrences and move on to address the primary pain issue. A tens unit can help manage the pain but is not as effective and has minimum carryover pain relief.
Electrode placements for tens or interferential essentially involve the passage of electricity from one electrode to the other with the area of pain between the two electrodes. In some situations, especially interferential, it's common to use 4 electrodes to inundate the pain area with multiple electrical pain interceptors to achieve relief.
Here is a video on electrode placement for sciatic pain, as well as foot pain treatments, knee pain relief, and ankle pain relief when using interferential therapy.