Electrical stimulation therapy for pain reduction was performed already 2000 years ago. In recent years many studies had proved the effectiveness of electrical stimulation in pain management, tissue healing and muscle strengthening. Today there are devices with many types of currents. Each current comes with different statements for its effectiveness and its penetration depth yet there is no consensus on the most effective current in the dimension of penetration depth.

The study shall be recruited patients who underwent implantation of electrodes in the spine (Spinal Cord Stimulation- SCS). The electrode will serve as a voltage reader deep in the tissue. The voltage is generated from electrodes applied on the skin and delivers therapeutic currents to the patients back. The study will be tested 4 different types of currents and number of electrode placement.

Inclusion Criteria:

• Normal cognitive status.
• language comprehension (understanding and speaking)a way that allows voluntary cooperation in research and compliance with the testing.

Exclusion Criteria:

• Pregnant women.
• neurological pathologies (such as -head injury) or other systemic diseases that affect the sensation (such as diabetes).
• Each participant which at any stage in research expresses his wish to resign.

Participants who undergo electrodes implantation in lumbar spine due to chronic pain. Thease patients arrives 7 days after implantation to the clinic for a procedure of removing the electrodes.