Electrical Stimulation of Dorsal Column of Spinal Cord for Pain Elimination

Abstract

Dorsal Column electrical Stimulation (DCS) of spinal cord is an effective and non-harmful way for the elimination of chronic or intractable pain. According to the gate control theory proposed by Melzack and Wall, chronic pain can be controlled by means of stimulating the nerve fibers of large diameter in the dorsal column, because the inhibitory neurons in the substentia gelatinosa areactivated by these fibers resulting in the abolition of pain transmission in the afferent system.
For successful stimulation on the dorsal column, electric signals have to be brought into the living body through an adequate interface apparatus. Two types of apparatus are treated in this paper. The first one consists of a pair of coils coupled through the skin and a small dipole electrode which can be inserted on the posterior surface of spinal cord without surgical incision. Electrical signal is applied to the external coil so that the inner coil gives pulses to the dipole and stimulates the dorsal column.
The other apparatus is the multi-channel transcutaneous stimulator having 5 independent outputs, which are to drive 5 pairs of electrodes arrayed on the skin along the dorsal column. With this apparatus, pain spreading over wide area can be treated effectively at rather lower current intensities.
Effects of pain relief using these two types of DCS were clinically tested. Dipole electrodes were inserted on the dorsal column of 4 patients suffering from intractable pain due to advanced carcinoma. The complete pain relief was recognized in 2 and partial pain elimination in 2 patients.
Transcutaneous DCS was applied to 16 patients complaining of chronic pain mainly due to carcinoma. Complete pain elimination was observed in 7 patients (44%), partial elimination in 4 patients (25%), and no effect was noticed in 5 patients (31%). The pain relief continued usually less than 2 hours after cessation of electrical current. Multichannel DCS is suitable for relievingpain spreading over a broad area in patients suffering from advanced carcinoma. Since DCS is no harmful way of controlling pain, it is recommended as first choice of procedure to relieve intractable pain due to cancer.