Although electricity has been used for centuries to treat pain & many other ailments, stimulation of dorsal column of spinal cord was first used by Shealy & his colleagues in 1967. Their study was based on the �Gate control theory of pain� by Melzack and Walls introduced in 1965. Initially they termed the procedure as dorsal column stimulation as they believed that stimulation is effective only at dorsal horn of spinal cord. As it is now known that electrical stimulation is effective in suppression of nociception when applied in almost anywhere of the spinal cord, so the better and more acceptable term is spinal �cord stimulation� by spinal cord stimulator.
Mechanism of action of spinal cord stimulation:
Spinal cord stimulator act in by several ways.
This therapy aims at pain relief in patients who are refractory to all other treatment modalities. They are very tough group to get good results.
Disadvantages & complications:
There are many advantages of using this therapy like:
There are certain disadvantages with respect to spinal cord stimulation.
- Cost is high compared to other treatment options although is cost-effective.
- Requires highly-efficient team.
- There may be some complications in rare occasions like lead migration, lead fractures, infection etc.
- Evaluation of pain
- Psychiatric evaluation
- Patient education: about pre- and post-procedure plan and long-term management, cost effectiveness
- Planning of procedure.
The procedure involves percutaneous insertion of lead, typically a �longitudinal� lead with a linear array of electrodes through an epidural needle into the epidural space and oriented parallel to spinal column. First step is the introduction of a trial electrode for temporary purpose. The lead is connected to an external battery source that transmits radiofrequency signals to the lead. The external transmitters help in adjusting the amplitude, pulse width and rate of stimulation. The low voltage electrical stimulation is applied to the spinal cord to create a current field that activates neurons in the dorsal column. This stimulation is done by the external power supply connected to lead by either a conducting wire or extension. The stimulation produces paraesthesia that interferes with or blocks pain signals to brain. The vertebral level at which it is placed depends upon the location of pain. If patient gets 50% or more pain relief after trial stimulation, then patient is considered for permanent implant. Replacing the temporary lead with permanent lead usually does this. Implanted pulse generator provides the power supply.
FAQ of Spinal Cord Stimulation