Spinal Cord Stimulation

What is pain?

Unfortunately pain is something everybody in the world has experienced. There are two general categories for pain that are widely accepted. The first category is known as acute pain. Acute pain is short lived and serves as a warning signal. When you fix whatever is wrong, the pain usually goes away. The second category is known as chronic pain. When pain lasts for a long time, it is called chronic pain. This type of pain is often caused by illness or injury and it is complicated because the source of the pain is often unknown. According to some doctors consider pain to be chronic when it lasts one month longer than expected, but the general medical definition is pain that has lasted for six months or longer. Chronic pain is difficult to treat because it varies so much from person to person and usually there is little known about why the pain does not go away. Because the source of pain can be difficult to identify, it is often said that doctors will treat the symptom of pain and not the source of the pain. When treating chronic pain, pain specialists often follow a series of treatment levels. This means that treatment often begins with simple and less expensive therapies such as bed rest, oral pain medications, physical therapy, and psychological therapy and continues through more expensive and more complicated therapies such as corrective surgery, therapeutic nerve blocks, and as a last resort, medical devices are used to modulate the pain signal before it reaches the brain.

What is a Spinal Cord Stimulator?

Spinal Cord Stimulation (SCS) is becoming an increasingly popular method for chronic pain relief. SCS is a medical device used to modulate the pain signal before it reaches the brain. SCS uses low voltage stimulation of the spinal nerves to block the feeling of pain. It helps to better manage pain and potentially decrease the amount of pain medication. It may be an option if you have long-term pain in a leg or arm and have not found relief through traditional methods. A small battery-powered generator implanted in the body transmits an electrical current to the spinal cord. The electrical current stimulates the nerves around the spinal cord and causes a tingling sensation to be felt instead of pain. By interrupting pain signals, the procedure has shown success in returning some people to a more active lifestyle.

About the Spinal Cord Stimulator System

Medtronic is the leader in spinal cord stimulation technology. There are other companies who manufacture the systems, but we will only be looking at the Medtronic system. The complete Spinal Cord Stimulation system consists of five parts (

'1. 'Nuerostimulator – The device that generates the electrical impulses. It is about the size of a stopwatch and is usually battery powered. The batteries are surgically replaced every two to five years.

'2. 'Leads – Special insulated wires designed to deliver neurostimulation to the spinal cord area. One (single channel) or two (dual channel) leads may be used. The leads are about 11 inches long and contain electrodes which deliver the electrical pulse to the spinal cord.

'3. 'Extension – Small cable about 20 inches long which connects the leads to the nuerostimulator. This is an optional accessory on some systems.

'4. 'Physicians Programmer – A computer at the doctor’s office which allows the doctor adjust the spinal cord stimulator system and set the parameters such as the strength of the stimulation. This programmer consists of a computer, programming head, and a printer. The programming head is placed over the area where the nuerostimulator is implanted and sets the parameters by use of radio waves.

'5. 'Patient’s Programmer – A handheld device the patient can use at home to customize stimulation within the settings the doctor has selected. The patient can use this to turn the nuerostimulator on and off. The system can also be adjusted for greater or lesser pain relief by increasing or decreasing the tingling. This device must be within a set distance from the nuerostimulator to make changes to prevent children from accidentally adjusting the stimulator.


Who is an Acceptable Candidate?

Determining whether a spinal cord stimulator will be a good pain management option is a complex process. Before a permanent stimulator can be implanted, the patient must undergo a trial to see if the device decreases their level of pain. Because pain also has psychological effects, a psychologist may assess the patient’s condition to determine the probability of a successful outcome. Patients selected for this procedure have usually had pain for more than 12 months and have experienced the pain moving to their lower back.

Surgical Implantation

There are two parts to the procedure: placement of the lead in the epidural space of the spinal cord and placement of the pulse generator in the buttock or abdomen. The entire surgical process takes about 3-4 hours.

'1. 'Placement of the Leads

a. The areas of the back and stomach are shaved and prepped where the leads and the generator are to be placed. Placement of the surgical leads is performed with the aid of fluoroscopy. A small skin incision is made in the middle of the back. The bony arch of the vertebra is exposed. A portion of the lamina is removed to allow room to place the leads. The leads are placed in the epidural space above the spinal cord and secured with sutures.

b. The patient will be awakened so that they can help the doctor determine how well the stimulation covers the pain pattern without feeling any pain or discomfort from the lead implantation itself. Several stimulation settings will be tried and the surgeon will ask you to describe the location of any tingling felt. These settings will be used to program the pulse generator at the end of surgery, so patient feedback during this part of the surgery is important for providing the best pain relief.

'2. 'Placement of the Pulse Generator

a. Once the leads are determined to be positioned correctly the patient is then sedated again. An extension wire is passed under the skin from the spine, around the torso to the abdomen or buttock where the generator will be implanted.

b. A 4 to 6 inch skin incision is made below the waistline. The surgeon creates a pocket for the generator between the skin and muscle layers. The extension wire is attached to the pulse generator. The generator is then positioned under the skin and attached to the thick layer overlying muscles. The two incisions are then closed and the surgery is complete.

One Patient’s Spinal Cord Stimulator Experience

A patient named Kieran was interviewed and agreed to share his story regarding the spinal cord stimulator. Kieran’s diagnosis for chronic pain was due to crushed nerves in his ankle. He had tried many therapies before he and his doctor decided on using a spinal cord stimulator. Attempted therapies included several different drugs, several different braces, surgeries to clean up scar tissue, and a process called freezing the ankle, where bone from the hip is was positioned around the ankle to prevent movement. A TENS (Transcutaneous Electrical Nerve Stimulator) unit was also used before deciding on the permanent implant. A TENS unit is similar to the spinal cord stimulator, but is external. Kieran said the TENS unit was helpful, but found it difficult to place the leads and it prevented him from going about daily activities.

When asked for about any side effects or problems encountered with the system Kieran said there were not too many problems with the device. He cited his only issues with it were: 1.Having to be careful not to pull the wires out by lifting too much weight or by excessive movements, 2. having to go through surgery about every five years, and 3. the thought and physiological side of carrying a machine around inside of him. When asked for his overall opinion of the device he said, “Overall it’s a good thing. It doesn’t cure all the pain for me…about 20% of it, but that’s a lot as far as I’m concerned. If you have a pain scale number of eight or nine out of ten and you can take it down to six or seven, you’ve done a really good thing.”

Works Cited

"Types of Pain." St. Jude Medical. Available from Internet; accessed 19 March 2010.

"Patient Education." Medtronic. Available from Internet; accessed 19 March 2010.

"Implant Procedure." Medtronic. Available from Internet; accessed 19 March 2010.

Allen, Roger. "Medtronic Sets The Pace With Implantable Electronics." Medtronic. Available from Internet; accessed 19 March 2010.

"Spinal Cord Stimulator." Mayfield Clinic. Available from Internet; accessed 19 March 2010.