Spinal cord stimulation (SCS) involves implanting an electronic device in the body to help relieve chronic back and leg pain. The device, called a “spinal cord stimulator” or “dorsal column stimulator,” sends electrical impulses through wires/electrodes placed near the spinal cord; the impulses block pain signals from reaching the brain. SCS does not cure chronic pain, but usually lessens it by 50 percent and more by replacing the feeling of pain with a pleasant vibration or tingling sensation. Before implantation, a patient is asked to go through a trial period with an external device; this allows pain levels to be evaluated by a patient to determine whether pain levels decrease when the device is used. The battery/generator is either rechargeable or long life; typically they can last for 10 years before replacement. The recharging takes place through the skin with the frequency dependent on how it is used. A control device allows the patient to use as needed and guided by the provider team; frequently the manufacturer’s technicians will adjust the device as needed with consultation with PCI providers.
Candidates for Spinal Cord Stimulation
Spinal cord stimulation works best for pain that arises in nerves whose function has been disturbed such that those nerves continue to send impulses to the brain that are perceived as painful. Often some improvement is obtained by using neuromodulating medications such as gabapentin, tricyclic antidepressants, or serotonin norepinephrine reuptake inhibitors but the improvement does not allow enough relief or much better function in life’s activities. Insurance companies have limited the indications for such treatment so SCS is not available for all cases of intractable pain. There are requirements that candidates have optimized mental health treatments, are not misusing or abusing pain medications, and have significant improvements in discomfort and function in life during the trial phase of the treatment. Common conditions accepted for treatment include failed back surgery, diabetic neuropathy, complex regional pain syndrome (CRPS) and some nerve injuries/diseases that produce neuropathic pain.
Trial Phase of Spinal Cord Stimulation
The trial phase is the first stage of spinal cord stimulation treatment. With local anesthesia and light sedation provided by an anesthetist in the office fluoroscopy suite, SCS leads will be place via needles into the approximate location that when stimulated with gentle intensity electrical impulses lessen pain in a targeted body part by replacing it with gentle vibration. The locations are approximately known through scientific studies that have been previously mapped in humans. The patient is allowed to awaken from the sedation so that sensations can be verbally reported to the provider team to fine tune the location of the electrical contacts in that overlie the spinal cord nerves. After the fine tuning, the introducer needles are gently removed and the leads taped to the back with sturdy adhesive bandages. After brief recovery, the patient is taught how to use the external trial generator to trial different types of programs, given contact information and briefed on complications and proper care. An oral antibiotic is prescribed to suppress possible infection during the trial. At the end of the 7-10 day trial, the lead(s) are pulled much like an IV being removed. The patient’s response during the trial is assessed for decreased in opioid/narcotic medication use, improvement of function, and reduction in pain.
Implantation Stage of Spinal Cord Stimulation
If the implantation criteria are met during the trial phase, then the permanent implantation is planned for the outpatient surgery department. The procedure takes about an hour and is done under local anesthesia and light sedation provided by an anesthetist. There is a small incision in the midline of the upper lumbar spine where the leads enter the spinal canal and in the left upper buttock for the internal battery/generator. The generator is placed between the skin associated fat layer and muscles below. Patients go home the same day and are seen in the office for follow-up in a week. There are usually no stitches to remove after the surgery. The device is activated and fine-tuned during the follow-up office visit. Activity is restricted for 6 weeks after surgery to allow thorough healing and strengthening of the incisions. It is preferred that permanently implanted patients do as little above the head work with their arms as possible since that movement makes it more likely to disturb the resting position of the electrical contacts of the system necessitating reprogramming.
Risks and Complications of Spinal Cord Stimulation
The most common complication from the trial and implantation stages of the care is a headache called a spinal headache which comes from a needle puncture of the sac containing the fluid in which the spinal cord floats. Rare complications include the risks of surgery such as infection, bleeding, stroke, heart attack and blood clot formation in the lung. The permanent implantation is meant to achieve the results of the trial on a permanent basis but additional complications can occur during this stage such as pain over the generator pocket, disturbance of the lead location, battery/generator malfunction, or lead breakage. Revision surgery may be necessary to achieve a functioning spinal cord stimulation system in some of these circumstances. The battery/generator typically lasts 10 years but, if it is non-rechargeable, replacement may be earlier in cases of heavy use of the device. There are different modes of stimulation that result in no feeling or sensation to a patient when the device is on as well as mixed modes which can modify the sensations perceived. Reprogramming can be done to respond to a patient’s changing needs when necessary. PCI providers are experts in patient selection, preparation, education, and trialing, implanting and managing spinal cord stimulators.