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| Spinal cord stimulation (SCS), formerly known as dorsal column stimulation, is an advanced surgical pain technique which works better on constant pain affecting the arms and legs more than the back or neck. It is a method of pain control used when all other conservative and medication attempts have failed to control pain adequately. Whereas intrathecal infusion therapy is useful in controlling pain throughout the body except the head, spinal cord stimulation is primarily used in extremity pain due to damaged nerves in the spine or in the extremity. The optimal candidate would have constant burning pain in the arm or leg which cannot be relieved through repositioning the body. Many patients also have low back pain along with the extremity pain, but the low back pain portion responds poorly to spinal cord stimulation. Currently accepted conditions for which spinal cord stimulation is useful include: Failed Back Surgery Syndrome (FBBS) Adhesive Arachnoiditis Peripheral Causalgia/Neuropathy Reflex Sympathetic Dystrophy (RSD) Phantom Limb/Stump Pain Ischemic Pain of Vascular Origin More recently, SCS has been used quite effectively in patients with severe angina chest pain in whom there are no other medical or surgical options. SCS has also been used in diabetic patients with severe aortoilliac occlusive disease of the arteries. There has been moderate to good success in these patients results. It is a requirement for most patients that physical therapy evaluations and MMPI psychological screening be completed prior to permanent implantation. Medicaid as the primary insurer will not pay for SCS therapies. There are three manufacturers of SCS: ANS, Medtronics, and Advanced Bionics. Because these devices are implanted and expensive, it is important to have a trial lead implantation. Whereas there are two methods to do this (permanent spinal lead implant with an extension lead attached under the skin for triallng or temporary percutaneous lead trialing), we believe the latter is the prudent and safer decision for most patients. There are occasional patients who do not derive substantial relief from a trial stimulation and therefore may not be appropriate for any invasive implants of leads or generators. Therefore, the percutaneous trial is the more logical choice. THE TRIAL: Outpatient procedure in which a spinal cord stimulator lead is placed through the skin using an epidural needle. Usually IV sedation is used for the needle placement. The lead is inserted through the needle into the lumbar epidural space and advanced under x-ray guidance to the mid-back, usually T9 or T10 level. For arm or hand pain, the lead is advanced to the level of C2-3 in the neck. The patient is then awakened and stimulation is performed using various electrode combinations to optimize coverage of the painful area. Sometimes the leads must be repositioned and this is usually painless. Once optimal coverage is achieved, the lead is taped in place and the patient is sent home for a 7-10 day trial using an external trial stimulator. If the patient achieves 70-100% pain relief, the trial is deemed a success and the lead is removed and plans made for permanent implantation. If there is insufficient pain relief, several adjustments are made to the electrodes and electrical pattern during the trial in an attempt to optimize coverage of the pain. Usually the patient will feel a mild buzzing or tingling sensation during spinal cord stimulation. THE PERMANENT IMPLANT: As an outpatient, the two part system is implanted through two separate incisions using sedation or general anesthesia. The spinal incision is usually close to the middle of the back and is about 2 inches long. It is carried down to the spinous processes which are the bones one can feel by pressing on the middle of the back. A needle is placed into the epidural space and a permanent lead is inserted through the needle into the epidural space where it is positioned to approximate that of the previously placed trial lead. The lead is then anchored to the spinal ligaments with heavy suture. A second incision is made over the top of the posterior buttock or the lateral flank and a pocket is created for placement of a SCS generator. There are three different types of generators: RC=Rechargeable generator (rechargeable battery that is recharged through the skin once a week or so), IPG= implantable programmable generator that is not rechargeable but lasts 3-5 years, or a radiofrequency (RF) receiver requiring wearing an external battery pack. The RC is the most common unit implanted with batteries that have been tested to 10 years but may last much longer. The IPG is larger, and has self contained batteries which last 3-5 years, after which the IPG is replaced through a small incision over the original generator. The RF system uses an implanted radio receiver which derives its power from a radio antenna placed on the skin, and is connected to an external battery pack. This battery pack uses rechargeable Lithium batteries which are changed daily. The RC and IPG systems are totally self contained whereas the RF system has an external battery pack which must be worn to activate the system. Consequently, those who are very active in sports, enjoy swimming, etc. may benefit more from the RC or IPG systems. The RF unit has largely been supplanted by the RC unit but those with extremely high power requirements (as determined during the trial) may benefit more from the RF system because the IPG battery life would be too short and the RC may require frequent recharges in such situations. In any case, the RC, IPG, or RF unit is connected to the lead without or with an extension wire tunneled under the skin from one incision to the other. The incisions are closed using layered stitches and skin staples or sutures. Dressings are applied, and the patient is discharged to home on oral antibiotics. On rare occasions, it may not be possible to adequately place the type of leads used by pain management and a open surgical laminectomy (removal of the bones of the spine) is necessary in order to place a flat neurosurgical lead. This is a much more invasive procedure and is not commonly employed in our practice. POST OPERATIVE CARE: The patient is instructed not to bend forward, sleep lying face down, engage in any physical activity or lifting, or raise the hands above the level of the head for 2 months which is enough time for the leads to become fixed in place in the epidural space and lessens the chance for lead migration. There should be no back massage or chiropractic of the spine after that point in time. After 2 months from the time of implantation, gradual increases in exercise are encouraged. Provided no staples are used, the RC unit and IPG units are activated immediately after implantation while the RF unit usually requires a week's delay in turning on the unit. Potential complications: Although complications from spinal cord stimulator system implantation are uncommon, it is possible that there could occur complications such as bleeding, infection, development of a spinal hematoma or abscess, development of cutaneous hematoma or abscess, lead migration resulting in dysfunction of the system, erosion of the leads or IPG through the skin, nerve injury, spinal cord injury, etc. These are rare but require prompt treatment. There it is mandatory that a local hospital be available to handle complications and the physician must have treating privileges in the same hospital. It is considered to be below the standard of care for a physician to implant these devices without having appropriate surgical or pain surgery coverage in the local hospital. Should there be an infection in the spine or around the RC/IPG/RF unit, immediate surgical removal of the unit is required. Alternatives to SCS include intrathecal therapies, interventional minimally invasive spine therapies, open surgery, medication management, injection therapies, other conservative therapies. For more information see the website of ANS, the manufacturer of SCS. |
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| Spinal Cord Stimulation |
