Stimulation does not eliminate the source of pain, it simply interferes with the signal to the brain, and so the amount of pain relief varies for each person. Also, some patients find the tingling sensation unpleasant. For these reasons a trial stimulation is performed before the device is permanently implanted. The goal for spinal cord stimulation is a 50-70% reduction in pain. However, even a small amount of pain reduction can be significant if it helps you to perform your daily activities with less pain and reduces the amount of pain medication you take. Stimulation does not work for everyone. If unsuccessful, the implant can be removed and does not damage the spinal cord or nerves.
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. There are five main steps of the procedure, which generally takes 3 to 4 hours.
There are many types of stimulation systems. The most common is an internal pulse generator with a battery. A SCS system consists of (Fig. 2):
An implantable pulse generator with battery that creates electrical pulses.
A lead with a number of electrodes (4-16) that delivers electrical pulses to the spinal cord.
An extension wire that connects the pulse generator to the lead.
A hand-held remote control that turns the pulse generator on and off and adjusts the pulses.
The battery inside the pulse generator delivers low voltage and needs to be surgically replaced every 2 to 5 years if it is a standard battery. Rechargeable battery systems may last up to 10 years, depending on usage. Your doctor will select the best type of system for you during the trial stimulation.
The pulse generator is programmable by the doctor and has three settings:
Frequency (rate): number of times stimulation is delivered per second. Too few results in no sensation. Too many results in a washboard or bumpy effect.
Pulse width: determines size of area stimulation will cover.
Pulse amplitude: determines threshold of perception to pain.
Who is a Candidate?
Before determining if spinal cord stimulation (SCS) is an option, your condition will be thoroughly evaluated and assessed. A comprehensive evaluation of your pain history will determine if your goals of pain management are appropriate to proceed with treatment.
Because pain also has psychological effects, a psychologist may assess your condition to increase the probability of a successful outcome. A neurosurgeon, pain specialist, or physiatrist will evaluate your current medication regime and physical condition. The doctor will want to review all previous treatments including medication, physical therapy, injections, and surgeries.
Patients selected for this procedure usually have had a disability for more than 12 months and have pain in their lower back and leg (sciatica). They've typically had one or more failed spinal surgeries.
You may be a candidate for SCS if you meet the following criteria:
Conservative therapies have failed
Your source of pain has been verified
You would not benefit from additional surgery
You are not seriously dependent on pain medication or other drugs
You do not have depression or other psychiatric conditions that contribute to your pain
You have no medical conditions that would keep you from undergoing implantation
You have had a successful trial stimulation
An SCS can help lessen chronic pain caused by:
Chronic leg (sciatica) or arm pain: ongoing, persistent pain caused by degenerative conditions like arthritis or spinal stenosis, or from nerve damage.
Failed back surgery syndrome: failure of one or more surgeries to control persistent leg pain (sciatica), but not technical failure of the original procedure.
Complex regional pain syndrome (CRPS): a progressive disease of the nervous system in which patients feel constant chronic burning pain, typically in the foot or the hand. Formerly called reflex sympathetic dystrophy (RSD).
Arachnoiditis: painful inflammation and scarring of the meninges (protective layers) of the spinal nerves.
Other: stump pain, angina, peripheral vascular disease, multiple sclerosis, spinal cord injury.
If your pain is caused by a correctable condition, then this must be fixed first. Also, if you have a cardiac pacemaker, you cannot have a stimulator
How Do I Prepare for Radiofrequency Ablation
To prepare for radiofrequency ablation treatment, you should take a few precautions, including: *Do not eat within six hours of your appointment. You may have clear liquids until two hours before the procedure.
*If you have diabetes and use insulin, you must adjust the dosage of insulin the day of the procedure. Your primary care doctor will help you with this adjustment. Bring your diabetes medication with you so you can take it after the procedure.
*Continue to take all other medications with a small sip of water. Bring all medication with you so you can take it after the procedure. Please note: Do not discontinue any medication without first consulting with your primary or referring doctor.
*You will need to bring someone with you to drive you home after the procedure. You should not drive or operate machinery for at least 24 hours after the procedure.
What Happens During the Surgery?
Step 1: prepare the patient You are placed lying on your side or on your stomach on the operative table. The team will work with you to make sure you are comfortable before you are given light sedation. Next, the areas of your back and stomach are shaved and prepped where the leads and the generator are to be placed. Local anesthetic will be injected where incisions are to be made to prevent pain during the procedure.
Step 2: place the leads Placement of the surgical leads is performed with the aid of fluoroscopy (a type of X-ray). A small skin incision is made in the middle of your back (Fig. 3). The bony arch of the vertebra is exposed. A portion of the lamina is removed (laminotomy) to allow room to place the leads. The leads are placed in the epidural space above the spinal cord and secured with sutures (Fig. 4). Your surgeon will decide how many leads and the number of electrodes on the lead to implant. Your surgeon will decide how many leads and the number of electrodes on the lead to implant.
Step 3: test stimulation You will be awakened so that you can help the doctor determine how well the stimulation covers your 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 you feel. These settings will be used to program the pulse generator at the end of surgery, so your feedback during this part of the surgery is important for providing you the best pain relief. In some cases, if the leads implanted during the trial are positioned perfectly, there is no need to reposition or insert new leads.
Step 4. tunnel the extension wire Once the leads are in place, sedation is again given. An extension wire is passed under the skin from the spine, around your torso to the abdomen or buttock where the generator will be implanted.
Step 5. place the pulse generator 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 correctly positioned under the skin and sutured to the thick fascia layer overlying the muscles.
Step 6. close the incisions The two incisions are closed with sutures or staples and a dressing is applied.