Spinal cord stimulation or neurostimulati is a pain-relief technique that works by masking the pain signals before they reach the brain by delivering a low-voltage electrical current, by a surgically implanted device, to the spinal cord.
The spinal cord stimulation device is the most commonly used implantable neurostimulation technology for management of chronic pain.
They can be used for many conditions but mostly used for chronic back pain or radiating pain in arm or leg.
Types of Spinal Cord Stimulators
Spinal cord stimulator device is similar to pacemaker devices and is implanted under the skin. A small wire carries the current from a pulse generator to the nerve fibers of the spinal cord. The electrical pulses mask the perception of pain signals or are replaced by a tingling feeling.
It is noteworthy that stimulation does not eliminate the source of pain, but simply interferes with the signal to the brain.
Therefore, the pain relief received is different in different people.
A trial stimulation is performed before the device is permanently implanted.
Spinal cord stimulator consists of following parts:
- Pulse generator with a battery
- Lead wire with electrodes to deliver electrical pulses to the spinal cord.
- A hand-held remote control
Two types of systems are available.
- One type has a non-rechargeable battery and needs to be surgically replaced every 2 to 5 years.
- Other type is with a rechargeable battery which may last 8-10 years or longer. But this kind needs regular charging.
Some devices are able to sense a change in body position and can adapt the stimulation level to your activity.
The pulse generator has programmable settings like rate of stimulation [frequency], area that stimulation will cover [pulse width] and how strong the pulse is [amplitude [determines the threshold of pain perception].
The adjustment can be made by by handheld remote to achieve the best possible pain relief.
There could be a difference in stimulation intensity depending on due to variations in the spread of electricity with change in position.
A device using radiofrequency systems can sustain therapy over long periods but the patient must wear an external power source to activate stimulation.
Following patients can be considered for treatment by neurostimulation
- Pain not associated with malignancy
- Poor response to conservative treatment [minimum of six months]
- No pacemaker or other medical contraindications
- No major psychiatric disorders, depression or drug addiction
- A successful spinal cord stimulator trial.
The conditions in which Spinal cord stimulation may be used are
- Chronic leg (sciatica) or arm pain:
- Degenerative disease
- Spinal stenosis
- Nerve compression or neuropathy
- Failed back surgery syndrome
- Complex regional pain syndrome
- Stump pain
- Peripheral vascular disease
- Multiple sclerosis
- Spinal cord injury
Trial Procedure of Spinal Cord Stimulation Device
The trial procedure is conducted to find if the device is suitable for the patient or not.
For the trial, under local anesthesia, a hollow needle is inserted through the skin into the epidural space. The trial lead is inserted and positioned over specific nerves. The wires are attached to an external generator worn on a belt. The trial stimulator is programmed with one or more stimulation programs customized to the pain requirement of the patient.
Over the next few days, patient analyzed whether the device is effective and if he would be able to carry it permanently. It also helps the patient to the type of spinal cord stimulation technology works best.
You will be sent home with instructions on how to use the trial stimulator and care for your incision site. Keep a written log of the stimulation settings during different activities and the level of pain relief. After 4 to 7 days, you will return to the doctor’s office to discuss permanently implanting the stimulator or removing the trial leads.
Implantation of SCS device
If the trial was successful, then a permanent system may be implanted. In spite of the name permanent, it is a reversible procedure and can be discontinued by removing the implant.
With the patient under sedation or anesthesia and trial leads are removed and the new leads are inserted in the epidural space above the spinal cord using a small needle or through a small incision.
[Sometimes, the leads implanted during the trial are perfect in position and are used for a permanent system as well.]
Laminotomy may be needed to allow room to place the leads. The leads are secured with sutures in the epidural space above the spinal cord.
The actual location of the leads would depend on the pain profile of the patient.
After leads are placed, the patient is awakened to get feedback the stimulation patterns and whether the placement works for the pain region involved.
After ascertaining, the lead wire is passed under the skin from the spine to the buttock, where the generator will be implanted.
The generator can also be implanted in the abdominal region.
[Once healed, most the patients do not feel the device]
Incisions are closed and dressed. The patient can be discharged on the same day or kept overnight.
The patient is instructed not to lift, bend, stretch or twist for at least two weeks. Walking and other light exercises are prescribed for strength building.
Strenuous activity should be avoided for the next few weeks.
Follow up is done for suture removal and adjustment of the device settings if required.
Complications/Risks of SCS Implantation
- Allergic reaction
- Hematoma or seroma formation
- Spinal cord compression
- CSF leakage
- Wound infection
- Paralysis or weakness
- Spinal fluid leakage
- Worsened pain
- Device malfunctions requiring revision surgery
- Undesirable changes in stimulation – stops or works intermittently, wrong location or overstimulation
- Scar tissue around electrodes
- Changes in electrode position
- Loose electrical connections
- Lead failure/migration
- Battery failure and/or battery leakage
- Persistent pain at the electrode or stimulator site
- Generator migration
- Local skin erosion
- Avoid using heavy equipment when the stimulator is active
- Avoid driving when the stimulator is active
- The device can set off metal detectors at security gates and physician provided ID should always be carried
- Anti-theft devices may temporarily increase stimulation if the system is on
- Magnet on the device may damage magnetic strips as in including credit cards, video or audiocassettes, and computer disks.
- Adverse effects of MRIs, ultrasound, defibrillators, electrocautery, diathermy, and cardiac pacemakers. The use should be restricted as directed by device type
About 60 percent of people who received spinal cord stimulator have reported pain reduction/relief.
In case of failed back surgery syndrome, early treatment has a better outcome.
- Verrills P, Sinclair C, Barnard A. A review of spinal cord stimulation systems for chronic pain. J Pain Res 9:481-92, 2016
- De la cruz P, Fama C, Roth S, et al. Predictors of Spinal Cord Stimulation Success. Neuromodulation 18(7):599-602, 2015
- Eldabe S, Buchser E, Duarte RV. Complications of Spinal Cord Stimulation and Peripheral Nerve Stimulation Techniques: A Review of the Literature. Pain Med 17(2):325-36, 2016
- Sundaraj SR, et al: Spinal cord stimulation: A seven-year audit. J Clin Neurosci 12:264-270, 2005