Spinal Cord Stimulation

Spinal Cord Stimulator (SCS) implantation is a minimally invasive technique for managing persistent neuropathic pain. It is a small-sized device (similar to a pacemaker), which is implanted in the patient’s body to modify pain signals before they reach the brain. In this way, it helps in reducing the need of opioid medications while also assisting in better managing the signs and symptoms of chronic pain.

 

What is a spinal cord stimulator?

A neurostimulator is a device placed under the skin and connected to electrodes implanted in the spine, which send a mild electrical current to the spinal cord. This reduces the amount of pain the patient experiences, masking or altering pain signals before they reach the brain.
There are various types of neurostimulation devices, some of which employ low-frequency current to replace the feeling of pain with a milder stimulus (paresthesia), and other devices which use high-frequency pulses or burst pulses to mask pain without causing paresthesia.
It should be noted that while neurostimulation alters how the brain experiences pain, it does not eliminate the source (cause) of it. As a result, each person experiences pain relief at a different rate. The aim is a 50%–70% reduction in pain. However, even a small relief of pain can be significant if it helps a patient carry out their daily activities, as well as if they succeed in reducing the intake of medications. Neurostimulation does not improve patient muscle strength.

 

Who is eligible for a spinal cord stimulator?

All patients should be aware that prior to being implanted with a spinal cord stimulator, their doctor should thoroughly evaluate their physical condition, pain history, and current medications. A psychologist should also evaluate the patient’s status to increase the likelihood of a positive outcome, as chronic pain also causes emotional disturbance.
Typically, patients who are approved for a stimulator suffer from chronic, ongoing pain for longer than 3 to 6 months.

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  • Conservative treatments have failed
  • No benefit from another surgery
  • Patient rejects additional surgery due to potential risks or prolonged recovery time.
  • Patient not depressed or addicted to drugs (these must be treated before a stimulator is implanted)

The stimulator works best in the early stages of a chronic condition, before a “pain-suffering-disability-pain” cycle is established.

 

A patient is a candidate for a stimulator if:

Good candidates are those who suffer from:

  • Chronic back pain, sciatica, or lumbosciatica
  • Failed back surgery syndrome
  • Complex regional pain syndrome
  • Multiple sclerosis
  • Spinal cord injury
  • Ischemic lower limb pain
  • Chronic refractory angina pectoris
  • Peripheral vascular disease (PVD)/Ischemic lower limb pain
  • Refractory diabetic peripheral polyneuropathy
  • Resistant peripheral neuropathy (postherpetic neuralgia, phantom limb syndrome, peripheral nerve injury, etc.)

Who performs the procedure?

Neurosurgeons and anesthesiologists are the two main medical specialties involved in implanting spinal cord stimulators.
Most of the time, the fitting procedure consists of two stages: the temporary placement (trial fitting) stage to verify that the pain has been reduced by at least 50%, and the permanent implantation stage.
Stage 1 – Testing the stimulator
Trial fitting is a trial period to determine if the patient is showing positive results in terms of pain control.
Stage 2 – Permanent stimulator
If the trial fitting is successful and the patient notices a more than 50% pain reduction, then permanent implantation of the spinal cord stimulator is planned.

 

What happens after the procedure?

Most patients are discharged home the next morning. Their neurostimulator is duly programmed prior to discharge.

Limitations:

  • Avoid vigorous activities for 2 weeks
  • Avoid driving for 1 month

 

What are the results?

The results of spinal cord stimulation depend on careful and appropriate patient selection, successful trial fitting, good permanent implantation, and patient education. Stimulation does not cure the condition causing the pain; it simply helps patients manage their pain. Implantation of a stimulator is considered successful if the pain is reduced by at least half.
According to published studies, spinal cord stimulation demonstrates good to excellent long-term relief in 50%-80% of patients suffering from chronic neuropathic pain[1-6].
Treatment is reversible. If a patient decides at any time to stop, all electrodes and the stimulation unit can be removed.

Are there any risks or complications?

No surgical procedure is risk-free. Any surgery can result in general complications such as bleeding, infection, thrombosis, etc.

Specific complications associated with neurostimulator placement include:

• Displacement of the electrodes or failure of the electrodes
• Epidural bleeding, hematoma, infection, spinal cord compression and/or paralysis
• Battery failure
• Cerebrospinal fluid leak
• Sharp pain at the site of the electrode or stimulation unit

 

 

Living with a spinal cord stimulator

Once the device is programmed, the patient is ready to go home. Prior to discharge, the doctor will provide instructions for adjusting the stimulator, which controls the intensity and length of each stimulation period. The doctor may also change the pulse width, amplitude, and frequencies at follow-up visits, if necessary.
The patient carries a portable programmer that allows them to activate/deactivate the stimulator, select a different program according to their needs, and adjust the intensity of the stimulation. Most people use multiple programs to achieve the best possible pain relief at any point during the day or during specific activities.
Depending on their posture (e.g., sitting or standing), some patients may feel varying stimulation intensities. This is typical and is caused by variations in the electrical current dispersion as the patient changes postures.
Similar to a pacemaker, the neurostimulation unit is unaffected by devices like cell phones, microwaves, security doors, and anti-theft sensors. The device is detectable by airport security gates. As a precaution, patients are advised to deactivate the system before they pass through the security gates.
Different restrictions apply to different stimulation units for use with magnetic resonance imaging (MRI), ultrasonography (ultrasound), defibrillator, electrocautery, diathermy, and heart pacemakers

 

References:

1. Verrills P, Sinclair C, Barnard A. A review of spinal cord stimulation systems for chronic pain. J Pain Res 9:481-92, 2016
2. De la cruz P, Fama C, Roth S, et al. Predictors of Spinal Cord Stimulation Success. Neuromodulation 18(7):599-602, 2015
3. Grider J, Manchikanti L, Carayannopoulos A, et al. Effectiveness of Spinal Cord Stimulation in Chronic Spinal Pain: A Systematic Review. Pain Physician 19:E33-E54, 2016
4. Deer TR, Skaribas IM, Haider N, et al. Effectiveness of cervical spinal cord stimulation for the management of chronic pain. Neuromodulation 17(3):265-71, 2014
5. Deer TR, Mekhail N, Provenzano D, et al. The appropriate use of neurostimulation of the spinal cord and peripheral nervous system for the treatment of chronic pain and ischemic diseases: the Neuromodulation Appropriateness Consensus Committee. Neuromodulation 17(6):515-50, 2014
6. 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
7. Sundaraj SR, et al: Spinal cord stimulation: A seven-year audit. J Clin Neurosci 12:264-270, 2005

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