Spinal Cord Stimulation: The Trial Period

A person considered a good candidate for spinal cord stimulation therapy is usually scheduled for a trial run, which involves insertion of thin wires with electrodes attached.

The trial period is similar to long-term therapy, except that the device transmitting current is not implanted in the body. Instead, just the wires are inserted and an external transmitter sends electrical pulses to the electrical contacts near the spinal cord.

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During the trial, which takes five to seven days on average, the patient is likely to be asked to note the level of pain relief in different situations during the day and night.

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What to Expect

The trial period procedure is usually performed in a doctor’s office or a surgical center. Procedures vary somewhat with the stimulation device used, but these are the typical steps.

  1. Local anesthesia is applied to the injection site and sedation may be provided.
  2. Guided by fluoroscopy (a type of X-ray), the doctor inserts a hollow needle into the area around the spinal canal called the epidural space. The needle contains thin, insulated wires, called leads, with electrical contacts attached. In some cases, a small incision may be needed to insert the needle.
  3. See Introduction to Diagnostic Studies for Back Pain

  4. The patient is awakened to provide feedback on the specific areas where pain is relieved by the stimulation, and where pain relief is still required. (If a low-frequency system is used, the goal will be to cover all painful areas with a slight tingling sensation known as paresthesia. Devices using newer technology generally avoid the tingling sensation and a wake-up test may not be needed.) Each electrode affects pain in a different area, so doctor-patient communication is crucial in making sure the doctor has adjusted the location of the electrical contacts to cover all the areas in pain. Once the patient has reported on the pain-relief coverage, the patient is again sedated.
  5. The leads are connected to an exterior pulse transmitter that the patient wears on a belt. The wire connecting to the external neurostimulator is taped to the person’s back during the trial to hold it in place.
  6. See Rechargeable Spinal Cord Stimulators for Chronic Pain (Research Article)

  7. The patient is given time to recover from the procedure before going home.
  8. A hand-held controller to adjust the amount of stimulation is programmed by the doctor based on the earlier feedback from the patient during adjustment of the electrical contacts.
  9. The patient is given the controller and can turn it on to send pulses of current to the electrodes as needed. The controller offers a range of adjustments in the intensity and duration of stimulation. With some models, adjustments are needed for significant body movements, such as getting up or lying down.
  10. See Electromyography (EMG)

  11. The doctor may ask the patient to track which stimulation settings are used at different times and how well the pain was relieved. If the pain is not relieved, the doctor should be contacted right away so the device can be reprogrammed.

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The site on the back where the leads and electrodes were inserted is usually uncomfortable for a few days. Any significant local pain should be reported to the doctor.

Peripheral nerve stimulation works similarly to spinal cord stimulation, but the electrodes are placed under the skin near peripheral nerves that carry pain signals or in painful areas.

Trial periods typically last about a week. When the trial is over, the individual tells the doctor whether permanent therapy is wanted. If the trial therapy has offered at least a 50% reduction in pain, surgery to insert the spinal cord stimulation implant is usually the next step.

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If a person decides against spinal cord stimulation, the leads and electrodes are removed and the temporary generator is detached from the skin.

Written by Neel Mehta, M.D.