About the 'pain pacemaker'
What is a 'pain pacemaker' or how does neuromodulation work?
The aim of a neuromodulatory pain therapy is to suppress the pain signals at the level of the spinal cord. This is done by using so-called 'rod electrodes', which are inserted into the spinal canal at the level of the spinal cord, exactly where the pain signals arrive. With special stimulation programs, electrical impulses can now be administered via these electrodes, which can counteract and suppress the pain signals that enter the spinal cord through the nerve root. Typically, during this type of stimulation, patients feel a subtle, pleasant tingling sensation (so-called 'tingling paraesthesia'), which masks the pain.
What are the possible indications?
In general, this therapy is suitable for patients with the following causes of complaints:
- Pain after back surgery (Failed Back Surgery Syndrome)
- Complex regional pain syndrome (CRPS, M. Sudeck).
- Peripheral neuropathic pain (nerve pain)
- Peripheral arterial occlusive disease
Prerequisites for therapy
Further prerequisites are that medication-based pain therapies were not sufficient or caused too many side effects. All eligible patients are evaluated on an interdisciplinary basis together with colleagues from neurosurgery, psychosomatics and pain therapy. We carry out this process (as well as the surgical intervention) as mandated physicians in collaboration with the Department of Neurosurgery of the University Hospital Zurich. If a patient qualifies for testing (see below) of such a therapy, we request a cost approval from the health insurance company to cover the costs.
Procedure of the therapy
The process consists of two steps: First, the electrodes are placed in the spinal canal whilst under local anesthesia and light sedation in the operating room. The process is monitored by X-rays. Impulses are then triggered by means of test stimulation and the patients give us feedback on where the stimulation is felt. According to this feedback, the optimal position of the electrodes is determined. The goal is to cover the entire pain area with 'tingling paresthesias' (see above). Once this is achieved, the electrode wires are passed out through the skin and connected to an external stimulator. Patients usually stay overnight in the hospital and are then discharged home for the so-called 'test phase'. This test phase lasts from 1 to a maximum of 4 weeks. During this time, the patients regularly visit us as outpatients for a dressing change and adjustment of the stimulation parameters. If the stimulation is successful and the pain and quality of life are significantly improved, a decision is made together with the patient whether to perform the definitive implantation. This consists of a second short operation in which the so-called 'neurostimulator' with a battery is implanted under the skin. However, if during the test phase it becomes clear that the therapy does not bring any great benefit, the electrodes are removed again in a short operation under local anesthesia.
Possible side effects and complications
- Bleeding, which can lead to temporary or, rarely, permanent paralysis and necessitate surgical relief
- Electrode displacement
- Connection problems between the electrodes and the battery
- Battery malfunctions
- Loss of stimulation effect
- Electrode breakage
- Cable breakage
- Battery malfunctions
- Pain in the battery pocket area
Kumar K et al. The effects of spinal cord stimulation in neuropathic pain are sustained: A 24-month follow-up of the prospective randomized controlled multicenter trial of the effectivness of spinal cord stimulation. Neurosurgery, Volume 63, Issue 4, October 2008, Pages 762–770