High frequency spinal cord stimulation

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The high-frequency spinal cord stimulation is a technical further development of the spinal cord stimulation (SCS). Spinal cord stimulation has been an established form of therapy for chronic back pain since the early 1990s . Special electrodes deliver electrical stimuli to the spinal cord in order to largely prevent the transmission of pain stimuli to the brain. With the high-frequency SCS, these pulses have a frequency of 10,000 Hertz. The conventional low-frequency SCS works with 40 to 70 Hertz.

That spinal cord stimulation using these high frequencies has better efficacy than conventional methods of SCS, occupied since 2015, as the first time the results of the largest study so far in the area of SCS have been published: The randomized controlled conducted multicenter study "Senza-RCT" ( Randomized Controlled Trial (RCT) was designed and monitored by the Food and Drug Administration ( FDA ). For the first time, she directly compared the safety and effectiveness of different SCS procedures. With evidence level Ib, this study meets the toughest evidence requirements that a clinical study can ever achieve. The results are therefore secure and sound.

Indications

The high-frequency spinal cord stimulation helps with chronic, predominantly neuropathic , therapy-refractory pain syndromes of the trunk and the upper and lower extremities .

Chronic pain

There are different definitions of when pain is considered chronic. According to the World Health Organization (WHO), pain is chronic if it lasts for three months or more. Alternatively, chronic pain is used when it lasts a month longer than expected for a particular injury, surgery, or illness.

Since chronic pain usually affects those affected extensively, its treatment is often not just about pain relief, but about regaining quality of life .

Neuropathic pain

Very simply, there is nociceptive pain , which has a specific cause, such as an injury, and neuropathic pain, which is based in the nervous system  itself. Neuropathic pain is the result of nerve damage or impairment and usually does not respond (anymore) or only for a short time to therapy for the cause.

Often these are mixed forms, which are initially nociceptive, but in the long run take on a neuropathic character when the pain has taken on a life of its own from the initial cause.

Clinical pictures

The effectiveness of high-frequency spinal cord stimulation has been demonstrated for chronic neuropathic pain syndromes of the trunk and the upper and lower extremities. In addition, the high-frequency SCS can be used for a large number of indications and diagnoses that are responsible for chronic pain in the back and / or leg area.

Indications recognized by health insurance companies :

  • Lumbo sciatica , back pain radiating to the legs
  • Chronic pain after spinal surgery ( Postdiskectomy Syndrome / Failed Back Surgery Syndrome)
  • chronic nerve root irritation ( radiculopathy / polyradiculopathy)
  • degenerative changes in intervertebral discs and vertebral bodies (degenerative disc disease, spondylosis )
  • And last but not least, high-frequency spinal cord stimulation can provide pain relief in patients who have not responded to conventional, low-frequency SCS treatment (non-response to conventional SCS)

Since a surgical procedure is required for high-frequency spinal cord stimulation, this type of therapy is reserved for the treatment of chronic pain. It is only used when simpler, non-invasive treatment options, such as painkillers, physiotherapy, etc., have not been successful in the long term.

Differences between high-frequency and conventional (low-frequency) treatment

No tingling

In conventional SCS procedures, which work with low frequencies, the perception of pain is masked by so-called tingling paresthesias . This tingling sensation is generally perceived as annoying by some of the patients. In addition, this can lead to unexpectedly strong fluctuations in paresthesia that feel like electrical surges. With high-frequency SCS, on the other hand, pain relief occurs immediately. The amplitudes of the current frequency are very close to one another and the current strength to be used is very low, so that tingling paresthesia does not even arise. The elimination of these abnormal sensations is an advantage in itself, but is also reflected in significantly fewer restrictions in everyday life for the patient: Under the high-frequency SCS, which works without noticeable, unexpected, electrical impulses, the patient is allowed to drive a car, for example sleep disorders are less common.

The high-frequency SCS also does not interfere with drugs that are administered or taken at the same time.

Easy to use pulse generator

Everyday use of the system is easy with the high-frequency SCS. Only the pulse generator has to be charged daily, which takes about 45 minutes. This can be done while sitting or lying down, for example very comfortably while watching TV.

Once set and checked regularly during a specialist doctor's consultation, the high-frequency SCS works without permanent readjustment. This means that the system regulates active and rest phases with one setting and can remain switched on while sleeping. In the case of low-frequency spinal cord stimulation, on the other hand, the pulse strength must be adapted to the respective activity such as lying, sitting or running.

Operation under general anesthesia

With high-frequency SCS, the patient can remain under general anesthesia while the pulse generator is being implanted because the surgeon does not need his feedback to place the electrodes. An intraoperative impedance measurement, i.e. the measurement of the alternating current resistance, is sufficient to validate the position and works reliably. This ensures the effective placement of the electrodes. For the low-frequency SCS therapy, however, the patient must be awakened from anesthesia when the electrodes are implanted. This “intraoperative mapping” is uncomfortable for the patient, but necessary so that he can provide information about the placement of the electrodes as to whether and where exactly he is feeling the tingling paresthesia. With the high-frequency SCS, however, this procedure is not applicable. This makes the procedure easier for both the patient and the surgeon.

Therapy / process

Once the indication has been established, before the pulse generator is permanently implanted, a test phase takes place during which the individual effectiveness of the high-frequency spinal cord stimulation is checked. A specialist performs the minimally invasive procedures necessary for this treatment. For this purpose, two electrodes are implanted close to the spinal cord, which is minimally invasive and reversible, i.e. the electrodes can be easily removed again if necessary. The patient documents the pain intensity in a test diary. A decision on further therapy will only be made after a few days. Only if the test is successful, i.e. if the test is effective, will the patient then receive the permanent pulse generator implanted. Nine out of ten patients who tried high-frequency spinal cord stimulation in this way stayed with it permanently.

During the test phase, the spinal cord is stimulated via an external device that can be worn on a belt. The permanent, rechargeable pulse generator is about the size of a matchbox and is usually placed under the skin in the lower back or in the buttocks area, which can show up as a small bump on the outside. Patients sometimes refer to this device as a "pain pacemaker".

Proof of effectiveness

The advantages that can be achieved with high-frequency SCS compared to low-frequency spinal cord stimulation are manifold - and its clinical evidence has been proven in several studies.

2009 US feasibility study

5 study centers, 24 patients tested with both conventional and high frequency SCS. Evidence of safety and effectiveness in humans. 88 percent of the patients preferred high-frequency spinal cord stimulation. Published in the journal "Neuromodulation".

2013 European multicenter 24-month study (Senza-EU)

2 test centers, 72 patients implanted. Evidence of long-term safety and efficacy in back pain and leg pain (24 month follow-up). Published in the journal "Pain Medicine".

2015 Senza-RCT - first, randomized, controlled, multicenter, prospective pivot study

In 2015, the results of the largest study to date in the area of ​​SCS were published for the first time in the 04/2015 issue of "Anesthesiology", the specialist magazine of the American Society of Anesthesiologists. The "Senza-RCT" (Randomized Controlled Trial, RCT) was monitored by the US licensing authority (FDA) and for the first time directly compared different SCS methods and thereby meets the toughest evidence requirements. Some of the patients were treated with the conventional form of SCS, i.e. with low-frequency impulses, the other group of patients received high-frequency spinal cord stimulation. The study was also the first randomized SCS comparative study in which subjects with back and leg pain took part and in which all participants were followed and monitored over a period of twelve months.

2016 Continuation of Senza-RCT for 24 months

The improved effectiveness of high-frequency SCS compared to low-frequency spinal cord stimulation, which was documented in 2015, was also confirmed in the continuation of the Senza RCT over 24 months. This is proven by the data published in September 2016 in the journal “Neurosurgery”. The superiority of the high-frequency SCS is shown in the higher responder rates and in the better effectiveness, documented among other things in the comparison of the remitter rates  (subjects who can be equated to a healthy person after the treatment) and the determined pain intensity via the visual analog scale (VAS).

Selected detailed results

The Senza RCT study showed that patients with a long history of pain also benefit from the treatment. The high number of previously operated Senza RCT subjects also shows that high-frequency SCS is suitable for providing pain relief to patients with Failed Back Surgery Syndrome, i.e. with persistent complaints after an intervertebral disc or spinal surgery.

In the Senza RCT study, a definition for so-called “remitters” was established, ie for patients who can be equated with a healthy person after treatment and are therefore considered cured. Accordingly, those patients who were able to achieve a VAS value of 2.5 or less under spinal cord stimulation belong to the remitters. This definition remained valid for the 24-month perspective. After 12 months, around 67 percent of the study participants who received high-frequency spinal cord stimulation achieved remitter status - both in those afflicted with leg pain and in those with back pain. After 24 months, the remitter rate remained stable at around 66 percent at the same high level. The proportion of patients treated with low-frequency SCS who achieved remission was between 31 and almost 43 percent at the different measurement times. Conclusion: With high-frequency spinal cord stimulation, about twice as many patients can be completely relieved of their pain than with conventional SCS. This reduction in pain scores was achieved even though the pain medication was reduced at the same time.

The concrete comparison of the pain intensity on the VAS scale over a period of 24 months of treatment shows particularly impressively how big the difference between the two SCS methods actually is. In the case of back pain, the VAS value was reduced from an average of 7.5 under high-frequency spinal cord stimulation to 2.5 after 12 months and to 2.4 after 24 months. In comparison, the VAS values ​​for the low-frequency SCS therapy, based on an average of 7.7, were 4.3 after 12 months and 4.5 after 24 months. The VAS values ​​for the high-frequency SCS were also significantly lower for leg pain: starting from 7.2, they fell to 2.1 after 12 months and to 2.4 after 24 months; while under low-frequency SCS therapy the baseline value was 7.4, the 12-month value 3.8 and the 12-month value 3.9.

Documented superiority of radiofrequency spinal cord stimulation

High-frequency spinal cord stimulation is the only SCS therapy that is effective without tingling paresthesia. More patients respond to it; With them, the therapy is at the same time more effective and relieves the pain better - these results not only came to the fore in the Senza RCT study, the FDA even explicitly allowed these statements.

Individual evidence

  1. ↑ S-3 guideline "Epidural spinal cord stimulation for the therapy of chronic pain". Register number 008 - 023. German Society for Neurosurgery eV et al., July 31, 2013, accessed on May 15, 2017 .
  2. ↑ back pain . In: Robert Koch Institute (ed.): Federal health reporting . Issue 53, 2012 ( gbe-bund.de [accessed on April 18, 2017]).
  3. ↑ a b Braunsdorf, Werner: EK: High-frequency neuromodulation in chronic back and leg pain . Ed .: MOT Medical-Orthopedic Technology. 136th year 2016, issue 1, p. 27-33 .
  4. ↑ a b c Kapural, L., et al .: Novel 10 kHz High Frequency Therapy (HF10 Therapy) is Superior to Traditional Low Frequency Spinal Cord Stimulation for the Treatment of Chronic Back and Leg Pain: The SENZA-RCT Randomized Controlled Trial . Ed .: Anesthesiology. V 123, no. 4 , 2015 ( asahq.org [accessed April 18, 2017]).
  5. ↑ Al-Kaisy, A., et al .: The Use of 10-Kilohertz Spinal Cord Stimulation in a Cohort of Patients With Chronic Neuropathic Limb Pain Refractory to Medical Management . Ed .: Neuromodulation. No. 18 , 2015, p. 18-23 .
  6. ↑ Al-Kaisy, A., et al .: Sustained Effectiveness of 10 kHz High-Frequency Spinal Cord Stimulation for Patients with Chronic, Low Back Pain: 24-Month Results of a Prospective Multicenter Study . Ed .: Pain Medicine. V 15, 2014, p. 347-354 .
  7. ↑ a b L. Kapural, C. Yu, et al .: Comparison of 10-kHz High-Frequency and Traditional Low-Frequency Spinal Cord Stimulation for the Treatment of Chronic Back and Leg Pain: 24-Month Results From a Multicenter, Randomized , Controlled Pivotal Trial. In: Neurosurgery. Volume 79, number 5, November 2016, pp. 667-677, doi : 10.1227 / NEW.0000000000001418 , PMID 27584814 , PMC 5058646 (free full text).