Occipital nerve stimulation
Called Occipital nerve stimulation ( ONS), and peripheral nerve stimulation ( PNS ) of the occipital nerves, is used to treat patients with chronic migraine who no longer respond to pharmaceutical treatment options.
In therapy, electrical impulses are used to the greater occipital nerve and stimulate the nervus occipitalis minor which parts of the peripheral nervous system. These are located at the back of the head just above the neck.
The electrical impulses are called a neurostimulator - a small generator similar to an artificial pacemaker - is generated. Possible implantation sites may be: In the buttocks, chest, lower abdomen, below the scapula or clavicle. The electricity is conducted to the nerve greater occipital nerve and lesser occipital means of small metallic contacts, which (also called electrodes) are arranged on thin cables and are implanted just under the skin. The intensity of the electrical pulses can be controlled using a handheld remote control.
History
The history of the PNS is discussed in detail in a publication by Slavin, 2011. The use of peripheral nerve stimulation for chronic pain was first reported by Wall and Sweet in 1967, although already the first implantations were performed by Shelden in 1962. These have proved that the electrical stimulation of the peripheral nervous suppresses perception of pain. One phase of the semi- experimental PNS use has continued for another 15-20 years. In the second half of the 80s, the PNS has established itself as a surgical procedure. In the late 90s, and Weiner Reed have reported the percutaneous method in which the contacts are inserted into the vicinity of the occipital nerves to treat Okzipitalisneuralgien. Weiner has shown that the placement of one electrode to the PNS in the vicinity of a nerve for the treatment of pain effectively and also a surgically technically simple method. This pioneering work has led to the dawn of the modern era of the PNS. It was proposed in 2003 as Popeney Alo and the use of PNS for the treatment of chronic migraine. Subsequently, randomized controlled prospective studies were initiated to create additional clinical evidence.
In September 2011, St. Jew Medical has become the first provider in the world, a European approval ( CE marking) for the treatment of chronic intractable migraine using the PNS.
Therapy candidates
Suitable patients in the PNS of the occipital nerves for the treatment of chronic migraine must have a chronic migraine, which has been classified as refractory to treatment ( treatment- resistant).
Chronic migraine is in the guidelines of the International Headache Society (IHS ) defined as follows:
Refractory chronic migraine is generally defined as follows: Chronic migraine with little or no relief from at least three different or combined preventive medication or not reasonable side effects of these drugs and at least moderate functional impairment in accordance with a recognized assessment tool for migraine (eg MIDAS or HIT -6 ) is defined.
Method
Preoperatively
Before implantation, patients usually undergo a psychological evaluation to determine their well-being and mental state. The process risks are discussed and patients are asked for their informed consent. The risks of the operation may, inter alia, following include: No guarantee effectiveness, risk of infection, nerve damage, painful direct muscle stimulation, electrode displacement with stimulation loss, electrode breakage, battery or battery failure and resultant change of the neurostimulator, hematoma and Seromformation.
Implantation
In most cases (country- specific differences ) is a trial (test) electrode placement performed to determine if the stimulation is functioning as intended. A local anesthetic is administered to the back of the neck and an epidural needle is advanced to the site of nerve greater occipital nerve and lesser occipital under fluoroscopic guidance. Once the implant site has been defined, a trial electrode is placed through the cannula before the cannula is removed carefully. Electrical impulses are sent through the electrode and its position is continuously adjusted until the patient is a " pins and needles ", also called paraesthesia, reports on the nerve areas. A paresthesia in place successfully achieved, usually permanent electrodes are implanted at a later time. In some cases, the trial electrodes are left for one week in the body, in order to check whether a alleviations of the symptoms occur.
The placement of the permanent electrodes can be performed either under general anesthesia or local anesthesia with sedation. First, a small incision at the base of the skull is performed, then an epidural needle is placed under fluoroscopic guidance to the site of nerve greater occipital nerve and lesser occipital on one side of the head. When the electrode is properly positioned under fluoroscopic guidance, the electrode is permanently placed. Since most patients require two electrodes in the same manner, a second electrode is commonly used on the other side of the head and fixed in place. The electrode (s) are tunneled in the following step to the neurostimulator, which is usually implanted in the buttocks, chest, lower abdomen below the scapula or clavicle.
Clinical evidence
Results of three randomized controlled trials have so far been published ( released ) been. About a randomized controlled study on 157 patients with chronic migraine was first reported as a summary in June 2011. The publication of the data in a scientific journal in October, 2012. Participants were supplied with the neurostimulator and randomly thereafter. The neurostimulator has a duration of 12 weeks either turned on ( treatment group ) or not ( control group). After 12 weeks, all participants received active treatment ( stimulation ) up to week 52. All participants received test stimulation, to ensure the correct placement of the contacts. A total of 153 participants completed the study ( 52 weeks) completed. There was a statistically significant difference ( p < 0.05) between the number of patients in the treatment group compared to the control group at 30 -percent reduction in pain by visual analog scale ( VAS). In addition, the study showed that the treatment group ( neurostimulator turned on), on average, 6.1 (27.2%) had less monthly headache days. This result is statistically significant ( p < 0.001), as it ( off neurostimulator ) more than twice, average reduction compared to the control group corresponded to (3.0 days; 14.9 %). The clinical trial, researchers reported that the rate of serious device-and procedure -related adverse events was 1.0%. Further included such a case each of infection and postoperative pain, which required an additional hospitalization.
In February 2011 ONSTIM study, researchers reported on three-month results from a randomized controlled trial of patients with chronic migraine. Participants were first subjected to an occipital nerve block. Means responsive to such treatment, participants were then randomized into three groups. The first group was a treatment group ( 33 participants ) and received an adjustable stimulation. The other two groups were control groups and received an ineffective stimulation ( " sham " stimulation) for one minute per day or standard medical care ( per 17 participants). Patients who had a minimum of 50 percent reduction in the number of monthly headache days, or - in terms of output values - reached a minimum reduction of overall average pain intensity of three points were defined as treatment responders. 39% of patients in the adjustable stimulation group were responders, 6 % in the sham- stimulation group and 0% in the medical treatment group. The differences between the response rates in the treatment group and the control groups were statistically significant. Other outcomes such as the number of headache days were not statistically significant between the groups. Yet was the percent reduction in headache days 27 % for the treatment group and less than 9 % for each of the two control groups, which corresponds to a numerical advantage for the treatment group. There have been no reported unexpected device-related complications. Electrodes shifts occurred in 24% of patients.
In December 2009, the PRISM study investigators reported as a summary of the three-month results from a randomized controlled trial of 125 patients with chronic migraine. The patients were randomized into two groups. Group one was a treatment group with an active stimulation. The second was the control group and received sham stimulation. In the patients of the treatment group, the monthly number of migraine days decreased by 5.5 days from a baseline of 20.2 days per month. In the patients of the control group, the monthly number of migraine days decreased by 3.9 days from a baseline of 19.2 days per month. The difference between the two groups was not statistically significant. Nevertheless, there was a tendency toward a greater difference between the two groups, provided there has been no medication overuse in patients in advance.