What Is a Spinal Cord Stimulator?

Spinal cord stimulator is an electronic device that can be placed under the skin to control the pain caused by spinal nerve injury. This system includes a stimulation electrode placed above the spinal cord, which sends out electrical impulses to interfere with pain signals generated at the peripheral or spinal level. When the stimulator is turned on, the patient often feels a stimulating sensation in the pain area through the weak current, which can be used to stop the pain.

Spinal cord stimulator is an electronic device that can be placed under the skin to control the pain caused by spinal nerve injury. This system includes a stimulation electrode placed above the spinal cord, which sends out electrical impulses to interfere with pain signals generated at the peripheral or spinal level. When the stimulator is turned on, the patient often feels a stimulating sensation in the pain area through the weak current, which can be used to stop the pain.

Generates pulsed electrical signals to stimulate the spinal cord to control chronic pain. Function This method is commonly used to stimulate the lumbar spine to treat spinal rigidity and improve walking ability. The simplest spinal cord stimulator includes a stimulation electrode implanted in the epidural space, and an electric pulse generator implanted in the lower abdomen or near gluteus muscle. Until now, the two are connected. Has a strong analgesic effect, mostly used for failed back surgery syndrome, complex regional pain syndrome, or pain due to ischemia.

It is a device used in spinal cord electrical stimulation therapy. Spinal cord electrical stimulation therapy is a method of implanting electrodes into the spinal canal of the spine to stimulate the spinal nerve with pulse current to treat diseases.

Chinese name

Spinal cord stimulator

First, the physical characteristics are similar to TENS. The wave shape mainly includes single-phase square wave, asymmetric two-phase square wave and so on. The frequency is generally between 10 ~ 120Hz (the frequency of early subarachnoid stimulation can reach 100 ~ 500Hz, which is not used now), and the wave width is 0.1 ~ 1.0ms.

2. Physiological and therapeutic effects (1) Analgesia

Clinical application: Mainly used for refractory chronic pain, rarely used for acute pain.
(1) Acute pain: Because acute pain can be controlled by drugs, surgery, TENS and other methods, it is rarely necessary to use SCS. (2) Chronic intractable pain: It is the largest indication for SCS.
Low back pain: This is the most frequently treated condition in SCS. Among them, the failed back surgery syndrome (failed backsurgerysyndrom, FBSS) is mainly the pain after lumbar disc herniation.

Other pain: Many studies have shown that SCS has varying degrees of pain in postherpetic neuralgia, phantom pain, peripheral nerve injury, trigeminal neuralgia, cancer pain, thrombotic vasculitis, spinal cord injury, and reflex sympathetic dystrophy. Analgesic effect.
(2) Treatment of Angina Pectoris SCS has significant socioeconomic benefits. Angola has conducted a survey. SCS treatment can save 56489 Danish cheerful expenses per person per year for patients with severe angina pectoris, including savings in hospital medical costs and family care. expenditure.

The mechanism of SCS in the treatment of angina pectoris is related to three aspects: one is the direct analgesic effect; the second is to increase myocardial blood perfusion; the third is similar to the effect of beta blockers, which can reduce myocardial oxygen consumption. However, some researchers have not found increased myocardial perfusion or decreased oxygen consumption.

(3) Improving peripheral blood circulation As early as the early 1970s, animal tests demonstrated that arterial blood flow in the limbs increased after SCS stimulation. Cook first used SCS to treat lower extremity vascular obstructive ischemic ulcers in 1976, but the effect was not good. Niglio was successful in 1981, and the patient's ulcers healed and the pain disappeared. In the future, it has been reported that the limb ischemic ulcer caused by severe scleroderma, diabetes, thrombotic vasculitis, Rayleigh syndrome, etc., although other conservative treatment methods and sympathectomy are not effective, even reconstructive surgery methods are also If it does not work, SCS treatment can still achieve better results.

(D) The treatment of neurogenic bladder in patients with neurogenic bladder spinal cord injury and multiple sclerosis is a very difficult problem that clinicians often encounter. SCS treatment was started in the 1970s. The neurogenic bladder after spinal cord injury generally stimulates the spinal cord cone or sacral nerve root. Due to the high sphincter tension in men, bladder neck or sphincterotomy is sometimes required. The electrode can be placed on the surface of the spinal cord (epidural space), and a special bipolar electrode can be inserted into the deep gray part of the spinal cord, which is about 2.5 mm deep.

(5) Other therapeutic effects SCS has the most exciting results in the treatment of refractory angina and peripheral vascular disease, and its analgesic effect is often "dramatic" incredible and difficult to achieve by other methods (Stanton-KicksM, 1997) . The cost of SCS treatment is high (currently $ 3,660 per person per year in the United States), but it is still lower than other therapies, and because other methods are difficult to work, SCS has application value.

3. Equipment and treatment methods (1) Equipment is divided into fully implanted and semi-implanted. The former refers to the electrodes, wires and stimulator / receiver are buried in the body, and the controller placed outside the body emits pulsed RF signals. Control the subcutaneous stimulator so that it emits stimulation current. The latter means that only the electrodes are implanted in the body, the stimulator is carried on the body, and the two are connected by wires, so the wires are half inside the body and half outside the body. Current controllers and stimulators use integrated circuits, which are small in size but complete in function. Most are multi-channel and program-controlled. The most famous stimulators are the Medtronic-QUAD system and the ITREL- system. Unlike other low-frequency currents, which are mostly constant-current types, SCS systems are generally constant-voltage types.
Early electrodes were large and required laminotomy to be implanted. After continuous improvement, current electrodes have been various, such as catheter electrodes, bipolar electrodes, tripolar electrodes, and the like. The dual-channel three-pole or four-pole electrodes have more and more applications due to their wide output range of intensity (difference between sensory threshold and motor threshold), difficulty in displacement, greater current output, and easier control of abnormal skin sensations.
The shape of the electrode is slender. Generally, platinum-iridium alloy is used as the electrode material, and the outer surface is coated with epoxy resin insulating material. Multiple strands of platinum-iridium alloy wire are wound to make the electrode wire. The diameter of the wire is between 80 ~ 250 microns, and the tip is bare. 2.5 ~ 5.0mm is the electrode. The wire can also be wound with stainless steel wire, with a length of about 22.5cm. Bipolar electrodes The polarity of the two electrodes can be alternated.

(II) Treatment method 1. Electrode placement: The unipolar method only implants the stimulation electrode (cathode) into the spinal canal, and the other electrode is placed on the body surface. Bipolar and multipolar methods require all electrodes to be implanted in the spinal canal. In the past, surgical methods were used (sometimes it was necessary to remove the lamina and expand the spinal canal), but now the electrodes can be sent into the spinal canal by percutaneous puncture. The patient is lying prone or laterally. Under local anesthesia, a Touhy needle or a thick 18-gauge epidural puncture needle is inserted into the epidural space, and then the electrode is sent into the spinal canal along the puncture needle. Use the evoked potential and electrical stimulation (the muscles dominated by the stimulated spinal nerve should tremble) to determine the precise location of the electrode.
2. Parameter selection: similar to TENS. It is reported in the literature that most of the pain and peripheral vascular diseases use a wave width of 0.1 ~ 0.2ms, a frequency of 80 ~ 100Hz, and an intensity of 2 ~ 8V; for a neurogenic bladder, the frequency should be reduced to 10 ~ 50Hz and the wave width increased to 0.2 ~ 0.5ms.
It can be treated several times a day, tens of minutes to several hours each time. The patient carries a controller / stimulator with him and can be treated at any time.
3. Patient screening treatment (trial treatment): Before the permanent electrode is formally implanted, the patient is usually screened for 1 to 3 weeks. Catheter electrodes or monopolar electrodes (such as Itrel, Xtrel electrodes) are often used to adjust the appropriate parameters for treatment. If the patient is unacceptable or the effect is poor (less than 25% pain reduction, etc.), the SCS treatment is abandoned. Instead, a formal electrode is implanted. Only in this way can we reduce the incidence of treatment failure and complications and reduce the medical burden on patients. After screening treatment, about 10-20% of patients are not suitable for SCS treatment. RainowNG and others suggested that patients should be subjected to detailed various assessments and questionnaires (both physical and psychological) before SCS treatment, that is, preliminary screening, and patients who meet the selection criteria can be shortened to 1 to 3 days. Reduce complications such as infection.
4. Parameter adjustment and patient follow-up: In the first month after electrode implantation, the impedance in the spinal canal changes the most, and the required current intensity also changes greatly (AndersenC has tested it, and the range of change (+ 406% ~ -34%), the impedance is basically stable after 2 months. Therefore, patients should be followed up several times within 1 month after surgery. The treatment parameters should be adjusted appropriately, and the follow-up interval will be gradually extended.

Factors affecting side effects and side effects (1) Factors affecting side effects It has been reported that the efficacy of female patients is better than that of men, and the efficacy of upper limb and trunk pain is better than lower limb pain. Patients with mental (psychological) pain who did not receive psychotherapy had poor results. For lower extremity arterial obstructive disease, the effect of normal blood pressure (reduced pain, limb preservation rate) is significantly higher than that of hypertension.
(B) Side effects and complications Side effects of SCS treatment have been reported differently. The incidence rate is as high as 40%, but most of them are very light. Patients can tolerate the discomfort caused by electrodes and current stimulation.


V. Indications and contraindications (1) Other indications Intractable angina pectoris, low back pain, limb pain, limb ischemic disease, spinal cord injury, cerebrovascular accident, etc. that are ineffective and cannot or should not be treated surgically.
(2) Contraindications: Infected skin or pacemaker with implanted skin.