Spinal cord stimulation (epidural) and peripheral nerve stimulation (for example, occipital level, inguinal)
Neurostimulation uses small electrodes that are surgically placed under the skin to send electrical impulses to the nervous system (perceived as a pleasant tingling sensation). The electrical impulses block the pain signal so the pain is relieved. Since neurostimulation works in the area where pain signals travel, electrical impulses can be directed to cover the specific areas where you feel pain. Neurostimulation does not involve any medication, so the side effects that often accompany other treatments are minimal.
What is the degree of effectiveness of neurostimulation?
Le neurostimulation is an effective alternative to reoperations of the back.
Patients who have success with neurostimulation typically experience a 50-88 % reduction in pain and improvement in their ability to participate in everyday activities.
Neurostimulation may also reduce or even eliminate the need for additional pain medications and reoperations.
Components of a neurostimulation system:
A fully implantable neurostimulator is a programmable system. It consists of two distinct parts: the electrode and battery. Both sides are implanted inside the body during surgery. The battery is usually implanted under the skin of the abdominal area for discretion and comfort, but your doctor will choose the implant site as best suited to you. Your doctor will use a programmer to adjust the neurostimulation system to your needs in a way to effectively treat your pain.
This process does not require surgery. Is carried out by telemetry through the skin. Your take a controller, the size of a television remote control, allowing you to modify the stimulation received within limits previously set by your doctor. You can also use the programmer to cycle your neurostimulation system.
The neurostimulation device battery usually lasts between 2 and 5 years depending on the number of hours per day that the system is used and the intensity of stimulation (electrical impulses) . When it’s time to replace the battery, the doctor will remove the device in a minor surgery and replaced by a new one.
How can I know if neurostimulation works for me?
Depending on your condition, your doctor may decide to perform a test to help predict whether neurostimulation will relieve your pain. Neurostimulation testing can be performed as an outpatient procedure or the patient may be admitted for a short hospital stay.
How safe is neurostimulation?
Clinical research has shown that small electrical pulses administered by neurostimulation are safe and do not harm the nervous system. Similarly, it has been shown that the materials of which are made the implanted components are also safe.
Research has also shown that the complications associated with the implanted components are harmless and infrequent. Neurostimulation is reversible, which means that , if necessary , can be turned off or remove the system.
Are there any side effects or complications?
Side effects and complications associated with neurostimulation are rare and appear only on a very small number of patients. However, neurostimulation requires a surgical intervention, which always carries some risk. Among these are infections, bleeding and discomfort at the site of implantation. Unlike some drugs used to control pain, neurostimulation does not cause sonmnolencia, disorientation or nausea.
The most common adverse events that may be experienced with neurostimulation system itself include: lack of stimulation, resulting in a loss of pain relief due to electrode displacement or other causes; intermittent stimulation, stimulation in the wrong place, unpleasant stimulation, described by some patients as shock or discharge; allergic response to the system, problems with the developer or telemetry or threshold elevation (which is necessary to modify neurostimulation settings to achieve the same pain relief).
New applications of neurostimulation:
Peripheral subcutaneous stimulation
They can be used in cases such as occipital neuralgia, placed under the skin. This is a very simple procedure with good results.
Other applications include inguinal pain after hernia repair, persistent back pain in patients who had lumbar surgery or in pain from post herpetic neuralgia.
Sacral neuroestimulation (sacral nerve stimulation)
What is Sacral Neuromodulation?
Since its introduction in 1990s sacral neuromodulation (SNM), also known as sacral nerve stimulation (SNS), has proven to be a useful treatment of chronic dysfunction of the urinary, bowel and pelvic floor. The sacral nerve controls a person’s bladder, bowel and pelvic floor and the muscles related to their function. The device is implanted surgically and stimulates the sacral nerve with mild electrical pulses. It enables the person to perceive the sensation of bladder fullness and the desire to void. It also helps a patient to spontaneously and completely empty the bladder.
Who Will Benefit from Sacral Neuromodulation?
Patients with chronic urinary retention, voiding dysfunction, bowel dysfunction and chronic pain syndromes can benefit from this device. Indeed, it may be the only therapy available in some patient groups. In patients with chronic urinary retention, the only known forms of treatment are clean intermittent self-catheterization (CISC) or indwelling suprapubic/transurethral catheters. At times CISC can be a painful and traumatic process, and SNM offers an effective therapeutic alternative.
Principle of Sacral Neuromodulation
The sacral nerves serve the lower urinary tract. To activate or inhibit urinary tract reflexes, SNM delivers mild electrical impulses to the sacral nerves. Besides the local stimulation, neuromodulation also influences the higher centres of bladder control in the brain (known as Pontine micturition centre) although its mechanism is not yet clear.
Once good amounts of urine are passed spontaneously, the CISC pattern is changed to post-void only to check residual urine volume.
The test phase allows clinicians to judge how much a patient will benefit from a permanent SNM implant. The duration of this evaluation can be from 2 to 8 weeks. This time period also allows patients to learn how they will need to adapt their lifestyle and day-to-day work with the implant. If the evaluation is successful, patients will proceed to the 2nd stage procedure and implantation of the permanent indwelling battery.
Possible Problems – Stage 1
The possible problems with the stage 1 procedure can be:
- Pain at the wound site – the pain may radiate down the back, buttock and thigh to the toes. Occasionally, transient weakness of the leg has been reported.
- Lead breakages – the externalised lead must be handled carefully. If it is pulled, the permanent electrode may move, leading to pain or loss of sensation. If this happens and the provider is in agreement, the patient will need Stage 1 repeated. Patients must avoid high intensity sport and strenuous work such as lifting weights and stretching to prevent dislodging the electrode for at least 6 months.
- Change of Sensation The settings on the SNM may need to be adjusted if the sensation changes or disappears. The settings will be checked and position of the electrode will be confirmed by X-ray.
The second stage involves insertion of the permanent battery, which is connected to the previously implanted permanent electrode. The temporary lead coming out of the skin is removed during this procedure, which is usually performed under local anaesthesia with sedation.
Once the SNM is turned on, patients are expected to experience a similar sensation as described in the 1st Stage information, and positive bladder/bowel response should be sustained.
Patients receive a handheld programmer and device card to carry at all times in order to inform any hospital, doctor or dentist of the implant.
Appliances – Occasionally, household appliances such as refrigerators and audio speakers that have magnets may interfere with the SNM, which then may need to be restarted. Be aware that even if the SNM is turned off, nearby strong electrical gadgets can still affect the lead, which could result in a sudden and brief shock or jolt.
Sports & Exercise
In the first three months after the operation, providers recommend that patients avoid heavy lifting and strenuous exercises, especially with bending or twisting movements. After this recovery period implant users can do most forms of exercise such as swimming, running, aerobics etc. Horseback riding, skiing, and contact sport, however, seem to be associated with more lead or electrode breakage.
The effect of SNM on pregnancy is largely unknown. Therefore, it is advised that you must have your SNM turned OFF by the hospital if you are planning to start a family or as soon as you know that you are pregnant. Having an SNM does not mean that you need to have an elective caesarean section. The decision for any obstetric intervention remains with your designated obstetrician.
Medical applications of sacral neuromodulation
Chronic nonmalignant pain syndromes of the pelvis or genitourinary are well described in both the gynecology and urology literature, though the origin and physiology of the pain syndromes are not well understood. Patients frequently have multisystem complaints including voiding dysfunction, chronic pelvic pain, and genitourinary hypersensitivity. Both the patient’s history and physical examination can be a powerful diagnostic tool in unmasking a chronic pain disorder. However, laboratory and imaging studies often are unrevealing, with no physical cause for the pain disorder being identified. This can lead to frustration and depression in these patients, which may lead them to develop complex psychologic adaptive and maladaptive methods of coping with their pain as it affects their lives. Although there are numerous pain syndromes involving the pelvis or sacrum and urogenital tract, syndromes that have had good pain control outcomes with sacral neuromodulation are interstitial cystitis (IC), prostadynia or epididymo-orchalgia, vulvodynia, and coccydynia.
Interstitial cystitis is a chronic debilitating condition of the urinary bladder characterized by symptoms of dyspareunia, irritative urinary symptoms, and nocturia. The epidemiology of the disorder is not well established, but there are an estimated 700,000 cases of IC in the United States. It occurs primarily in women. Onset is predominately in adulthood, although IC does occur in childhood. The median age of onset is 40 years; however, there is a bimodal distribution with one peak in the twenties and a later one in the fifties. In general, patients suffer with the symptoms for 3 to 7 years before the correct diagnosis is made. Numerous pathophysiologic mechanisms have been proposed, but none have been proven.
Bladder wall defects, auto-immune disorder, viral or bacterial infection, toxin exposure, pelvic floor dysfunction, and inflammatory response are possible causes. An animal model, the naturally occurring disease in cats, may help to provide insight into the bladder response to injury. The feline interstitial cystitis follows a similar chronic waxing and waning time course as interstitial cystitis in humans.
The diagnosis is made clinically and by cystoscopy with hydrodistention and sometimes biopsy when other pathologies have been excluded. In symptomatic patients, glomerulations on bladder distension are indicative but not pathognomonic for nonulcerative interstitial cystitis. Patients with IC will often have characteristic findings on cystoscopic examination including small petechial hemorrhages called glomerulations, although the classic Hunter’s ulcer is seen in only about 10% of patients. Histologic examination of bladder biopsies from patients with long-standing interstitial cystitis reveal marked edema and injury to blood vessels and nerves within the muscularis layer, which are all consistent with the pathologic findings of neurogenic inflammation. The traditional nonsurgical management of interstitial cystitis includes dietary changes, antihistamines, tricyclic antidepressants, oral and intravesicle glucosaminoglycans, hydrodistention, pain management, and emotional support.
Prostadynia is defined as persistent complaints of urinary urgency, dysuria, poor urinary flow, and genital or perineal pain. The new classification of prostatitis syndromes by the National Institutes of Health clearly defines the diagnostic criteria for categorization according to the clinical symptoms. National Institutes of Health (NIH) consensus classification identifies chronic prostatitis or chronic pelvic pain syndrome (CP/CPPS) based on the presence or absence of leukocytes in expressed prostatic secretions (EPS), postprostatic massage urine (VB3), or seminal fluid analysis. In the United States, approximately 25% of men presenting with genitourinary tract problems are diagnosed with ‘‘prostatitis’’, and prostadynia accounts for approximately 30% of those cases. Up to 65% of patients with chronic prostatitis have the nonbacterial form. The disorder is seen in 5 of every 10,000 outpatient visits by men. On physical examination, the prostate is typically normal with no sign of tenderness on palpation. The diagnosis of prostadynia is one of exclusion. It has been suggested that prostadynia may be a male variant of interstitial cystitis and in fact represent different manifestations of the same disease process.
Vulvodynia is defined as chronic vulvar discomfort, characterized by the patient’s complaint of vulvar burning, itching, and dyspareunia. Greater than 50% of the time all therapeutic interventions tried by patients made the vulvar symptoms no better or worse. Although the true incidence of this disorder is unknown, reports have shown that as many as 15% of patients seen in a general gynecologic practice meet the criteria for this diagnosis. Currently there remains no universally established classification, assessment, and treatment for vulvodynia. Like most pelvic pain syndromes, the physical examination is often unremarkable.
However, histologic studies of vulvar biopsies show a chronic inflammatory reaction of the mucosa along with neural hyperplasia. These findings are similar to those seen in IC and are also consistent with neurogenic inflammation. There is a serious need for greater understanding of this disorder as the evidence suggests that, although not life-threatening, vulvodynia seems to have a significant impact on quality of life.
Coccydynia is defined as pain or discomfort in and around the coccyx, typically worsened when sitting and especially with rising from the sitting position. Apart from those patients with local trauma the cause of this pain disorder is not known.
Rarely lesions have been identified including hemangioma, intradural schwannoma, intra-osseous lipoma, although most cases are idiopathic.
This pain disorder can be significantly debilitating for patients and should be readily treated aggressively.