Spinal cord stimulation in chronic pain: a review of the evidence

This review looks at the evidence for the effectiveness of spinal cord stimulation in various chronic pain states. Spinal cord stimulation can only be effective when appropriate dorsal column fibres in the spinal cord are preserved and able to be stimulated. Spinal cord stimulation has been shown to have little to offer for patients with some diagnoses. Although 50 to 60% of patients with failed back surgery syndrome obtain significant pain relief with this technique, the strength of the evidence available is insufficient to clearly advocate its use in all patients with this condition. Though limited in quantity and quality, better evidence exists for its use in neuropathic pain, complex regional pain syndrome, angina pectoris and critical limb ischaemia. There is a lack of high quality evidence relating to spinal cord stimulation due to difficulties in conducting randomized controlled trials in this area. Serious methodological problems are encountered in blinding, recruitment and assessment in nearly all published trials of spinal cord stimulation. Suggestions regarding appropriate methodologies for trials which would produce better quality evidence are summarized.     

An analysis of 1505 consecutive patients receiving continuous interscalene analgesia at home: a multicentre prospective safety study

Continuous interscalene brachial plexus block has been shown to be the most effective analgesic technique following shoulder surgery; however, its use is uncommon due to logistical and safety concerns related to ambulatory administration. We prospectively studied 1505 consecutive patients undergoing shoulder surgery who received continuous interscalene analgesia at home. Catheter removal was by the patient between postoperative days two and five. There were no major complications although 27% of patients reported mild dyspnoea, 13% hoarseness and 7% dysphagia. Twelve percent sought medical advice and 2% reported technical issues with the pump or tubing. Complications and technical issues were associated with patient age; weight; use of ultrasound or concomitant nerve stimulation as the endpoint for final needle tip position; local anaesthetic placement via the catheter or needle; whether a catheter‐related intervention for pain relief was required in the recovery area; and the type of ambulatory pump. We conclude that this study supports the safety of this underused analgesic technique.     

应用显微外科及带蒂皮管技术一期修复尿道下裂(附254例报告)

目的　提高尿道下裂一期手术疗效。　方法　应用显微外科技术 ,选择带蒂皮管法一期修复尿道下裂 2 54例。　结果　一期手术成功率 90 .2 % ,其中 <1岁者成功率 1 0 0 % ,1岁～者94 5% ,3岁～者 89.6% ,>1 4岁者 76.5%。　结论　应用显微外科技术 ,选择适宜的手术方法 ,提早接受手术治疗的年龄 ,能明显提高尿道下裂一期成形术的成功率     

Remifentanil vs. alfentanil infusion in non-paralysed patients: a randomized, double-blind study

BACKGROUND AND OBJECTIVE: Remifentanil has a short duration of action and constant elimination, which allow administration of high doses, without prolonging recovery. Remifentanil has been compared to alfentanil, as part of a total intravenous anaesthetic technique, where remifentanil provided better anaesthetic conditions than alfentanil, without adverse effect on recovery. However, these results were obtained during anaesthesia involving neuromuscular blockade, which may mask both signs of insufficient anaesthesia and side-effects such as muscle rigidity. The aim of this study was to compare remifentanil with alfentanil for anaesthesia without neuromuscular blockade. METHODS: We performed a prospective, randomized, double-blind, four-centre study to compare remifentanil infusion 15 microg kg(-1) h(-1) and alfentanil infusion 60 microg kg(-1) h(-1), using a total intravenous technique for non-paralysed patients, and the laryngeal mask airway for airway management. We enrolled 192 patients, 18-65 yr of age with ASA I-II, undergoing minor surgery. The primary endpoint was the number of patients having pre-defined responses to surgical stimulation. A number of secondary criteria was evaluated to assess undesirable properties of the procedures. RESULTS: In the alfentanil group, 85% of patients responded to surgical stimulation, vs. 35% in the remifentanil group (P < 0.0001). No difference was found in recovery data, or in any other parameter than those related to insufficient anaesthesia. CONCLUSIONS: The remifentanil-based technique provided significantly better anaesthetic conditions than the alfentanil-based technique in the setting of this study, without causing any significant adverse effects.     

Electrical stimulation of the epidural space using a catheter with a removable stylet

BACKGROUND AND OBJECTIVES: Electrical stimulation can be used to verify the location of epidural catheters. With the traditional technique, the latter must be primed with saline to allow for electrical conduction: any air lock will, thus, hinder the flow of current. Therefore, we set out to explore an alternative mode of stimulation by use of a catheter containing a removable stylet. This study examines the reliability of this new technique. METHODS: In 71 patients undergoing surgery, a thoracic epidural catheter was inserted preoperatively. Loss of resistance was used to identify the epidural space. The TheraCath was introduced 5 cm into the space and connected to a neurostimulator via a 2-headed alligator clip. The intensity, pulse width, and level of myotomal contractions were recorded upon stimulation of the epidural space. A bolus of lidocaine was then injected and the patient assessed for sensory block to ice. RESULTS: The failure rate in proper epidural catheter placement was 8.5%. Epidural stimulation yielded a mean threshold of 1.90 +/- 1.80 nanocoulombs. A total of 37 catheters produced a unilateral muscular response; however, block to ice was bilateral. When compared with the ice test, the sensitivity, specificity, positive predictive value, and negative predictive value of epidural stimulation with the TheraCath were 92%, 83%, 98%, and 50%, respectively. CONCLUSION: We conclude that the TheraCath, because of the removable stylet, provides effective electrostimulation of the epidural space. Its use was simple and devoid of complications. Nonetheless, further studies are required before implementing its routine use in clinical settings.     

The usefulness of electrical stimulation for assessing pedicle screw placements

The purpose of this study was to further establish the efficacy of pedicle screw stimulation as a monitoring technique to avoid nerve root injury during screw placement. The study population consisted of 662 patients in whom 3,409 pedicle screws were placed and tested by electrical stimulation. If stimulation resulted in a myogenic response at a stimulation intensity of 10 mA or less, the placement of the screw was inspected. Inspection was necessary for 3.9% of the screw placements in 15.4% of the study population. None of the patients in the study experienced any new postoperative neurologic deficits. These findings provide guidelines for the interpretation of stimulation data and support the use of this technique as an easy, inexpensive, and quick method to reliably assess screw placements and protecting neurological function.     

A randomized controlled comparison of electro-acupoint stimulation or ondansetron versus placebo for the prevention of postoperative nausea and vomiting

In this study we evaluated the efficacy of electro-acupoint stimulation, ondansetron versus placebo for the prevention of postoperative nausea and vomiting (PONV). Patients undergoing major breast surgery under general anesthesia were randomized into active electro-acupoint stimulation (A), ondansetron 4 mg IV (O), or sham control (placement of electrodes without electro-acupoint stimulation; placebo [P]). The anesthetic regimen was standardized. The incidence of nausea, vomiting, rescue antiemetic use, pain, and patient satisfaction with management of PONV were assessed at 0, 30, 60, 90, 120 min, and at 24 h. The complete response (no nausea, vomiting, or use of rescue antiemetic) was significantly more frequent in the active treatment groups compared with placebo both at 2 h (A/O/P = 77%/64%/42%, respectively; P = 0.01) and 24 h postoperatively (A/O/P = 73%/52%/38%, respectively; P = 0.006). The need for rescue antiemetic was less in the treatment groups (A/O/P = 19%/28%/54%; P = 0.04). Specifically, the incidence and severity of nausea were significantly less in the A group compared with the other groups, and in the O group compared with the P group (A/O/P = 19%/40%/79%, respectively). The A group experienced less pain in the postanesthesia care unit, compared with the O and P groups. Patients in the treatment groups were more satisfied with their management of PONV compared with placebo. When used for the prevention of PONV, electro-acupoint stimulation or ondansetron was more effective than placebo with greater degree of patient satisfaction, but electro-acupoint stimulation seems to be more effective in controlling nausea, compared with ondansetron. Stimulation at P6 also has analgesic effects.     

Sacral nerve stimulation for faecal incontinence

Faecal incontinence is a common problem. Conservative measures are effective in a significant proportion of patients. Failure of conservative management has until recently meant recourse to surgical intervention. Surgical treatment is often associated with disappointing results. Recently, sacral nerve stimulation (SNS) has been developed as a minimally invasive, effective technique for idiopathic and acquired faecal incontinence. The technique uses chronic low-level electrical stimulation of the sacral nerves, or neuromodulation, to produce a clinically beneficial effect on the distal colon and rectum, the pelvic floor and the anal sphincter complex. SNS is a 2-stage procedure: a diagnostic stage - temporary percutaneous nerve evaluation (PNE), and a therapeutic stage - permanent SNS. The predictive value of PNE is high, and the surgical trauma and morbidity of both procedures extremely low. The technique has been adapted from its original application in urinary dysfunction. It is almost impossible to produce level 1 evidence for this type of intervention; however, the results are superior to other interventions. Patient selection criteria are evolving, but there is a growing body of evidence that supports its use as first-line treatment for faecal incontinence in patients where conservative measures have failed.     

Accuracy of intramuscular injection of botulinum toxin A in juvenile cerebral palsy: a comparison between manual needle placement and placement guided by electrical stimulation

Most clinicians who perform botulinum toxin A injections for children with cerebral palsy do so using the "free-hand" or manual technique without using radiologic or electrophysiologic guidance to aid needle placement. The objective of this study was to investigate the accuracy of manual needle placement compared with needle placement guided by electrical stimulation. A total of 1,372 separate injections for upper and lower limb spasticity were evaluated in 226 children with cerebral palsy. The accuracy of manual needle placement compared with electrical stimulation was acceptable only for gastroc-soleus (>75%); it was unacceptable for the hip adductors (67%), medial hamstrings (46%), tibialis posterior (11%), biceps brachii (62%), and forearm and hand muscles (13% to 35%). The authors recommend using electrical stimulation or other guidance techniques to aid accurate needle placement in all muscles except the gastroc-soleus. Further study is needed to determine whether more accurate injecting will lead to better functional outcomes and more efficient use of botulinum toxin A.     

Intérêt du monitoring électrophysiologique au cours d’une chirurgie éveillée en neurochirurgie

Brain tumor surgery is at risk when lesions are located in eloquent areas. The interindividual anatomo-functional variability of the central nervous system implies that brain surgery within eloquent regions may induce neurological sequelae. Brain mapping using intraoperative direct electrical stimulation in awake patients has been for long validated as the standard for functional brain mapping. Direct electrical stimulation inducing a local transient electrical and functional disorganization is considered positive if the task performed by the patient is disturbed. The brain area stimulated is then considered as essential for the function tested. However, the exactitude of the information provided by this technique is cautious because the actual impact of cortical direct electrical stimulation is not known. Indeed, the possibility of false negative (insufficient intensity of the stimulation due to the heterogeneity of excitability threshold of different cortical areas) or false positive (current spread, interregional signal propagation responsible for remote effects, which make difficult the interpretation of positive or negative behavioural effects) constitute a limitation of this technique. To improve the sensitivity and specificity of this technique, we used an electrocorticographic recording system allowing a real time visualization of the local. We provide here evidence that direct cortical stimulation combined with electrocorticographic recording could be useful to detect remote after discharge and to adjust stimulation parameters. In addition this technique offers new perspective to better assess connectivity of cerebral networks.     

Electrical stimulation as a strength improvement technique: a review

The dominant philosophy within rehabilitation has been that electrical stimulation is a valuable kinesthetic muscle reeducation technique, but voluntary exercise is of greater benefit in restoring voluntary muscular control and improving the strength of injured muscle. Much publicized Soviet research has suggested that this preference for voluntary exercise may be inappropriate and that electrical stimulation is the technique of choice for strengthening normally innervated muscle. This position has not been supported by the limited non-Soviet research. Whether this lack of support is attributable to an inability to duplicate the Soviet current format and/or application technique, or simply that electrical stimulation programs are not more effective than voluntary exercise programs, is presently unknown. To date, neither the voluntary exercise philosophy nor the nonvoluntary exercise (electrical stimulation) philosophy has overwhelming scientific support. Electrical stimulation programs must be compared with traditional voluntary exercise programs before practitioners are in a position to confidently accept or to refute either method. Until an adequate number of research studies have been conducted, practitioners cannot meet their obligation to know what the most effective strength improvement techniques are and to make such treatment available.J Orthop Sports Phys Ther 1982;4(2):91-98.     

Brain stimulation

Electrical stimulation in the PAG has been shown to elicit profound analgesia in experimental animals that is at least in part due to the release of endogenous opioid substances. Electrical stimulation in the thalamic nuclei VPL and VPM inhibits the activation of spinal dorsal horn neurons by noxious stimuli. Acute electrical stimulation in these two targets relieves chronic pain in about 80% of patients. Chronic electrical stimulation by permanently implanted electrodes relieves pain in about 70% of patients with pain of peripheral or nociceptive origin but in only about 50% of patients with central pain resulting from deafferentation. Stimulating electrodes are implanted stereotactically by a burr hole under local anesthesia. Transient complications occur in 15% to 25% of patients and include infections, malfunctions of the stimulating hardware, pain at the implant sites, and mild temporary neurologic deficits. Permanent complications, including hemiparesis, intracranial hemorrhage, and death, occur in 1% to 2% of patients. Brain stimulation is recommended for the treatment of chronic pain in patients in whom other forms of treatment have failed. The technique is reasonably safe and provides pain relief for a group of patients who have exhausted all other therapeutic modalities. Unfortunately, not all patients receive effective pain relief with brain stimulation. Other stimulation targets such as the K-F nucleus in the parabrachial region of the brain stem are currently being explored in an attempt to provide pain relief to a greater proportion of patients. In addition, improvements in stimulation hardware have made the technique easier and more effective.     

Electrical stimulation for stress incontinence

Electrical stimulation has been reported to be effective for stress incontinence, cure and improvement rates being reported to range from 30% to 50%, and from 6% to 90%, respectively. However, clinical application of this treatment is not common because there is little physiological and technical information. Electrodes for electrical stimulation are divided into two types: external (non-implantable) and internal (implantable), and there are two methods of stimulation: chronic (long-term, continuous) and short-term. Frequencies of 20–50 Hz, with a pulse duration of 1–5 ms, have been reported to be effective for urethral closure. The effectiveness of the treatment should be verified with placebo-controlled double-blinded trials, and four such studies using an active and a sham device have been reported. Two of these verified the superiority of the active device over the sham device, but the others did not demonstrate any significant difference between the two with regard to efficacy. Electrical stimulation has been reported to result in a long-term continuation of therapeutic effect. The effect has been explained as a re-education or a reactivation of lost functions of the pelvic floor muscles. As to adverse effects, there may be some complications in relation to anesthesia or surgical procedures, such as infection, pain and bleeding with implantable electrodes. The incidence of adverse effects in short-term electrical stimulation is less than 14%. In conclusion, short-term electrical stimulation using non-implantable anal or vaginal electrodes is the most recommendable because of safety and ease of use.     

Treatment of nonunion with a constant direct current: a totally implantable system

There is now sufficient basic research and clinical experience to establish that electrical stimulation produces osteogenesis. Furthermore, electrical stimulation significantly helps union where impaired bone healing exists. The implanted bone growth stimulator is one effective method of electrical stimulation. It can be used in a wide variety of problems: delayed union and nonunion of bones with or without chronic infection and in failed posterior spinal fusion. Successful treatment of congenital pseudarthrosis of the tibia has been encouraging. The implanted bone growth stimulator technique requires a simple operation with strict adherence to detail. There is minimal postoperative discomfort and a short hospital stay. The average time to union is 16 weeks. The Osteostim can be used in the presence of chronic infection and internal fixation. Above all, the technique does not require any cooperation from the patient. The implanted bone growth stimulator should be accepted as a method of treatment for delayed and nonunion of bones, as it is at least as effective as other more conventional methods of surgical treatment for this situation. It has been proved that electrical stimulation produces osteogenesis. Orthopedic surgeons should no longer be skeptical about this.     

Expanding the surgical indication to the cases with high risk valve diseases

Four hundred and fifty eight cases of valve surgery were performed at this institution over the past 7 years, during which the surgical indication has been gradually expanded to cases of three types. The first type is serious disease complicated by cardiac cachexia; in these cases, in addition to the aggressive use of IABP, we also use the intrapulmonary artery balloon pumping (IPBP) technique we developed. IVH therapy for two months before surgery has been especially effective and given good results to cases with low liver function and low respiratory function. The second type consists of cases necessitating special surgical technique, for example, cases with very narrow valvular annuli and cases complicated by acute endocarditis. Good results have been obtained in the former with a new technique that we developed, called "Coupling Valve Grafting", and in the latter with a technique of "Collared Prosthesis". The third type is elderly patients aged 70 years or more. In particular, the greatest problem now seems to lie in low liver function of which ICG (15 min) is higher than 40% and total serum bilirubin is over 3 mg/dl; in these cases, progression to MOF is frequent and the patient's life is saved in only 40% of cases.     

Management of Chronic Cluster Headache

Primary cluster headache (CH) is an excruciatingly severe pain condition. Several pharmacologic agents are available to treat chronic CH, but few double-blind, randomized clinical trials have been conducted on these agents in recent years, and the quality of the evidence supporting their use is often low, particularly for preventive agents. We recommend sumatriptan or oxygen to abort ongoing headaches; the evidence available to support their use is good (Class I). Ergotamine also appears to be an effective abortive agent, on the basis of experience rather than trials. We consider verapamil and lithium to be first-line preventives for chronic CH, although the trial evidence is at best Class II. Steroids are clearly the most effective and quick-acting preventive agents for chronic CH, but long-term steroid use carries a risk of several severe adverse effects. We therefore recommend steroids only if verapamil, lithium, and other preventive agents are ineffective. In rare cases, patients experience multiple daily cluster headaches for years and are also refractory to all medications. These patients almost always develop severe adverse effects from chronic steroid use. Such patients should be considered for neurostimulation. Occipital nerve stimulation is the newest and least invasive neurostimulation technique and should be tried first; the evidence supporting its use is encouraging. Hypothalamic stimulation is more invasive and can be performed only in specialist neurosurgical centers. Published experience suggests that about 60% of patients with chronic CH obtain long-term benefit with hypothalamic stimulation.     

Optically mediated nerve stimulation: Identification of injury thresholds

BACKGROUND AND OBJECTIVE: Transient optical nerve stimulation is a promising new non-contact, spatially precise, artifact-free neural excitation technique useful in research and clinical settings. This study evaluates safety of this pulsed infrared laser technique by histopathologic examination of stimulated peripheral nerves. STUDY DESIGN/MATERIALS AND METHODS: Exposed rat sciatic nerves were functionally stimulated with the pulsed Holmium:YAG laser, previously validated as an effective tool for optical stimulation. Nerves were removed immediately and up to 2 weeks after stimulation and assessed histologically for thermal damage. Laser parameters studied include upper limits for radiant exposure, repetition rate, and duration of stimulation. RESULTS: Radiant exposures with <1% probability of thermal tissue damage (0.66-0.70 J/cm(2)) are significantly greater than radiant exposures required for reliable stimulation (0.34-0.48 J/cm(2)). The upper limit for safe laser stimulation repetition rate occurs near 5 Hz. Maximum duration for constant low repetition rate stimulation (2 Hz) is approximately 4 minutes with adequate tissue hydration. CONCLUSION: Results confirm that optical stimulation has the potential to become a powerful non-contact clinical and research tool for brief nerve stimulation with low risk of nerve thermal damage.     

Multicenter trial of a noninvasive stimulation method for idiopathic scoliosis. A summary of early treatment results

Lateral electrical surface stimulation (LESS) for the treatment of idiopathic scoliosis has been applied to 548 patients by 54 principal investigators in North America and Western Europe. The purpose of the multicenter investigation was to determine whether this noninvasive stimulation technique alone is a viable alternative to bracing in routine clinical use. Only patients with rapidly progressing scoliosis and at least one year of growth remaining were included in the study. When stimulation was applied, a pretreatment curvature progression rate of 1 degree/month reversed to a reduction rate of 0.5 degrees/month over the initial 6 months of treatment. The longest follow-up in treatment was 51 months, and the mean time in treatment was 12 months. At the time of this analysis, 72% of the patients had either reduced or stabilized their scoliosis. Thirteen percent (13%) of the patients had experienced temporary progression with subsequent stabilization and treatment continuation. Progression resulted in termination of 15% of the patients from the program. The final treatment result at skeletal maturity was maintained posttreatment.     

Ergebnisse der sakralen Neuromodulation bei Therapie der überaktiven Blase

Currently, sacral nerve modulation (SNM) is an effective treatment for overactive bladder symptoms which are refractory to anticholinergic or muscarinergic treatment. However, SNM requires the implantation of stimulation electrodes at the sacral nerves and a subcutaneous impulse generator. The SNM procedure can be divided into three phases: the acute phase comprising the implantation of the test stimulation electrodes, the subchronic stimulation phase over a period of 7-14 days during which neurostimulation takes place by means of an external impulse generator, and finally chronic SNM after implantation of the final impulse generator.In 1981 the SNM technique for treatment of bladder dysfunctions was first developed by Tanagho and Schmidt and has since been refined, while the range of indications has been extended continuously. It has been shown that patients with neurogenic bladder dysfunctions are able to gain the greatest benefit from SNM. The long-term results of SNM are very encouraging so far. In addition, a highly innovative and promising technique is the implantation of a miniaturized impulse generator with integrated stimulation electrode at the n. pudendus. However, the outcome of these trials has not fully been capable of living up to the expectations so far.