Spinal cord stimulation and limb ischemia: Neurophysiological mechanisms involved in pain relief

Summary   Background: Spinal cord stimulation is a spin-off of the well-known “Gate Control Theory of Pain” presented byMelzack undWall in 1965. However, up to now very little is known about the mechanisms behind the beneficial effects. Methods: Several different mechanisms are activated by spinal cord stimulation. The present state of knowledge is reviewed. Results: The “Gate Control Theory of Pain” comprehends a model in which the nociceptive unmyelated afferents are inhibited by stimulation of non-nociceptive myelinated afferents. Although the concept of this theory is not longer tenable in all its aspects, the idea remains unchanged. At present, several hypotheses are discussed: a simple blocking of pain transmission by a direct effect on the spinothalamic tracts, activation of descending inhibitory pathways, segmental inhibition via coarse fibre activation and brain stem loops to thalamocortical mechanisms, long-term suppression of the sympathic activity and antidromic effects on peripheral reflex circuits and the release of neurotransmitters. Conclusions: Several different mechanisms are activated by spinal cord stimulation. Further research is necessary to increase knowledge of the neurophysiological and neurochemical changes activated by stimulation.      

骨科术后护理应用经皮神经电刺激缓解疼痛及其对止痛药物用量的影响

目的研究经皮神经电刺激(TENS)对于骨科老年患者手术后不同程度疼痛的治疗效果、能否减少术后镇痛药的使用量及其护理配合。方法选择65例接受骨科开放式手术的老年患者(年龄65岁)为研究对象并分成两组,接受TENS治疗组(TENS组,34例),没有接受TENS治疗组(对照组,31例)。所有患者术后两天接受患者自控镇痛,使用视觉模拟评分(VAS)评估术后止痛药需求和疼痛强度变化,记录镇痛相关副作用的发生。结果 TENS治疗组术后24小时和48小时,芬太尼的消耗量低于非TENS治疗组(P0.05)。同样TENS治疗组的阿片类药物相关副作用明显少于非TENS治疗组;应急用药次数减少。少数患者出现轻微皮肤症状。结论应用TENS治疗加上相应适当的护理可以减少老年骨折患者术后镇痛需求,易操作、无创伤,可作为一辅助的减少患者疼痛的处理方法。     

Transcutaneous nerve stimulation for pain relief in labour

Transcutaneous nerve stimulation (TNS) was asessed for use on thirty-five patients in labour. It was of great benefit to 20% of patients and some benefit to a total of 82%. It was especially appreciated by those patients who complained of backache and further studies should be undertaken with the original idea of TNS in mind--stimulating those areas which feel most painful for the patient. If the method could be made more universally available and could be used by patients and midwives alone with the minimum of supervision and explanation, it would be a safe and useful addition to the present methods of pain relief in labour.     

团体活动式延续护理对慢性阻塞性肺疾病患者自我效能的影响

目的 通过实施团体活动式的延续护理,以提高社区慢性阻塞性肺疾病（COPD）患者自我效能.方法 随机抽取长沙市某社区21例稳定期COPD患者为观察组,另外抽取另一社区20例稳定期COPD患者为对照组.对照组入组后由社区医护人员给予一般健康教育,发放课题组编制的COPD自我管理知识手册.观察组在此基础上接受每周1次、每次约60 min的团体活动式延续护理,共8周.结果 观察组观察期间平均住院次数、住院天数与总费用显著低于对照组;干预结束和干预后6个月自我效能得分显著高于对照组（P＜0.05,P＜0.01）.结论 团体活动式延续护理可以改善社区COPD患者的自我效能感,减少患者住院次数及医疗费用.     

Spinal cord stimulation for relief of abdominal pain in two patients with familial Mediterranean fever

Familial Mediterranean fever is a hereditary disease characterizedby recurrent attacks of fever and serosal inflammation thatcommonly presents as severe abdominal pain. Though colchicineremains the mainstay of treatment, a significant proportionof patients are partially responsive, unresponsive or intolerantto it. We present two such cases where spinal cord stimulation(SCS) was used to manage the paroxysmal abdominal pain associatedwith this disease. Abdominal visceral pain pathways and theapplication of SCS techniques in its management are discussed.     

Transcutaneous electrical nerve stimulation: an effective treatment for pain caused by renal colic in emergency care

PURPOSE: Acute renal colic is one of the most anguishing forms of pain in humans. We hypothesized that TENS is an effective pain treatment in patients with acute renal colic. MATERIALS AND METHODS: A total of 100 patients with acute flank pain and suspected renal colic consented to participate in our study. Paramedic 1 recorded baseline parameters at the emergency site and at the end of transportation. Paramedic 2 performed TENS in patients randomly assigned to G1 with actual TENS or to G2 with sham TENS. Pain and anxiety were measured using paper based visual analog scales on a scale of 0 to 100 mm. RESULTS: Of 100 screened patients 73 had renal colic, including 39 in G1 and 34 in G2. There was no significant difference with regard to potentially influencing factors, such as patient age, sex, weight, height, blood pressure and heart rate, pain, nausea and anxiety between the groups before treatment. G1 showed a significant mean pain decrease +/- SD of more than 50% (85.7 +/- 10.5 to 33.3 +/- 16.0 mm, p <0.01). G2 showed no variation in mean pain scores (85.8 +/- 18.0 to 82.6 +/- 14.3 mm). G1 showed changes in the mean anxiety score (69.0 +/- 8.4 to 37.7 +/- 15.1 mm, p <0.01), nausea score (90.7 +/- 9.2 to 44.9 +/- 22.0 mm) and heart rate (92 +/- 10 to 64 +/- 8 bpm), while G2 showed nonsignificant changes. CONCLUSIONS: This trial shows that local TENS is a rapid and effective treatment for renal colic pain. We found TENS to be a good nondrug therapy under the difficult circumstances of out of hospital rescue.     

Tramadol for pain relief in children undergoing tonsillectomy: a comparison with morphine

BACKGROUND: Pain control for paediatric patients undergoing tonsillectomy remains problematic. Tramadol is reported to be an effective analgesic and to have a side-effect profile similar to morphine, but is currently not licensed for paediatric use in the UK. METHODS: We conducted a prospective, double-blind, randomized controlled trial in children who were scheduled for elective tonsillectomy or adenotonsillectomy at the Royal Aberdeen Children Hospital. Following local ethics committee approval and after obtaining a drug exemption certificate from the Medicines Licensing Agency for an unlicensed drug, we recruited 20 patients each into morphine (0.1 mg.kg(-1)), tramadol (1 mg.kg(-1)) and tramadol (2 mg.kg(-1)) groups. These drugs were given as a single injection following induction of anaesthesia. In addition, all patients received diclofenac (1 mg.kg(-1)) rectally. The postoperative pain scores, analgesic requirements, sedation scores, signs of respiratory depression and nausea and vomiting, as well as antiemetic requirements, were noted at 4-h intervals until discharge. RESULTS: There were no statistically significant differences in age, weight, type of operation or induction of anaesthesia, 4-h sedation and pain scores and further analgesic requirements. There were no episodes of respiratory depression. Morphine was associated with a significantly higher incidence of vomiting following discharge to the wards (75% versus 40%, P=0.03) compared with both tramadol groups. CONCLUSIONS: Tramadol has similar analgesic properties, when compared with morphine. The various pharmaceutical presentations and the availability as a noncontrolled substance may make it a useful addition to paediatric anaesthesia if it becomes licensed for paediatric anaesthesia in the UK.     

Spinal cord stimulation in complex regional pain syndrome: cervical and lumbar devices are comparably effective

Background. Spinal cord stimulation (SCS) has been used since1967 for the treatment of patients with chronic pain. However,long-term effects of this treatment have not been reported.The present study investigated the long-term effects of cervicaland lumbar SCS in patients with complex regional pain syndrometype I. Methods. Thirty-six patients with a definitive implant wereincluded in this study. A pain diary was obtained from all patientsbefore treatment and 6 months and 1 and 2 years after implantation.All patients were asked to complete a seven-point Global PerceivedEffect (GPE) scale and the Euroqol-5D (EQ-5D) at each post-implantassessment point. Results. The pain intensity was reduced at 6 months, 1 and 2years after implantation (P<0.05). However, the repeatedmeasures ANOVA showed a statistically significant, linear increasein the visual analogue scale score (P=0.03). According to theGPE, at least 42% of the cervical SCS patients and 47% of thelumbar SCS patients reported at least ‘much improvement’.The health status of the patients, as measured on the EQ-5D,was improved after treatment (P<0.05). This improvement wasnoted both from the social and from the patients’ perspective.Complications and adverse effects occurred in 64% of the patientsand consisted mainly of technical defects. There were no differencesbetween cervical and lumbar groups with regard to outcome measures. Conclusion. SCS reduced the pain intensity and improves healthstatus in the majority of the CRPS I patients in this study.There was no difference in pain relief and complications betweencervical and lumbar SCS. Br J Anaesth 2004; 92: 348–53     

Testing of a new pneumatic device to cause pain in humans

Background. Surgical pain typically combines superficial anddeep pain. We wished to generate pain that resembled surgicalpain, reliably and reproducibly, in volunteers. Methods. We constructed a computer-controlled pneumatic deviceto apply pressure to the anterior tibia. The reproducibilityof the pain was tested by rating the pressure that caused painrated 4–5 on a visual analogue scale (VAS) on days 0,7, and 24 in 10 volunteers. The effect of remifentanil (0.025,0.05, 0.075, and 0.1 µg kg^–1 min^–1) on paintolerance in another set of volunteers (n=11) was used as anindirect measure of the reliability of pain production. Results. The pressure needed (0.7 (0.3) to 0.9 (0.4) atm (mean(SD)) to induce pain rated 4–5 (VAS) did not vary, showinglong-term reproducibility of the method. When pressure was appliedto cause increasing pain in volunteers (n=11) 0.05 µgkg^–1 min^–1 remifentanil increased pain toleranceby 50%. An approximate doubling of the dose (0.1 µg kg^–1min^–1) increased pain tolerance significantly more. Thelinear logarithmic dose-effect relationship shows that the devicecauses pain reliably, and this can be reduced with opioid treatment. Conclusion. This pneumatic device can apply pain reliably andreproducibly. Br J Anaesth 2004; 92: 532–5     

Suppression of bladder overactivity by activation of somatic afferent nerves in the foot

What’s known on the subject? and What does the study add? It is known that electrical stimulation of the sacral root, pudendal nerve, or tibial nerve can inhibit bladder overactivity. These stimulation methods require surgery or repeated clinical visits that are expensive and inconvenient. This study shows for the first time that electrical stimulation of the foot can suppress bladder overactivity. Stimulation of the foot is non‐invasive, easily accessible, and convenient, which could be a widely acceptable treatment for bladder overactivity.

OBJECTIVE

To investigate the possibility of suppressing bladder overactivity by electrical activation of somatic afferent nerves in the foot.

MATERIALS AND METHODS

Cats with an intact spinal cord were studied under α‐chloralose anaesthesia. Bladder pressure was recorded via a urethral catheter. Foot stimulation was applied via surface pad electrodes attached to the skin of the front or hind foot.

RESULTS

Reflex micturition was inhibited by electrical stimulation of the hind foot at either low (5 Hz) or high (20 Hz) frequencies, but stimulation of the front foot was ineffective. The mean (sem ) bladder capacity during a saline infusion cystometrogram (CMG) was significantly (P < 0.05) increased to 153.2 (18.2)% and 136.9 (14.3)% of the control bladder capacity by stimulation at frequencies of 5 Hz and 20 Hz, respectively. Intravesical infusion of 0.25% acetic acid (AA) induced bladder overactivity and reduced bladder capacity to 20.3 (8.9)% of the control capacity measured during saline infusion. Foot stimulation inhibited the AA‐induced bladder overactivity recorded under isovolumetric conditions, and significantly (P < 0.05) increased bladder capacity during AA infusion. However, it only restored the small bladder capacity caused by AA irritation to 40–50% of the control bladder capacity measured during saline infusion. The effect of foot stimulation did not persist after termination of stimulation during repeated CMG tests.

CONCLUSIONS

This study shows the potential of noninvasive transcutaneous electrical stimulation of somatic nerves in the foot to inhibit reflex bladder activity and treat overactive bladder symptoms.     

A comparison of intramuscular tenoxicam with intramuscular morphine for pain relief following tonsillectomy in children

A double blind trial was conducted to evaluate the analgesic efficacy of intramuscular tenoxicam for pain relief following tonsillectomy in children. Fifty children, aged 3–10 years, were randomly allocated to receive intramuscular tenoxicam 0.75 mg·kg^?1 or intramuscular morphine sulphate 0.2 mg·kg^?1 after induction of anaesthesia. Although the tenoxicam group required significantly more postoperative morphine (mean 57.8 μg·kg^?1 compared with 26.9 μg·kg^?1, P=0.025), the total morphine dose was significantly reduced after tenoxicam (57.8 μg·kg^?1 compared with 226.9 ug·kg^?1, P<0.0001). There was no difference between the quality of analgesia after discharge from recovery. The incidence of postoperative vomiting was significantly reduced after tenoxicam (20%) compared with morphine (71%).     

Concentration-dependent suppression of F-waves by sevoflurane does not predict immobility to painful stimuli in humans

Background. Decreased spinal excitability contributes to theimmobilizing effects of halogenated ethers during general anaesthesia.Recurrent spinal responses such as F-waves reflect spinal excitabilityand are suppressed by volatile anaesthetics. To evaluate whetherF-waves are suitable for monitoring immobility, the concentration-dependenteffects of sevoflurane on F-waves were compared with effectson the Bispectral Index^TM (BIS^TM). The predictive power of allparameters for movement responses to noxious stimuli was tested.In addition, the effect of the noxious stimulus itself on F-waveswas investigated. Methods. In 28 patients, F-waves were recorded during sevofluraneanaesthesia at a frequency of 0.2 Hz at the lower limb. To inserta laryngeal mask, the sevoflurane concentration was initiallyincreased to     

生物反馈和电刺激联合治疗慢性前列腺炎/慢性骨盆疼痛综合征

目的:通过临床试验的方法,探讨生物反馈和电刺激联合治疗慢性前列腺炎/慢性骨盆疼痛综合征(CP/CPPS)的效果。方法:收集湘雅医院门诊诊断为CP/CPPS符合研究标准患者140例。将患者随机分为对照组、生物反馈组、电刺激组和生物反馈加电刺激组;对照组20例,生物反馈组、电刺激组和生物反馈加电刺激组各40例。采用Laborie-Urostym生物反馈电刺激治疗仪,生物反馈组行生物反馈治疗,电刺激组行电刺激治疗,生物反馈加电刺激组行生物反馈电刺激治疗;每周5次,连续2周;对照组不予上述治疗,随诊1个月。治疗前后进行NIH-CPSI评分以及尿流率检查。结果:生物反馈组、电刺激组和生物反馈加电刺激组治疗后NIH-CPSI疼痛与不适评分、NIH-CPSI排尿症状评分、NIH-CPSI生活质量评分、NIH-CPSI总评分、最大尿流率较治疗前均有显著改善(P<0.05);治疗前各组积分及最大尿流率比较无显著差异(P>0.05);治疗后上述参数生物反馈组、电刺激组比较没有显著差异(P>0.05),生物反馈加电刺激组与生物反馈组、电刺激组比较有显著差异(P<0.05)。而对照组治疗前后的以上各组评分及最大尿流率比较无显著差异(P>0.05)。结论:生物反馈和电刺激治疗能明显改善CP/CPPS患者疼痛与不适症状,排尿症状,提高生活质量,以及提高最大尿流率。生物反馈和电刺激联合治疗CP/CPPS有协同作用。     

电刺激治疗腰椎间盘突出下肢放射痛的前瞻性研究

目的 电刺激对腰椎间盘突出症下肢放射痛症状的病人进行治疗,观察电刺激对下肢放射痛症状的缓解情况.方法 2005年6月-2006年8月在经过预试验确定样本量后,将28名确诊腰椎间盘突出症并有下肢放射痛症状的病人随机分为试验、对照两组,单盲状态下,进行只存在有无电刺激差别,其余状态都一样的治疗.我们以达到50%下肢放射痛缓解率的天数为衡量标准.结果 试验组天数明显短于对照组,并且差异有统计学意义.结论 电刺激对缓解腰椎间盘突出症引起的下肢放射痛症状有效.     

Activation of healing and reduction of pain by single-use automated microcurrent electrical stimulation therapy in patients with hard-to-heal wounds

Evidence shows that Electrical Stimulation Therapy (EST) accelerates healing and reduces pain, but EST has yet to become widely used. One reason is the historical use of complex, clinic-based EST devices. This evaluation assessed the early response of different hard-to-heal wounds to a simple, wearable, single-use, automated microcurrent EST device (Accel-Heal, Accel-Heal Technologies Limited - Hever, UK). Forty wounds (39 patients: 18 female - 21 male), mean age 68.9 ± 14.0 years comprised of: seven post-surgical, three trauma, 12 diabetic foot (DFU), 10 venous (VLU), four pressure injuries (PI), four mixed venous or arterial ulcers (VLU/arterial) received automated microcurrent EST for 12 days. Early clinical responses were scored on a 0–5 scale (5-excellent—0-no response). Pain was assessed at 48 h, seven days, and 14 days on a 0–10 visual analogue scale (VAS). Overall, 78% of wounds showed a marked positive clinical response (scores of 5 and 4). Sixty eight percent of wounds were painful with a mean VAS score of 5.5. Almost every patient (96%) with pain experienced reduction within 48 h. All patients with painful wounds experienced pain reduction after seven days: 2.50 VAS (45% reduction) and further pain reduction after 14 days: 1.83 VAS (33%).     

The suppression of spinal F-waves by propofol does not predict immobility to painful stimuli in humans

Background. The immobilizing effects of volatile anaestheticsare primarily mediated at the spinal level. A suppression ofrecurrent spinal responses (F-waves), which reflect spinal excitability,has been shown for propofol. We have assessed the concentration-dependentF-wave suppression by propofol and related it to the logisticregression curve for suppression of movement to noxious stimuliand the effect on the bispectral index^TM (BIS^TM). The predictivepower of drug effects on F-waves and BIS for movement responsesto noxious stimuli was tested. Methods. In 24 patients anaesthesia was induced and maintainedwith propofol infused by a target controlled infusion pump atstepwise increasing and decreasing plasma concentrations between0.5 and 4.5 mg litre^–1. The F-waves of the abductor hallucismuscle were recorded at a frequency of 0.2 Hz. BIS values wererecorded continuously. Calculated propofol concentrations andF-wave amplitude and persistence were analyzed in terms of apharmacokinetic–pharmacodynamic (PK/PD) model with a simplesigmoid concentration–response function. Motor responsesto tetanic electrical stimulation (50 Hz, 60 mA, 5 s, volarforearm) were tested and the EC_50tetanus was calculated usinglogistic regression. Results. For slowly increasing propofol concentrations, computerfits of the PK/PD model for the suppression by propofol yieldeda median EC₅₀ of 1.26 (0.4–2.3) and 1.9 (1.0–2.8)mg litre^–1 for the F-wave amplitude and persistence, respectively.These values are far lower than the calculated EC₅₀ for noxiouselectrical stimulation of 3.75 mg litre^–1. This differenceresults in a poor prediction probability of movement to noxiousstimuli of 0.59 for the F-wave amplitude. Conclusions. F-waves are almost completely suppressed at subclinicalpropofol concentrations and they are therefore not suitablefor prediction of motor responses to noxious stimuli under propofolmono-anaesthesia. Presented in part at the annual meeting of the American Societyof Anesthesiologists 2004 in Las Vegas.     

Postoperative pain relief by topical lidocaine in the surgical wound of hysterectomized patients

Background: To improve postoperative analgesia, local anesthetics have been administered perioperatively as infiltration or as aerosol in the surgical area. A previous study showed good analgesic effects by topical lidocaine in the wound in minor extraabdominal surgery (herniorraphy), while the same treatment in minor lower laparotomies did not improve postoperative analgesia. The present study investigated the effect of topical wound anesthesia using lidocaine aerosol on postoperative pain following major lower abdominal surgery.
Methods: Postoperative pain and analgesic requirements were studied in a double-blind randomized trial including 30 hysterectomized patients. Patients were randomized to receive single wound treatment either with lidocaine aerosol 500 mg (100 mg/ml; Xylocain® aerosol, ASTRA, Sweden) (n=15) or placebo aerosol (n=15). Postoperative pain was evaluated by visual analogue scale (VAS). Requirements of opiate analgesics (buprenorphine) after surgery were monitored.
Results: Lidocaine aerosol induced a significantly ( P <0.001) better analgesia at rest (VAS) and a significant ( P <0.001) reduction in postoperative requirements of buprenorphine during the first 24 hours after surgery compared to placebo aerosol. Differences between the groups in pain scores (VAS) and buprenorphine requirements during the second postoperative day were not significant. Mean pain scores upon mobilization 24 h after surgery were significantly lower in the group receiving lidocaine aerosol ( P <0.05). The plasma lidocaine concentration 4 h after the administration of lidocaine was well below toxic level and plasma lidocaine was detectable 48 h postoperatively. No drug-related side effects were reported.
Conclsuion: A single dose of lidocaine aerosol topically administered in the surgical wound of hysterectomy patients improved analgesia during the first postoperative day with minimal risk of side effects.     

控制性降压联合穴位电刺激对术后认知功能障碍的影响

目的：探讨七氟烷麻醉下以硝酸甘油行控制性降压联合穴位电刺激对术后认知功能障碍的影响。方法：选择ASAⅠ～Ⅲ级,45～65岁行单节段腰椎切开复位内固定手术患者75例,随机分为穴位刺激联合硝酸甘油控制性降压组（T组,n=36）及单纯硝酸甘油控制性降压组（N组,n=39）,分别给予相应的治疗。结果：术后1、3dT组术后认知功能障碍发生率较N组明显降低（P〈0.05,P〈0.01）;5d发生率两组无显著差异（P〉0.05）。术后各时间点两组患者血清S-100β浓度均较术前升高（P〈0.05,P〈0.01）。术后1、3dT组血清S-100β较N组明显减低（P〈0.05,P〈0.01）,术后5d两组无显著差异。结论：七氟烷麻醉下行控制性降压联合经皮穴位电刺激可降低术后认知功能障碍的发生率。