Millimetric devices for nerve stimulation:a promising path towards miniaturization

Nerve stimulation is a rapidly developing field,demonstrating positive outcomes across several conditions.Despite potential benefits,current nerve stimulation devices are large,complicated,and are powered via implanted pulse generators.These facto rs necessitate invasive surgical implantation and limit potential applications.Reducing nerve stimulation devices to millimetric sizes would make these interventions less invasive and facilitate broader therapeutic applications.However,device miniaturization presents a serious engineering challenge.This review presents significant advancements from several groups that have overcome this challenge and developed millimetricsized nerve stimulation devices.These are based on antennas,mini-coils,magneto-electric and optoelectronic materials,or receive ultrasound power.We highlight key design elements,findings from pilot studies,and present several considerations for future applications of these devices.

Sacral neuromodulation and peripheral nerve stimulation in patients with anal incontinence:an overview of techniques,complications and troubleshooting

Sacral neuromodulation(SNM)therapy has revolutionized the management of many forms of anal incontinence,with an expanded use and a medium-term efficacy of 75%overall.This review discusses the technique of SNM therapy,along with its complications and troubleshooting and a discussion of the early data pertaining to peripheral posterior tibial nerve stimulation in incontinent patients.Future work needs to define the predictive factors for neurostimulatory success,along with the likely mechanisms of action of their therapeutic action.

Pulsed electrical stimulation protects neurons in the dorsal root and anterior horn of the spinal cord after peripheral nerve injury

Most studies on peripheral nerve injury have focused on repair at the site of injury, but very few have examined the effects of repair strategies on the more proximal neuronal cell bodies. In this study, an approximately 10-mm-long nerve segment from the ischial tuberosity in the rat was transected and its proximal and distal ends were inverted and sutured. The spinal cord was subjected to pulsed electrical stimulation at T10 and L3, at a current of 6.5 m A and a stimulation frequency of 15 Hz, 15 minutes per session, twice a day for 56 days. After pulsed electrical stimulation, the number of neurons in the dorsal root ganglion and anterior horn was increased in rats with sciatic nerve injury. The number of myelinated nerve fibers was increased in the sciatic nerve. The ultrastructure of neurons in the dorsal root ganglion and spinal cord was noticeably improved. Conduction velocity of the sciatic nerve was also increased. These results show that pulsed electrical stimulation protects sensory neurons in the dorsal root ganglia as well as motor neurons in the anterior horn of the spinal cord after peripheral nerve injury, and that it promotes the regeneration of peripheral nerve fibers.

Effect of low-frequency pulse percutaneous electric stimulation on peripheral nerve injuries at different sites

BACKGROUND： The postoperative recovery of nerve function in patients with peripheral nerve injury is always an important problem to solve after treatment. The electric stimulation induced electromagnetic field can nourish nerve, postpone muscular atrophy, and help the postoperative neuromuscular function. OBJECTIVE： To observe the effects of low-frequency pulse percutaneous electric stimulation on the functional recovery of postoperative patients with peripheral nerve injury, and quantitatively evaluate the results of electromyogram （EMG） examination before and after treatment. DESIGN ： A retrospective case analysis SETTING： The Sixth People＇s Hospital affiliated to Shanghai Jiaotong University PARTICIPANTS： Nineteen postoperative inpatients with peripheral nerve injury were selected from the De- partment of Orthopaedics, the Sixth People＇s Hospital affiliated to Shanghai Jiaotong University from June 2005 to January 2006, including 13 males and 6 females aged 24-62 years with an average of 36 years old. There were 3 cases of brachial plexus nerve injury, 3 of median nerve injury, 7 of radial nerve injury, 3 of ul- nar nerve injury and 3 of common peroneal nerve injury, and all the patients received probing nerve fiber restoration. Their main preoperative manifestations were dennervation, pain in limbs, motor and sensory disturbances. All the 19 patients were informed with the therapeutic program and items for evaluation. METHODS： ① Low-frequency pulse percutaneous electric stimulation apparatus： The patients were given electric stimulation with the TERESA cantata instrument （TERESA-0, Shanghai Teresa Health Technology, Co., Ltd.）. The patients were stimulated with symmetric square waves of 1-111 Hz, and the intensity was 1.2-5.0 mA, and it was gradually adjusted according to the recovered conditions of neural regeneration following the principle that the intensity was strong enough and the patients felt no obvious upset. They were treated for 4- 24 weeks, 10-30 minutes for each time, 1-3 times a day, and 6 weeks as a course. ② EMG examination was applied to evaluate the recoveries of recruitment, motor conduction velocity （MCV） and sensory conduction velocity （SCV） before and after treatment. The patients were examined with the EMG apparatus （DIS- A2000C, Danmark） before and after the treatment of percutaneous electric stimulation. ③Standards for evaluating the effects included cured （complete recovery of motor functions, muscle strength of grade 5, no abnormality in EMG examination）, obviously effective [general recovery of motor function, muscle strength of grade 4, no or a few denervation potentials, motor conduction velocity （MCV） and sensory conduction velocity （SCV）], improved （partial recovery of motor function, muscle strength of grade 3, denervation potentials and reinneration potentials, slowed MCV and SCV, invalid （no obvious changes of motor function）. MAIN OUTCOME MEASURES： ① Ameliorated degree of the nerve function of the postoperative patients with peripheral nerve injury treated with percutaneous electric stimulation; ② Changes of EMG examination before and after treatment. RESULTS： All the 19 postoperative patients with peripheral nerve injury were involved in the analysis of results. ① Comparison of nerve function before and after treatment in 19 patients with peripheral nerve injury of different sites： For the patients with radial nerve injury （n=7）, the nerve functions all completely recovered after 8-week treatment, and the cured and obvious rate was 100% （7/7）; For the patients with brachial plexus nerve injury （n=3）, 1 case had no obvious improvement, and the cured and obvious rate was 67% （2/3）; For the patients with common peroneal nerve injury （n=3）, the extension of foot dorsum generally recovered in 1 case of nerve contusion after 4-week treatment, and the cured and obvious rate was 67% （2/3）; For the patients with median nerve injury （n=3）, muscle strength was obviously recovered, and the cured and obvious rate was 100% （3/3）; For the patients with ulnar nerve injury （n=3）, 1 case only had recovery of partial senses, and the cured and obvious rate was 67% （2/3）. Totally 9 cases were cured, 7 were obviously effective, 1 was improved, and only 2 were invalid. After 4 courses, the cured rate of damaged nerve function after four courses was 47% （9/19）, and effective rate was 89% （17/19）.② Comparison of EMG examination before and after treatment： Before and after percutaneous electric stimulation, he effective rates of recruitment, MCV and SCV were 89% （17/19）, 58% （11/19）, 47% （9/19） respectively, and there were extremely obvious differences （P〈 0.01）. CONCLUSION： ①Low-frequency pulse percutaneous electric stimulation can improve the nerve function of postoperative patients with peripheral nerve injury of different sites, especially that the injuries of radial nerve and median nerve recover more obviously. ②Percutaneous electric stimulation can ameliorate the indexes of EMG examination, especially the recruitment, in postoperative patients with peripheral nerve injury.

Delayed peripheral nerve repair: methods, including surgical ‘cross-bridging' to promote nerve regeneration

Despite the capacity of Schwann cells to support peripheral nerve regeneration, functional recovery after nerve injuries is frequently poor, especially for proximal injuries that require regenerating axons to grow over long distances to reinnervate distal targets. Nerve transfers, where small fascicles from an adjacent intact nerve are coapted to the nerve stump of a nearby denervated muscle, allow for functional return but at the expense of reduced numbers of innervating nerves. A 1-hour period of 20 Hz electrical nerve stimulation via electrodes proximal to an injury site accelerates axon outgrowth to hasten target reinnervation in rats and humans, even after delayed surgery. A novel strategy of enticing donor axons from an otherwise intact nerve to grow through small nerve grafts（cross-bridges） into a denervated nerve stump, promotes improved axon regeneration after delayed nerve repair. The efficacy of this technique has been demonstrated in a rat model and is now in clinical use in patients undergoing cross-face nerve grafting for facial paralysis. In conclusion, brief electrical stimulation, combined with the surgical technique of promoting the regeneration of some donor axons to ‘protect＇ chronically denervated Schwa nn cells, improves nerve regeneration and, in turn, functional outcomes in the management of peripheral nerve injuries.

Ultrasound guidance for brachial plexus block decreases the incidence of complete hemi-diaphragmatic paresis or vascular punctures and improves success rate of brachial plexus nerve block compared with peripheral nerve stimulator in adults

Background The use of traditional techniques （such as landmark techniques, paresthesia and peripheral nerve stimulator） for upper-limb anesthesia has often been restricted to the expert or enthusiast, which was blind. Recently, ultrasound （US） has been applied to differ blood vessel, pleura and nerve, thus may reduce the risk of complications while have a high rate of success. The aim of this study was to determine if the use of ultrasound guidance （vs. peripheral nerve stimulator, （PNS）） decreases risk of vascular puncture, risk of hemi-diaphragmatic paresis and risk of Homer syndrome and improves the success rate of nerve block. Methods A search strategy was developed to identify randomized control trials （RCTs） reporting on complications of US and PNS guidance for upper-extremity peripheral nerve blocks （brachial plexus） in adults available through PubMed databases, the Cochrane Central Register of Controlled Trials, Embase databases, SinoMed databases and Wanfang data （date up to 2011-12-20）. Two independent reviewers appraised eligible studies and extracted data. Risk ratios （OR） were calculated for each outcome and presented with 95% confidence intervals （CI） with the software of Review Manager 5.1.0 System （Cochrane Library）. Results Sixteen trials involving 1321 adults met our criteria were included for analysis. Blocks performed using US guidance were more likely to be successful （risk ratio （RR） for block success 0.36, 95% CI 0.23-0.56, P 〈0.00001）, decreased incidence of vascular puncture during block performance （RR 0.13, 95% CI 0.06-0.27, P 〈0.00001）, decreased the risk of complete hemi-diaphragmatic paresis （RR 0.09, 95% CI 0.03-0.52, P=-0.0001）. Conclusions US decreases risks of complete hemi-diaphragmatic paresis or vascular puncture and improves success rate of brachial plexus nerve block compared with techniques that utilize PNS for nerve localization. Larger studies are needed to determine whether or not the use of US can decrease risk of neurologic complications.

Review on Tactile Sensory Feedback of Prosthetic Hands for the Upper-Limb Amputees by Sensory Afferent Stimulation

Loss of sensory function for upper-limb amputees inevitably devastates their life qualities, and lack of reliable sensory feedback is the biggest defect to sophisticated prosthetic hands, greatly hindering their usefulness and perceptual embodiment. Thus, it is extremely necessary to accomplish an intelligent prosthetic hand with effective tactile sensory feedback for an upper-limb amputee. This paper presents an overview of three kinds of existing sensory feedback approaches, including cutaneous mechanical stimulation(CMS), transcutaneous electrical nerve stimulation(TENS) and direct peripheral nerve electrical stimulation(DPNES). The emphasis concentrates on major scientific achievements, advantages and disadvantages. The TENS on the skin areas with evoked finger sensation(EFS) at upper-limb amputees' residual limbs might be one of the most promising approaches to realize natural sensory feedback.