Direct Electrical Nerve Stimulation Research Articles

Flexible Peripheral Nerve Interfacing Electrode for Joint Position Control in Closed-Loop Neuromuscular Stimulation.

Addressing peripheral nerve disorders with electronic medicine poses significant challenges, especially in replicating the dynamic mechanical properties of nerves and understanding their functionality. In the field of electronic medicine, it is crucial to design a system that thoroughly understands the functions of the nervous system and ensures a stable interface with nervous tissue, facilitating autonomous neural adaptation. Herein, we present a novel neural interface platform that modulates the peripheral nervous system using flexible nerve electrodes and advanced neuromodulation techniques. Specifically, we have developed a surface-based inverse recruitment model for effective joint position control via direct electrical nerve stimulation. Utilizing barycentric coordinates, this model constructs a three-dimensional framework that accurately interpolates inverse isometric recruitment values across various joint positions, thereby enhancing control stability during stimulation. Experimental results from rabbit ankle joint control trials demonstrate our model's effectiveness. In combination with a proportional-integral-derivative (PID) controller, it shows superior performance by achieving reduced settling time (less than 1.63 s), faster rising time (less than 0.39 s), and smaller steady-state error (less than 3 degrees) compared to the legacy model. Moreover, the model's compatibility with recent advances in flexible interfacing technologies and its integration into a closed-loop controlled functional neuromuscular stimulation (FNS) system highlight its potential for precise neuroprosthetic applications in joint position control. This approach marks a significant advancement in the management of neurological disorders with advanced neuroprosthetic solutions.

Long-term results following electrical stimulation of the peroneal nerve using the ActiGait® system in 33 patients with central drop foot.

ObjectiveDirect electrical stimulation of the peroneal nerve, using the implantable ActiGait® system, enables a therapy of the centrally caused drop foot, to improve the gait of the patients. In this paper, we present long-term results at 36-month follow-up post implantation.MethodA total of 33 patients, 27 stroke and six multiple sclerosis (MS) patients, suffering from spastic drop foot were implanted in our center and assessed in terms of gait endurance, speed, risk of fall, and life quality at baseline and 36 months following implantation.ResultsThe six min gait endurance test increased significantly from 202 ± 41 m without walking aids to 380 ± 30 m (p=0.038), while using the implant. Moreover, the time in the gait speed measured over 20 m decreased from 31.8 ± 10.2 s without to 18.5 ± 4.6 s by using the ActiGait® system (p=0.039). Similarly, gait steadiness, measured by the Timed Up and Go (TUG) test improved by 36.6%, with patients demonstrating a reduced time from 18.6 ± 5.5 to 11.2 ± 3.8 s (p=0.041) upon implant activation. Most importantly, 31 of 33 patients reported remarkable improvements of their quality of life following direct electrical nerve stimulation.ConclusionOur findings confirm previously published efficacy data at 12 months after implantation and underline the long-lasting effect of the ActiGait® system.

Tinnitus and cochlear implants

Objective Several published studies seem to confirm the clinical observation that cochlear implants (CI) have a suppressive effect on tinnitus in most CI users. The aim of this paper is to present our personal experiences on tinnitus improvement after cochlear implantation. Methods Before surgery, 51 post-lingually profoundly deaf adults, who underwent cochlear implantation between 2005 and 2007, filled out a questionnaire reporting tinnitus characteristics and the Italian version of the Tinnitus Handicap Inventory (THI-I). Moreover, they were asked to scale tinnitus loudness and annoyance. Six months after implant activation, patients repeated the same evaluations. Scores were statistically analysed by means of a Wilcoxon signed ranks test on the hypothesis that a CI could change the tinnitus magnitude and/or its annoyance. Results In our series of 36 patients, 36.10% reported total loudness suppression and another 41.6% reported a reduction. Annoyance scores reduced in 75% of patients. THI reduced in 72.2% of patients. Conclusion Tinnitus reduction after CI may manifest as several mechanisms, such as habituation, acoustic masking, direct electrical nerve stimulation and cortical reorganization. Nevertheless, it is our opinion that data on CI benefits on tinnitus should be interpreted with caution and it seems reasonable to admit that further data is still necessary before considering CI as a treatment of tinnitus especially in unilateral deafness.

Refining the sensory and motor ratunculus of the rat upper extremity using fMRI and direct nerve stimulation

It is well understood that the different regions of the body have cortical representations in proportion to the degree of innervation. Our current understanding of the rat upper extremity has been enhanced using functional MRI (fMRI), but these studies are often limited to the rat forepaw. The purpose of this study is to describe a new technique that allows us to refine the sensory and motor representations in the cerebral cortex by surgically implanting electrodes on the major nerves of the rat upper extremity and providing direct electrical nerve stimulation while acquiring fMRI images. This technique was used to stimulate the ulnar, median, radial, and musculocutaneous nerves in the rat upper extremity using four different stimulation sequences that varied in frequency (5 Hz vs. 10 Hz) and current (0.5 mA vs. 1.0 mA). A distinct pattern of cortical activation was found for each nerve. The higher stimulation current resulted in a dramatic increase in the level of cortical activation. The higher stimulation frequency resulted in both increases and attenuation of cortical activation in different regions of the brain, depending on which nerve was stimulated.

SOMATIC VERSUS SYMPATHETIC MEDIATED CHRONIC LIMB PAIN

It has been helpful in our practice to separate somatic from sympathetic-mediated peripheral nerve pain. We would recommend application of the new nomenclature of type I complex regional pain (sympathetic dystrophy) and type II complex regional pain (causalgia) (see Table 1). We believe it is essential that both of these conditions be separated into their early and late phases and that the treatment alternatives be customized for the individual patient and the peripheral nerve involved. If a cast, pin, or external fixation apparatus is associated with peripheral nerve pain, the offending apparatus must be removed immediately and other forms of treatment initiated for the underlying injury. For acute injury and postsurgical pain, narcotic pain medications should be used no longer than 72 hours and careful patient re-examination must be performed if pain persists. Prescription of narcotic pain medications on a continuing basis is often the primary reason for the development of chronic pain syndromes. Physical therapy for the patient with chronic peripheral limb pain must be performed in a pain-free environment. "No pain, no gain" does not apply in the treatment of chronic limb pain-rather the reverse: "Only gain with no pain." In differentiating between sympathetic pain and somatic pain, the use of the reflex sympathetic dystrophy (RSD) score can be helpful (Table 4). If the pain is somatic, treatment options include: Somatic Pain: Treatment Isolated nerve block Continuous nerve block TENS (external) Direct electrical nerve stimulation (internal) Nerve ablation If the pain is sympathetic in origin, treatments to be considered are: Sympathetic Nerve Pain: Treatment Protection of limb (garment or splint) Combine with active use Sympathetic blocks single continuous Sympathectomy In addition, the treatment of each of those conditions must be directed at the primary condition. Once the two conditions are separated, a careful program of pain management is required. In patients who present with late pain dysfunction, the more commonly observed phenomenon at our institution, the combination of physician, surgeon, and anesthesiologist is essential. The role of physical therapist in restoring function to the injured limb must be discussed and planned carefully. Initial pain management is organized through a qualified anesthesiologist dedicated to this field. Physical therapy follows but only in a pain-free environment. The surgeon's role is to assist and direct the pain management program. Surgeons can be involved in the placement of percutaneous catheters, as well as isolated peripheral nerve blocks. Surgical intervention is limited to the release of compressive neuropathies, nerve transfers, and revascularization of the peripheral nerve bed. The surgeon occasionally may be involved in the manipulation and pinning of contracted joints, as well as release of muscle or joint contractures, followed by a supervised program of early range of motion. Finally, it is important that both physician and surgeon serve as patient advocates when questions of workers' compensation intervene that could deter proper treatment programs or when the patient needs the encouragement and guidance to continue with treatments that don't always initially appear to have immediate results. Finally, requests to the surgeon to find an operative cure must be resisted while continued psychological encouragement is provided.

Chronic peripheral nerve pain treated with direct electrical nerve stimulation

Chronic somatic peripheral nerve pain was treated prospectively in 24 nonrandomized patients by a program of direct electrical nerve stimulation. Patients qualified for the program if anesthetic (lidocaine) nerve block of the involved cutaneous zone of the peripheral nerve relieved symptoms and transcutaneous electrical nerve stimulation transiently improved and did not exacerbate somatic pain. Results were judged according to a pain score. Patients noted improved sleep and complete absence of the need for narcotic pain medication. On the basis of subjective and objective criteria, 18 patients had good or excellent results and 6 had implant failures. Of the six patients with failures, three failed the trial period and did not have implantation, and three had no significant pain relief and were judged as treatment failures. Three patients had late equipment failure after initial good results. Most patients had some relief of pain, which increased their quality of life and eliminated the need for narcotic analgesia. Direct electrical nerve stimulation should be considered for somatic peripheral nerve pain that has not been ameliorated with other methods. It will reduce, although not necessarily eliminate, pain and pain behavior in most patients.