Selective neural electrical stimulation restores hand and forearm movements in individuals with complete tetraplegia.

BACKGROUND: We hypothesized that a selective neural electrical stimulation of radial and median nerves enables the activation of functional movements in the paralyzed hand of individuals with tetraplegia. Compared to previous approaches for which up to 12 muscles were targeted through individual muscular stimulations, we focused on minimizing the number of implanted electrodes however providing almost all the needed and useful hand movements for subjects with complete tetraplegia. METHODS: We performed acute experiments during scheduled surgeries of the upper limb with eligible subjects. We scanned a set of multicontact neural stimulation cuff electrode configurations, pre-computed through modeling simulations. We reported the obtained isolated and functional movements that were considered useful for the subject (different grasping movements). RESULTS: In eight subjects, we demonstrated that selective stimulation based on multicontact cuff electrodes and optimized current spreading over the active contacts provided isolated, compound, functional and strong movements; most importantly 3 out of 4 had isolated fingers or thumb flexion, one patient performed a Key Grip, another one the Power and Hook Grips, and the 2 last all the 3 Grips. Several configurations were needed to target different areas within the nerve to obtain all the envisioned movements. We further confirmed that the upper limb nerves have muscle specific fascicles, which makes it possible to activate isolated movements. CONCLUSIONS: The future goal is to provide patients with functional restoration of object grasping and releasing with a minimally invasive solution: only two cuff electrodes above the elbow. Ethics Committee / ANSM clearance prior to the beginning of the study (inclusion period 2016-2018): CPP Sud Méditerranée, #ID-RCB:2014-A01752-45, first acceptance 10th of February 2015, amended 12th of January 2016. TRIAL REGISTRATION: (www.clinicaltrials.gov): #NCT03721861, Retrospectively registered on 26th of October 2018.

Ultrasound-guided permanent implantation of peripheral nerve stimulation (PNS) system for neuropathic pain of the extremities: original cases and outcomes.

OBJECTIVE: Our objective is to describe our experience applying a minimally invasive, ultrasound-assisted technique for peripheral nerve stimulation (PNS) trial and permanent implantation in patients with neuropathic extremity pain. DESIGN: Retrospective case series and review of the literature. Setting. Tertiary referral center and academic medical center. PATIENTS: Patients with upper or lower extremity neuropathic pain resistant to other therapies who responded to an ultrasound-guided peripheral nerve block at a proximal location. Interventions. Ultrasound-assisted through-the-needle placement of percutaneous neurostimulation electrodes on target major peripheral nerves for fully percutaneous trial, staged trial or permanent implantation of PNS system. A PNS trial period of 3-7 days was used. OUTCOME MEASURES: Pain relief at last follow-up, complications, therapeutic limitations due to technique as applied. Results. Six of eight (75%) patients and 7/9 (78%) peripheral nerves had a successful trial and underwent permanent PNS system implantation using a minimally invasive, ultrasound-assisted technique from November 2007 to December 2008. All but one patient with an implanted PNS system had > or =50% pain relief at last follow-up and 3/7 (43%) permanent systems were associated with > or =80% relief. Loss of paresthesia required revision to dual-lead systems in upper extremity radial nerve PNS. Infection led to explant in one case. CONCLUSIONS: In a small series of patients, a minimally invasive, ultrasound-assisted technique for PNS trial, and permanent PNS implantation proved feasible. Patients without adequate analgesia during neurostimulation trial avoided surgical incision and those undergoing permanent implantation were not subjected to the potential morbidity associated with nerve dissection.

Muscle preservation using an implantable electrical system after nerve injury and repair.

The value of continuous electrical stimulation of denervated muscles after nerve injury and repair has been clearly shown in a series of laboratory experiments in three animal models. This experimental background, which showed improved muscle preservation and better functional results, evolved into a clinical study that included 15 patients with peripheral nerve injuries in the upper extremities, 3 patients with brachial plexus injuries, and three patients with facial nerve paralysis. Improved functional results were obtained using this implantable system, which were similar to those achieved with the animal experiments. All patients had muscle stimulation for extended periods ranging from 127 to 346 days. Analysis of the results showed satisfactory nerve regeneration on clinical examination and with electromyographic studies. Functional muscle analysis varied somewhat from patient to patient, but every patient had a satisfactory to excellent recovery. The results from this study have clearly shown the benefits of continuous muscle stimulation using an implantable electrical system after nerve injury and repair expansion of the project to a larger patient cohort is indicated.

A clinical pilot study to assess functional return following continuous muscle stimulation after nerve injury and repair in the upper extremity using a completely implantable electrical system.

This clinical pilot study evolved from a 10-year experience in the experimental laboratory using continuous muscle stimulation in a series of animal studies following nerve injury and microsurgical repair. A completely implantable system was developed (Medtronic) to provide electrical stimulation to the denervated muscles until nerve regeneration had occurred. Both peripheral nerve injuries in the extremities and facial nerve severances were studied, and a definite improvement in functional capacity was obtained as well as improved morphology compared with nonstimulated controls. In this study, 13 patients with peripheral nerve injuries in the upper extremity are included. All patients had muscle stimulation for extended periods until nerve regeneration was evident; a careful analysis of their functional capacity was then completed. There were five patients with median nerve injuries, four with ulnar nerve or combined median-ulnar nerve injuries, and four with severed radial nerves. All patients showed satisfactory nerve regeneration on clinical examination and electromyographic studies. Motor recovery was usually better than sensory return. Functional muscle analysis varied somewhat from patient to patient, but every patient had a satisfactory to excellent recovery. Patients with low nerve lesions had better results, but muscle recovery even in patients with mid-forearm or higher nerve injuries was most encouraging. Functional recovery in radial nerve injuries was close to normal in all cases. The results from this pilot study have clearly shown the benefits of continuous muscle stimulation using an implantable system following nerve injury and repair.