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OBJECTIVE: Direct 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. METHOD: A 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. RESULTS: The 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. CONCLUSION: Our findings confirm previously published efficacy data at 12 months after implantation and underline the long-lasting effect of the ActiGait® system.

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BACKGROUND: Central drop foot is a common problem in patients with stroke or multiple sclerosis (MS). For decades, it has been treated with orthotic devices, keeping the ankle in a fixed position. It has been shown recently that semi-implantable functional electrical stimulation (siFES) of the peroneal nerve can lead to a greater gait velocity increase than orthotic devices immediately after being switched on. Little is known, however, about long-term outcomes over 12 months, and the relationship between quality of life (QoL) and gait speed using siFES has never been reported applying a validated tool. We provide here a report of short (3 months) and long-term (12 months) outcomes for gait speed and QoL. METHODS: Forty-five consecutive patients (91% chronic stroke, 9% MS) with central drop foot received siFES (Actigait®). A 10 m walking test was carried out on day 1 of stimulation (T1), in stimulation ON and OFF conditions, and repeated after 3 (T2) and 12 (T3) months. A 36-item Short Form questionnaire was applied at all three time points. RESULTS: We found a main effect of stimulation on both maximum (p < 0.001) and comfortable gait velocity (p < 0.001) and a main effect of time (p = 0.015) only on maximum gait velocity. There were no significant interactions. Mean maximum gait velocity across the three assessment time points was 0.13 m/s greater with stimulation ON than OFF, and mean comfortable gait velocity was 0.083 m/s faster with stimulation ON than OFF. The increase in maximum gait velocity over time was 0.096 m/s, with post hoc testing revealing a significant increase from T1 to T2 (p = 0.012), which was maintained but not significantly further increased at T3. QoL scores showed a main effect of time (p < 0.001), with post hoc testing revealing an increase from T1 to T2 (p < 0.001), which was maintained at T3 (p < 0.001). Finally, overall absolute QoL scores correlated with the absolute maximum and comfortable gait speeds at T2 and T3, and the increase in overall QoL scores correlated with the increase in comfortable gait velocity from T1 to T3. Pain was reduced at T2 (p < 0.001) and was independent of gait speed but correlated with overall QoL (p < 0.001). CONCLUSIONS: Peroneal siFES increased maximal and comfortable gait velocity and QoL, with the greatest increase in both over the first three months, which was maintained at one year, suggesting that 3 months is an adequate follow-up time. Pain after 3 months correlated with QoL and was independent of gait velocity, suggesting pain as an independent outcome measure in siFES for drop foot.

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OBJECTIVE: Neurogenic drop foot is a common result of acquired damage of the central nervous system and can cause severe restriction of mobility. ActiGait, an implantable functional electrical stimulation device, restores ankle dorsiflexion by active peroneal nerve stimulation. The aim of our study was to evaluate its effect on foot contact pattern during normal walk. METHODS: Eight patients with drop foot who used ActiGait in everyday life performed a 20-meter comfortable walk test. Gait parameters were evaluated with an insole system (Medilogic). Percentage of biped stance in a double-step, effective foot length, width of gait, and overall plantar load were measured in comparison with and without activated drop foot stimulation. RESULTS: Effective foot length increased in all patients on average from 46.0% to 60.2% (P = 0.038). However, percentage of biped stance in a double-step showed no significant difference (31.2% vs. 27.8% on average, P = 0.063), nor did width of gait (2.6% vs. 2.4% on average, P = 0.73) and overall plantar load (3.51 N/cm2 vs. 3.39 N/cm2, P = 0.25). CONCLUSION: The ActiGait implantable drop foot stimulator significantly improves effective foot length during normal walk of patients with neurogenic drop foot. Further investigation is needed to confirm whether ActiGait has no effect on the other parameters or whether it facilitates permanent gait adaptations that persist without the activated device.

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BACKGROUND: Recent studies have shown that stimulation of the peroneal nerve using an implantable 4-channel peroneal nerve stimulator could improve gait in stroke patients. OBJECTIVES: To assess structural cortical and regional cerebral metabolism changes associated with an implanted peroneal nerve electrical stimulator to correct foot drop related to a central nervous system lesion. METHODS: Two stroke patients presenting a foot drop related to a central nervous system lesion were implanted with an implanted peroneal nerve electrical stimulator. Both patients underwent clinical evaluations before implantation and one year after the activation of the stimulator. Structural magnetic resonance imaging (MRI) and [18F]-fluorodeoxyglucose-positron emission tomography (FDG-PET) were acquired before and one year after the activation of the stimulator. RESULTS: Foot drop was corrected for both patients after the implantation of the stimulator. After one year of treatment, patient 1 improved in three major clinical tests, while patient 2 only improved in one test. Prior to treatment, FDG-PET showed a significant hypometabolism in premotor, primary and supplementary motor areas in both patients as compared to controls, with patient 2 presenting more widespread hypometabolism. One year after the activation of the stimulator, both patients showed significantly less hypometabolism in the damaged motor cortex. No difference was observed on the structural MRI. CONCLUSION: Clinical improvement of gait under peroneal nerve electrical stimulation in chronic stroke patients presenting foot drop was paralleled to metabolic changes in the damaged motor cortex.

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OBJECTIVE Direct stimulation of the peroneal nerve by the ActiGait implantable drop foot stimulator is a potent therapy that was described previously for stroke-related drop foot. The authors report here successful long-term application of the ActiGait implantable drop foot stimulator in patients with multiple sclerosis (MS). METHODS Six patients with MS and 2 years of persisting central leg paresis received an implantable ActiGait drop foot stimulator after successful surface test stimulation. Ten weeks and 1 year after surgery, their gait speed, endurance, and safety were evaluated. Patient satisfaction was assessed with a questionnaire. RESULTS In the 20-m gait test, stimulation with the ActiGait stimulator significantly reduced the time needed, on average, by approximately 23.6% 10 weeks after surgery, and the time improved further by 36.3% after 1 year. The median distance covered by patients with the stimulator after 6 minutes of walking increased significantly from 217 m to 321 m and remained stable for 1 year; the distance covered by patients after surface stimulation was 264 m. Patients with an implanted ActiGait stimulator noticed pronounced improvement in their mobility, social participation, and quality of life. CONCLUSIONS The ActiGait implantable drop foot stimulator improved gait speed, endurance, and quality of life in all patients over a period of 1 year. It may serve as a new therapeutic option for patients with MS-related drop foot.

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OBJECT The ActiGait drop foot stimulator is a promising technique for restoration of lost ankle function by an implantable hybrid stimulation system. It allows ankle dorsiflexion by active peroneal nerve stimulation during the swing phase of gait. In this paper the authors report the outcome of the first prospective study on a large number of patients with stroke-related drop foot. METHODS Twenty-seven patients who experienced a stroke and with persisting spastic leg paresis received an implantable ActiGait drop foot stimulator for restoration of ankle movement after successful surface test stimulation. After 3 to 5 weeks, the stimulator was activated, and gait speed, gait endurance, and activation time of the system were evaluated and compared with preoperative gait tests. In addition, patient satisfaction was assessed using a questionnaire. RESULTS Postoperative gait speed significantly improved from 33.9 seconds per 20 meters to 17.9 seconds per 20 meters (p < 0.0001), gait endurance from 196 meters in 6 minutes to 401 meters in 6 minutes (p < 0.0001), and activation time from 20.5 seconds to 10.6 seconds on average (p < 0.0001). In 2 patients with nerve injury, surgical repositioning of the electrode cuff became necessary. One patient showed a delayed wound healing, and in another patient the system had to be removed because of a wound infection. Marked improvement in mobility, social participation, and quality of life was confirmed by 89% to 96% of patients. CONCLUSIONS The ActiGait implantable drop foot stimulator improves gait speed, endurance, and quality of life in patients with stroke-related drop foot. Regarding gait speed, the ActiGait system appears to be advantageous compared with foot orthosis or surface stimulation devices. Randomized trials with more patients and longer observation periods are needed to prove the long-term benefit of this device.

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A drop foot occurs in up to 20% of stroke patients and leads to an increased risk of falls. Until recently, only a foot orthosis or surface stimulation was able to improve the gait of these patients. Recent studies have shown that direct peroneal nerve stimulation with an implantable 4-channel peroneal nerve stimulator (ActiGait) allows independent electrode adjustment and leads to better functional results and an improved quality of life. The application of this therapeutic option is restricted to patients with a drop foot attributable to a lesion of the first motor neuron caused by stroke, multiple sclerosis, or tumors. In this paper, we present the first technical note with possible pitfalls of the surgical procedure and the perioperative care after implantation of ActiGait drop foot stimulators in 50 patients.

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