ABSTRACT
Ahead of Print article withdrawn by publisher.
ABSTRACT
PURPOSE: Functional electrical stimulation represents an alternative to conventional and passive ankle foot orthosis (AFO) for the treatment of stroke-related drop foot. We evaluated the implantable 4-channel stimulator ActiGait, which selectively and directly stimulates the peroneal nerve. In addition, it bypasses the need for surface electrodes and cables. METHODS: Walking speed (10-meter gait test, [m/s]) and walking endurance (6-minute gait test [m/6min]) of 5 patients were tested prior to, as well as 6 and 12 weeks after, the implantation of the ActiGait implantable drop foot stimulator system. In addition, ankle joint angles were assessed during specific phases of the gait cycle, i.e. initiation angle (IA) at the first contact of the foot to the floor, initial plantar flexion (IPF), dorsiflexion (DF) and final plantar flexion (FPF) in [°] during stance phase. The ankle joint angles were measured at baseline and 12 weeks after ActiGait implantation. RESULTS: At the first follow-up, patients' gait speed was found to have increased (0.55; 0.77 m/s) as had walking endurance (211; 260 m). Improvement in gait speed (0.55; 0.77 m/s) and endurance (214; 248 m) was still present after 12 weeks. In addition, gait analysis after 12 weeks revealed a nearly normal physiological initiation angle (113° vs 122°) and an increase in the initial plantar flexion (7° vs. 0°). The initiation angle (IA) represents a well-suited parameter for adequate pre-positioning of the foot at the beginning of the stance phase and is necessary to prevent stumbling and falling. Furthermore, IA is identical to the maximum achieved dorsiflexion during the swing phase of gait. Thus, analysis of the IA of subjects walking with the implantable drop foot stimulator systems ActiGait is particularly useful in showing that the implantable system restores the IA towards physiological ankle movements. CONCLUSION: The ActiGait system increased gait speed, walking endurance and the physiology of important ankle joint kinematics. This is most likely a result of ankle dorsiflexion by active peroneal stimulation during the swing phase of gait and optimized prepositioning (IA) of the foot at the beginning of stance phase. The ActiGait system represents a therapeutic option for the treatment of patients suffering drop foot due to a cerebrovascular insult.
Subject(s)
Ankle Joint/physiology , Electrodes, Implanted , Gait Disorders, Neurologic/physiopathology , Gait Disorders, Neurologic/therapy , Stroke/physiopathology , Stroke/therapy , Adult , Aged , Female , Follow-Up Studies , Humans , Longitudinal Studies , Male , Middle Aged , Movement/physiology , Prostheses and Implants , Treatment Outcome , Walking/physiologyABSTRACT
PURPOSE: EMG-triggered electrostimulation (EMG-ES) may improve the motor performance of affected limbs of hemiparetic stroke patients even in the chronic stage. This study was designed to characterize cortical activation changes following intensified EMG-ES in chronic stroke patients and to identify predictors for successful rehabilitation depending on disease severity. METHODS: We studied 9 patients with severe residual hemiparesis, who underwent 8 weeks of daily task-orientated multi-channel EMG-ES of the paretic arm. Before and after treatment, arm function was evaluated clinically and cortical activation patterns were assessed with functional MRI (fMRI) and/or transcranial magnetic stimulation (TMS). RESULTS: As response to therapy, arm function improved in a subset of patients with more capacity in less affected subjects, but there was no significant gain for those with Box & Block test values below 4 at inception. The clinical improvement, if any, was accompanied by an ipsilesional increase in the sensorimotor cortex (SMC) activation area in fMRI and enhanced intracortical facilitation (ICF) as revealed by paired TMS. The SMC activation change in fMRI was predicted by the presence or absence of motor-evoked potentials (MEPs) on the affected side. CONCLUSIONS: The present findings support the notion that intensified EMG-ES may improve the arm function in individual chronic hemiparetic stroke patients but not in more severely impaired individuals. Functional improvements are paralleled by increased ipsilesional SMC activation and enhanced ICF supporting neuroplasticity as contributor to rehabilitation. The clinical score at inception and the presence of MEPs have the best predictive potential.
