Variation of Finger Activation Patterns Post-stroke Through Non-invasive Nerve Stimulation (original) (raw)
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Exploration of Hand Grasp Patterns Elicitable Through Non-Invasive Proximal Nerve Stimulation
Scientific Reports, 2017
Various neurological conditions, such as stroke or spinal cord injury, result in an impaired control of the hand. One method of restoring this impairment is through functional electrical stimulation (FES). However, traditional FES techniques often lead to quick fatigue and unnatural ballistic movements. In this study, we sought to explore the capabilities of a non-invasive proximal nerve stimulation technique in eliciting various hand grasp patterns. The ulnar and median nerves proximal to the elbow joint were activated transcutanously using a programmable stimulator, and the resultant finger flexion joint angles were recorded using a motion capture system. The individual finger motions averaged across the three joints were analyzed using a cluster analysis, in order to classify the different hand grasp patterns. With low current intensity (<5 mA and 100 µs pulse width) stimulation, our results show that all of our subjects demonstrated a variety of consistent hand grasp patterns including single finger movement and coordinated multi-finger movements. This study provides initial evidence on the feasibility of a proximal nerve stimulation technique in controlling a variety of finger movements and grasp patterns. Our approach could also be developed into a rehabilitative/assistive tool that can result in flexible movements of the fingers. After an injury to the central nervous system, such as a stroke or a spinal cord injury, a majority of individuals have impairments in their ability to voluntarily activate their muscles, manifested as a weakness in both their upper and lower extremities 1-4. Among the different motor and sensory functions involved in daily activities, regaining hand grasp function is considered a top priority in improving the quality of life for individuals with paralysis 5. In order to help restore some of these lost hand functions, a wide variety of functional electrical stimulation (FES) techniques have been developed 6-8. However, the utility of FES has been limited due to several key factors. First, with electrical stimulation, motor units are believed to be recruited in a reverse physiological order, in that the large and fast-fatigable motor units are recruited earlier. Although other factors, such as the electrode location and the relative location of the motor points in the imposed electrical potential field, can also influence the recruitment order 9 , which can lead to random recruitment. Nevertheless, the control of graded muscle forces through stimulation tends to be difficult, and rapid fatigue onset is also common. Secondly, most of the stimulation approaches use a large diameter electrode pad placed on the skin surface in proximity to the innervation zones of the targeted muscles. These techniques can typically only access a limited number of muscles, most of which are superficial muscles 10. For example, most stimulation methods only target extrinsic finger muscles during the stimulation, which can lead to unnatural movement kinematics 11,12. The large size of the electrode pad also limits the selectivity of muscle activation, and therefore, the elicited movements are largely gross hand opening and closing, rather than dexterous finger movements. Lastly, in order to elicit functionally meaningful muscle forces, the delivered current intensity tends to be uncomfortably high. Various recent developments in FES techniques have sought to address these issues. For example, a spatially distributed multi-pad electrode grid has been used to distribute the stimulus current to different regions of the muscle belly 8,13,14. This approach has been shown to be able to delay muscle fatigue onset, reduce discomfort, and increase the selectivity of muscle activation. However, since the stimulation targets the motor points, the required current amplitude is still high (typically well above 10 mA). Alternatively, invasive procedures involving implantable electrodes with a direct interface to the peripheral nerves have also been developed 6,15,16. Specifically,
Stroke, 2000
Background and Purpose-After stroke, many individuals have chronic unilateral motor dysfunction in the upper extremity that severely limits their functional movement control. The purpose of this study was to determine the effect of electromyography-triggered neuromuscular electrical stimulation on the wrist and finger extension muscles in individuals who had a stroke Ն1 year earlier. Methods-Eleven individuals volunteered to participate and were randomly assigned to either the electromyographytriggered neuromuscular stimulation experimental group (7 subjects) or the control group (4 subjects). After completing a pretest involving 5 motor capability tests, the poststroke subjects completed 12 treatment sessions (30 minutes each) according to group assignments. Once the control subjects completed 12 sessions attempting wrist and finger extension without any external assistance and were posttested, they were then given 12 sessions of the rehabilitation treatment.
Somatosensory & motor research, 2014
Somatosensory stimulation modulates cortical and corticospinal excitability and consequently affects motor output. Therefore, low-amplitude transcutaneous electrical nerve stimulation (TENS) has the potential to elicit favorable motor responses. The purpose of the two presented pilot studies was to shed light on TENS parameters that are relevant for the enhancement of two desirable motor outcomes, namely, electromyographic (EMG) activity and contraction strength of the finger flexors and wrist muscles. In 5 and 10 healthy young adults (in Study I and Study II, respectively) TENS was delivered to the volar aspect of the forearm. We manipulated TENS frequency (150 Hz vs. 5 Hz), length of application (10, 20, and 60 min), and side of application (unilateral, right forearm vs. bilateral forearms). EMG amplitude and grip force were measured before (Pre), immediately after (Post), and following 15 min of no stimulation (Study I only). The results indicated that low-frequency bursts of TEN...
Brain Injury, 2013
Background: Electric stimulation (ES) has been recognized as an effective method to improve motor function to paralysed patients with stroke. It is important for ES to synchronize with voluntary movement. To enhance this coordination , the finger-equipped electrode (FEE) was developed. The purpose of this study was to evaluate FEE in improving motor function of upper extremities (UEs) in patients with chronic stroke. Methods and subjects: The study participants included four patients with chronic stroke who received FEE electronic stimulation (FEE-ES) plus passive and active training and three control patients who underwent training without FEE-ES. The patients were treated five times weekly for 4 weeks. UE motor function was evaluated before and after treatment using Fugl-Meyer Assessment (FMA) and Brunnstrom recovery staging. Results: The mean age of patients in each group was 60-years and there was a mean of 49 months since the onset of symptoms. All patients had severe UE weakness. The patients receiving FEE-ES had greater improvement in UE function than control patients (total, proximal and distal FMA, p < 0.05; Brunnstrom staging of UE, p < 0.05). Discussion: The results indicate that FEE-ES may be an effective treatment for patients with chronic stroke.
A multi-pad electrode based functional electrical stimulation system for restoration of grasp
Journal of NeuroEngineering and Rehabilitation, 2012
Background: Functional electrical stimulation (FES) applied via transcutaneous electrodes is a common rehabilitation technique for assisting grasp in patients with central nervous system lesions. To improve the stimulation effectiveness of conventional FES, we introduce multi-pad electrodes and a new stimulation paradigm. Methods: The new FES system comprises an electrode composed of small pads that can be activated individually. This electrode allows the targeting of motoneurons that activate synergistic muscles and produce a functional movement. The new stimulation paradigm allows asynchronous activation of motoneurons and provides controlled spatial distribution of the electrical charge that is delivered to the motoneurons. We developed an automated technique for the determination of the preferred electrode based on a cost function that considers the required movement of the fingers and the stabilization of the wrist joint. The data used within the cost function come from a sensorized garment that is easy to implement and does not require calibration. The design of the system also includes the possibility for fine-tuning and adaptation with a manually controllable interface.
2014 IEEE Global Humanitarian Technology Conference - South Asia Satellite (GHTC-SAS), 2014
Functional electrical stimulation applied via surface electrode can be used for hand rehabilitation particularly for enabling grasp in patients with stroke or spinal cord injury. The use of multi-pad electrode and multi-channel electrical stimulator based improve the effectiveness of conventional FES. Such a system consists of a multi-pad surface electrode and a matching multi-channel stimulator. This system will allow the targeting of motor neurons which activate muscle groups to produce corresponding functional movements of the hand. This paper presents our study on normal subjects to quantify the movement resulting from stimulation of electrodes spatially distributed around the forearm. The device was tested on four healthy subjects and the results show that multi-pad electrode provide desired amount of selectivity and can be used for generating functional grasp. The results also show that the effect of stimulation varies from person to person reflecting inters subject anatomical variability.
Neuromuscular electrical stimulation to augment reach and hand opening after stroke
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2011
Functional Electrical Stimulation (FES) may be able to augment functional arm and hand movement after stroke. However, neuroprostheses that combine voluntary effort and FES must take into account the co-contraction patterns (synergies) that are common across multiple joints. The goal of this study is to determine the principles under which voluntary effort and FES can be combined to achieve useful reach and hand opening. A reach and hand opening task is performed where different levels of voluntary effort and FES are applied to produce reach while measuring the level of hand opening that FES can produce at the hand. Initial results indicate that low levels of voluntary effort allow both greater reach and the largest hand opening response to FES.