Wearable hip-assist robot modulates cortical activation during gait in stroke patients: a functional near-infrared spectroscopy study

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Wearable hip-assist robot modulates cortical activation during gait in stroke patients: a functional near-infrared spectroscopy study

• Su-Hyun Lee,
• Hwang-Jae Lee,
• Youngbo Shim,
• Won Hyuk Chang,
• Byung-Ok Choi,
• Gyu-Ha Ryu &
• Yun-Hee Kim 

Journal of NeuroEngineering and Rehabilitation volume 17, Article number: 145 (2020) Cite this article

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Abstract

Background

Gait dysfunction is common in post-stroke patients as a result of impairment in cerebral gait mechanism. Powered robotic exoskeletons are promising tools to maximize neural recovery by delivering repetitive walking practice.

Objectives

The purpose of this study was to investigate the modulating effect of the Gait Enhancing and Motivating System-Hip (GEMS-H) on cortical activation during gait in patients with chronic stroke. Methods. Twenty chronic stroke patients performed treadmill walking at a self-selected speed either with assistance of GEMS-H (GEMS-H) or without assistance of GEMS-H (NoGEMS-H). Changes in oxygenated hemoglobin (oxyHb) concentration in the bilateral primary sensorimotor cortex (SMC), premotor cortices (PMC), supplemental motor areas (SMA), and prefrontal cortices (PFC) were recorded using functional near infrared spectroscopy.

Results

Walking with the GEMS-H promoted symmetrical SMC activation, with more activation in the affected hemisphere than in NoGEMS-H conditions. GEMS-H also decreased oxyHb concentration in the late phase over the ipsilesional SMC and bilateral SMA (P < 0.05).

Conclusions

The results of the present study reveal that the GEMS-H promoted more SMC activation and a balanced activation pattern that helped to restore gait function. Less activation in the late phase over SMC and SMA during gait with GEMS-H indicates that GEMS-H reduces the cortical participation of stroke gait by producing rhythmic hip flexion and extension movement and allows a more coordinate and efficient gait patterns.

Trial registration NCT03048968. Registered 06 Feb 2017

Background

Stroke survivors can suffer several neurological impairments or deficits, such as hemiparesis, sensory and motor skills disorder, cognitive deficits, or disorders in communication and visuo-spatial perception. Hemiplegia is one of the most common impairments after stroke and significantly reduces walking ability. Poststroke hemiplegic gait is typically characterized by a reduced gait velocity and asymmetry of bilateral kinetic, kinematic and spatiotemporal parameters [1,2,3]. Gait function is an important factor in determining the ability to independently perform activities of daily living. Therefore, regaining gait ability is a primary goal in the rehabilitation program for stroke patients.

Robot-assisted therapy for gait rehabilitation after stroke is a potential and novel approach for facilitating the restoration of function and enhancing the neural recovery process after stroke. Advanced and intelligent robotic devices are able to provide high-intensity, high-dosage, and consistent training, while potentially reducing strain on therapists [4,5,6]. The relative merits of wearable versus stationary robots include potability and the ability to shift the location of treatment into a more real-world environment, including the home, community, and society. The Gait Enhancing and Motivating System-Hip (GEMS-H), developed by Samsung Electronics Co., Ltd. (Suwon, Republic of Korea), is a hip-type robotic exoskeleton. Our previous studies showed that GEMS-H improved gait function, muscle efficiency, and cardiopulmonary metabolic efficiency [7,8,9,10]. However, it is not yet known how GEMS-H assisted gait training modulates cortical activity of stroke patients.

Gait is mediated through complex neuronal networks in the central nervous system involving cortical, subcortical, and spinal regions [11]. Repetitive gait training may modify these networks and induce physiological plasticity to improve ambulation [12]. Assessment of cortical activation while the subject is moving is a key factor in promoting a better understanding of neural motor control. Currently, limited information is available on the cerebral mechanisms underlying locomotor recovery after stroke because of technical limitations in assessing cerebral activation during execution of motor tasks. To date, various non-invasive methods have been used to acquire brain signals, including functional magnetic resonance imaging (fMRI), electroencephalography (EEG), positron emission tomography (PET), and functional near-infrared spectroscopy (fNIRS). fNIRS is a relatively new optical neuroimaging technique that enables visualization of cortical activation during human gait [13]. Although fNIRS has limited depth sensitivity that restricts the measurements of brain activity to cortical layers [14], this technique allows the noninvasive measurement of cortical activity with relatively good spatial and temporal resolution [15]. Compared to other neuroimaging devices, its advantages such as less sensitive to motion artifacts, cheap, portable, safe, and silent, [16] make it the choice for comprehensive and promising results in examination of stroke patients during rehabilitation [13, 17,18,19,20].

In this study, we aimed to identify how the wearable hip-assist robot modulates cortical activation during gait in patients with stroke. We hypothesized that GEMS-H-assisted walking would induce better automatic control of gait compared with walking without assistance of GEMS-H (NoGEMS-H), expressed as a reduction in cortical activation compared with the NoGEMS-H conditions. We also speculated that assistance with GEMS-H would lead to a more symmetrical cortical activation compared with NoGEMS-H conditions.