fNIRS-based brain functional response to robot-assisted training for upper-limb in stroke patients with hemiplegia

Congcong Huo; Zhifang Sun; Gongcheng Xu; Xinglou Li; Hui Xie; Ying Song; Zengyong Li; Yonghui Wang

doi:10.3389/fnagi.2022.1060734

fNIRS-based brain functional response to robot-assisted training for upper-limb in stroke patients with hemiplegia

Front Aging Neurosci. 2022 Dec 9:14:1060734. doi: 10.3389/fnagi.2022.1060734. eCollection 2022.

Authors

Congcong Huo^{1

2

3}, Zhifang Sun¹, Gongcheng Xu^{1

2}, Xinglou Li¹, Hui Xie^{1

2}, Ying Song¹, Zengyong Li^{3

4}, Yonghui Wang¹

Affiliations

¹ Rehabilitation Center, Qilu Hospital of Shandong University, Jinan, Shandong, China.
² Beijing Advanced Innovation Centre for Biomedical Engineering, Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China.
³ Beijing Key Laboratory of Rehabilitation Technical Aids for Old-Age Disability, National Research Center for Rehabilitation Technical Aids, Beijing, China.
⁴ Key Laboratory of Rehabilitation Aids Technology and System of the Ministry of Civil Affairs, Beijing, China.

Abstract

Background: Robot-assisted therapy (RAT) has received considerable attention in stroke motor rehabilitation. Characteristics of brain functional response associated with RAT would provide a theoretical basis for choosing the appropriate protocol for a patient. However, the cortical response induced by RAT remains to be fully elucidated due to the lack of dynamic brain functional assessment tools.

Objective: To guide the implementation of clinical therapy, this study focused on the brain functional responses induced by RAT in patients with different degrees of motor impairment.

Methods: A total of 32 stroke patients were classified into a low score group (severe impairment, n = 16) and a high score group (moderate impairment, n = 16) according to the motor function of the upper limb and then underwent RAT training in assistive mode with simultaneous cerebral haemodynamic measurement by functional near-infrared spectroscopy (fNIRS). Functional connectivity (FC) and the hemisphere autonomy index (HAI) were calculated based on the wavelet phase coherence among fNIRS signals covering bilateral prefrontal, motor and occipital areas.

Results: Specific cortical network response related to RAT was observed in patients with unilateral moderate-to-severe motor deficits in the subacute stage. Compared with patients with moderate dysfunction, patients with severe impairment showed a wide range of significant FC responses in the bilateral hemispheres induced by RAT with the assistive mode, especially task-related involvement of ipsilesional supplementary motor areas.

Conclusion: Under assisted mode, RAT-related extensive cortical response in patients with severe dysfunction might contribute to brain functional organization during motor performance, which is considered the basic neural substrate of motor-related processes. In contrast, the limited cortical response related to RAT in patients with moderate dysfunction may indicate that the training intensity needs to be adjusted in time according to the brain functional state. fNIRS-based assessment of brain functional response assumes great importance for the customization of an appropriate protocol training in the clinical practice.

Keywords: cortical reorganization; functional connectivity; functional near-infrared spectroscopy; motor rehabilitation; stroke.