Altered Proprioceptive Input During Passive Ankle Movements in Patients With Chronic Stroke: A fNIRS Study of Cortical Activity
Hogene Kim, Jieun Cho, Sangwoo Cho, Joonho ShinBackground
Stroke-related hemiparesis frequently results in impaired proprioception, particularly within the lower limbs, where the ankle joint serves as a critical regulator of balance and postural stability. Despite its importance in fall prevention, the cortical mechanisms underlying multi-directional ankle movements remain poorly understood in the stroke population. This study addresses this gap by investigating real-time brain activity during complex ankle mobilization.
Objective
This study aimed to investigate cortical activation patterns using functional near-infrared spectroscopy (fNIRS) imaging during passive bi-axial ankle movements in older patients with chronic stroke hemiparesis.
Methods
fNIRS imaging was used to compare cortical activation during four bi-axial passive ankle movements in 12 patients with stroke and age-matched healthy controls. While seated with a paretic foot on a custom-made ankle-movement device, participants underwent isokinetic passive bi-axial ankle movements in four directions: plantar flexion; dorsiflexion; inversion; and eversion.
Results
Compared to healthy control, significant negative changes (p<0.05) in normalized beta values within a generalized linear model were observed in the motor cortex during inversion and eversion. Cortical activation was significantly lower during inversion than during the other movements in patients with stroke (p<0.01).
Conclusion
This study employed functional near-infrared spectroscopy (fNIRS) to evaluate real-time cortical hemodynamics during bi-axial ankle movements in stroke survivors and healthy controls. The findings reveal significant neuroplastic alterations in cortical activity related to ankle proprioception, suggesting a fundamental reorganization of sensory-motor processing following a stroke.