Influence of Visual Stimulation-Induced Passive Reproduction of Motor Images in the Brain on Motor Paralysis After Stroke

Abstract

Finger flexor spasticity, which is commonly observed among patients with stroke, disrupts finger extension movement, consequently influencing not only upper limb function in daily life but also the outcomes of upper limb therapeutic exercise. Kinesthetic illusion induced by visual stimulation (KINVIS) has been proposed as a potential treatment for spasticity in patients with stroke. However, it remains unclear whether KINVIS intervention alone could improve finger flexor spasticity and finger extension movements without other intervention modalities. Therefore, the current study investigated the effects of a single KINVIS session on finger flexor spasticity, including its underlying neurophysiological mechanisms, and finger extension movements. To this end, 14 patients who experienced their first episode of stroke participated in this study. A computer screen placed over the patient’s forearm displayed a pre-recorded mirror image video of the patient’s non-paretic hand performing flexion–extension movements during KINVIS. The position and size of the artificial hand were adjusted appropriately to create a perception that the artificial hand was the patient’s own. Before and after the 20-min intervention, Modified Ashworth Scale (MAS) scores and active range of finger extension movements of the paretic hand were determined. Accordingly, MAS scores and active metacarpophalangeal joint extension range of motion improved significantly after the intervention. Moreover, additional experimentation was performed using F-waves on eight patients whose spasticity was reduced by KINVIS to determine whether the same intervention also decreased spinal excitability. Our results showed no change in F-wave amplitude and persistence after the intervention. These results demonstrate the potential clinical significance of KINVIS as a novel intervention for improving finger flexor spasticity and extension movements, one of the most significant impairments among patients with stroke. The decrease in finger flexor spasticity following KINVIS may be attributed to neurophysiological changes not detectable by the F-wave, such as changes in presynaptic inhibition of Ia afferents. Further studies are certainly needed to determine the long-term effects of KINVIS on finger spasticity, as well as the neurophysiological mechanisms explaining the reduction in spasticity.

Effects of Visual–Motor Illusion via Image Videos Showing Increased Exercise Intensity on the Tibial Anterior during Sit-to-Stand Movement: A Study of Healthy Participants

“…Recent research has demonstrated that visual–motor illusion (VMI) can elicit kinesthetic sensations through visual stimulation [ 9 , 10 , 11 ]. VMI employs a video image displayed on a monitor to mimic limb motion, creating the illusion that the patient’s limbs are in motion, even though they are not physically moving [ 12 , 13 , 14 , 15 , 16 , 17 ]. Similarly, as another intervention that uses illusions, the effectiveness of mirror therapy has been reported [ 18 ].…”

Effects of Virtual Reality Therapy and Range of Motion Exercise on Range of Motion in Stroke Patients: Meta-Analysis

“…Visual stimulation plays an important role in increasing neurological stimulation and increasing the range of motion of post stroke patients. Interventions given through visual stimulation for 20 minutes can increase muscle flexibility and reduce muscle spasticity in 70.1% of stroke patients (Aoyama et al, 2021). One of the visual stimulation that is currently mostly done using virtual reality technology.…”