The development of a novel virtual reality intervention for chronic stroke upper limb rehabilitation

Introduction
Upper limb impairment affects up to 80% of stroke survivors, with approximately 50% reporting limitations in their affected arm use beyond 6 months post-stoke [1]. Mirror therapy [2], music therapy [3] and Virtual Reality (VR) [4] have all been shown to improve upper limb function independently, however, have not been investigated together.
Aims
This project aims to promote motor function improvements in chronic stroke survivors by exploring the effect of a combined music-based mirror therapy and virtual reality rehabilitation program. The VR prototype’s development was informed and optimised through a series of co-design sessions (n = 25) with stroke survivors (n = 13) and professionals (n = 12).
Materials & Methods
The VR application was designed in Unity and written in C#. Three technical challenges were solved:
1. Virtual Mirroring: Mirroring both the VR controller and the physical hand of the non-affected side (Fig. 1E) onto the affected side (Fig. 1D), including positional and
rotational aspects
2. Positional Sonification: Translating the position of the user’s hands into a musical
output (Fig. 1A)
3. Scoring: Assessing the accuracy of the user’s hand position compared to the robot
avatar’s (Fig. 1C)
Results
1. Natural hand mirroring was achieved by inverting the x-axis and rotations in the y- and
z-axes in real-time
2. Hand position was converted into an integer representing a Musical Instrument Digital Interface (MIDI) note number, paired with a MIDI instrument index
3. Two animations were configured to control the robot’s movement and measure the
user’s movement. A note is played if the difference is within the acceptable threshold
(Fig. 1B), customised for each user This application’s effect on upper limb function, independence, mood, and cognition will be assessed during an 8-week pilot trial in the homes of stroke survivors in 2025 – 2026.