BCI-Based Control for Ankle Exoskeleton T-FLEX: Comparison of Visual and Haptic Feedback With Stroke Survivors

Brain-Computer Interface (BCI) remains an emerging tool that seeks to improve the patient interaction with the therapeutic mechanisms and to generate neuroplasticity progressively through neuromotor abilities. Motor Imagery (MI) analysis is the most used paradigm based on the motor cortex's electrical activity to detect movement intention. It has been shown that motor imagery mental practice with movement-associated feedback may offer an effective strategy to facilitate motor recovery in brain injury patients. This protocol will study a BCI system associated with visual and haptic feedback to facilitate MI generation and, to control a T-FLEX ankle exoskeleton. In this study, a group of five post-stroke patients will test four different strategies using T-FLEX: Passive movement, Active movement, Motor Imagination with Visual stimulation and Motor Imagination with Visual-Haptic stimuli. The quantitative characterization of BCI performance will be made by using statistical analysis of electroencephalographic data. Finally, the patient's satisfaction will be evaluated by a questionnaire.

Inclusion criteria

• Unilateral lower extremity paresis
• Hemorrhagic or ischemic stroke
• A minimum of six months after the acute infarction/onset of the disease
• Full passive range of motion in lower extremity or at least at neutral position
• Be able to stand freely
• Be able to walk with or without aid for at least 20 meters in less than 2 minutes

Exclusion criteria

• Peripheral nervous system pathology
• Epilepsy
• Weight over 100 kg
• No cognitive ability to follow the study instructions
• Pregnancy
• Use of implanted devices
• Instable lower extremity joints or fixed contracture