Because virtual reality can provide more enriched environment, repetitive goal-oriented tasks, and increased patients' interest and motivation, it is expected to stimulate neuroplasticity of injured brain and promote recovery in patients with brain disorders. On the other hand, immersive virtual reality using a head-mounted display has not yet been attempted in the rehabilitation of patients with brain disorders. In addition to the benefits of existing virtual reality or game rehabilitation, immersive virtual reality can further enhance brain plasticity, such as the effect of mirror therapy or action observation, through self-awareness of the body in the virtual space. The purpose of this study is to investigate the feasibility of applying the immersive virtual reality using a head-mounted display in patients with upper extremity dysfunction due to brain disorders.

Inclusion Criteria:

• Patients with upper extremity dysfunction due to brain disorders (eg, stroke, traumatic brain injury, brain tumor, etc.)
• Patient who can move the upper limb against the gravity (MRC grade 3 or above in both shoulder and elbow flexion)
• Patient who can maintain stable sitting position
• Adults over 18 years old
• Patients who voluntarily agreed to participate in the study

Exclusion Criteria:

• A moderate-to-severe cognitive impairment score of 18 or less in Mini-Mental Status Examination (MMSE)
• Peripheral nerve injury, joint disease, other diseases of the upper extremity dysfunctions other than brain disorders
• Patients with a history of severe dizziness or epilepsy
• Patients with other medical illness that are difficult to participate in the study