Peripheral nerve injury is common and can result in loss of sensation and motor function, reduced quality of life, and prolonged time to return to work. Maladaptive cortical reorganization occurs after nerve injury or immobilization and can further impair the recovery process. To improve the sensorimotor prognosis of people with peripheral nerve injury, methods such as mirror therapy, motor imagery, and electrical stimulation have been used in addition to usual care. However, no studies have shown the effect of integrating mirror therapy, motor imagery, and electrical stimulation in these individuals. Furthermore, the real-time effect of mirror therapy on cortical activation in this population remains unexplored. This study aims to determine the real-time cortical modulation effects of mirror therapy combined with electrical stimulation in individuals with peripheral nerve injury.

Two groups of subjects (a group of peripheral nerve injury group and a group of healthy adults) will perform hand exercises in three randomized conditions: (1) mirror therapy with electrical stimulation and motor imagery, (2) electrical stimulation and motor imagery, and (3) motor imagery. Each participant performs specific sets of two exercises based on the type of nerve injury: (1) Median nerve injury: Picking up and putting down a pen using the thumb and index finger, and picking up and putting down a marble using the thumb and little finger. (2) Ulnar nerve injury: Picking up and putting down a card using the thumb and index finger, and picking up and putting down a marble using the thumb and little finger.(3) Brachial plexus injury: Picking up and putting down an empty cup, and picking up and putting down a pair of pliers. For combined median nerve and ulnar nerve injuries and healthy adult groups, movements corresponding to median nerve injuries are performed. Each experimental condition consists of 20 repetitions, lasting 60 seconds, followed by a 30-second rest between conditions. Relative alpha and beta band power in the sensorimotor cortex will be recorded and analyzed.

Inclusion Criteria:

• newly diagnosed median or ulnar nerve transection injury of the forearm in the past 6 months
• sufficient communication in the Chinese language
• being able to follow instructions
• muscle atrophy or lack of voluntary contraction over the injured hand, with maximum voluntary isometric contraction (MVIC) recorded with surface electromyography (EMG) less than 10% compared to the non-affected hand
• achieve an average score of 2 or above in the Kinesthetic and Visual Imagery Questionnaire-10 (KVIQ-10) for kinesthetic imagery

Exclusion Criteria:

• had central nervous disease
• had a recent (1 year) history of nerve entrapment syndrome
• had a history of latent neuropathy, such as diabetes or dialysis