Cerebral plasticity after contralateral cervical nerve transfer in human by longitudinal PET evaluation

The treatment of brachial plexus avulsion injury remains a challenging problem. Admittedly, central nervous mechanisms play a significant role in the motor recovery of the paralyzed hand after peripheral nerve surgery. The present study aimed at investigating the relationship between cerebral reorganization and motor recovery after a unique peripheral crossing nerve transfer surgery in brachial plexus injury patients.

In the present study, two brachial plexus avulsion injury patients with were followed up for 4 years after contralateral C7 nerve transfer surgery. In the surgery, an intact nerve root from the intact limb was transferred to repair the injured nerves. One patient showed a good motor recovery in the paralyzed hand while the other showed relatively poor outcomes. In the longitudinal follow-up, 9 PET scans of the brain were conducted in both patients at regular intervals of every 6 months. A correlation analysis between cerebral glucose metabolism and flexion power of the paralyzed wrists and fingers was performed to investigate the involvement of brain reorganization during the process of motor recovery.

The cerebral glucose metabolism in the corpus callosum, premotor cortex (Broadmann Area 6) and the precuneus were found positively correlated with the motor recovery of the paralyzed hand in Patient A (P < .01). Positive correlation between the cerebral glucose metabolism and the motor recovery of the paralyze hand was only present in the corpus callosum in Patient B (P < .01).

Corpus callosum, premotor cortex and precuneus were related with motor recovery after contralateral cervical nerve transfer surgery. The accumulating activation of these cortical regions potentially represented the recovery of high-order motor networks and may have facilitated the motor recovery.