Radial nerve injury causes long-lasting forelimb sensory impairment and motor dysfunction in rats

Peripheral nerve injury is a common cause of lifelong disability in the United States. Although the etiology varies, most traumatic nerve injuries occur in the upper limb and include damage to the radial nerve. In conjunction with the well-described effects of peripheral damage, nerve injuries are accompanied by changes in the central nervous system. A comprehensive understanding of the functional consequences of nerve injury is necessary to develop new therapeutic interventions. We sought to characterize changes in sensory and motor function and central neurophysiology after radial nerve injury in rats. To evaluate somatosensory function in the forelimb, we assessed mechanical withdrawal threshold, spontaneous forelimb use, and cold sensitivity in rats 10 and 16 weeks after radial nerve injury. To evaluate motor function, we assessed performance on a forelimb supination task for up to 16 weeks after nerve injury. Physiological changes in the motor and somatosensory cortex were assessed using intracortical microstimulation and multiunit recordings, respectively. Our results indicate that radial nerve injury causes long-lasting sensory and motor dysfunction. These behavioral deficits are accompanied by abnormal cortical activity in the somatosensory and motor cortex. Our results provide a novel characterization of functional deficits that are consistent with the clinical phenotype in patients with radial nerve injury and provide a framework for future studies to evaluate potential interventions.