Enhanced Reticulospinal Output in Subacute Spinal Cord Injury Patients with Spasticity

Although spasticity is a common complication after spinal cord injury (SCI), its underlying mechanisms have remained poorly understood. Our findings show that, in the subacute phase (approximately one-month post-injury) after SCI, spasticity is characterized by increased reticulospinal influence that persists chronically. Notably, this upregulation of reticulospinal pathways was specific to individuals who developed spasticity, whereas corticospinal responses are reduced regardless of spasticity. These results suggest that early enhancement of reticulospinal drive following injury plays a critical role in the pathogenesis of spasticity.