Objective:To study the correlation between the acute-phase characteristics of motor evoked potential (MEP) and severities of spinal cord injury in patients with acute cervical hyperextension injury and central cord syndrome (CCS).Methods:Retrospectively analyzed were the data of 45 patients with acute cervical hyperextension injury and CCS (observation group) who had been admitted to Department of Orthopedics, Tongji Hospital Affiliated to Tongji University from December 2018 to July 2021 and 20 healthy controls. Examination of transcranial magnetic stimulation-induced MEP was performed in patients with CCS and healthy controls using a magpro x100 magnetic stimulator, and recording was conducted in bilateral abductor pollicis brevis (APB). The characteristics of MEP waveform latency, amplitude and motor threshold were described and compared between the healthy control and observation groups; the correlations were analyzed between the MEP latency and the severity of spinal cord injury [American Spinal Injury Association (ASIA) total score and motor function of Upper Extremity Motor Subscores (UEMS)] in the observation group. According to different MEP-induced states, the patients in the observation group were divided into a resting group ( n=19), a facilitation group ( n=18), and a no-waveform group ( n=8). The severity of spinal cord injury (ASIA total score) and the functional independence of the spinal cord (SCIM-Ⅲ score) were compared among the 3 groups to analyze the correlation between the MEP-induced state and the severity of spinal cord injury (ASIA total score). Results:The observation group had a significantly longer MEP latency [(30.16±6.32) ms], a significantly smaller amplitude [(0.54±0.30) mV] and a significantly higher motor threshold [(65%±11%)] than the healthy control group (all P<0.05). The MEP latency in the observation group was significantly correlated with ASIA total score ( r=-0.730, P<0.001) and UEMS ( r=-0.740, P<0.001). The ASIA total score and SCIM-Ⅲ score were significantly different among the 3 groups ( P<0.05), and the MEP-induced state was significantly correlated with the severity of spinal cord injury (ASIA total score) ( r=0.668, P<0.001). Conclusions:In patients with acute cervical hyperextension injury and CCS, the MEP latency is prolonged, the amplitude lowered, and the motor threshold enhanced. The MEP latency is strongly correlated with the severity of spinal cord injury and upper limb motor function. The MEP-induced state is also closely related to the severity of spinal cord injury.