ObjectiveTo review the definition and possible etiologies for C5 palsy. MethodsThe literature on C5 palsy at home and abroad in recent years was extensively reviewed, and the possible etiologies were analyzed based on clinical practice experience. ResultsThere are two main theories (nerve root tether and spinal cord injury) accounting for the occurrence of C5 palsy, but both have certain limitations. The former can not explain the occurrence of C5 palsy after anterior cervical spine surgery, and the latter can not explain that the clinical symptoms of C5 palsy is often the motor dysfunction of the upper limb muscles. Based on the previous reports, combining our clinical experience and research, we propose that the occurrence of C5 palsy is mainly due to the instrumental injury of anterior horn of cervical spinal cord during anterior cervical decompression. In addition, the C5 palsy following surgery via posterior approach may be related to the nerve root tether caused by the spinal cord drift after decompression. ConclusionIn view of the main cause of C5 palsy after cervical decompression, it is recommended to reduce the compression of the spinal cord by surgical instruments to reduce the risk of this complication.