王辉　丁文元

Cervical-5 nerve root palsy is a common postoperative complication of cervical spondylosis, which is defined as the deltoids and/or biceps brachii paralysis after the decompression of cervical vertebral canal without aggravation of the original symptom of the spinal cord. Its occurrence has nothing to do with the postoperative improvement of spinal symptoms, but nerve root palsy brings great psychological pressure to patients. Nerve root palsy may occur in either anterior or posterior approach. Nerve root palsy happens ranging from immediately to a few weeks postoperatively, and while most occurs 1 week after surgery. Unilateral nerve root palsy is more to be seen than bilateral nerve root palsy. Although the etiology of nerve root palsy is studied in many literatures, a unanimous understanding on the exact pathogenesis and preventive measures is lacking. The latest literatures were reviewed. Firstly, a summarization was made from the 6 perspectives of anatomical factors, nerve root injury, tethering effects, operation methods, high signal intensity of the spinal cord and ossification of posterior longitudinal ligament (OPLL). And then, the preventive measures and treatment methods for nerve root palsy were further analyzed. The unique anatomical structure of cervical-5 nerve root and stenosis of cervical-4/5 nerve root canal are risk factors for the occurrence of nerve root palsy. Intra-operative nerve root injury is a direct cause for the occurrence of postoperative palsy, but this hypothesis cannot explain the occurrence of unilateral nerve root palsy. Many researchers endorse that tethering effects induced by the posterior shift of the spinal cord may lead to postoperative nerve root palsy, and nerve root injury or ischemia caused by tethering may finally lead to nerve root palsy. Surgery options such as single door laminoplasty, double door laminoplasty, anterior or posterior approach may perform different effects for the occurrence rate of nerve root palsy. High signal intensity of the spinal cord represents spinal cord ischemia, which is often caused by chronic spinal cord compression. It is a risk factor for the occurrence of nerve root palsy. Cervical OPLL is a special form of cervical spondylosis. The compression of ossification sites to the spinal cord performs gradually. When decompression is achieved after posterior approach, mechanism of ischemia and reperfusion injury of the spinal cord may be the reason for higher incidence of nerve root palsy in OPLL group than non-OPLL group. Therefore, OPLL is recommended as a risk factor for the occurrence of nerve root palsy. Hormones, dehydrating agents and neurotrophic drugs may be effective for the recovery of nerve root palsy. Preoperative electromyography and intra-operative nerve root canal enlargement are effective measures to prevent the occurrence of nerve root palsy. The angle of expanded laminar and the extent of decompression may influence the occurrence of nerve root palsy in laminoplasty. Although hyperbaric oxygen therapy can shorten the recovery time of nerve root palsy, its value needs to be further observed.