[Clinical analysis of C5 nerve root palsy in hinge side and different angles in lamina open-door after expansion of open-door cervical laminoplasty].

OBJECTIVE: To evaluate and compare the relation of the clinical results of expansion of open-door cervical laminoplasty (EOLP), C5 nerve root palsy in hinge side, and reclose of the opened laminae with different angles in lamina open-door.

METHODS: Between July 2006 and January 2009, 198 patients with cervical myelopathy were treated by EOLP. According to different opening angles which were measured by CT scan after operation, the patients were divided into group A (> 30 degrees, 76 patients including 44 males and 32 females) and group B (15-30 degrees, 122 patients including 71 males and 51 females). There was no significant difference in gender, age, disease duration, and segmental lesions between 2 groups (P > 0.05). The Japanese Orthopaedic Association (IOA) score before and after operation was used for neurological assessment and improvement rate, and the postoperative C5 nerve root palsy and reclose of the opened laminae were recorded.

RESULTS: There was no significant difference in operation time, bleeding volume, and hospitalization days between 2 groups (P > 0.05). After 3 weeks of operation, C5 nerve root palsy in the hinge side occurred in 7 patients (9.2%) of group A, and in 2 patients (1.6%) of group B, were restored after symptomatic treatment, showing significant difference between 2 groups (chi2 = 4.568, P = 0.033). All patients were followed up 24 to 48 months. Between group A and group B, no significant difference was found in JOA improvement rate at 24 months after operation (P > 0.05), and in JOA score at preoperation and at 24 months after operation (P > 0.05), but JOA score was significantly improved at 24 months after operation when compared with preoperative score in the same group (P < 0.05). The function of limb lifting restored in 9 cases of C5 nerve root palsy at 24 months after operation; CT examination revealed that no reclose occured in group A and reclose occurred in 4 cases (3.3%) of group B, but no persistent symptoms or worsen situation were found during follow-up.

CONCLUSION: Different angles in lamina open-door have the same clinical result; C5 nerve palsy has good prognosis. The opening angle between 15 degrees and 30 degrees will reduce the incidence of C5 nerve root palsy in the hinge side, but the open side should be firmly fixed to prevent further reclose of the opened laminae.