[Etiology and treatment of postoperative spinal cord injury for patients undergoing laminectomy for fluorosis thoracic canal stenosis].

OBJECTIVE: To elucidate the etiology of postoperative spinal cord injury (PSCI) for patients undergoing laminectomy for fluorosis thoracic canal stenosis (FTCS) and summarize the methods of diagnosis and treatment. METHODS: From 2006 to 2009, a total of 192 FTCS cases underwent laminectomy. Among them, 16 cases with gradual postoperative neural deterioration were finally diagnosed as PSCI on MRI.One case of intraoperative spinal cord injury was excluded so that only 15 cases were included. RESULTS: All cases were treated immediately with incision cite puncture and dehydration.Neural function recovered after secondary operation as JOA score improved from 3.00 ± 1.14 to 7.72 ± 1.41 at 12 months follow-up.Statistical analysis demonstrated a linear correlation between the diagnosis time and the improvement of JOA score. CONCLUSION: Hematoma and fluid leakage are the common reasons of PSCI for FTCS patients. Meticulous hemostasis, usage of artificial dura matter and partial negative pressure drainage are valuable preventive measures.

[Damage of blood brain barrier of spinal cord in rats with chronic fluorosis].

OBJECTIVE: To explore the impairment mechanisms of blood brain barrier in spinal cord and observe the changes of matrix metalloproteinase-9 (MMP-9) and functional improvement in rats with chronic fluorosis. METHODS: A total of 120 Wistar rats were divided randomly into 4 groups, high fluoride (fed by water with a high concentration of sodium fluoride at 200 mg/L), high fluoride control (fed by distilled water), defluorination (fed by water with a high concentration of sodium fluoride at 200 mg/L for 12 weeks and then distilled water for 12 weeks) and defluorination control (n = 30 each). The urinary contents of fluoride were detect for 4 groups at Weeks 4, 8 and 12. The high fluoride and control groups were sacrificed at Week 12 while the defluorination and defluorination control groups at Week 24. Their cervical spinal cords were collected for electron microscope examinations. The expression of MMP-9 protein in thoracic cord was detected by immunohistochemistry and Western blot. Quantitative analysis of function of blood brain cord barrier was performed by the technique of Evans blue. The comparison of measurement data was performed with F test and correlation analysis. The cytological changes of neurons in thoracic spinal cord were detected after chronic fluorosis. RESULTS: Under electron microscope, the pathological manifestations of chronic damage in blood brain barrier could be found. As compared with the high fluoride control group, the content of Evans blue increased markedly in spinal cord of the high fluoride group (29.2 ± 0.1 vs 0.7 ± 0.1 mg/L, P < 0.01). It was higher in the defluorination group than that in the defluorination control group. But there was no significant difference with the high fluoride group (29.2 ± 0.1 vs 28.9 ± 0.2 mg/L, P > 0.01). And the expression of MMP-9 increased in spinal cord of the fluorosis and defluorination groups in comparison with those in the control group. But no difference existed among them. CONCLUSION: The damage of blood brain barrier of spinal cord occurs probably as a result of a higher expression of MMP-9 in rats with chronic fluorosis. Defluorination for a short time may not recover.

Influence of hinge position on the effectiveness of open-door expansive laminoplasty for cervical spondylotic myelopathy.

OBJECTIVE: To assess the influence of different hinge positions on clinical results of expansive open-door laminoplasty (EOLP) for cervical spondylotic myelopathy (CSM). METHODS: A total of 102 CSM patients who underwent EOLP from February 2006 to February 2007 were enrolled in this randomized controlled trial. Using a random digits table, 57 patients with the hinge located at the inner margin of the lateral mass were classified as wide-open group, while 45 patients with the hinge positioned at the lamina margin served as narrow-open group. All patients were observed over 24 months, and the clinical and radiological results were analyzed statistically. RESULTS: There were no significant differences in operation duration, intraoperative bleeding volume, Japanese Orthopaedic Association (JOA) scores, cervical curvature index, range of motion and neural function recovery rate. The neural functions were satisfactorily improved after surgery in both groups, while the severity of axial symptoms was significantly lower in the narrow-open group than in the wide-open group (P equal to 0.003). The incidence of C(5) palsy in the wide-open group was higher than that in the narrow-open group (5.3% vs 0), even though the difference did not reach statistical significance (one tailed Fisher's exact test, P equal to 0.17). CONCLUSIONS: Proper inward shift of the hinge can ensure effectiveness of surgical decompression, avoid an excessive backward shift of the spinal cord, decrease the incidence of C(5) palsy and alleviate the severity of axial symptoms.

[Clinical validity of hinge position to expansive semi open-door laminoplasty].

OBJECTIVE: To evaluate and compare the efficacy and clinical results of cervical expansive open door laminoplasty (EOLP) with different hinge position. METHODS: From February 2006 to February 2007, a total of 102 cases with cervical spondylotic myelopathy were assessed in this randomized controlled trial. Fifty-seven patients underwent EOLP with the hinge located at the inner margin of the lateral mass classified as wide-open group. Forty-five cases who underwent EOLP with the hinge positioned at the lamina margin served as narrow-open group. The clinical results and radiological examinations of both groups were evaluated 24 months after surgery. RESULTS: There were no significant differences in operation time, bleeding quantity and recovery rate of Japanese Orthopaedic Association (JOA) scores. The incidence of C(5) palsy and severity of axial symptoms in the wide-open group were significantly lower than those in the narrow-open group (P < 0.05). There were no significant differences in cervical curvature index and range of motion between the two groups. CONCLUSIONS: Well-suited and appropriated inwardly shift the hinge could promote clinical outcomes after EOLP, especially decrease the incidence of the C(5) palsy and the severity of axial symptom, but it is contraindication for patients with ossification of posterior longitudinal ligament, ossification of ligament flavum and fluorosis cervical stenosis.