Objective To investigate the effects of duration of surgery on flash-induced visual evoked potentials (VEP) in patients undergoing spinal surgery in prone position.Methods Eighty-two ASA Ⅰ or Ⅱ patients of both sexes aged 20-76 yr weighing 43-96 kg undergoing spinal surgery in prone position were divided into 3 groups according to the duration of surgery:group S≤2 h ( n =34) ; group M 2-4 h ( n =38) and group L≥4 h ( n =10).VEP was monitored using protektor VEP monitoring device (Xltek Co.,Canada).The latency,amplitude and recovery time of wave P100 were recorded before and 10 min after induction of anesthesia and at the end of surgery.Results Compared with group S,the amplitude of wave P1000 was significantly decreased at the end of surgery in group M,the lantency of wave P100 was significantly prolonged,while the amplitude of wave P100 was decreased at the end of surgery in group L ( P ＜ 0.05).Compared with group M,the lantency of wave P100 was significantly prolonged,while the amplitude of wave P100 was decreased at the end of surgery in group L ( P ＜ 0.05).Compared with groups S and M,the recovery time of wave P100 was significantly prolonged in group L ( P ＜0.05).There was no significant difference in the recovery time of wave P100 between groups S and M ( P ＞ 0.05).Conclusion Duration of surgery (≥4 h) can affect flash-induced VEP,the longer the duration,the stronger the effects.

Objective:To analyze the effect of spine-pelvis sagittal parameters and sagittal orientation of facet joint on degeneration of cranial L 3,4 facet joint (facet joint degeneration, FJD) after L 4-S 1 posterior lumbar interbody fusion (PLIF). Methods:Patients with lumbar degenerative diseases who underwent L 4-S 1 PLIF from January 2012 to December 2016 were retrospectively investigated, there were 54 cases, including 28 males and 26 females. Age: 54.59±5.48 years (range, 45-60 years). X-ray, CT, MRI and Weishuapt grade was used to evaluate the degeneration of L 3,4 facet joint at the cranial adjacent segment. The general information and the sagittal parameters of spine pelvis at the last follow-up were compared between the two groups. The former included age, gender, body mass index (BMI), bone mineral density (BMD), follow-up time and preoperative diagnosis. The latter included lower lumbar lordosis angle (LLL), lumbar lordosis angle (LL), pelvis incidence (PI), pelvis tilt (PT), sacrum slope (SS), the height of the intervertebral space (HD), the angle of cranial facet joint, Oswestry disability index (ODI), Japanese Orthopedic Association (JOA) lumbar function score and improvement rate were compared at the same time. Independent sample t-test was used to compare continuous variables between groups; comparison of categorical variable components χ 2 test or Fisher's exact test. Multivariate logistic regression analysis was used to predict the risk factors of adjacent FJD. Results:Postoperative follow-up was 33.44±6.85 months (range, 24-36 months), there were 17 patients in the degenerative group and 37 patients in the non degenerative group. There were no significant differences in age, gender, BMI, BMD, follow-up time or preoperative diagnosis between the two groups. LLL, LL and SS also showed no significant difference. At the last follow-up, PI (56.28°±6.03° vs. 47.87°±8.30°, t=3.74, P=0.001), PT (17.90°±7.06° vs. 14.41°±5.51°, t=1.97, P=0.042) and the joint angle of the cephalic facet (58.48°±2.00° vs. 54.69°±3.01°, t=4.72, P=0.072) in the degenerative group were greater than those in the non-degenerative group. In the subgroup analysis of lumbar lordosis distribution, the difference between the two groups was statistically significant (χ 2=9.90, P=0.006). The HD in the degenerative group 7.50±3.60 mm was significantly lower than that in the non degenerative group 9.30±2.79 mm ( t=2.00, P=0.031). Multivariate logistic regression analysis showed that increase of PI ( OR=1.22, P=0.005) and magnified cephalic facet joint angle ( OR=2.04, P=0.008) were risk factors for adjacent segment facet degeneration. At the last follow-up, the ODI improvement rate in the degenerative group (58.14%±13.41% vs. 70.18%±8.03%, t=4.11, P<0.001) and the JOA score improvement rate (44.72%±9.53% vs. 68.86%±8.55%, t=0.43, P=0.001) were lower than those in the non degenerative group. Conclusion:The increase of PI and sagittal facet (increased joint angle of proximal facet) are risk factors of adjacent segment FJD after lumbar fusion; The abnormal distribution of lower lumbar lordosis and poor PT recovery in adjacent segment FJD patients after lumbar fusion are more obvious, which may be related to the increase of PI; After lumbar fusion, the orientation of adjacent facet joint tended to be sagittal.