Spinal cord monitoring during posterior spinal instrumentation and fusion

Two hundred seventy-five consecutive patients who were treated by posterior spinal instrumentation and fusion with iliac crest bone graft were intraoperatively monitored using cortical somatosensory-evoked potentials without a planned wake-up test. The monitoring was performed using a TECA TE-4 system that included an electromyograph, a nerve stimulator, and a digital averager. Intraoperatively, six patients (2%) demonstrated significant changes in evoked potentials, consisting of either marked increase in latency or a loss of wave form during instrumentation of the spine. The instrumentation was removed immediately and the evoked potentials returned to base-line tracing within 15-30 minutes in all six cases. Five patients who had instruments refitted to maintain a lesser amount of correction had no subsequent change in the evoked potentials. One patient had spinal fusion without instrumentation. Postoperatively, all patients are neurologically normal.     

The safety of instrumented outpatient anterior cervical discectomy and fusion

Background contextReported hospitalization times after an anterior cervical discectomy and fusion (ACDF) procedure range between 20 hours to 4 days. Reasons for this wide variation are manifold, but the safety of an instrumented ACDF in the setting of a hostile medical-legal climate is most likely the primary concern influencing such a discrepancy.PurposeThe purpose of this study was to evaluate the safety and feasibility of performing single, two- and three-level ACDF with instrumentation on an outpatient or 23-hour observation period basis in order to potentially diminish the additional cost of hardware without compromising the purported benefits of surgery.Study design/settingA retrospective chart review of patients undergoing instrumented ACDF on an outpatient basis was performed.Patient sampleA total of 103 patients with neck pain and/or radiculopathy undergoing ACDF were enrolled into this study.Outcome measuresIncluded the evaluation of intraoperative and perioperative complications, which were reported for a total of 6 months after surgery. Clinical examination and radiographical assessment, including plain radiographs and computed tomography and magnetic resonance imaging (when required), were performed to assess complications.MethodsComplications were divided into two groups: major and minor. Major complications included vertebral fracture and dehydration resulting in readmission. Minor complications included allergic reactions to medications that did not require hospitalization, and transient (≤3 months) neurologic deficit. A comprehensive literature search and meta-analysis was performed to generate a large comparison group in order to compare the complication rates in our outpatient series to those reported in the literature.ResultsA total of 99 patients (96.1%) undergoing single and two-level ACDF were discharged less than 15 hours after their surgeries (median time: 8 hours; range: 2–15 hours), and 4 patients (3.9%) were discharged after a 23-hour observation period following three-level ACDF. The overall complication rate in our outpatient series was 3.8% (n=4), including 1.9% (n=2) major and 1.9% (n=2) minor complications. The overall complication rate in the 633 patient meta-analysis derived comparison group was 0.95% (n=6). The difference between overall complication rates was not found to be significantly different (p=.12). The hardware-related complication rate in the meta-analysis comparison group was 0.5% (n=3), and was not found to be significantly different from our rate of 0% (p≤1).ConclusionPerforming ACDF with instrumentation on an outpatient basis is feasible, and it is not associated with higher overall or hardware-related complication rates as compared with complication rates reported in the literature, suggesting that this procedure is safe to perform on an outpatient basis.     

Comparison of instrumented anterior interbody fusion with instrumented circumferential lumbar fusion

Posterior lumbar interbody fusion (PLIF) restores disc height, the load bearing ability of anterior ligaments and muscles, root canal dimensions, and spinal balance. It immobilizes the painful degenerate spinal segment and decompresses the nerve roots. Anterior lumbar interbody fusion (ALIF) does the same, but could have complications of graft extrusion, compression and instability contributing to pseudarthrosis in the absence of instrumentation. The purpose of this study was to assess and compare the outcome of instrumented circumferential fusion through a posterior approach [PLIF and posterolateral fusion (PLF)] with instrumented ALIF using the Hartshill horseshoe cage, for comparable degrees of internal disc disruption and clinical disability. It was designed as a prospective study, comparing the outcome of two methods of instrumented interbody fusion for internal disc disruption. Between April 1994 and June 1998, the senior author (N.R.B.) performed 39 instrumented ALIF procedures and 35 instrumented circumferential fusion with PLIF procedures. The second author, an independent assessor (S.M.), performed the entire review. Preoperative radiographic assessment included plain radiographs, magnetic resonance imaging (MRI) and provocative discography in all the patients. The outcome in the two groups was compared in terms of radiological improvement and clinical improvement, measured on the basis of improvement of back pain and work capacity. Preoperatively, patients were asked to fill out a questionnaire giving their demographic details, maximum walking distance and current employment status in order to establish the comparability of the two groups. Patient assessment was with the Oswestry Disability Index, quality of life questionnaire (subjective), pain drawing, visual analogue scale, disability benefit, compensation status, and psychological profile. The results of the study showed a satisfactory outcome (score30) on the subjective (quality of life questionnaire) score of 71.8% (28 patients) in the ALIF group and 74.3% (26 patients) in the PLIF group (P>0.05). On categorising Oswestry Index scores into "excellent", "better", "same", and "worse", we found no difference in outcome between the two groups: 79.5% (n=31) had satisfactory outcome with ALIF and 80% (n=28) had satisfactory outcome with PLIF. The rate of return to work was no different in the two groups. On radiological assessment, we found two nonunions in the circumferential fusion (PLIF) group (94.3% fusion rate) and indirect evidence of no nonunions in the ALIF group. There was no significant difference between the compensation rate and disability benefit rate between the two groups. There were three complications in ALIF group and four in the PLIF (circumferential) group. On the basis of these results, we conclude that it is possible to treat discogenic back pain by anterior interbody fusion with Hartshill horseshoe cage or with circumferential fusion using instrumented PLIF.     

内窥镜辅助下小切口前路矫形治疗青少年特发性脊柱侧凸

目的:探讨应用前路内窥镜辅助下小切口技术矫正青少年特发性脊柱侧凸的治疗效果.方法:2003年1月～2007年3月间共对33例特发件脊柱侧凸患者行内窥镜辅助下小切口前路矫形术,男13例,女20例,年龄11～17岁,平均14.6±1.5岁.Lenke Ⅰ型21例,包括1AN 10例,1BN 7例,1CN 4例,术前主胸弯Cobb角54.5°±6.3°(40°～64°):Lenke Ⅴ型12例,均为5CN,术前主弯Cobb角38°～62°,平均48.8°±8.0°.均采用胸腔镜辅助下小切口、非穿透椎体对侧皮质螺钉置入技术行胸椎侧凸前路矫形融合术.对所有患者的融合节段、矫正效果、围手术期参数和并发症以及SRS-22评分进行分析.结果:平均融合节段5.3个,平均手术时间223±48min,术中失血量263±50ml,术后伤口引流最169±28ml,伤口引流管放置时间3.0±1.8d,住院时间12.3±3.3d,并发症发生率6.1%.平均随访2.2年,主弯矫正率平均68.2%±10.5%(Lenke Ⅰ型65.1%±10.5%,Lenke Ⅴ型73.5%±8.4%).末次随访时与术后1周相比较主弯矫正丢失率为4.8%±1.7%,顶椎去旋转率为59.4%±12.2%,冠状面与矢状面均获得良好平衡.末次随访时患者SRS-22评分的"外表"、"心理"和"总分"得分较术前明显提高.结论:采用胸腔镜辅助下小切口内固定进行侧凸前路矫形具有微创、操作简便、矫形效果满意和经济等优势,配套操作器械和远期疗效需进一步研究.     

Mid- to long-term outcome of instrumented anterior cervical fusion for subaxial injuries

The management of patients with subaxial cervical injuries lacks consensus, particularly in regard to the decision which surgical approach or combination of approaches to use and which approach yields the best clinical outcome in the distinct injury. The trauma literature is replete with reports of surgical techniques, complications and gross outcome assessment in heterogeneous samples. However, data on functional and clinical outcome using validated outcome measures are scanty. Therefore, the authors performed a study on plated anterior cervical decompression and fusion for unstable subaxial injuries with focus on clinical outcome. For the purpose of a strongly homogenous subgroup of patients with subaxial injuries without spinal cord injuries, robust criteria were applied that were fulfilled by 28 patients out of an original series of 131 subaxial injuries. Twenty-six patients subjected to 1- and 2-level fusions without having spinal cord injury could be surveyed after a mean of 5.5 years (range 16–128 months). The cervical spine injury severity score averaged 9.6. Cross-sectional outcome assessment included validated outcome measures (Neck pain disability index, Cervical Spine Outcome Questionnaire, SF-36), the investigation of construct failure and successful surgical outcome were defined by strict criteria, the reconstruction and maintenance of local and total cervical lordosis, adjacent-segment degeneration and intervertebral motion, and the fusion-rate using an interobserver assessment. Self-rated clinical outcome was excellent or good in 81% of patients and moderate or poor in 19% that corresponded to the results of the validated outcome measures. Results of the NPDI averaged 12.4 ± 12.7% (0–40). With the SF-36 mean physical and mental component summary scores were 47.0 ± 9.8 (18.2–59.3) and 52.2 ± 12.4 (14.6–75.3), respectively. Using merely non-constrained plates, construct failure was observed in 31% of cases and loss of local lordosis, expressed as a mean injury angle of 14°, postoperative angle of −5.5° and follow-up angle of −1°, was significant. However, total cervical lordosis was within the limits of normalcy (−24.3° ± 13.3) and fusion-rate was 88.5%. The progression of adjacent-level degeneration was shown to be significantly influenced by a decreased plate-to-disc-distance. Adjacent-level intervertebral motion was not altered due to the adjacent fusion, but reduced in the presence of advanced adjacent-level degeneration. Patients were more likely to maintain a high satisfaction level if they succeeded to maintain segmental lordosis (<0°), had a solid fusion, an increased plate-to-disc distance, and if they were judged to have a successful surgical outcome that included the absence of construct failure and reconstruction of lordosis within ±1 SD of normalcy. Using validated outcome vehicles the interdependencies between radiographical, functional and clinical outcome parameters could be substantiated with statistically significant correlations. The use of validated outcome vehicles in a subgroup of patients with plated anterior cervical fusions for subaxial injuries is recommended. With future studies, it enables objective comparison of surgical techniques and related radiographical, functional and clinical outcome. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

一期前路手术治疗脊柱角状后凸畸形

目的:探讨一期前路松解、椎管减压、植骨、内固定手术治疗脊柱角状后凸畸形的安全性和疗效。方法:1999年9月至2003年5月23例脊柱角状后凸畸形患者接受手术治疗,其中男9例,女14例,平均年龄27岁。先天性脊柱后凸14例,脊柱结核后凸畸形5例,外伤后脊柱后凸畸形4例。后凸Cobb角平均76°。所有患者均采用一期前路松解或椎管减压、椎体间植骨及钉-棒系统矫形固定治疗。结果:所有患者安全完成手术,无脊髓及神经根损伤等严重手术并发症,后凸平均矫正47°(矫正率61.8%)。术后随访平均24个月,植骨节段全部融合,融合时间平均为4.2个月。随访中82.6%的患者对治疗结果满意。结论:一期前路手术可有效地矫正脊柱角状后凸畸形,同时能行椎管减压和重建脊柱稳定性。     

零切迹颈椎前路椎间融合固定系统治疗颈椎病及无骨折脱位颈脊髓损伤

目的：探讨零切迹颈椎前路椎间融合固定系统（简称 Zero-P 系统）治疗颈椎病及无骨折脱位颈脊髓损伤患者的临床疗效。方法对行颈椎前路手术的14例颈椎病患者（16节段）和5例无骨折脱位颈脊髓损伤患者（5节段）采用 Zero-P 系统进行减压固定。观察手术时间、术中出血量、术后早期并发症;颈椎病患者采用 JOA 评分评价疗效。结果手术时间为55～120（75±16）min;术中出血量为50～450（150±85）ml。术后11例出现吞咽困难,2～5 d 基本恢复,未出现其他早期并发症。患者均获随访,时间3个月～3年6个月,末次随访时14例颈椎病患者 JOA 评分改善率为72．7％,其中优9例,良3例,中2例;5例颈脊髓损伤患者Frankel 分级均为 E 级。影像学资料提示术后椎间融合良好,未出现临近节段椎间盘退变。结论仅需处理椎间盘的颈椎前路手术采用 Zero-P 系统进行减压固定,可以取得早期良好的临床疗效,但应注意患者的选择。     

Spinal cord injury as a complication of elective anterior cervical fusion.

The true incidence of spinal cord injury as a complication of elective anterior discectomy and interbody fusion is not known. It would appear that the risk of encountering this complication increases if the surgical procedure includes instrumentation within the spinal canal. In 5 of the cases reported herein the cause for spinal cord injury was identifiable; in the remaining 5, the mechanism of injury is either obscure or not reported. All 10 patients reported had their surgery performed using the drill and dowel technique. The role of the posterior osteophyte in spondylosis and the rationale for routinely entering the spinal canal in order to decompress the spinal cord and nerve roots are examined. Since the majority of refractory disk problems that require surgery can be satisfactorily managed by discectomy and interbody fusion alone, routine instrumentation within the spinal canal may be an avoidable hazard in the majority of instances. The pathogenesis and prognosis of the anterior cord syndrome is reviewed, a possible etiology is suggested, and the anatomy, the autonomy and the importance of the anterior spinal artery system are noted. Its vulnerability in the treatment of degenerative disk disease and a possible mechanism for its occult impairment is mentioned.     

Spinal cord monitoring. Electrophysiological measures of sensory and motor function during spinal surgery

Various recording methods were tested in 60 patients who underwent scoliosis surgery to find the most suitable technique for the spinal cord monitoring and to elucidate the neuroanatomic relationship of the evoked potentials recorded by these methods. Responses were recorded from the scalp and spine after stimulation of the tibial nerve or the spinal cord. The potentials from electrodes placed over the muscles and the tibial nerve after stimulation of the spinal cord were also recorded. Epidurally recorded spinal evoked potentials after stimulation of the tibial nerve generally consisted of two major negative peaks, NI and NII, and subsequent multiple waves. NI may be mediated through the spinocerebellar tract, and NII is most likely mediated through the dorsal column. The polyphasic waves are probably conducted through the slower sensory ascending pathways. The potentials recorded from the muscle after spinal cord stimulation may be mediated through the motor tract. Various recording techniques described in this study were mutually complimentary in confirming the results of tests recorded in the technically difficult environment of the operating room. In general, spinal cord stimulation recorded from the scalp or the spine was superior to peripheral nerve stimulation in yielding better defined responses. If the potential recorded from the muscle after stimulation of the spinal cord is indeed mediated through the motor pathway, this would be useful to assess motor function during surgery.     

同种异体骨圈在颈椎前路融合术中的应用

目的 了解同种异体骨圈 (allograft fusion cage, AFC)在颈椎前路椎体融合术中应用的效果。方法 从 1995年 9月 ,在 31例颈椎病、 6例颈椎骨折脱位、 2例急性颈椎间盘脱出症患者行颈椎前路手术中 ,将自制 AFC植入到 61个病变椎间隙。术后观察临床效果及手术并发症 ,并行 X线评价。结果 39例患者随访平均 28.6个月 ,临床效果满意,无神经并发症发生,无 AFC移位脱出。术后 3个月摄动态 X线片, 61个椎间隙平均 3.9个月完全骨性愈合。 59个椎间隙无塌陷、成角畸形, 2例 2个椎间隙因过早去除外固定,椎间高度轻度丢失。结论 与传统颈椎前路减压椎间融合术相比, AFC植入操作简便、固定稳定、手术创伤小、时间短,椎间骨融合率相近,并因无需取自体髂骨和应用金属支架,消除了取髂骨及金属内固定物永久植入所引起的一些并发症。