Surgical outcome of ossification of the posterior longitudinal ligament (OPLL) of the thoracic spine: implication of the type of ossification and surgical options

OBJECTIVE: Ossification of the posterior longitudinal ligament (OPLL) in the thoracic spine produces myelopathy through anterior spinal cord compression that is usually progressive and unaffected by conservative treatment. Therefore, early decompressive surgery is imperative. However, decompression surgery of thoracic myelopathy is difficult, and the outcome is often poor. A retrospective study was conducted to investigate the surgical outcome of 21 patients with thoracic OPLL to evaluate which type of surgical approach is better and which type of thoracic OPLL results in a better surgical outcome. METHODS: A total of 21 patients with thoracic OPLL (10 men and 11 women; mean age 54 years), who underwent surgical treatment at our department from March 1985 to October 2000, were included in the study. Seven patients exhibited the flat-type OPLL and underwent either anterior decompression and fusion (one patient), anterior decompression via a posterior approach (three patients), or expansive laminoplasty (three patients). Fourteen patients exhibited the beak-type OPLL and also underwent either anterior decompression and fusion (two patients), anterior decompression via a posterior approach (six patients), or expansive laminoplasty (six patients). RESULTS: Regarding of operative time and blood loss, there were no marked differences between the two types of OPLL, regardless of the type of surgical procedure; anterior decompression and fusion and anterior decompression via a posterior approach yielded longer operative times and larger blood loss volumes than expansive laminoplasty. Concerning clinical outcome, there were five cases of neurologic deterioration. All of the five deteriorated cases were of the beak-type OPLL treated by a posterior approach. Two of these patients were treated with expansive laminoplasty. CONCLUSIONS: There were five instances of neurologic deterioration in our thoracic OPLL series, and all of them exhibited beak-type OPLL. In the beak-type OPLL, a subtle alteration in the spinal alignment during posterior decompression procedures may increase spinal cord compression, leading to the deterioration of symptoms. A potential increase in kyphosis following laminectomy should be avoided by fixation with a temporary rod. If intraoperative monitoring suggests spinal cord dysfunction, an anterior decompression procedure should be attempted as soon as possible.     

Cervical ossification of the posterior longitudinal ligament: factors affecting the effect of posterior decompression

Objective: Decompression procedures for cervical myelopathy of ossification of the posterior longitudinal ligament (OPLL) are anterior decompression with fusion, laminoplasty, and posterior decompression with fusion. Preoperative and postoperative stress analyses were performed for compression from hill-shaped cervical OPLL using 3-dimensional finite element method (FEM) spinal cord models.

Methods: Three FEM models of vertebral arch, OPLL, and spinal cord were used to develop preoperative compression models of the spinal cord to which 10%, 20%, and 30% compression was applied; a posterior compression with fusion model of the posteriorly shifted vertebral arch; an advanced kyphosis model following posterior decompression with the spinal cord stretched in the kyphotic direction; and a combined model of advanced kyphosis following posterior decompression and intervertebral mobility. The combined model had discontinuity in the middle of OPLL, assuming the presence of residual intervertebral mobility at the level of maximum cord compression, and the spinal cord was mobile according to flexion of vertebral bodies by 5°, 10°, and 15°.

Results: In the preoperative compression model, intraspinal stress increased as compression increased. In the posterior decompression with fusion model, intraspinal stress decreased, but partially persisted under 30% compression. In the advanced kyphosis model, intraspinal stress increased again. As anterior compression was higher, the stress increased more. In the advanced kyphosis +?intervertebral mobility model, intraspinal stress increased more than in the only advanced kyphosis model following decompression. Intraspinal stress increased more as intervertebral mobility increased.

Conclusion: In high residual compression or instability after posterior decompression, anterior decompression with fusion or posterior decompression with instrumented fusion should be considered.     

颈椎前路融合术后邻近节段退变性疾病的原因分析及治疗策略

 目的 探讨颈椎前路融合术后邻近节段退变性疾病的发生原因及治疗策略。方法 对2005年12月至2012年8月颈椎前路减压融合术后并发邻近节段退变性疾病的14例进行回顾性分析。男10例,女4例,初次手术年龄36~68岁,平均（52.0±11.0）岁。测量初次手术后颈椎整体曲度、手术节段局部曲度、钢板与上、下间隙的距离。二次手术时对节段数量≤2个且不伴严重后纵韧带或黄韧带骨化的9例采用颈椎前路减压融合内固定术,对节段数量≥3个且不伴明显后凸畸形、排列不稳及严重黄韧带骨化的3例采用颈椎后路减压椎管扩大成形术,对伴有明显后凸畸形、排列不稳且因技术原因无法行前路减压及合并严重黄韧带骨化的2例采用颈椎后路全椎板切除减压融合术。结果 初次术后邻近节段退变性疾病的发生时间为（9.3±4.4）年,二次手术时患者年龄（61.3±12.4）岁。初次术后颈椎整体曲度与手术节段局部曲度分别为12.4°±10.8°、1.5°±6.8°;钢板与上、下间隙的距离分别为（0.9±1.8）mm、（3.8±3.2）mm。二次术后平均随访（30.4±17.8）个月,末次随访时日本骨科学会颈椎病疗效评分改善率为73.9%±9.7%。结论钢 板与邻近间隙距离过小、手术节段局部曲度恢复不良可能是前路融合术后邻近节段退变性疾病的发生原因;二次手术方案的选择应根据病变累及节段、致压因素、颈椎曲度等因素进行综合分析。     

Long-term follow-up results of anterior interbody fusion applied for cervical myelopathy due to ossification of the posterior longitudinal ligament

STUDY DESIGN: A long-term follow-up study was carried out in 30 patients who underwent anterior interbody fusion for cervical myelopathy associated with ossification of the posterior longitudinal ligament (OPLL). OBJECTIVE: To investigate whether anterior interbody fusion without decompression is an appropriate surgical method for long-term relief of cervical OPLL myelopathy. SUMMARY OF BACKGROUND DATA: Several studies of operative results after posterior decompression for cervical myelopathy due to ossification of the posterior longitudinal ligament have been reported. There has been no report about anterior interbody fusion without decompression. The postoperative results of this treatment method applied in cervical OPLL myelopathy have been evaluated by the authors of the present study for more than 10 years. No reports on such a long-term follow-up study have been published in the literature. METHODS: Thirty patients who underwent anterior interbody fusion for cervical OPLL myelopathy were evaluated clinically and radiographically. The mean follow-up period was 14.7 years (range, 10-23 years). RESULTS: Clinical results were evaluated according to Okamoto's classification. At the time of the final follow-up evaluation, 16 patients had improved in functional score by two grades, and their surgical results were regarded as excellent; eight patients improved by one grade, and their clinical outcomes were regarded as good; five patients showed no change; and the condition of one patient deteriorated. As for radiographic analysis, the type of ossification had changed in four cases. Ossification width and thickness increased in 26 patients. Postoperative alignment of the cervical spine showed kyphosis in three patients, straight spine in 11 patients, and lordosis in 16 patients. CONCLUSION: Anterior interbody fusion without decompression is an effective treatment for cervical OPLL myelopathy that resulted in stable long-lasting conditions.     

Impact of preoperative cervical sagittal alignment for cervical myelopathy caused by ossification of the posterior longitudinal ligament on surgical treatment

BackgroundSurgical procedures for cervical myelopathy caused by ossification of the posterior longitudinal ligament (OPLL) are often chosen based on OPLL size and cervical spine alignment. Recently, cervical sagittal alignment based on sagittal vertical axis (SVA) has received increased attention as an important determinant of radiological and clinical outcomes after surgery. This study aimed to investigate the impact of SVA-based cervical sagittal alignment on surgical treatment for cervical OPLL by reviewing a previous retrospective cohort in which its concept was not taken into account in the surgical procedure choices.MethodsWe reviewed a total of 96 consecutive patients who underwent surgery for cervical myelopathy caused by OPLL from 2008 to 2014. We performed anterior decompression with fusion (ADF) or posterior decompression with fusion (PDF) on patients with massive OPLL or kyphotic alignment, and we performed laminoplasty (LAMP) on patients without massive OPLL or kyphotic alignment. CSVA (center of gravity of the head - C7 SVA), CL (C2-7 lordotic angle) and C7 slope were measured in cervical X-ray at standing position. Clinical results were evaluated using C-JOA score. We divided patients into two subgroups based on the preoperative CSVA: the Low-CSVA (CSVA <40 mm) and High-CSVA (CSVA ≥40 mm) subgroups.ResultsIn the Low-CSVA subgroup, none of the three operations had an effect on the CL. In contrast, in the High-CSVA subgroup, while ADF and PDF had no effect on the CL, LAMP worsened the CL postoperatively. The recovery rates of the C-JOA scores in the Low-CSVA subgroup showed no significant differences among the three operations; however in the High-CSVA subgroup, LAMP resulted in worse recovery rate of the C-JOA score than ADF or PDF.ConclusionsLAMP is not suitable for patients with cervical myelopathy caused by OPLL who have high CSVA alignment, even in cases without massive OPLL or kyphotic alignment.     

Cervical spondylotic myelopathy. Approaches to surgical treatment

Cervical spondylotic myelopathy is the leading cause of spinal cord dysfunction in older patients. This review article looks at the natural history of the condition and examines the role of different surgical treatments for it. Anterior and posterior surgical approaches have a role in the treatment of cervical spondylotic myelopathy dependent on the number of levels involved and the alignment of the spine. Anterior decompression and fusion is useful in patients who have disease at three or fewer levels or in patients with kyphotic alignment. In more extensive disease, a posterior decompression and fusion is usually best. Canal expansive laminoplasty is useful in the treatment of myelopathy without radiculopathy in a patient with lordotic alignment. With the exception of laminoplasty, nonfusion procedures have little role in the treatment of cervical spondylotic myelopathy.     

Effect of posterior instrumented fusion on three-dimensional volumetric growth of cervical ossification of the posterior longitudinal ligament: a multiple regression analysis

Background Context

Despite the fact that ossification of posterior longitudinal ligament (OPLL) is a three-dimensional disease, conventional studies have focused mainly on a two-dimensional measurement, and it is difficult to accurately determine the volume of OPLL growth and analyze the factors affecting OPLL growth after posterior decompression (laminoplasty or laminectomy and fusion).

Expansive laminoplasty for myelopathy in ossification of the longitudinal ligament

Laminectomy, which had long been used for treatment of cervical spondylotic myelopathy, including ossification of the longitudinal ligament in the cervical spine, had numerous complications such as postoperative malalignment of the cervical spine and vulnerability of the spinal cord caused by total removal of the posterior structures. In 1977 Hirabayashi devised an open door expansive laminoplasty, which is a relatively easier and safer procedure than laminectomy, that eliminated such problems by preserving the posterior elements. The decompression effect of the expansive laminoplasty against a compressed spinal cord is comparable with that of laminectomy and anterior decompression followed by fusion, whereas the expansive laminoplasty has no structural problems and adverse effects on adjacent disc levels that often are associated with anterior decompression followed by fusion. Average recovery rate of expansive laminoplasty for cervical spondylotic myelopathy has been reported to be approximately 60% (Japanese Orthopaedic Association score) and with long term stability. At present, authors consider all patients with cervical spondylotic myelopathy candidates for expansive laminoplasty except for those having preoperative kyphosis and single level lesion without canal stenosis. Two remaining problems of expansive laminoplasty to be solved are prevention of C5,C6 radicular pain and/or paresis, the most frequent complication that occurs in approximately 5% to 10% of the patients, although most complications resolve spontaneously within 2 years, and correction of nonlordotic alignment to lordosis which are essential for posterior decompression effect of expansive laminoplasty by allowing the spinal cord to shift dorsally.     

单开门椎管扩大椎板成形术在颈椎病再手术中的应用及疗效分析

目的 评价应用单开门椎管扩大椎板成形术进行颈椎病再手术的适应证及临床疗效.方法 自2003年2月至2009年6月,对15例颈椎前路融合术后症状复发或加重的患者行后路单开门椎管扩大椎板成形术.分析再手术的原因和疾病进展过程,采用日本骨科学会制定的JOA评分系统评估患者脊髓神经功能恢复情况,Nurick分级评价患者行走功能.结果 1例失随访,1例术后随访时间过短,未统计入本组.其余13例患者随访时间13～52个月,平均26个月.前后两次手术间隔时间为5个月～6年,平均24个月.再手术原因包括:邻近节段退变压迫颈髓2例,首次手术减压不彻底5例,后纵韧带骨化症(OPLL)误诊颈椎病4例,局限型OPLL进展2例.再手术均采用C3-6或C7后路单开门椎管扩大椎板成形术.13例患者JOA评分术前和末次随访时分别为10.5和13.8分(P＜0.05),平均神经功能改善率为53.0%.Nurick分级术前和随访时分别为3.1和1.9级(P＜0.05),平均改善1.2级.术后并发症包括脑脊液漏1例,颈肩部轴性痛1例,C5神经根麻痹l例.结论 对于颈椎前路融合术后减压不彻底、邻近节段退变或OPLL进展导致症状复发者采用后路单开门椎管扩大椎板成形术可以有效缓解脊髓压迫,改善脊髓神经功能,避免再次经前方入路引起的手术风险.     

Laser-assisted anterior cervical corpectomy versus posterior laminoplasty for cervical myelopathic patients with multilevel ossification of the posterior longitudinal ligament

OBJECTIVE: This study reports on the comparative results of a series of patients with multilevel cervical ossification of the posterior longitudinal ligament (OPLL) who were treated with laser-assisted anterior corpectomy or laminoplasty. METHODS: Forty-eight patients (21 patients with anterior corpectomy and 27 patients with laminoplasty) with cervical OPLL involvement of three or more vertebral bodies were retrospectively reviewed. Both pre- and postoperatively neurological status was graded according to the Nurick grading system. The anteroposterior (AP) diameter change at the narrowest part of the spinal canal, the change in the regional and the overall cervical Cobb's angle, and the change in cervical range of motion (ROM) were all measured. The mean follow-up periods were 21.8 mo and 29.1 mo for the corpectomy and laminoplasty patients, respectively. RESULTS: The mean changes in the pre- to postoperative Nurick grades were 1.9 for the corpectomy group and 1 for the laminoplasty group (p < 0.05). The mean changes in the pre- to postoperative spinal canal AP diameters were 9.1 mm and 4.11 mm, respectively, for the corpectomy group and the laminoplasty group (p < 0.05). The mean changes of the regional Cobb's angle were 1.7 degrees and -3.1 degrees (p = 0.06), and the mean changes of the overall cervical Cobb's angle were 1.1 degrees and -1.6 degrees , respectively, for the corpectomy group and the laminoplasty group (p > 0.05). The changes in the cervical degree of ROM were -19.6 degrees and -19.7 degrees , respectively, for the corpectomy group and the laminoplasty group (p > 0.05). CONCLUSIONS: Direct decompression of the spinal cord by laser-assisted anterior cervical corpectomy was shown to be a better surgical option on long-term follow-up, yielding more recovery of neurological deficits, achieving adequate decompression of the spinal canal, and preventing the development of regional kyphosis at the operated level of the spine, in patients with multilevel cervical OPLL.     

颈椎前路减压分段融合术和后路椎管扩大成形术治疗多节段脊髓型颈椎病的病例对照研究

目的 :比较颈椎前路减压分段融合术和后路椎管扩大成形术治疗多节段脊髓型颈椎病的临床疗效。方法:对2009年7月至2012年6月收治的56例多节段脊髓型颈椎病病例进行回顾性分析,男32例,女24例;年龄42~79岁,平均(56.9±12.8)岁,病程2个月~16年,平均(10.6±3.2)年。所有患者术前经影像学检查显示有多节段颈椎间盘突出,并具有脊髓型颈椎病的临床表现。其中34例采用颈椎前路减压分段融合术(前路组),22例采用后路椎管扩大成形术(后路组)。通过影像学资料对两组患者手术前后的病变节段前柱高度和颈椎前曲度进行比较,并采用JOA评分评价手术效果。结果:两组患者无神经血管并发症发生,并获得24~36个月的随访(平均28.6个月)。前路组,术后2周时颈椎病变节段前柱高度较术前明显增高(P0.05),颈椎前曲度较术前明显降低(P0.05)。后路组,术后2周及末次随访时,病变节段前柱高度和颈椎前曲度较术前差异均无统计学意义(P0.05)。两组间在术后2周及末次随访时颈椎前曲度差异有统计学意义(P0.05)。术后两组JOA评分均出现了明显恢复,术后3个月及末次随访时,前路组明显高于后路组(P0.05),且JOA评分改善率前路组也优于后路组(P0.05)。结论:这种分段式前路融合手术可以有效地恢复颈椎前柱高度,并且与颈椎后路椎管扩大成形术相比,可以显著地改善脊髓功能,是治疗多节段脊髓型颈椎病的有效方案。     

Cervical laminoplasty to enlarge the spinal canal in multilevel ossification of the posterior longitudinal ligament with myelopathy

We studied 23 patients with severe myeloradiculopathy involving multiple (more than three) levels of ossification of the posterior longitudinal ligament (OPLL) of the cervical spine, who were treated with laminoplasty to enlarge the spinal canal. The resected spinous processes were used as bone grafts to support the opened laminae. These patients were analyzed pre- and postoperatively with a neurological evaluation according to the Japanese Orthopedic Association (JOA) score system for cervical myelopathy. Follow-up was from 2.0 to 5.3 years with an average of 31.5 months. The results were compared with those in 31 patients with the same degree (multilevel) of OPLL who had been operated upon previously by laminectomy (14 cases) or anterior resection (17 cases). Postoperative neurological recovery by improvement ratio of the JOA score was observed in 81.2% of those who had undergone expansive laminoplasty, in 72.4% of those with laminectomy, and in 63.6% of those with anterior decompression. We concluded that expansive laminoplasty is a safer procedure with fewer complications. Stability is achieved by fixing the expanded laminae permanently with a bone graft. The neurological recovery following our technique of laminoplasty and fusion appears to be superior to that with laminectomy or anterior decompression.     

Diagnosis and surgical management of cervical ossification of the posterior longitudinal ligament.

BACKGROUND CONTEXT: The diagnosis and treatment of multilevel cervical ossification of the posterior longitudinal ligament (OPLL) is continuing to evolve as its effects become more readily recognized and surgical alternatives expand. PURPOSE: To review the clinical, neurodiagnostic and surgical management of OPLL. STUDY DESIGN/SETTING: Patients with early OPLL, often in their mid-forties, present with radiculopathy or mild/moderate myelopathy. Radiographically, hypertrophy of the posterior longitudinal ligament with punctate ossification appears opposite multiple disc spaces. Patients with classic OPLL frequently become symptomatic in their mid-fifties with radiographic characteristics showing ossification of the ligament behind the vertebrae alone (segmental), behind the vertebrae including the intervertebral disc spaces (continuous), and combinations of the segmental and continuous variants and OPLL opposite disc spaces alone. Both magnetic resonance imaging (MRI) and computed tomography (CT) examinations are critical. MRI better delineates the extent of soft tissue abnormalities in three dimensions, including the cervicothoracic junction, whereas CT more readily identifies the foci of frank ossification. Surgical alternatives include anterior, posterior or combined approaches. Anterior surgical options include plated multilevel anterior discectomy and fusion, anterior cervical corpectomy with fusion (ACF), or plated multilevel ACF with differing posterior fusion techniques. Posterior surgical options vary from laminectomy with or without simultaneous fusion and laminoplasty. Although outcomes with different approaches vary, many direct anterior resection techniques achieve more favorable results because of appropriate and adequate resection of the ligament. CONCLUSIONS: The clinical and neuroradiographic documentation of OPLL and its appropriate surgical management anteriorly, posteriorly or circumferentially remain a therapeutic challenge.     

Cervical myelopathy. current diagnostic and treatment strategies.

Cervical myelopathy is a varied clinical syndromes resulting from spinal cord dysfunction. Underlying causes are numerous, but spondylosis at one or more levels is the most common etiology. Natural history studies have demonstrated a variable clinical course with gradual neurologic deterioration in a majority of patients. While prospective clinical comparisons are limited, existing literature suggests that operative management reliably arrests the progression of myelopathy and may lead to functional improvement in a majority of patients. The selection of surgical procedures must be carefully individualized based on specific clinical and radiographic factors. Whereas anterior decompression and fusion procedures at one or two motion segments have predictable results, procedures involving three or more levels are associated with increased morbidity. Newer techniques for the treatment of multilevel cervical myelopathy include anterior decompression with 360-degree fusion, hybrid corpectomy/anterior cervical discectomy and fusion techniques and the use of dynamic anterior cervical plates. An alternative technique for patients with a lordotic sagittal alignment is laminoplasty, which has a proven track record of long-term good to excellent results.     

Cervical alignment,range of motion,and instability after cervical laminoplasty

It has been reported that flexibility of the neck decreases after cervical laminoplasty. It also is known that kyphosis can be an unfavorable result after posterior decompression surgery of the cervical spine. To examine whether a decrease in cervical mobility resulting from contracture of the cervical spine helps prevent postoperative kyphotic alignment, changes in radiographic findings after cervical expansive laminoplasty were evaluated. There was a strong correlation postoperatively between range of motion of the cervical spine and cervical lordotic alignment, namely, the more that cervical mobility was maintained, the more that cervical lordosis was preserved. This relationship was not found preoperatively. A postoperative increase in the number of unstable vertebrae was found only in a few patients and was not associated with any deterioration in clinical outcome. The current results suggest that postoperative cervical lordosis is preserved not through intervertebral soft tissue contracture or bony fusion, but through more dynamic factors such as muscles or ligaments, therefore implicating the importance of early removal of cervical orthosis and early postoperative rehabilitation.     

Significance of segmental instability in cervical ossification of the posterior longitudinal ligament and treated by a posterior hybrid technique

Study design

Retrospective cohort case study.

Objective

To evaluate significance of segmental instability (SI) in cervical ossification of the posterior longitudinal ligament (OPLL) myelopathy and effectiveness of a posterior hybrid technique in the treatment of OPLL associated with SI.

Summary and background data

Some studies suggested both static and dynamic compression factors accounted for the pathogenesis of myelopathy in the OPLL patients.

Method

Between May 2005 and August 2007, 15 patients with multilevel cervical OPLL, diagnosed to be associated with SI, were treated by a posterior hybrid technique including laminoplasty and fusion at instable levels with lateral mass screw fixation. Another 15 cohort patients without SI treated by laminoplasty in the same period were included in the control group. Radiological and clinical data were compared between two groups.

Results

There were no significant differences in Preop. lordotic angle, extent of OPLL, type of OPLL and occupying rate, but more patients tended to present high-intensity zone (HIZ) on MRI in the group with SI. In 15 patients with SI, 17 intervertebral levels had SI, which were distributed at the noncontinuous levels of mixed-type OPLL or the adjacent levels of continuous-type OPLL. They were also consistent with the presence of HIZ levels in the major of patients. After operation, the lordotic angle was maintained well by the posterior hybrid technique in the OPLL with SI group, and was significantly greater than that in the OPLL without SI at the 3- and 4-year follow-up point. Postoperative kyphotic change of the cervical spine and postoperative progression of the ossified lesion were not observed in the OPLL with SI group, but they were respectively observed in four cases (26.7 %) and two cases (13.3 %) in the OPLL without SI group at the 4-year follow-up point. The preoperative C-JOA score in the OPLL with SI group was lower than that in the OPLL without SI group. The average C-JOA score and improvement rate were comparable in the first 2 years after operation between two groups, but there was a decrease in C-JOA score and improvement rate in the following 2 years in the OPLL without SI group. At the 3- and 4-year follow-up points, both postoperative C-JOA score improvement rate in the OPLL with SI group were superior to those in the OPLL without SI group. Each group had one case developing C5 palsy, but three cases in the OPLL without SI group developed late neurological deterioration due to postoperative kyphotic change or progression of the ossified lesion.

Conclusions

Segmental instability, a degenerative dynamic factor, is important to the OPLL myelopathy. The posterior hybrid technique seemed to be effective and safe in the treatment of selective OPLL patients associated with SI. The benefits may include providing stabilization environment for spinal cord recovery, and preventing progressive kyphotic change and progression of OPLL.     

C5 nerve root palsy after cervical laminoplasty and posterior fusion with instrumentation

STUDY DESIGN: Consecutive case series. OBJECTIVE: To compare the incidence and clinical characteristics of postoperative fifth cervical nerve root palsy (C5 palsy) in patients with cervical myelopathy treated by laminoplasty alone and laminoplasty with posterior instrumentation. SUMMARY OF BACKGROUND DATA: In patients who have multilevel cervical myelopathy with reducible kyphosis or instability, the authors have performed laminoplasty together with instrumented fusion to restore lordosis and stability. There seems to be a high incidence of postoperative C5 palsy in these patients. METHODS: Seventy-three patients with a mean age of 60.5 years and multilevel cervical myelopathy treated by laminoplasty from 1995 to 2005 were reviewed. Incidence, side, and severity of muscle weakness from patients with C5 palsy after posterior instrumented fusion (instrumented group) was compared with those without instrumentation (noninstrumented group). Radiologic parameters were assessed to identify predisposing factors. RESULTS: Overall 10 of 73 (14%) patients developed the C5 palsy, of which 5 (50%) of 10 patients were in instrumented group, and 5 of 63 (8%) patients were in noninstrumented. Three of 5 (60%) had the palsy on the same side of the opened lamina in the instrumented group, in the same proportion as the noninstrumented. Three (60%) patients in instrumented group developed deltoid weakness grade 1, but none in the noninstrumented had weaker than grade 3. All of the palsied in the instrumented group recovered within 2 years after surgery without removal of implant. Of the 5 patients with the palsy in the instrumented group, 3 had anterolisthesis before surgery and posterior translation of C4 on C5 by the surgery, and no patient without the palsy had the anterolisthesis. CONCLUSIONS: Posterior cervical fusion using instrumentation for restoration of lordotic alignment combined with laminoplasty is highly associated with severe postoperative C5 palsy in patients with multilevel cervical myelopathy and C4 anterolisthesis.     

Spinal canal size in ossification of the posterior longitudinal ligament of the cervical spine

BACKGROUND: The size of the spinal canal is a factor that contributes to the neurologic deficits associated with cervical ossification of the posterior longitudinal ligament (OPLL). METHODS: Bone-window computed tomography (CT) examinations of the cervical spine in 64 patients with cervical OPLL were reviewed. Forty-two patients underwent surgical treatment (anterior decompression: 16 patients, posterior decompression: 26 patients). The remaining 22 patients were managed conservatively. Selection of the surgical approach, anterior or posterior, was based on the longitudinal extent of cord compression. RESULTS: The mean developmental size of the spinal canal in the posterior decompression group (10.7 mm at C4) was significantly smaller than the other 2 groups. The spinal canal was narrowed by OPLL to 2.9 to 10.0 mm. The proportion of the patients showing motor deficits of the lower extremities significantly increased when the sagittal canal diameter was narrowed to less than 8 mm. CONCLUSIONS: This study demonstrates critical values of CT-determined spinal canal stenosis. Developmental size of the spinal canal and the residual anterior-posterior canal diameters resulting from OPLL spinal cord compression are important factors influencing clinical management and the neurologic state.     

Relationships between sagittal alignment of the cervical spine and morphology of the spinal cord and clinical outcomes in patients with cervical spondylotic myelopathy treated with expansive laminoplasty

A total of 103 patients with cervical spondylotic myelopathy undergoing laminoplasty were retrospectively reviewed to evaluate whether sagittal alignment of the cervical spine and morphology of the spinal cord influence surgical outcomes. Sagittal alignment of the cervical spine did not influence surgical outcomes. Neurologic recovery in patients with anterior convexity of the spinal cord was better than in those without this type of spinal cord. In patients with supplementation of decompression at C2, sagittal morphology of the spinal cord did not influence neurologic recovery. It is important to acquire anterior convexity of the spinal cord after surgery if laminoplasty is performed below C3. In patients with kyphosis, where anterior convexity of the spinal cord is not thought to be obtained postoperatively, it is possible that additional decompression of C2 improves outcome.