Cervical spinal canal stenosis: the differences between stenosis at the lower cervical and multiple segment levels

The lower cervical segments are commonly the level responsible for cervical spondylotic myelopathy; however, we rarely encounter stenosis at the upper cervical segment in a clinical setting. We assumed that there might be some differences between the pathogenetic mechanisms underlying the development of cervical canal stenosis at different segments. We performed positional MRI in the weight-bearing position for 295 consecutive symptomatic patients. All subjects were classified into four groups (A: normal; B: C3-4 stenosis; C: C5-6 stenosis; D: two-level cervical segments stenosis, stenosis at C3-4 and C5-6). Age, sagittal cervical canal diameter, cervical intervertebral disc degeneration, cervical cord compression, and cervical mobilities were evaluated for each group. Group B showed a narrow cervical spinal canal structure at the C3 to C4 pedicle levels, while groups C and D showed narrow structures at the C4 to C6 pedicle levels in the cervical spine. Additionally, the sagittal cervical canal diameters at all pedicle levels, except C7, in group D were significantly smaller than those observed in group C. We demonstrated the differences in the pathogenetic processes for the development of cervical spinal canal stenosis between C3-4, C5-6, and two-level cervical segments stenosis. Our results suggest that the developmental morphological structure of the cervical spinal canal plays an important role in the development of cervical canal stenosis at different segments. Moreover, individuals with sagittal cervical canal diameters of less than 13 mm may be exposed to an increased risk for future development of cervical spinal canal stenosis at the upper cervical segments following stenosis at the lower cervical segments.     

炎性细胞在腹主动脉瘤形成中的作用

目的研究炎性细胞在腹主动脉瘤（ａｂｄｏｍｉｎａｌａｏｒｔｉｃａｎｅｕｒｙｓｍ,ＡＡＡ）组织中的浸润情况及其作用。方法２０例ＡＡＡ患者的动脉瘤组织及４例正常人腹主动脉组织,分别行弹力纤维和胶原纤维的特殊染色、单抗白细胞共同抗原（ＣＤ４５阳性）和巨噬细胞（ＣＤ６８阳性）的免疫组化染色,了解纤维组织的变化及炎性细胞的浸润程度;原位杂交方法观察ＡＡＡ组织中基质金属蛋白酶（ｍａｔｒｉｘｍｅｔａｌｏｐｒｏｔｅｉｎａｓｅｓ,ＭＭＰｓ）之ＭＭＰ９的ｍＲＮＡ表达。结果ＡＡＡ组织均有不同程度的炎性细胞浸润,炎性细胞浸润程度与基质弹力纤维的损伤程度呈平行趋势,正常腹主动脉组织无炎性细胞浸润;原位杂交结果显示２０例ＡＡＡ组织中的巨噬细胞和淋巴细胞均出现ＭＭＰ９ｍＲＮＡ的阳性表达,１３例（６５％）ＡＡＡ组织中的平滑肌细胞出现ＭＭＰ９ｍＲＮＡ的阳性表达。正常腹主动脉组织无ＭＭＰ９ｍＲＮＡ的阳性表达。结论炎性细胞在ＡＡＡ形成中通过复杂的生化、细胞及免疫等过程参与并促进了ＡＡＡ的形成。     

脊髓型颈椎病术后颈椎间盘突出自行消失的原因探讨

目的：了解脊髓型颈椎病颈椎管扩大成型术后，颈椎间盘突出自行消失的原因并由此提出脊髓型颈椎病新的致病学说。方法：自１９９４年６月～１９９８年５月对脊髓型颈椎病行后路单开门椎管扩大成型术患者行临床及ＭＲＩ检查。结果：８例患者，术后４～１３个月，平均５．８个月复查时，颈椎ＭＲＩ检查发现，其术前ＭＲＩ显示的颈椎间盘突出影像消失，相应部位硬膜、脊髓无压迫。结论：（１）颈椎间盘退变突出后，出现颈椎节段性不稳定，刺激突出间盘周围组织，产生炎症性反应；（２）颈椎间盘突出、颈椎退变或颈椎管狭窄，致硬膜外腔压力增高，导致硬膜外静脉回流障碍，出现硬膜外静脉瘀滞、怒张。上述为脊髓型颈椎病发病的又一可能因素     

Effect of Modic changes on spinal canal stenosis and segmental motion in cervical spine

Purpose

Few studies have reported the characteristics of Modic changes (MCs) in the cervical spine in contrast to the lumbar spine. The purpose of this study was to identify the prevalence of MCs in the cervical spine and to elucidate the relationship of MCs with spinal canal stenosis and angular motion.

Methods

437 consecutive, symptomatic patients with neck pain with or without neurogenic symptoms were included in this study. MRI in multiple positions was performed with dynamic motion of the cervical spine in upright, weight-bearing neutral, flexion and extension positions. Type of MC, intervertebral disc degeneration grade, spinal cord compression grade and sagittal angular motion between flexion and extension for each segment from C2–3 to C6–7 were evaluated.

Results

MCs were observed in 84 out of 437 patients (19.2 %) and in 109 out of 2,185 motion segments (5.0 %) with type 2 changes predominating. Disc degeneration grades and spinal cord compression grades of segments with MCs were significantly higher than those without MCs. Sagittal angular motion of segments with MCs were significantly lower than those without MCs. Multiple logistic regression analysis revealed that significantly elevated odds ratios for MCs were observed in segments with severe disc degeneration, severe spinal canal compression and less angular motion.

Conclusion

The cervical segments with MCs were significantly more likely to have disc degeneration and spinal canal stenosis. In addition, the segments with MCs had significantly less angular motion, which suggests MCs may correlate with loss of mobility.     

Cervical spinal canal narrowing and cervical neurological injuries

Cervical spinal canal narrowing can lead to injury of the spinal cord and neurological symptoms including neck pain,headache,weakness and parasthesisas.According to previous and recent clinical researc...     

急性颈椎间盘突出症2例误诊分析

急性颈椎间盘突出症２例误诊分析宋丽华１朱宾２李丹１１内蒙电管局中心医院神经科２放射科０１４０３０内蒙包头市青山区收稿日期：１９９５－１－２６修回日期：１９９５－０３－２０例１，男，５７岁。入院前１ｈ突感头晕，继由１ｍ高处摔下，头部着地，当即昏迷。约３...     

颈椎椎间盘退行性改变与颈椎不稳

探讨颈椎椎间盘退性改变与颈椎不稳定的关系。方法对２６０例怀疑有颈椎疾患的者行Ｘ线及ＭＲＩ检查。在颈椎屈曲／伸展侧位片上测量椎体水平位及成象程度,并根据ＭＲＩＴ２加权像椎间盘信号强度判断其退变程度。结论颈椎的节段性不稳定是颈椎椎间盘退行改变的早期表现之一。     

Cervical spinal stenosis and sports-related cervical cord neurapraxia in children.

STUDY DESIGN: Congenital spinal stenosis has been demonstrated to contribute to cervical cord neurapraxia after cervical spinal cord injury in adult athletes. A sagittal canal diameter <14 mm and/or a Torg ratio (sagittal diameter of the spinal canal: midcervical sagittal vertebral body diameter) of <0.8 are indicative of significant cervical spinal stenosis. Although sports-related cervical spine injuries are common in children, the role of congenital cervical stenosis in the etiology of these injuries remains unclear. OBJECTIVES: The authors measured the sagittal canal diameter and the Torg ratio in children presenting with cervical cord neurapraxia resulting from sports-related cervical spinal cord injuries to determine the presence of congenital spinal stenosis. METHODS: A total of 13 children (9 male, 4 female) presented with cervical cord neurapraxia after a sports-related cervical spinal cord injury. Age ranged from 7 to 15 years (mean +/- SD, 11.5 +/- 2.7 years). The sports involved were football (n = 4), wrestling (n = 2), hockey (n = 2), and soccer, gymnastics, baseball, kickball, and pogosticking (n = 1 each). Lateral cervical spine radiographs were used to determine the sagittal canal diameter and the Torg ratio at C4. RESULTS: The sagittal canal diameter (mean +/- SD, 17.58 +/- 1.63 mm) and the Torg ratio (mean +/- SD, 1.20 +/- 0.24) were normal in all of these children. CONCLUSION: Using the sagittal canal diameter and the Torg ratio as a measurement of congenital spinal stenosis, the authors did not find evidence of congenital cervical spinal stenosis in a group of children with sports-related cervical spinal cord neurapraxia. The occurrence of cervical cord neurapraxia in pediatric patients can be attributed to the mobility of the pediatric spine rather than to congenital cervical spinal stenosis.     

Effect of cervical dynamics on adjacent segment degeneration after anterior cervical fusion with cages

The objective of this study is to evaluate the effect of anterior cervical discectomy and fusion (ACDF) on the motion of the cervical spine and dynamic stress (tendency to kyphosis) on adjacent segments and on the overall spinal alignment which may predispose to symptomatic disc diseases at other levels. Twenty consecutive patients underwent ACDF with a mean follow-up of 28 months (range 13-38). Preoperative and postoperative clinical assessments were done by using the neck disability index (NDI) and the Japanese Orthopedic Association (JOA) score. In all cases, at the last follow-up control, a neuro-radiographic assessment [cervical spine static and dynamic X-ray and magnetic resonance imaging (MRI)] was done. The angle of the operated disc space, the disc space angle of contiguous segments, and their range of motion (ROM) and the kyphotic Cobb angle (C2-7) were measured by computer software. The study was done at Sant'Andrea Hospital, Rome, Italy in the period from November 2003 to November 2005. We observed that: the mean Cobb angle improved significantly (p < 0.001) from 3.4 degrees (kyphosis) to postoperative 14.5 degrees . This normalization of angle showed a direct effect on improvement of myelopathic patients, but it had a statistically nonsignificant effect on adjacent segments degeneration (ASD). The mean segmental ROM of adjacent segments did not show significant instability. The mean was 11.1 degrees at upper and 10.2 degrees at lower levels (close to normal). In six cases, the ROM was higher than normal: five of these patients demonstrated symptomatic adjacent segment pathology. Postoperative improvement of mean JOA and NDI scores was statistically significant (p < 0.001). Anyway, symptomatic ASD was observed in five patients (20%): in four of them, the higher disc spaces and in one, the lower disc spaces were involved. In four cases, the preoperative MRI showed slight and asymptomatic disc degeneration at the same levels involved subsequently. This ASD was significantly related to the increased ROM at the segments involved. Follow-up X-rays showed solid fusion with absence of movement in all but one case (at 13-month follow-up), who showed slight movement in the operated level in spite of clinical improvement. The follow-up MRI showed, in all cases, good decompression in the treated levels. Compensatory increase in ROM of the contiguous motion segments in patients subjected to ACDF may lead to ASD especially in those cases with asymptomatic adjacent subclinical degenerative disease. If these preliminary results will be confirmed by larger series, it could be reasonable in young selected patients with soft disc herniation to adopt total disc arthroplasty instead of fusion after cervical micro-discectomy.     

Normal morphology, age-related changes and abnormal findings of the cervical spine. Part II: magnetic resonance imaging of over 1,200 asymptomatic subjects

Purpose

The aim of this study is to establish standard MRI values for the cervical spinal canal, dural tube, and spinal cord, to evaluate age-related changes in healthy subjects, and to assess the prevalence of abnormal findings in asymptomatic subjects.

Methods

The sagittal diameter of the spinal canal and the sagittal diameter and cross-sectional area of the dural tube and spinal cord were measured on MRIs of 1,211 healthy volunteers. These included at least 100 men and 100 women in each decade of life between the third (20s) and eighth (70s). Abnormal findings such as spinal cord compression and signal changes in the spinal cord were recorded.

Results

The sagittal diameter of the spinal canal was 11.2 ± 1.4 mm [mean ± standard deviation (SD)]/11.1 ± 1.4 mm (male/female) at the mid-C5 vertebral level, and 9.5 ± 1.8/9.6 ± 1.6 mm at the C5/6 disc level. The cross-sectional area of the spinal cord was 78.1 ± 9.4/74.4 ± 9.4 mm² at the mid-C5 level and 70.6 ± 11.7/68.9 ± 11.3 mm² at the C5/6 disc level. Both the sagittal diameter and the axial area of the dural tube and spinal cord tended to decrease with increasing age. This tendency was more marked at the level of the intervertebral discs than at the level of the vertebral bodies, especially at the C5/6 intervertebral disc level. The spinal cord occupation rate in the dural tube at the C5 vertebral body level averaged 58.3 ± 7.0%. Spinal cord compression was observed in 64 cases (5.3%) and a T2 high-signal change was observed in 28 cases (2.3%).

Conclusions

Using MRI data of 1,211 asymptomatic subjects, the standard values for the cervical spinal canal, dural tube, and spinal cord for healthy members of each sex and each decade of life and the age-related changes in these parameters were established. The relatively high prevalence of abnormal MRI findings of the cervical spine in asymptomatic individuals emphasizes the dangers of predicating operative decisions on diagnostic tests without precisely correlating these findings with clinical signs and symptoms.     

Predicting the risk and severity of acute spinal cord injury after a minor trauma to the cervical spine

Background contextAcute spinal cord injury (SCI) after a minor trauma to the cervical spine has been reported in patients without preceding neurologic symptoms. Spinal canal stenosis may be the reason for the discrepancy between the severity of the injury and that of the trauma. The spinal canal to vertebral body ratio is often used to assess canal stenosis on conventional radiographs. However, the ratio does not appraise soft-tissue stenosis and canal narrowing at the level of the intervertebral disc. Parameters measured on magnetic resonance (MR) images may thus be more meaningful. The relevance of MR image parameters for predicting the risk and severity of acute SCI in patients after a minor trauma to the cervical spine has not yet been established.PurposeTo investigate MR image parameters of the cervical spine in patients suffering from acute SCI after a minor trauma to the cervical spine. To investigate the use of these parameters for predicting the risk and severity of acute cervical SCI after a minor trauma to the cervical spine.Study design/settingRetrospective radiological study of consecutive patients.Patient sampleFifty-two patients suffering from acute cervical SCI and 131 patients showing no neurologic deficits after a minor trauma to the cervical spine.Outcome measuresOn sagittal MR images: vertebral body diameter, midvertebral canal diameter, disc-level canal diameter, and spinal cord diameter. On lateral conventional radiographs: vertebral body diameter and midvertebral canal diameter.MethodsConventional lateral radiographs and sagittal T2-weighted MR images of the cervical spine (C3–C7) were analyzed. The following calculations were performed using measurements from MR images: the spinal canal to vertebral body ratio, the space available for the cord, and the canal-to-cord ratio. Using measurements from conventional radiographs, the spinal canal to vertebral body ratio was determined. Receiver-operating curves were calculated for evaluating the classification accuracy of the different parameters for predicting the risk, severity, and course of SCI.ResultsAll investigated MR image parameters in the SCI group were significantly (p<.001) smaller compared with the control group. However, there was no significant (p>.9) difference in any parameter among the different American Spinal Injury Association impairment score groups. A cutoff value of 8.0 mm for the minimal sagittal disc-level canal diameter yielded the largest positive predictive value and likelihood ratio for predicting SCI.ConclusionsPatients at risk of acute SCI after a minor trauma to the cervical spine can be identified by applying a disc-level canal diameter cutoff value (measured on MR images) of 8 mm. Additional factors to the radiological characteristics of the spinal canal affect the severity of acute SCI after a minor trauma to the cervical spine.     

人工椎间盘置换术治疗跳跃型多节段颈椎病的中期疗效

 目的 评价 Bryan 人工间盘置换术治疗跳跃型多节段颈椎病的疗效。方法 回顾性分析 2002 年 2 月至 2012 年 5 月接受 Bryan 间盘置换术（Bryan 组）或颈前路减压植骨融合术（ACDF 组）治疗的跳跃型多节段颈椎病患者相关资料。临床功能评估采用日本矫形外科协会（Japanese orthopaedic association,JOA）评分、颈椎功能障碍指数（neck disability index,NDI）、疼痛视觉模拟评分（visual analoguc scale,VAS）,影像学评估采用颈椎矢状位曲度、颈椎整体活动度及中间节段活动度,并于末次随访时评估邻近节段退变情况。结果 49 例患者随访超过 24 个月,Bryan 组 18 例,ACDF 组 31 例。两组患者性别、年龄、疾病类型等人口学资料的差异无统计学意义。两组患者术后 JOA、NDI、VAS 评分均较术前有明显改善。两组间各时间节点比较仅末次随访时 VAS 评分的差异有统计学意义。Bryan 组术后轴性症状发生率、颈椎活动度和未手术节段活动度分别为 11.1%、35.5°±5.9°和 7.3°±1.4°,ACDF 组分别为 45.2%、24.5°±6.2°、10.1°±1.6°,差异均有统计学意义。Bryan 组患者邻近节段无明显退变,ACDF 组 2 例出现退变,但无需再次手术。结论 应用 Bryan 间盘置换术治疗跳跃型多节段颈椎病,可有效改善神经功能,保留颈椎整体活动度,减少未手术节段活动度的代偿性增加,从而降低邻近节段退变及轴性症状发生率。     

Anterolisthesis and retrolisthesis of the cervical spine in cervical spondylotic myelopathy in the elderly

Background Degenerative spondylolisthesis of the cervical spine has received insufficient attention in contrast to that of the lumbar spine. The authors analyzed the functional significance of anterior and posterior degenerative spondylolisthesis (anterolisthesis and retrolisthesis) of the cervical spine to elucidate its role in the development of cervical spondylotic myelopathy (CSM) in the elderly. Methods A total of 79 patients aged 65 or older who eventually had surgical treatment for CSM were evaluated radiographically. Results Altogether, 24 patients (30%) had displacement of 3.5 mm or more (severe spondylolisthesis group), 31 had displacement of 2.0–3.4 mm (moderate spondylolisthesis group), and 24 had less than 2.0 mm displacement (mild spondylolisthesis group). The severe spondylolisthesis group consisted of 14 patients with anterolisthesis (anterolisthesis group) and 10 patients with retrolisthesis (retrolisthesis group). Patients with severe spondylolisthesis had a high incidence (93%) of degenerative spondylolisthesis at C3/4 or C4/5 and significantly greater cervical mobility than those with mild spondylolisthesis. The anterolisthesis group, but not the retrolisthesis group, had a significantly wider spinal canal than the mild spondylolisthesis group, although the degree of horizontal displacement and cervical mobility did not differ significantly between the anterolisthesis and retrolisthesis groups. Severe cord compression seen on T1-weighted magnetic resonance imaging (MRI) scans and high-intensity spinal cord signals seen on T2-weighted MRI scans corresponded significantly to the levels of the spondylolisthesis. Conclusions Degenerative spondylolisthesis is not a rare radiographic finding in elderly patients with CSM, which tends to cause intense cord compression that is seen on MRI scans. Greater mobility of the upper cervical segments may be a compensatory reaction for advanced disc degeneration of the lower cervical segments, leading to the development of degenerative spondylolisthesis. With a similar degree of displacement, anterolisthesis tends to have a greater impact on the development of CSM than retrolisthesis.     

Tandem age-related lumbar and cervical intervertebral disc changes in asymptomatic subjects

Purpose

To investigate the frequency of tandem lumbar and cervical intervertebral disc degeneration in asymptomatic subjects.

Methods

We evaluated magnetic resonance imaging (MRI) results from 94 volunteers (48 men and 46 women; mean age 48 years) for age-related intervertebral disc degeneration in the lumbar and cervical spine.

Results

MRI indicated degenerative changes in the lumbar spine in 79 subjects (84 %), with decreased disc signal intensity in 74.5 %, posterior disc protrusion in 78.7 %, anterior compression of the dura in 81.9 %, disc space narrowing in 21.3 %, and spinal canal stenosis in 12.8 %. These findings were more common in older subjects at caudal levels. MRI showed degenerative changes in both the lumbar and cervical spine in 78.7 % of the volunteers.

Conclusions

Degenerative findings in both the lumbar and cervical spine, suggesting tandem disc degeneration, was common in asymptomatic subjects. These results provide normative data for evaluating patients with degenerative lumbar and cervical disc diseases.     

颈椎前路融合术后发生症状性邻近节段退变的临床研究

目的:探讨分析与颈椎前路融合术后发生症状性邻近节段退变相关的因素。方法:自2001年3月-2006年7月共收治354例颈椎病患者,获得随访的263例,其中男185例,女78例,手术时年龄35~76岁,平均51岁,其中神经根型颈椎病54例,脊髓型颈椎病183例,合并两者的有26例。所有患者均接受前路减压、自体髂骨植骨、前路钢板内固定。根据门诊随访,综合评估所有患者的术后临床表现、神经系统及术前术后影像学表现,评价对象包括年龄,性别,融合椎体数,术前颈椎的曲度、活动度,椎管的前后径以及邻近节段的椎间盘突出和椎体前缘骨赘形成等,并根据随访时的侧位X线片将头尾两端邻近椎间隙的骨赘形成程度分为4级,统计学分析引起症状性邻近节段退变的相关因素以及邻近节段退变与骨赘形成程度的关系。结果:263例患者中有39例(14.8%)出现了症状性邻近节段病变,其中男23例,女16例,手术时年龄42~65岁,平均55岁,从手术后到出现邻近节段病变的时间为4~11年,出现邻近节段病变的平均年龄为61岁。这些症状表现为原有颈椎病症状部分或完全缓解后再次出现与邻近节段椎间盘突出相对应的神经症状与体征,而在原手术节段没有脊髓受压的表现。术前脊髓MRI上邻近节段硬膜有压迹或融合节段头侧邻近节段椎间盘低信号的患者,术后发生症状性邻近节段退变的概率明显高于未出现症状的患者,而年龄,性别,融合椎体数,术前颈椎的曲度,活动度,椎管的前后径等研究对象与症状性邻近节段退变没有明显的相关性(P>0.05)。对于发生症状性邻近节段退变的患者,有26例(67%)钢板头端邻近节段发生了骨化,与尾端骨化相比,P<0.01,骨化程度随临床症状的加重而加重。结论:对于因颈椎病而行颈椎前路融合钢板内固定的患者,术前脊髓MRI示有邻近节段硬膜有压迹或融合节段头侧邻近节段椎间盘退变表现者,术后容易发生症状性邻近节段退变,这种退变在侧位X线上可表现钢板头端邻近椎间隙骨化。     

前路选择性椎体切除分节段减压植骨融合术治疗多节段脊髓型颈椎病

目的 回颐性分析多节段脊髓型颈椎病前路选择性椎体次全切除分节段减压植骨融合术的疗效,并评估其相关影响因素.方法 25例多节段(≥3个节段)脊髓型颈椎病患者,均接受前路选择性椎体次全切除+分节段颈椎间盘切除减压+自体髂骨或钛网植骨融合+前路钢板固定术.男14例,女11例;年龄49～77岁,平均52岁.在病变严重部位行椎体次全切除+钛网或髂骨块植骨,其余部位则仅行椎间盘切除减压钛网或自体髂骨植骨术;均结合应用前路钢板多组螺钉(≥3组)固定.术后测量颈椎矢状面的活动度(range of motion,ROM);采用日本矫形外科学会(Japanese Orthopaedic Association,JOA)评估系统评估其功能恢复情况;采用正侧位、动力位X线片和三维CT重建方法评估融合程度;同时进行MR检查,以观察脊髓减压程度和脊髓情况.结果 所有病例均获得平均35.2(12～70)个月的有效随访.JOA评分:术前为9.5±1.3,术后6个月为13.8±0.8,与术前比较差异有统计学意义(P＜0.05),末次随访为13.6±0.9,与术后6个月比较差异无统计学意义(P＞0.05).术后12个月和末次随访,所有病例均已达到骨性融合,且椎管减压明显.术前ROM为68.1°±2.5°,术后6个月则为45.6°±3.5°,二者间差异有统计学意义(P＜0.05);末次随访时为50.0°±3.2°,与术前比较差异有统计学意义(P＜0.05).结论 前路选择性椎体次全切除结合分节段减压植骨融合术治疗多节段脊髓型颈椎病效果可靠;因为并没有全部切除所有节段的椎体,并结合应用多组螺钉固定钢板,所以初始稳定性较强,避免因为跨多节段植骨内固定而导致的内置物失败.     

Myelopathy hand characterized by muscle wasting. A different type of myelopathy hand in patients with cervical spondylosis

While the authors have often observed the hand presenting spastic dysfunction and deficient pain sensation in patients with cervical compression myelopathy, which has been termed "Myelopathy hand," they have occasionally seen a different type of myelopathy hand characterized by muscle wasting and motor dysfunction in patients with cervical spondylosis. This type of myelopathy hand they have termed "amyotrophic type of myelopathy hand." Because it is similar to the hand of a patient suffering from motor neuron disease, and yet is treatable, the authors thought it worthwhile to report this type of hand in detail. The main clinical features are localized wasting and weakness of the extrinsic and intrinsic hand muscles, but not accompanied by either sensory loss or spastic quadriparesis. For an accurate diagnosis, attention should be paid to the narrow anteroposterior (AP) canal diameter of the cervical spine (less than 13mm), multisegmental spondylosis in C5-6 and C6-7 disc levels and a reduced transectional area of the spinal cord at the C7, C8, or T1 spinal cord segments. To date the authors have seen 15 patients with this hand; seven underwent either spondylectomy or laminoplasty. In six patients who were satisfied with surgical results, recovery from muscle wasting and weakness was seen.     

Long-term impact of atlantoaxial arthrodesis on the pediatric cervical spine

Background  This study was conducted to elucidate radiographically the long-term impact of atlantoaxial arthrodesis on the pediatric cervical spine. Methods  The records of eight children who underwent atlantoaxial arthrodesis for the treatment of upper cervical spinal disorders and were followed up to their adulthood were retrospectively reviewed. Changes in the curvature of the whole cervical spine, and anteroposterior diameters of the spinal canal at C1 and C2 levels were investigated on lateral radiographs before surgery, at 6 months after surgery, and at the final follow-up. Results  The cervical curvature was lordosis or straight before surgery in all children and became sigmoid in six children at 6 months after surgery. At the final follow-up, three of the six children with postoperative sigmoid curvatures regained some degree of lordosis and became straight. The anteroposterior diameters of the spinal canal at C1 and C2 levels did not increase during the follow-up period. Conclusions  Development of postoperative malalignment of the lower cervical spine and impaired growth of the spinal canal at C1 and C2 levels are common after atlantoaxial arthrodesis in children. Postoperative malalignment diminishes during the follow-up period possibly due to remodeling of the pediatric cervical spine, although remodeling of the spinal canal diameter cannot be expected, suggesting the importance of anatomical reduction before or at the time of surgery.     

Laminar hook instrumentation in the cervical spine. An experimental study on the relation of hooks to the spinal cord

Several anterior and posterior methods are today available for stabilization of the cervical spine. Factors such as level and degree of instability, method of decompression, bone quality, length of fixation and safety factors influence the choice of method for a particular patient. The use of laminar hooks in the cervical spine has been restricted by fear of cord compression with the potential of tetraplegia. The aim of the present study was to assess the safety and determine the anatomical relation between hooks inserted in the cervical spinal canal and the dura and spinal cord. Thirteen cadavers from seven women and six men with no evidence of cervical spine disorder were included. The mean age was 81.3 years (range 65-101 years). The cervical spine was instrumented with cervical Compact Cotrel Dubousset hooks and rods. The effect of the hook on the dura was studied by myelography in nine cadavers. The deformation of the dural sac was quantified by measurement of the maximal width of the indentation of the contrast column at each level. A CT myelography scan was obtained in three cadavers. The ratio between the distance of maximal hook intrusion into the spinal canal and the canal diameter in the direction of the hook was calculated. The relation between inserted hooks and the spinal cord and dura was documented in a fresh cadaver studied with CT myelography. A hemilaminectomy was performed at all levels in three cadavers with direct visual inspection and photography of the hook sites before and after excision of the dura. A dural deformation of 2 mm or less, as observed by myelography, was found at four out of 77 (5%) hook sites. The deformation was caused by a supralaminar hook at C3, C6 and C7 and by an infralaminar hook at C6. The mean hook intrusion in the spinal canal, as observed on CT, was 27% (range 8-43) of the canal diameter. On visual inspection, 14 out of 18 hooks were in contact with the dura. After removal of the dura, two out of the 18 hooks in the same cadaver were in contact with the spinal cord. However, no deformation of the cord was observed. To our knowledge this is the first study systematically documenting the relation between hooks and the spinal cord in cadavers. In 95% of the hooks no deformation of the dural sac was observed and there was no evidence of spinal cord deformation. From an anatomical point of view, laminar hook instrumentation can be considered a safe procedure. The study shows, however, that hooks inserted in the cervical spine have a close anatomical relationship with the neuraxis, and at stenotic levels the use of other techniques is therefore recommended.