Flexibility and alignment of the cervical spine after laminoplasty for spondylotic myelopathy. A radiographic study

Is laminectomy necessary for C1-C2 epidural schwannomas?

PURPOSE

Spinal schwannomas often require laminectomy for gross total resection. However, laminectomy may not be necessary due to the unique anatomy of epidural schwannomas at the C1-2 level, even with the intradural part. This study aimed to determine the need for laminectomy by comparing factors between patients who underwent laminectomy and those who did not and to identify the benefits of not performing laminectomy.

METHODS

Fifty patients with spinal epidural schwannoma confined to C1-C2 level were retrospectively collected and divided into groups based on whether laminectomy was intended and performed. In all cases where laminectomy was conducted, patients underwent laminoplasty using microplate-and-screws, which deviates from the conventional laminectomy approach. Tumor characteristics were compared, and a cut-off value for laminectomy was determined. Outcomes were compared between groups, and factors influencing laminectomy were identified. Postoperative changes in cervical curves were measured.

RESULTS

The diameter of the intradural part of the tumor was significantly longer in the laminectomy performed group, with a 14.86 mm cut-off diameter requiring laminectomy. Recurrence rates did not differ significantly between groups. Surgery time was substantially longer for the laminectomy performed group. No significant changes were observed in Cobb's angles of Oc-C2, C1-C2, and Oc-C1 before and after surgery.

CONCLUSION

The study showed that the diameter of the intradural part of the tumor influenced the decision to perform laminectomy for removing epidural schwannomas at C1-C2. The cut-off value of the diameter of the intradural part of the tumor for the laminectomy was 14.86 mm. Not performing laminectomy can be a viable option with no significant differences in removal and complication rates.

Usefulness of K-line in predicting prognosis of laminoplasty for cervical spondylotic myelopathy

BACKGROUND

K-line is widely recognized as a useful index for evaluating cervical alignment and the size of the cervical ossification at the posterior longitudinal ligament (OPLL). The purpose of this study was to investigate whether the K-line could be a useful clinical tool for predicting the prognosis of laminoplasty (LP) for cervical spondylotic myelopathy (CSM).

METHODS

Adult CSM patients scheduled for cervical LP were recruited for this study. C2-7 angle, local kyphosis angle, and K-line was evaluated by T2-weighted sagittal magnetic resonance imaging (MRI). Clinical findings were evaluated by the JOA score and the recovery rate. Clinical and radiological findings were evaluated preoperation and final follow-up. Patients were grouped into K-line ( +) and K-line (-). Patients with Kline (-) were further divided into two sub-groups: disc type (anterior cord compression due to disc protrusion with kyphosis) and osseous type (due to osseous structure such as osteophyte).

RESULTS

Sixty-eight patients were included in the analysis. The recovery rate of K-line (-) group (n = 11,19.4%) was significantly worse than that of K-line ( +) group (n = 57, 50.6%, p<0.05). Among 11 K-line (-) patients, 7 were disc type and 4 were osseous type. Over the period of follow-up, the disc type K-line (-) patients changed to K-line ( +) and showed significantly better recovery rate (27.6%) compared to the osseous type K-line (-) group (5.0%, p < 0.05).

CONCLUSION

The present of this study indicate that K-line may have a predictive value for clinical outcome in patients undergoing LP for CSM. K-line (-) of osseous type was worse than k-line (-) of disc type.

Hemipartial Laminectomy and Bilateral Flavectomy Technique With Unilateral Approach in Patients With Cervical Spinal Stenosis Due to Ligamentum Flavum Hypertrophy: A Technique Note

The aim of this procedure is to widen the spinal canal by using minimally invasive techniques to do hemipartial laminectomy and bilateral flavectomy in patients with cervical spinal stenosis due to ligamentum flavum hypertrophy.

A 66-year-old man presented with increasing neck and right shoulder pain for one year to Koç University Hospital. He reported a three-month history of numbness in his hands. The Japanese Orthopedic Association (JOA) and Visual Analogue Scale (VAS) scores were 15 and 8, respectively. Preoperative magnetic resonance imaging (MRI) revealed spinal canal stenosis at the C3-4 level secondary to ligamentum flavum hypertrophy. Hemi-partial laminectomy at the C3 level, flavectomy, and bilateral decompression were performed using the right unilateral approach. The patient's complaints of symptoms considerably decreased three months later. The VAS and JOA scores were 2 and 16, respectively.

This minimally invasive approach can be an alternative to classic laminectomy in patients who have radiculopathy and myelopathy due to posterior origin spinal stenosis in order to safely resolve pain and neurologic dysfunction.

Kinematics after cervical laminoplasty: risk factors for cervical kyphotic deformity after laminoplasty

BACKGROUND CONTEXT

Laminoplasty of the cervical spine is widely used as an effective surgical method to treat compressive myelopathy of the cervical spine; however, there is an adverse effect of kyphosis after surgery. The risk factors or predictors of kyphosis have not been sufficiently evaluated.

PURPOSE

To assess the risk factors for kyphosis following laminoplasty.

STUDY DESIGN

Retrospective study.

PATIENT SAMPLE

Patients diagnosed with cervical spondylotic myelopathy (CSM) or ossification of the posterior longitudinal ligament (OPLL) who underwent laminoplasty between May 2011 and October 2018 were enrolled.

OUTCOME MEASURES

Changes in lordosis and range of motion (ROM).

METHODS

Radiological imaging data were collected from simple neutral and flexion-extension radiographs at baseline and at 2-year follow-up. The ROM from the neutral position to complete flexion was defined as the flexion capacity, and the ROM from the neutral position to complete extension was defined as the extension capacity.

RESULTS

This study included 53 patients (mean age, 59.3 years). Multivariate linear regression analysis revealed that, the smaller the preoperative extension capacity, the greater was the decrease in lordosis (p=.025), while the larger the T1 slope, the greater was the decrease in lordosis following laminoplasty (p= .008). Correlation analysis revealed that C2-7 lordosis increased with increasing baseline T1 slope before surgery (p< .01). In patients with large preoperative C2-7 lordosis, the postoperative decrease in ROM tended to be greater (p= .028). However, the degree of lordosis and ROM reduction did not demonstrate a clear correlation with the clinical outcomes at 2 years after surgery.

CONCLUSIONS

Kyphotic changes in the cervical spine following laminoplasty were related to preoperative radiological parameters. The greater the preoperative extension capacity, the lower was the decrease in lordosis, and the greater the T1 slope, the greater was the decrease in lordosis.

Surgical treatment and outcomes of intramedullary tumors by minimally invasive approach

Intramedullary tumors are uncommon neoplasms which, without treatment, can cause neurologic morbidity or mortality. The goal of the treatment is complete surgical resection with a minimally invasive approach while preserving neurological status and also spinal stability. Out of 1972 patients with tumors of the spinal canal treated between 1994 and 2017, 168 intramedullary tumors of 417 intradural tumors have been presented. All patients had undergone one surgical resection. The mean age is 43 ± 12 years (range 11-67 years). Tumors were subdivided into 4 groups: cervically located-tumors (n = 43), cervicothoracic-region-tumors (n = 32), thoracic-region-tumors (n = 57), and lumbosacral-region-tumors (n = 36). The mean follow-up time was 37 ± 29 months. Gross-total resection rate was higher in cervical located intramedullary tumors compared to the thoracic intramedullary tumors. Cervical intramedullary tumors showed better postoperative functional outcome than the thoracic intramedullary lesions. In intramedullary tumors, extending more than 3 spinal segments, postoperative worsening was significantly increased. A minimally invasive approach (the bilateral decompression via unilateral hemilaminectomy) was used to remove the tumor while preserving spinal stability. Perioperative permanent morbidity was very low. Intramedullary tumors should be surgically treated as soon as neurological symptoms appear. Patients with thoracic intramedullary tumors and tumor extension of more than three segments were at a higher risk for permanent morbidity. The minimally invasive approach allowed complete removal of the intramedullary tumors, and adequate preservation of vertebral stability while providing a good postoperative course.

Preservation of Deep Cervical Extensor Muscle Volume: Comparison Between Conventional Open-Door and Muscle Preserving Laminoplasty Approaches in the Same Patients

BACKGROUND

Surgical laminoplasty techniques have been developed to reduce cervical kyphosis and postoperative axial neck pain and preserve the posterior cervical extensor muscles. We compared a unilateral conventional open approach (OA) and a contralateral muscle preserving approach (MPA) for laminoplasty in the same patients to determine differences in the preservation of the posterior cervical muscles after the 2 approaches.

METHODS

This study was a prospective observational study involving 44 patients who underwent laminoplasty with unilateral OA and contralateral MPA for cervical myelopathy from January 2005 to December 2013. The cross-sectional area (CSA) changes in the posterior cervical extensor muscles (multifidus, semispinalis cervicis, and semispinalis capitis muscles) were measured on computed tomography scan, both pre- and postoperatively.

RESULTS

Using an OA, the multifidus and semispinalis cervicis muscle preservation was 58.2% and 67.0%, but using an MPA, muscle preservation was 97% and 90.8% (P < 0.001 and P = 0.042), respectively. However, the CSA of the semispinalis capitis muscle did not differ significantly between the 2 groups. In terms of the level, conservation of the multifidus muscle was significantly different according to the approach at all levels, and the conservation of the deep extensor muscles was significantly different at the C3-4 level.

CONCLUSIONS

MPA was effective in preserving the volume of deep cervical extensor muscles and helping minimize postoperative musculoskeletal complications. In addition, muscle preservation was more effective at the C3-4 level.

Cervical rotation before and after hinge-door cervical laminoplasty for cervical spondylotic myelopathy

Background:

Hinge-Door Cervical laminoplasty is commonly performed procedure in patients with cervical spondylotic myelopathy. Most available studies have established restriction of flexion and extension motion post laminoplasty but the literature on post-laminoplasty axial rotation is sparse.

Objective:

To study the axial neck rotation on either side following hinge door cervical laminoplasty.

Materials and Methods:

Twenty consecutive patients of cervical spondylotic myelopathy planned for cervical laminoplasty were included in the study. Preoperative and postoperative radiological data was recorded for each patient and analysed by an experienced neuroradiologist. The clinical and radiological follow-up was recorded at 6 months post surgery. All patients underwent standard hinge door C3-C6 laminoplasty preserving the muscle attachments to C2 and C7 vertebra.

Results:

There were 13 men and 7 women with a mean age of 60.5 years, age range 58-70 years. The mean preop C1 C2 rotation was 46.5 degrees and mean post-operative C1-C2 rotation was 44.3 degrees. The average subaxial cervical spine rotation was 11.66 degrees preoperatively and 12.47 degrees postoperatively. The global cervical spine rotation was 80.95 degrees preoperatively and 76.82 degrees postoperatively. There is no significant change in segmental, subaxial and global cervical spine rotation following hinge door C3-C6 laminoplasty preserving the muscle attachments to C2 and C7 vertebra.

Conclusion:

Cervical laminoplasty preserves cervical ROM and is a motion-preserving surgery as far as axial rotation is concerned.

Effectiveness of titanium plate usage in laminoplasty

Background:

Laminoplasty is an established technique for the treatment of cervical stenosis. However, the usage of plates to maintain patency of the laminoplasty door has not been well reported. This study plans to compare the clinical outcomes of laminoplasty with the usage of Sofamor-Danek laminoplasty plates versus techniques without plate usage.

Materials and Methods:

This study conducted a 2-year medical record review of all patients with multilevel cervical myelopathy who were treated with laminoplasty at UCLA or Cedars-Sinai medical center. Of 46 patients 18 had sufficient documentation to assess clinical outcome, 11 of which had placement of laminoplasty plates. Clinical outcomes were assessed using Odom's scoring criteria.

Results:

Blood loss and hospital stay are decreased with plate usage during laminoplasty. Average Estimated Blood Loss (EBL) was 160 cc with plate and 380 cc without. Hospital stay was 4.8 days with plate and 5.6 days without. There were no complications during any of the laminoplasty procedures regardless of instrumentation. All patients demonstrated improvement in symptoms after laminoplasty, with 73% of patients in the plate cohort having Odom Scores of “Excellent” versus 44% in the nonplate group. All patients, regardless of technique, showed improvement in symptoms.

Conclusions:

Laminoplasty with plate utilization is an effective treatment for cervical myelopathy. The similarity in outcomes and complications between these two similar cohorts suggests plate usage in laminoplasty is an attractive alternative to other methods. We hope that future efforts will continue to demonstrate the effectiveness and perhaps superiority of plate utilization in laminoplasty.

Efficacy of Laminoplasty in Patients with Cervical Kyphosis

Background

The efficacy of laminoplasty in patients with cervical kyphosis is controversial. The purpose of this study was to investigate the impact of the initial pathogenesis on the clinical outcomes of laminoplasty in patients with cervical kyphosis.

Material/Methods

A total of 137 patients with cervical spondylotic myelopathy (CSM) or ossification of the posterior longitudinal ligament (OPLL) underwent laminoplasty from April 2013 to May 2015. The patients were divided into the following 4 groups: lordosis with CSM (LC), kyphosis with CSM (KC), lordosis with OPLL (LO), and kyphosis with OPLL (KO). The clinical outcome measures included the visual analogue scale (VAS) and modified Japanese Orthopedic Association (mJOA) scores, the range of motion (ROM), and the cervical global angle (CGA).

Results

The mean VAS and mJOA scores improved significantly in all groups after surgery. The changes in VAS and mJOA scores were significantly smaller, and the JOA recovery rate was significantly lower, in the KC group than in the LC and KO groups. The mean change in the CGA was greatest in the KC group (>8° towards kyphosis). The preoperative ROM was negatively correlated with the change in CGA and the JOA recovery rate in the KO and KC groups.

Conclusions

We found that laminoplasty is suitable for patients with cervical lordosis and those with mild cervical kyphosis and OPLL, but is not recommended for patients with kyphosis and CSM, particularly those with a large ROM preoperatively.

[The effect of spinal cord stretching on development of spondylogenic cervical myelopathy associated with kyphotic spinal deformity]

OBJECTIVE

The study objective was to specify the role of spinal cord stretching in the pathogenesis of spondylogenic cervical myelopathy associated with kyphotic spinal deformity.

MATERIAL AND METHODS

We analyzed long-term outcomes of surgical treatment for spondylogenic cervical myelopathy accompanied by kyphotic spinal deformity.

RESULTS

The surgical treatment outcomes were significantly better (p<0.000001) in the case of simultaneous decompression/correction of kyphotic deformity and spine stabilization.

CONCLUSION

Spinal cord stretching associated with kyphotic spinal deformity significantly contributes to the pathogenesis of clinical manifestations of spondylogenic cervical myelopathy.

Clinical Outcomes of Cervical Laminoplasty: Results at Two Years

BACKGROUND

Laminoplasty is an established treatment for cervical myelopathy. Multiple variations have emerged, many advocating the use of allograft, but controversy persists.

OBJECTIVE

To assess medium-term clinical outcomes in patients who underwent laminoplasty with autograft at our institution.

METHODS

Thirty-two consecutive patients (19 male, 13 female, average age 66 yr) from our prospective outcome registry that underwent cervical laminoplasty between 2009 and 2013 were reviewed. Computed tomography (CT) scan was performed immediately postoperatively and at 6-mo follow-up. Parameters included patient perception of outcome, Nurick score, Neck Disability Index (NDI), visual analog scale for neck pain, and SF-36.

RESULTS

On retrospective analysis, all patients felt improved at 3 mo postoperatively; at 2 yr, this rate was 91%. Improvements were seen in Nurick scores, from 3.16 ± 0.9 preoperatively to 1.94 ± 0.8 at 2 yr; NDI score from 28.7% ± 9% preoperatively to 20.8% ± 9.6% at 2 yr; visual analog scale from 2.8 ± 1.2 preoperatively to 1.7 ± 0.9 at 2 yr; and SF-36 physical component summary from 27.9 ± 10 preoperatively to 37.8 ± 11.9 at 2 yr. All values reached significance at all follow-up points ( P < .05) with the exception of 6-mo NDI values ( P = .062). No C5 palsy, graft complications, or reclosure was observed in any patient during the follow-up period.

CONCLUSION

Laminoplasty with autograft is a safe and effective method to treat cervical myelopathy, with good medium-term clinical outcome. No reclosures were observed. Bony fusion was seen in all cases on CT scan. Our study found good outcomes in the performance of open-door laminoplasty without hardware, in the treatment of cervical stenosis.

Increased Segmental Range of Motion Is Correlated With Spondylolisthesis in the Cervical Spine After Laminoplasty

STUDY DESIGN

A retrospective study.

OBJECTIVE

The aim of this study was to determine the incidence of increased segmental range of motion (ROM) after laminoplasty and to clarify whether increased ROM is associated with spondylolisthesis. Finally, we explored the effect of increased segmental ROM on clinical results.

SUMMARY OF BACKGROUND DATA

Cervical laminoplasty for cervical spondylotic myelopathy causes reduced ROM, possibly due to the unintended contracture of the facet joint or a bony union. Although it is rarely studied, ROM may also increase following laminoplasty. Thus far, there are no reports describing the correlation between increased segmental ROM and segmental spondylolisthesis after laminoplasty.

METHODS

We evaluated 187 segments from 39 cervical spondylotic myelopathy patients who underwent bilateral open door laminoplasty from C2 to C7. The segmental ROM and spondylolisthesis were measured using dynamic radiographs that were obtained preoperatively and 2 years postoperatively. The Japanese Orthopedic Association (JOA) score was used for clinical evaluation. To compare the clinical results, we compared the cases with increased ROM in at least one segment with the remaining cases.

RESULTS

Increased segmental ROM (i.e., ≥5° increase) was observed in 25 of 187 segments (13.4%) from 14 cases. There was a strong correlation between increased ROM and spondylolisthesis. A high preoperative disc height was associated with increased segmental ROM 2 years postoperation. Regardless of the correlation with spondylolisthesis, there was no statistically significant correlation between increased segmental ROM and JOA score.

CONCLUSION

The decrease in segmental ROM after laminoplasty was not uniform. Approximately 13.4% of all segments showed increased ROM. The preoperative disc height might influence the risk for increased segmental ROM. Furthermore, increased ROM was correlated with spondylolisthesis in the segment, though it was not correlated with clinical results.

LEVEL OF EVIDENCE

4.

The Change of Range of Motion at Anterior Compression of the Cervical Cord after Laminoplasty in Patients with Cervical Spondylotic Myelopathy

Objective

Degenerative diseases of the spine, such as cervical spondylotic myelopathy (CSM), are increasing among the old age population, and surgical treatment of CSM is becoming more and more common. The aim of this study was to investigate how functional recovery can be influenced by anterior compression of the spinal cord (ACS) after laminoplasty for treatment of patients with CSM.

Methods

We retrospectively analyzed 32 patients admitted to Ewha Womans Mok-Dong Hospital with CSM who underwent open-door laminoplasty from January 2012 to December 2014. We divided patients into 2 groups according to whether ACS was or not preoperatively. Each group was analyzed clinical and radiological parameters which were Japanese Orthopedic Association (JOA) scores and its recovery rate, sagittal alignment and range of motion (ROM).

Results

The mean duration of symptom was 11.2 months (range, 6-22 months). A significant difference in recovery rate of the total JOA score was shown between the 2 groups, especially upper extremity motor function. No difference in preoperative JOA score between the 2 groups, but recovery rate of each group was 20.05%±18.1%, 32.21%±25.4%, statistically significant (p<0.005). Upper motor and sensory function was not significantly different in the 2 groups. Preoperative, postoperative and preservation of ROM was 44.3°±10.1°, 41.8°±15.7°, 87.9%±35.4% each at ACS (-) group. A significant difference in postoperative ROM was identified between ACS (-) and ACS (+) group. Postoperative anterior compression of the spinal cord was recognized 14 cases which were classified from its causes.

Conclusion

Cervical ROM decreased significantly after laminoplasty, but 85.3% of the preoperative ROM was preserved. The postoperative reduction of ROM in group with anterior compression of spinal cord was identified.

Bony ankylosis of the facet joint of the cervical spine in rheumatoid arthritis: Its characteristics and relationship to the clinical findings

OBJECTIVES

The purpose of this study was to clarify the characteristics of bony ankylosis of the facet joint of the cervical spine in rheumatoid arthritis (RA) patients who required cervical spine surgery, and its relationship to the clinical findings.

METHODS

Eighty consecutive RA patients with cervical spine disorder who received initial surgery were reviewed. The occurrence of bony ankylosis of the facet joint of the cervical spine was investigated using computed tomography (CT) before surgery. We also evaluated the severity of neurological symptoms and the plain wrist radiographs taken before surgery; furthermore, we evaluated each patient's medical history for total knee arthroplasty (TKA) or hip arthroplasty (THA).

RESULTS

The preoperative CT imaging demonstrated bony ankylosis of the facet joint of the cervical spine in 45 facet levels of 19 cases (BA + group). In all patients, responsible instability or stenosis was demonstrated just caudal or on the cranial side of those bony ankylosis. Before surgery, the BA + group included significantly more patients showing severe cervical myelopathy (p < 0.05), and significantly more cases showing progressed ankylosis in the wrist joint bilaterally (p < 0.01). There were also significantly more patients who received two or more TKA or THA before the cervical spine surgery in the BA + group (p < 0.01).

CONCLUSIONS

Bony ankylosis of the facet joint of the cervical spine may be a risk factor of instability or stenosis at the adjacent disc level and severe cervical myelopathy. Furthermore, its ankylosis was demonstrated in RA patients with severe destroyed joints.

Expansive Open-Door Cervical Laminoplasty: In Situ Reconstruction of Extensor Muscle Insertion on the C2 Spinous Process Combined With Titanium Miniplates Internal Fixation

Retrospective cohort study. To evaluate efficacy and relevant problems of in situ reconstruction of extensor muscle insertion on the C2 spinous process combined with titanium miniplates internal fixation in expansive open-door cervical laminoplasty in order to improve surgical treatment effect. Expansive open-door cervical laminoplasty has been widely applied in clinical practice, but there are a series of postoperative problems. Therefore, decreasing postoperative complications in order to more effectively relieve symptoms remains a subject for additional research. From October 2011 to September 2013, a total of 60 patients who suffered cervical canal stenosis were treated by expansive open-door laminoplasty with in situ reconstruction of extensor muscle insertion on the C2 spinous process combined with titanium miniplates internal fixation. Changes of cervical curvature index (CI) and range of motion (ROM) were calculated using data from preoperative and postoperative cervical spine X-ray examinations. Clinical function was scored using the Japanese Orthopedics Association Scoring System (JOA) and the neck disability index (NDI). The mean CI before the operation and at 1-year postoperation were 10.49% ± 3.93% and 14.14 ± 2.85 (P < 0.05). The mean ROM values were 43.35 ± 7.55 before the operation, 34.83 ± 7.41 at 1-year postoperation (P < 0.05). The NDI scores decreased from 19.42 ± 4.12 to 7.37 ± 2.58, and the JOA scores increased from 8.87 ± 1.99 to 13.55 ± 1.72, representing significant improvement (P < 0.05). One patient had postoperative C5 nerve root palsy and completely recovered 1 month later. Neither collapse nor door closure in the open-door side occurred in any of the patients. Expansive open-door cervical laminoplasty with in situ reconstruction of extensor muscle insertion on the C2 spinous process combined with titanium miniplates internal fixation is a safe and effective surgical method, and can effectively decrease postoperative complications and achieve satisfactory clinical results.

Cervical open-door laminoplasty technique with simple sutures and bone grafts: a single institutional study with 30 consecutive cases

Background

Expansive open-door laminoplasty is widely accepted as a reliable procedure for cervical myelopathy. However, one acknowledged complication is spring-back complication or closure of the door which may result in restenosis of cervical canal and neurologic deterioration. The study aimed for addressing our cervical open-door laminoplasty technique with sutures and bone grafts and subsequently the follow-up outcomes.

Methods

Thirty consecutive patients who underwent open-door laminoplasty with the novel technique were included and followed for minimum 5 years from Jan 2006 to Dec 2007. Anteroposterior diameter (APD) of the vertebral canal of C4 was measured in lateral cervical radiographs. Neurologic scenarios were noted using the Japanese Orthopaedic Association (JOA) scores.

Results

Twenty-five males (83.3%) and five (16.7%) females with an average follow-up of 68 months were enrolled. The preoperative APD was 13.22 mm (±1.15), whereas the postoperative APD increased to 31.23 mm (±2.43) with an expansion ratio of 136.23% (P < 0.05). The JOA score increased from 8.5 preoperatively to 13.45 postoperatively with a recovery rate of 58.2% (P < 0.05). The elevated laminas were maintained open during the follow-up period.

Conclusions

Our technique with sutures and bone graft for laminoplasty is a simple and efficient method for maintaining the decompression of cervical canal and neurologic improvement.

Does intramedullary signal intensity on MRI affect the surgical outcomes of patients with ossification of posterior longitudinal ligament?

Objectives

Patients with cervical ossification of posterior longitudinal ligament (OPLL) are susceptible to cord injury, which often develops into myelopathic symptoms. However, little is known regarding the prognostic factors that are involved in minor trauma. We evaluated the relationship between minor trauma and neurological outcome of OPLL and investigated the prognostic factors with a focus on compressive factors and intramedullary signal intensity (SI).

Methods

A total of 74 patients with cervical myelopathy caused by OPLL at more than three-levels were treated with posterior decompression surgeries. We surveyed the space available for spinal cord (SAC), the severity of SI change on T2-weighted image, and diabetes mellitus (DM). The neurological outcome using Japanese Orthopedic Association (JOA) scale was assessed at admission and at 12-month follow-up.

Results

Among the variables tested, preoperative JOA score, severity of intramedullary SI, SAC, and DM were significantly related to neurological outcome. The mean preoperative JOA were 11.3±1.9 for the 41 patients who did not have histories of trauma and 8.0±3.1 for the 33 patients who had suffered minor traumas (p<0.05). However, there were no significant differences in the recovery ratios between those two groups.

Conclusions

Initial neurological status and high intramedullary SI in the preoperative phase were related to poorer postoperative outcomes. Moreover, the patients with no histories of DM and larger SACs exhibited better improvement than did the patients with DM and smaller SACs. Although the initial JOA scores were worse for the minor trauma patients than did those who had no trauma prior to surgery, minor trauma exerted no direct effects on the surgical outcomes.

Minimally invasive posterior cervical decompression using tubular retractor: The technical note and early clinical outcome

Background:

The aim of this work is to present a novel decompression technique that approaches cervical spine posteriorly, but through minimal invasive method using tubular retractor avoiding detachment of posterior musculature.

Methods:

Six patients underwent minimally invasive posterior cervical decompression using the tubular retractor system and surgical microscope. Minimally invasive access to the posterior cervical spine was performed with exposure through a paramedian muscle-splitting approach. With the assistance of a specialized tubular retraction system and deep soft tissue expansion mechanism, multilevel posterior cervical decompression could be accomplished. This approach also allows safe docking of the retractor system on the lateral mass, thus avoiding the cervical spinal canal during exposure. A standard operating microscope was used with ×10 magnification and 400 mm focal length. The hospital charts, magnetic resonance imaging studies, and follow-up records of all the patients were reviewed. Outcome was assessed by neurological status and visual analog scale (VAS) for neck and arm pain.

Results:

There was no significant complication related to operation. The follow-up time was 4-12 months (mean, 9 months). Muscle weakness improved in all patients; sensory deficits resolved in four patients and improved in two patients. Analysis of the mean VAS for radicular pain and VAS for neck pain showed significant improvement.

Conclusions:

The preliminary experiences with good clinical outcome seem to promise that this minimally invasive technique is a valid alternative option for the treatment of cervical spondylotic myelopathy.

Outcomes of surgical intervention for cervical spondylotic myelopathy accompanying local kyphosis (comparison between laminoplasty alone and posterior reconstruction surgery using the screw-rod system)

PURPOSE

The surgical strategy for cervical spondylotic myelopathy (CSM) accompanying local kyphosis is controversial. The purpose of the present study was to compare and evaluate the outcomes of two types of surgery for CSM accompanying local kyphosis: (1) laminoplasty alone (LP) and (2) posterior reconstruction surgery (PR) in which we corrected the local kyphosis using a pedicle screw or lateral mass screw.

METHODS

Sixty patients who presented with local kyphosis exceeding 5° were enrolled. LP and PR were each performed on a group of 30 of these patients; 30 CSM patients without local kyphosis, who had undergone LP, were used as controls. The follow-up period was 2 years or longer. Preoperative local kyphosis angles in LP and PR were 8.3° ± 4.4° and 8.8° ± 5.7°, respectively. Preoperative C2-7 angles in LP, PR and controls were -1.7° ± 9.6°, -0.4° ± 7.2° and -12.0° ± 5.6°, respectively. The recovery rate of the JOA score, local kyphosis angle and C2-7 angle at post-op and follow-up were compared between the groups.

RESULTS

The recovery rate of the JOA score in the LP group (32.6 %) was significantly worse than that in the PR group (44.5 %) and that of controls (53.8 %). Local kyphosis angles in the PR and LP groups at follow-up were 4.0° ± 8.6° and 8.0° ± 6.0°, respectively. However, although the C2-7 angle at follow-up was improved to -11.1° ± 12.7° in PR, and maintained at -11.6° ± 6.2° in controls, it deteriorated to 0.5° ± 12.7° in LP.

CONCLUSIONS

The present study is the first to compare the outcomes between LP alone and PR for CSM accompanying local kyphosis. It revealed that PR resulted in a better clinical outcome than did LP alone. This result may be due to reduction of local kyphosis, stabilization of the unstable segment, and/or the maintenance of C2-7 angle until follow-up in the PR group.

Laminoplasty techniques for the treatment of multilevel cervical stenosis

Laminoplasty is one surgical option for cervical spondylotic myelopathy. It was developed to avoid the significant risk of complications associated with alternative surgical options such as anterior decompression and fusion and laminectomy with or without posterior fusion. Various laminoplasty techniques have been described. All of these variations are designed to reposition the laminae and expand the spinal canal while retaining the dorsal elements to protect the dura from scar formation and to preserve postoperative cervical stability and alignment. With the right surgical indications, reliable results can be expected with laminoplasty in treating patients with multilevel cervical myelopathy.

"Spring-back" closure associated with open-door cervical laminoplasty

BACKGROUND CONTEXT

Spring-back complication after open-door laminoplasty as described by Hirabayashi is a well-known risk, but its definition, incidence, and associated neurologic outcome remain unclear.

OBJECTIVE

To investigate the incidence and the neurologic consequence of spring-back closure after open-door laminoplasty.

STUDY DESIGN

A retrospective radiographic and clinical review.

OUTCOME MEASURES

Lateral cervical spine X-rays were evaluated. Anteroposterior diameters (APD) of the vertebral canal of C3-C7 were measured. Spring-back was defined as loss of APD on follow-up in comparison to immediate postoperative canal expansion. The loss of the end-on lamina silhouette with consequent reappearance of the lateral profile of the spinous processes was also assessed to verify the presence of spring-back. Spring-back closure was classified based on whether the collapse was total or partial, and whether all the operated levels or only a subset had collapsed (ie, complete vs. partial closure, segmental closure vs. total-construct closure). Neurologic status was documented using the Japanese Orthopaedic Association (JOA) score.

METHODS

Thirty consecutive patients who underwent open-door laminoplasty from 1995 to 2005 at a single institution with a minimum follow-up of 2 years were assessed. They were all operated on using the classic Hirabayashi technique. Radiographic outcomes were assessed independently by two individuals.

RESULTS

Sixteen men and 14 women with an average follow-up of 5 years (range, 2-12 years) were included. Of these patients, 24 had cervical spondylotic myelopathy and six had ossification of the posterior longitudinal ligament. Spring-back closure was found in three patients (10%) and 7 of 117 laminae (6%) within 6 months of the operation, which was further confirmed by computed tomography and magnetic resonance imaging. All spring-back closures were partial segmental closures. Gender and age were not significant factors related to spring back (p>.05). The mean JOA score on follow-up was 12.5, with a recovery rate of 40%. All patients with spring back and available JOA data exhibited postoperative neurologic deterioration. Of the three patients with spring back, two patients underwent revision surgery, whereas one declined.

CONCLUSIONS

Spring-back closure occurred in 10% of our patients at or before 6 months after surgery. The incidence of spring-back by level (ie, 117 laminae) was 6%, mainly occurring at the lower cervical spine. All spring-back closures were partial segmental closures, most commonly involving C5 and C6. Postoperative neurologic deficit was associated with spring-back closure; therefore, surgeons should adopt preemptive surgical measures to prevent the occurrence of such a complication.

The clinical usefulness of preoperative dynamic MRI to select decompression levels for cervical spondylotic myelopathy

The study subjects included 54 patients with cervical spondylotic myelopathy who underwent a selective laminoplasty. The patients were divided into three groups according to the number of decompressed levels: two levels, three levels and four or five levels. The number of cord compressions at every intervertebral level was determined in the flexion, neutral, and extension position using a dynamic magnetic resonance imaging (MRI) scan in consideration of both static and dynamic compressions. For each group, the clinical outcomes were evaluated. Moreover, the patients were divided into two groups according to their age. Then, the appearance ratios of cord compression between the neutral and extension position were compared at each intervertebral level. The clinical outcomes were satisfactory. There were no statistical differences among the three groups, except for the age and operation time. The position of the neck influenced the number of cord compressions. The appearance ratios of cord compression, which were especially prominent at C2/3, C3/4 and C4/5, showed high scores in the aged. The preoperative dynamic MRI scan was clinically useful. In the aged, attention should be given to C2/3, C3/4 and C4/5.

Outcomes for combined anterior and posterior surgical approaches for patients with multisegmental cervical spondylotic myelopathy

Corpectomy is widely used to treat cervical spondylotic myelopathy (CSM). However, when this technique alone is performed at 1 or 2 levels for a multisegmental involvement (3 or more vertebrae), the incidence of post-operative complications is high. The optimal treatment for multisegmental CSM is still debatable. The aim of this study was to assess clinical and radiological outcomes for patients with multisegmental CSM who underwent combined anterior and posterior (AP) surgical approaches. Forty adults (17 women and 23 men; age range, 41-76 y) treated at our center between 2004 and 2007 were reviewed retrospectively. Their neurological function was assessed at different times using the Nurick classification (Grades 0 [root symptoms only] to 5 [wheelchair- or bed-bound]). Patients' satisfaction with the surgery was evaluated using Odom's criteria (poor, fair, good, or excellent). Pre-operatively, 20% of patients were assessed as Nurick Grade 0, 60% as Grade 1, and 20% as Grade 2. At the 1-year follow-up, only 10% of patients were assessed as Grade 1. At 1 year after surgery, 85% of patients rated their satisfaction with the operation as "excellent" and 15% rated it as "good". These outcomes suggest that, when surgery is indicated and patients with multisegmental CSM are carefully selected, the combined AP approach yields symptom relief comparable to that of corpectomy alone and a lower incidence of post-operative complications.

Preservation of the nuchal ligament plays an important role in preventing unfavorable radiologic changes after laminoplasty

STUDY DESIGN

Prospective study.

OBJECTIVE

To examine whether preservation of the funicular section of the nuchal ligament attached to the C6 and C7 spinous processes could prevent unfavorable radiologic changes such as kyphotic deformity and destabilization at the C6/7 segment, and to investigate possible correlations between adverse radiologic changes and neurologic recovery or incidence of axial neck pain after laminoplasty in patients with cervical spondylotic myelopathy.

SUMMARY OF BACKGROUND DATA

Adverse radiologic changes after cervical laminoplasty have been reported to result from detachment of cervical extensor muscles.

METHODS

Subjects comprised 37 patients who underwent modified C3-6 laminoplasty. Our procedure preserves the funicular section of the nuchal ligament attached to the C6 and/or C7 spinous processes in addition to all muscles attached to the C2 and C7 spinous processes and the subaxial deep extensor muscles on the hinged side. The funicular section of the ligament attached only to the C7 spinous process was preserved in 18 patients (C7 group). This funicular section attaching both to the C7 and C6 spinous processes was preserved in 19 patients (C6+7 group). Radiologic and clinical data were prospectively collected.

RESULTS

Postoperative loss of lordosis and destabilization at the C6/7 segment were significantly reduced in the C6+7 group compared with the C7 group. As of final follow-up, neurologic recovery was significantly poorer in the 3 patients with kyphosis than in the 34 patients with straight spinal alignment or lordosis. Frequencies of axial pain showed no significant differences between groups. This value did not vary with the differences in sagittal alignment.

CONCLUSIONS

These results indicate that the preserved funicular section of the nuchal ligament attached both to the C6 and C7 spinous processes plays an important role in preventing undesirable radiologic changes after laminoplasty.

Exploration and decompression of the spinal canal using split laminotomy and its modification, the "archbone" technique

OBJECTIVE

To develop a novel minimally invasive approach suitable for exploring different pathologies located in the spinal canal, allowing moderate enlargement of the canal with preservation of the majority of posterior structures so muscle attachments remain intact and postoperative complications are reduced.

METHODS

The authors developed a multilevel spinous process splitting and distracting laminotomy technique with or without complementary corticocancellous iliac crest "archbone" autografting. Technical details are discussed. The multilevel spinous process splitting and distracting laminotomy technique with or without complementary iliac bone grafting was used in 19 patients with different pathologies of the spinal canal.

RESULTS

Satisfactory surgery of the lesions located within the spinal canal, especially intramedullary, was achieved in all patients using this new approach. The affected area of the spine was cervical in seven patients, cervicothoracic in four patients, thoracic in five patients, and thoracolumbar in three patients. The average number of split laminae was three (range, 2-6). Histological results were as follows: seven intramedullary astrocytomas, eight ependymomas, two cavernous hemangiomas, one dural arteriovenous malformation, and one hemangioblastoma. Of the eight ependymomas, 75% were removed completely and 25% were partially removed. Of the seven astrocytomas, 28.7% were removed completely, 14.3% were removed subtotally, and 57% were partially removed. The cavernous hemangiomas and the hemangioblastoma were completely removed. The approach used did not affect the extent of resection or neurological outcome. The spinous processes were closed directly in 13; in six cases, a tricortical iliac bone graft was placed between the facing bony parts of the spinous processes. The mean duration of splitting and distracting the spinous process was 16 minutes (range, 11-28 min) for the first process and 8 minutes (range, 5-14 min) for each additional spinous process. The mean duration of the whole surgical procedure, including intraspinal surgery, was 159 minutes (range, 90-290 min). The mean blood loss was 158 ml (range, 48-442 ml). The average length of hospital stay was 7.2 days. The average follow-up period was 15.4 months. Fifty-one of the 57 (89.5%) spinous process computed tomographic scans demonstrated bony healing with or without a graft between the osteotomized faces. Of the 57 spinous process computed tomographic scans, fracture of the spinous process was seen in nine (15.8%) and traumatic bony changes of the body of the vertebra in the midline in three (5.2%); these were without clinical significance and they later showed complete healing.

CONCLUSION

This surgical approach fulfills the requirements of other laminotomy techniques and helps prevent damage to the crucial posterior stabilizers of the spine. In contrast to conventional spinal canal approaches, preservation of the majority of posterior structures leaves muscle attachments on the spinous processes and laminae completely intact. Furthermore, the technique for exposure and decompression of the spinal canal is a suitable method for all spinal segments, the cervical, thoracic, and the lumbar spine in all age groups.

Limitation of activities of daily living accompanying reduced neck mobility after laminoplasty preserving or reattaching the semispinalis cervicis into axis

Although difficulties with neck mobility often interfere with patients' activities of daily living (ADL) after cervical laminoplasty, there was no detailed study on the relation between the limitations of ADL accompanying postoperative reduced neck mobility and the cervical posterior approach. The aim of this study was to compare retrospectively the frequency of limitations of ADL accompanying neck mobility after laminoplasty preserving the semispinalis cervicis inserted into the C2 spinous process with that after laminoplasty reattaching the muscle to C2. Forty-nine patients after C4-C7 laminoplasty with C3 laminectomy preserving the semispinalis cervicis inserted into C2 (Group A) and 24 patients after C3-C7 laminoplasty reattaching the muscle (Group B) were evaluated. The frequency of postoperative limitations of ADL accompanying each of three neck movements of extension, flexion and rotation were investigated. The postoperative O-C7 angles at extension and flexion was measured on lateral extension and flexion radiographs of the cervical spine, respectively. The postoperative cervical range of motion in rotation was measured in the cranial view using a digital camera. Frequency of limitations of ADL accompanying extension was lower (P = 0.037) in Group A (2%) than in Group B (17%). Frequency of limitations of ADL accompanying flexion was similar in Group A (8%) and Group B (4%). Frequency of limitations of ADL accompanying rotation was lower (P = 0.031) in Group A (12%) than in Group B (33%). Average O-C7 angle at extension was significantly larger (P = 0.002) in Group A (147 degrees ) than in Group B (136 degrees ). Average O-C7 angle at flexion was similar in Group A (93 degrees ) and Group B (91 degrees ). Average range of motion in rotation was significantly larger (P = 0.004) in Group A (110 degrees ) than in Group B (91 degrees ). This retrospective study suggested that the frequency of limitations of ADL accompanying neck extension or rotation was lower after laminoplasty preserving the semispinalis cervicis inserted into C2 than after laminoplasty reattaching the muscle.

Assessing Range of Cervical Rotation After Laminoplasty Using Axial CT

PURPOSE

Although many authors have reported on cervical range of motion after laminoplasty, they have focused on flexion and extension based on lateral radiographs, not on axial rotation. In this study, we assessed cervical rotation from C1 to T1 after laminoplasty using computed tomography.

PATIENTS AND METHODS

Eighteen consecutive patients with cervical myelopathy who had undergone laminoplasty were observed. Patient was placed in the supine position on the computed tomography scan table. After the scans in this neutral position were completed, the patient actively rotated his neck as far as possible taking care that the shoulders remained in the horizontal plane. We measured the C1 to T1, C1 to C2, and C2 to T1 rotation angles preoperatively, and at 2 weeks and 6 months after surgery.

RESULTS

The average C1 to T1 rotation angles preoperatively were 46 degrees on the right and 45 degrees on the left. The percentage of C1 to C2 rotation during global cervical rotation (C1 to T1) was 62%. C1 to T1 rotation angle significantly decreased at two weeks after surgery but recovered to almost preoperative levels (11% decreases) by 6 months after surgery with no difference between right and left motion. The average C2 to T1 subaxial rotation angles did not significantly decreased after surgery.

CONCLUSIONS

Rotation angle after laminoplasty decreased slightly at 2 weeks after surgery but recovered almost to preoperative levels by 6 months. Subaxial rotation (C2 to T1) angles did not significantly decreased after surgery.

Laminoplasty: a review of its role in compressive cervical myelopathy

BACKGROUND CONTEXT

The currently accepted surgical treatments for compressive cervical myelopathy include both anterior and posterior decompression. Anterior approaches including multilevel discectomy with fusion or vertebral corpectomy with strut grafting, both with and without instrumentation, have enjoyed successful outcomes, but have been associated with select postoperative complications. Laminoplasty has been developed to decompress the spine posteriorly while avoiding the spinal destabilization seen after laminectomy.

PURPOSE

The purpose of this article is to provide a review of the various techniques, biomechanical basis, predictive value of imaging modalities, clinical outcomes, and postoperative complications associated with cervical laminoplasty.

STUDY DESIGN

A review of the literature.

METHODS

A comprehensive literature review using Medline was performed identifying relevant articles that addressed the techniques, clinical outcomes, and complications after cervical laminoplasty, as well as preoperative radiographic predictors of outcome.

RESULTS

The various modifications of cervical laminoplasty have generally been associated with excellent clinical outcomes when used for myelopathy secondary to cervical spondylosis or ossification of the posterior longitudinal ligament (OPLL). Recent long-term studies have identified issues with this technique including axial neck pain, canal restenosis, nerve root palsy, diminished cervical motion, and loss of cervical lordotic alignment.

CONCLUSIONS

Cervical laminoplasty remains a reliable procedure for posterior decompression of the spine, but the optimal approach to cervical myelopathy must take into account both patient and disease characteristics, as well as the capabilities and experience of the surgeon.

Enlargement of Cervical Spinal Cord Correlates With Improvement of Motor Function in Upper Extremities After Laminoplasty for Cervical Myelopathy

OBJECTIVE

The correlation between postoperative spinal cord enlargement at the most compressive disc level and clinical outcome is controversial. The relationship between spinal cord enlargement at neurologically symptomatic disc level and clinical recovery has not been explored. The purpose of this study was to clarify the relationship between postoperative spinal cord enlargement at neurologically symptomatic disc level and neurologic outcome.

METHODS

We studied 55 consecutive patients between 1995 and 2002. All patients underwent preoperative neurologic examination to determine the neurologically symptomatic disc level of the spinal cord and computed tomographic myelography twice before and 4 weeks after laminoplasty. The cross-sectional areas of both spinal cord and dural sac from C3/4 to C7/T1 disc levels were measured on computed tomographic myelography images. The Japanese Orthopedic Association scoring system was used for clinical evaluation before and 1 year after surgery.

RESULTS

Total score improved significantly from 10.2+/-2.8 (SD) to 13.0+/-3.0 after operation. Motor and sensory function scores of upper and lower extremities also improved significantly. The enlargement of spinal cord area at the neurologically symptomatic disc level correlated significantly with improvement in motor function scores of upper extremities (rs=0.421 P=0.0052). However, there were no significant relationships between the enlargement of the spinal cord at the most compressive disc level or that at the dural sac and any categories of Japanese Orthopedic Association scoring system.

CONCLUSION

Postsurgical enlargement of the cervical spinal cord at the neurologically symptomatic disc level at 4 weeks postoperatively correlated with recovery of motor function of the upper extremities at 1 year.

Square cervical laminoplasty incorporating spinous process: surgical technique

BACKGROUND

We have used a laminoplasty technique in multilevel cervical canal stenosis that incorporates spinous process in the neural arch and does not require free graft or foreign material.

METHODS

In this technique, laminae and spinous processes were used to enlarge stenotic cervical spinal canal. Three patients (mean age 34.6 years) formed the study group with a mean follow-up period of 24.6 months. Postoperative computed tomography (CT) and lateral radiographs were used to assess results in terms of bony union, canal diameter, and alignment of cervical spine.

RESULTS

All patients noted some improvement in both sensory and motor functions. The average increase in sagittal diameter of cervical spinal canal was 4.2 mm, and decrease in range of motion (ROM) was 13.2 degrees. Bony fusions at the gutters were seen after 6 months.

CONCLUSION

This new technique of cervical laminoplasty is safe, effective, relatively easy, and avoids complications related to free grafts or metallic or nonmetallic foreign materials used in other techniques

Minimum 10-year followup after en bloc cervical laminoplasty

The long-term outcome (> 10 years) after cervical laminoplasty was assessed and the postoperative problems were clarified. One hundred thirty-three patients had laminoplasty between 1981 and 1989 for treatment of cervical myelopathy and 126 patients were available for the current study. The clinical results were evaluated using the Japanese Orthopaedic Association score. The radiologic findings were analyzed by postural anomalies and range of motion. The average preoperative score was 9.1 points, and the postoperative score improved to 13.7 points within a year. The Japanese Orthopaedic Association score and recovery rate were maintained at 13.4 points and 55.1% at the last followup. In 20 patients, the Japanese Orthopaedic Association score worsened during the followup. The causes of deterioration were axial spread of ossification of the posterior longitudinal ligament, other spinal lesions, cerebral infarction, and peripheral neuropathy. Postoperative cervical radiculopathy occurred in nine patients. Postoperative radiculopathy resolved in five patients, but remained in four patients. Kyphotic changes were observed in eight patients. The recovery rate in patients with kyphosis was poor. The postoperative range of motion decreased to 25.1% of preoperative range of motion. Sixty one percent of patients had a reduction of range of motion. Satisfactory results of cervical laminoplasty were maintained for more than 10 years after surgery; however, there were several postoperative problems, such as neurologic deterioration, postoperative radiculopathy, progression of kyphosis, and range of motion limitation.

Skip laminectomy--a new treatment for cervical spondylotic myelopathy, preserving bilateral muscular attachments to the spinous processes: a preliminary report

BACKGROUND CONTEXT

Techniques in current use for expansive laminoplasty operations (ELAP) on the cervical spine damage the extensor mechanisms, resulting in restriction of neck motion, loss of lordosis and persistent axial pains.

PURPOSE

This article introduces a new surgical technique called skip laminectomy, which reduces morbidity after decompression of the cervical spinal canal.

STUDY DESIGN/SETTING

A prospective study is presented of all patients with multilevel cervical spondylotic myelopathy (CSM), treated by this new procedure between December 1998 and March 2000.

PATIENT SAMPLE

Since December 1998, 61 patients with CSM have undergone the procedure, of whom 24 (13 men and 11 women) were selected for this study. Follow-up periods ranged from 12 to 25 months, with an average of 18 months. Average age at operation was 69 years (range, 50 to 82 years). Eighteen patients with CSM on whom C3-C7 open-door laminoplasties had been performed by the author before 1998 were selected as controls for study of postoperative atrophy of the deep extensor cervical muscles. There were 11 men and 7 women, average age 67 years (range, 45 to 81).

OUTCOME MEASURES

Axial symptoms and Japanese Orthopaedic Association (JOA) scores were recorded. Pre- and postoperative ranges of neck motion were measured on lateral flexion and extension radiographs. Pre- and postoperative cervical curvature indexes were calculated according to Ishihara's method. For quantitative analysis of damage to the posterior cervical muscles, atrophy rates were calculated from cross-sectional areas of the deep extensor muscles on the pre- and postoperative axial magnetic resonance imaging.

METHODS

In skip laminectomy, standard laminectomies are performed at selected levels, combined with partial laminectomies of the cephalad halves of laminae at other selected levels, where the muscular attachments to the spinous processes are left undisturbed. Instead of a standard laminectomy, an interlaminar decompression can be performed at levels where the anterior spinal cord compression is insignificant. It is accomplished by simply removing the cephalad half of the inferior lamina and ligamentum flavum without detaching the semispinalis cervicis and multifidus muscles from the adjacent spinous processes.

RESULTS

Using JOA scores, the average recovery rate was 61.0%. None of the patients complained of persistent axial symptoms. The postoperative range of flexion-extension motion averaged 97% of the preoperative measures. The cervical curvature index was reduced in 1 of the 24 patients. The atrophy rate of the deep extensor muscles after skip laminectomy was 20% of that seen after open-door laminoplasty.

CONCLUSIONS

Skip laminectomy for cervical spinal canal decompression is less invasive than conventional laminectomy and ELAP. It is effective in preventing postoperative problems, such as persistent axial symptoms, restriction of neck motion and loss of cervical lordosis.

Relationship between cervical curvature index (Ishihara) and cervical spine angle (C2--7)

The purpose of this study was to determine the relationship between the cervical curvature index (Ishihara) and the cervical spine angle (C2--7) from both cervical lateral radiographs and a geometrical model. The cervical lateral radiographs of 295 outpatients with no cervical symptoms were reviewed to measure the cervical curvature index (Ishihara) and the cervical spine angle (C2--7). The average cervical curvature index (Ishihara) was 10.9 (SD, 15.3) and the average cervical spine angle (C2--7) was 20.3 (SD, 14.3). A highly significant correlation (0.95; 95% confidence interval [CI], 0.94--0.96) was found between the cervical curvature index (Ishihara) and the cervical spine angle (C2--7). Their linear correlation was also validated in the geometrical model. Their correlation diminished, however, in subjects with an S-shaped cervical spine. The cervical curvature index (Ishihara) and the cervical spine angle (C2--7) were interchangeable, but this interchangeability was lost in the S-shaped cervical spines.