Cervical spondylotic myelopathy treated with corpectomy: technique and results in 44 patients

Misplaced Cervical Screws Requiring Reoperation

STUDY DESIGN

A multicenter, retrospective case series.

OBJECTIVE

In the past several years, screw fixation of the cervical spine has become commonplace. For the most part, this is a safe, low-risk procedure. While rare, screw backout or misplaced screws can lead to morbidity and increased costs. We report our experiences with this uncommon complication.

METHODS

A multicenter, retrospective case series was undertaken at 23 institutions in the United States. Patients were included who underwent cervical spine surgery from January 1, 2005, to December 31, 2011, and had misplacement of screws requiring reoperation. Institutional review board approval was obtained at all participating institutions, and detailed records were sent to a central data center.

RESULTS

A total of 12 903 patients met the inclusion criteria and were analyzed. There were 11 instances of screw backout requiring reoperation, for an incidence of 0.085%. There were 7 posterior procedures. Importantly, there were no changes in the health-related quality-of-life metrics due to this complication. There were no new neurologic deficits; a patient most often presented with pain, and misplacement was diagnosed on plain X-ray or computed tomography scan. The most common location for screw backout was C6 (36%).

CONCLUSIONS

This study represents the largest series to tabulate the incidence of misplacement of screws following cervical spine surgery, which led to revision procedures. The data suggest this is a rare event, despite the widespread use of cervical fixation. Patients suffering this complication can require revision, but do not usually suffer neurologic sequelae. These patients have increased cost of care. Meticulous technique and thorough knowledge of the relevant anatomy are the best means of preventing this complication.

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.

Predictors of outcome in patients with degenerative cervical spondylotic myelopathy undergoing surgical treatment: results of a systematic review

PURPOSE

To conduct a systematic review of the literature to determine important clinical predictors of surgical outcome in patients with cervical spondylotic myelopathy (CSM).

METHODS

A literature search was performed using MEDLINE, MEDLINE in Process, EMBASE and Cochrane Database of Systematic Reviews. Selected articles were evaluated using a 14-point modified SIGN scale and classified as either poor (<7), good (7-9) or excellent (10-14) quality of evidence. For each study, the association between various clinical factors and surgical outcome, evaluated by the (modified) Japanese Orthopaedic Association scale (mJOA/JOA), Nurick score or other measures, was defined. The results from the EXCELLENT studies were compared to the combined results from the EXCELLENT and GOOD studies which were compared to the results from all the studies.

RESULTS

The initial search yielded 1,677 citations. Ninety-one of these articles, including three translated from Japanese, met the inclusion and exclusion criteria and were graded. Of these, 16 were excellent, 38 were good and 37 were poor quality. Based on the excellent studies alone, a longer duration of symptoms was associated with a poorer outcome evaluated on both the mJOA/JOA scale and Nurick score. A more severe baseline score was related with a worse outcome only on the mJOA/JOA scale. Based on the GOOD and EXCELLENT studies, duration of symptoms and baseline severity score were consistent predictors of mJOA/JOA, but not Nurick. Age was an insignificant predictor of outcome on any of the functional outcomes considered.

CONCLUSION

The most important predictors of outcome were preoperative severity and duration of symptoms. This review also identified many other valuable predictors including signs, symptoms, comorbidities and smoking status.

Perioperative and delayed complications associated with the surgical treatment of cervical spondylotic myelopathy based on 302 patients from the AOSpine North America Cervical Spondylotic Myelopathy Study

OBJECT

Rates of complications associated with the surgical treatment of cervical spondylotic myelopathy (CSM) are not clear. Appreciating these risks is important for patient counseling and quality improvement. The authors sought to assess the rates of and risk factors associated with perioperative and delayed complications associated with the surgical treatment of CSM.

METHODS

Data from the AOSpine North America Cervical Spondylotic Myelopathy Study, a prospective, multicenter study, were analyzed. Outcomes data, including adverse events, were collected in a standardized manner and externally monitored. Rates of perioperative complications (within 30 days of surgery) and delayed complications (31 days to 2 years following surgery) were tabulated and stratified based on clinical factors.

RESULTS

The study enrolled 302 patients (mean age 57 years, range 29-86) years. Of 332 reported adverse events, 73 were classified as perioperative complications (25 major and 48 minor) in 47 patients (overall perioperative complication rate of 15.6%). The most common perioperative complications included minor cardiopulmonary events (3.0%), dysphagia (3.0%), and superficial wound infection (2.3%). Perioperative worsening of myelopathy was reported in 4 patients (1.3%). Based on 275 patients who completed 2 years of follow-up, there were 14 delayed complications (8 minor, 6 major) in 12 patients, for an overall delayed complication rate of 4.4%. Of patients treated with anterior-only (n = 176), posterior-only (n = 107), and combined anterior-posterior (n = 19) procedures, 11%, 19%, and 37%, respectively, had 1 or more perioperative complications. Compared with anterior-only approaches, posterior-only approaches had a higher rate of wound infection (0.6% vs 4.7%, p = 0.030). Dysphagia was more common with combined anterior-posterior procedures (21.1%) compared with anterior-only procedures (2.3%) or posterior-only procedures (0.9%) (p < 0.001). The incidence of C-5 radiculopathy was not associated with the surgical approach (p = 0.8). The occurrence of perioperative complications was associated with increased age (p = 0.006), combined anterior-posterior procedures (p = 0.016), increased operative time (p = 0.009), and increased operative blood loss (p = 0.005), but it was not associated with comorbidity score, body mass index, modified Japanese Orthopaedic Association score, smoking status, anterior-only versus posterior-only approach, or specific procedures. Multivariate analysis of factors associated with minor or major complications identified age (OR 1.029, 95% CI 1.002-1.057, p = 0.035) and operative time (OR 1.005, 95% CI 1.002-1.008, p = 0.001). Multivariate analysis of factors associated with major complications identified age (OR 1.054, 95% CI 1.015-1.094, p = 0.006) and combined anterior-posterior procedures (OR 5.297, 95% CI 1.626-17.256, p = 0.006).

CONCLUSIONS

For the surgical treatment of CSM, the vast majority of complications were treatable and without long-term impact. Multivariate factors associated with an increased risk of complications include greater age, increased operative time, and use of combined anterior-posterior procedures.

Intramedullary high signal intensity and neurological status as prognostic factors in cervical spondylotic myelopathy

PURPOSE

The neurological outcome of cervical spondylotic myelopathy (CSM) may depend on multiple factors, including age, symptom duration, cord compression ratio, cervical curvature, canal stenosis, and factors related to magnetic resonance (MR) signal intensity (SI). Each factor may act independently or interactively with others. To clarify the factors in prognosis, we prospectively analyzed the outcomes of patients with myelopathy caused by soft disc herniation in correlation with magnetic resonance imaging (MRI) findings and other clinical parameters.

MATERIALS AND METHODS

From June 2006 to July 2009, we performed surgical operations in 137 patients with CSM. Of these patients, 70 (51.1%), including 45 men and 25 women with ventral cord compression at one or two levels, underwent anterior cervical discectomy and fusion. The mean duration of follow-up was 32.7 months. We surveyed the cervical curvature index (CCI), canal stenosis (Torg-Pavlov ratio), cord compression ratio, the length of SI change on T2WI, and clinical outcome using the Japanese Orthopedic Association (JOA) score for cervical myelopathy. The MRI SI was evaluated by grade: grade 0, no change in signal intensity; grade 1, light signal change; and grade 2, bright signal change on the T2WI. Multifactorial effects were identified by regression analysis.

RESULTS

The mean preoperative and postoperative JOA scores were 10.5 ± 2.9 and 14.9 ± 2.1, respectively (p < 0.05). The mean recovery rate based on the JOA score was 70.0 ± 20.1%. The respective preoperative JOA scores and recovery ratios(%) were 11.6 ± 2.3 and 81.5 ± 17.0% in 20 patients with SI grade 0; 10.8 ± 2.3 and 70.1 ± 17.3% in 25 patients with grade 1; and 9.2 ± 3.6 and 60.7 ± 20.9% in 25 patients with grade 2, respectively. Post-surgical neurological outcome showed no significant relationship to age, symptom duration, cervical alignment, stenosis, or cord compression.

CONCLUSIONS

Among the variables tested, preoperative neurological status and intramedullary signal intensity were significantly related to neurological outcome. The better the preoperative neurological status was, the better the post-operative neurological outcome. The SI grade on the preoperative T2WI was negatively related to neurological outcome. Hence, the severity of SI change and preoperative neurological status emerged as significant prognostic factors in post-operative CSM.

“Skip” corpectomy in the treatment of multilevel cervical spondylotic myelopathy and ossified posterior longitudinal ligament

Object

The authors reviewed the results of “skip” corpectomy in 29 patients with multilevel cervical spondylotic myelopathy (CSM) and ossified posterior longitudinal ligament (OPLL).

Methods

The skip corpectomy technique, which is characterized by C-4 and C-6 corpectomy, C-5 osteophytectomy, and C-5 vertebral body preservation, was used for decompression in patients with multilevel CSM and OPLL. All patients underwent spinal fixation using C4–5 and C5–6 grafts, and anterior cervical plates were fixated at C-3, C-5, and C-7.

Results

The mean preoperative Japanese Orthopaedic Association score increased from 13.44 ± 2.81 to 16.16 ± 2.19 after surgery (p < 0.05). The cervical lordosis improved from 1.16 ± 11.74° to 14.36 ± 7.85° after surgery (p < 0.05). The complications included temporary hoarseness in 3 cases, dysphagia in 1 case, C-5 nerve palsy in 1 case, and C-7 screw pullout in 1 case. The mean follow-up was 23.2 months. The final plain radiographs showed improved cervical lordosis and fusion in all cases.

Conclusions

The authors conclude that the preservation of the C-5 vertebral body provided an additional screw purchase and strengthened the construct. The results of the current study demonstrated effectiveness and safety of the skip corpectomy in patients with multilevel CSM and OPLL.

Surgical approach to cervical spondylotic myelopathy on the basis of radiological patterns of compression: prospective analysis of 129 cases

This is a prospective analysis of 129 patients operated for cervical spondylotic myelopathy (CSM). Paucity of prospective data on surgical management of CSM, especially multilevel CSM (MCM), makes surgical decision making difficult. The objectives of the study were (1) to identify radiological patterns of cord compression (POC), and (2) to propose a surgical protocol based on POC and determine its efficacy. Average follow-up period was 2.8 years. Following POCs were identified: POC I: one or two levels of anterior cord compression. POC II: one or two levels of anterior and posterior compression. POC III: three levels of anterior compression. POC III variant: similar to POC III, associated with significant medical morbidity. POC IV: three or more levels of anterior compression in a developmentally narrow canal or with multiple posterior compressions. POC IV variant: similar to POC IV with one or two levels, being more significant than the others. POC V: three or more levels of compression in a kyphotic spine. Anterior decompression and reconstruction was chosen for POC I, II and III. Posterior decompression was chosen in POC III variant because they had more incidences of preoperative morbidity, in spite of being radiologically similar to POC III. Posterior surgery was also performed for POC IV and IV variant. For POC IV variant a targeted anterior decompression was considered after posterior decompression. The difference in the mJOA score before and after surgery for patients in each POC group was statistically significant. Anterior surgery in MCM had better result (mJOA = 15.9) versus posterior surgery (mJOA = 14.96), the difference being statistically significant. No major graft-related complications occurred in multilevel groups. The better surgical outcome of anterior surgery in MCM may make a significant difference in surgical outcome in younger and fitter patients like those of POC III whose expectations out of surgery are more. Judicious choice of anterior or posterior approach should be made after individualizing each case.

Cervical compression myelopathy: is fusion the main prognostic indicator?

Object

A variety of factors may affect the neurological improvement in patients with cervical compression myelopathy (CCM) after surgery. The aim of this study was to report and discuss the prognostic factors in a group of patients with insufficient decompression of the spinal canal.

Methods

A prospective follow up and analysis of 20 consecutive patients with CCM treated between 2000 and 2002 was performed. All patients were surgically treated via an anterior approach, either by anterior cervical discectomy and fusion with instrumentation or by cervical corpectomy and fusion with instrumentation. The surgical results were examined using the modified Japanese Orthopaedic Asssociation disability scale, with reference to the findings of magnetic resonance imaging, computed tomography, and radiography. Seventeen patients (85%) experienced a 50% or more recovery rate as calculated using the Hirabayashi formula during the follow-up period (mean 32.5 months), despite a persistently narrow spinal canal and permanent or increased intramedullary high-intensity signal after surgery.

Conclusions

Results of the study showed that patients with CCM benefited from anterior cervical discectomy and fusion with instrumentation or cervical corpectomy and fusion with instrumentation procedures despite insufficient decompression of the spinal canal. Fusion of the affected level(s) might be the reason for the acquired high recovery rates. The authors also conclude that the neurological improvement is not correlated with the reversal of or decrease in the intramedullary high-intensity signal change after surgery.

Expandable cylindrical cages in the cervical spine: a review of 22 cases

Object

Expandable cylindrical cages (ECCs) have been utilized successfully to reconstruct the thoracic and lumbar spine. Their advantages include ease of insertion, reduced endplate trauma, direct application/maintenance of interbody distraction force, and one-step kyphosis correction. The authors present their experience with ECCs in the reconstruction of the cervical spine in patients with various pathological conditions.

Methods

Data obtained in 22 patients were reviewed retrospectively. A standard anterior cervical corpectomy was performed in all cases. Local vertebral body bone was harvested for use as graft material. Patients underwent pre- and postoperative assessment involving the visual analog scale (VAS), Nurick grading system for determining myelopathy disability, and radiographic studies to determine cervical kyphosis/lordosis and cage subsidence. Fusion was defined as the absence of motion on flexion–extension x-ray films.

Sixteen patients presented with spondylotic myelopathy, two with osteomyelitis, two with fracture, one with tumor metastasis, and one with severe stenosis. Fourteen patients underwent supplemental posterior spinal fusion, seven underwent single-level corpectomy, and 15 patients underwent multilevel corpectomy. No perioperative complications occurred. The mean follow-up period was 22 months. In 11 patients with preexisting kyphosis (mean deformity +19°), the mean correction was 22°. There was no statistically significant difference in subsidence between single- and multilevel corpectomy or between 360º fusion and anterior fusion alone. The VAS scores improved by 35%, and the Nurick grade improved by 31%. The fusion rate was 100%.

Conclusions

The preliminary results support the use of ECCs in the cervical spine in the treatment of patients with various disease processes. No significant subsidence was noted, and pain and functional scores improved in all cases. Expandable cylindrical cages appear to be well suited for cervical reconstruction and for correcting sagittal malalignment.

Treatment options and results in cervical myelopathy

Cervical myelopathy is a clinical entity resulting from external compression of the cervical medulla. The clinical course can be divided into the acute form (secondary to trauma) versus subacute (progression within weeks to months) and chronic cervical myelopathy (months to years). The clinical picture of myelopathy is that of unsteady gait with long-tract signs, such as hyperreflexia, spasticity and extensor plantar responses. Between 1997 and 2000, 359 consecutive patients have been operated on in our department presenting with a variety of symptoms related to compression of the cervical medulla. Beside of standard MRI for all patients we applied SSEPs, gait analysis and dynamic MRI studies as additional helpful tools in evaluating selected patients pre- and postoperatively. We prefer the anterior approach as first-line approach because in the majority of patients the osteophytic spurs are more dominant anteriorly, and after anterior decompression and stabilization the posterior approach appears safer. We also favor the more extended approach of spondylectomy versus multilevel decompression in patients with bisegmental or multisegmental spinal canal stenosis. However it seems to be that radicular decompression is better achieved through multilevel decompression than through spondylectomy.