A late neurological complication following posterior correction surgery of severe cervical kyphosis

Morphometric analysis of cervical neuroforaminal dimensions from C2-T1 using computed tomography of 1,000 patients

BACKGROUND

Race and sex differences are not consistently reported in the literature. Fundamentally, anatomical differences of cervical neuroforaminal dimensions (CNFD) amongst these groups would be important to know.

PURPOSE

To establish normative radiographic morphometric measurements of CNFD and uncover the influence of patient sex, race, and ethnicity while also considering anthropometric characteristics.

STUDY DESIGN

Retrospective radiographic morphometric study.

PATIENT SAMPLE

A total of 1,000 patients between 18 and 35 years of age who were free of spinal pathology.

OUTCOME MEASURES

Foraminal height, axial width, and area of cervical neural foramen.

METHODS

Cervical CTs were reviewed to measure CNFD, defined as follows: foraminal height, axial width, and area. Statistical analyses were performed to assess associations between CNFD, and patient height, weight, sex, race, and ethnicity.

RESULTS

CNFD measurements followed a bimodal distribution pattern moving caudally from C2-T1. Irrespective of disc level, cervical CNFD were as follows: left and right widths of 6.6±1.5 and 6.6±1.5 mm, heights of 9.4±2.4 and 9.4±3.2 mm, and areas of 60.0±19.5 and 60.6±20.7 mm2. Left and right foraminal width were highest at C2-C3 and lowest at C3-C4. Left and right foraminal height were highest at C7-T1 and C6-C7, respectively and lowest at C3-C4. Left and right foraminal areas were highest at C2-C3 and lowest at C3-C4. Significant differences were observed for all CNFD measurements across disc levels. CNFD did not vary based on laterality. Significant CNFD differences were observed with respect to patient sex, race, and ethnicity. Male height and area were larger compared to females. In contrast, female foraminal width was larger compared to males. The Asian cohort demonstrated the largest foraminal widths. White and Hispanic patients demonstrated the largest foraminal heights and areas. Black patients demonstrated the smallest foraminal widths, heights, and areas. Patient height and weight were only weakly correlated with CNFD measurements across all levels from C2-T1.

CONCLUSIONS

This study describes 36,000 normative measurements of 12,000 foramina from C2-T1. CNFD measurements vary based on disc level, but not laterality. Contrasting left- versus right-sided neuroforamina of the same level may aid in determining the presence of unilateral stenosis. Patient sex, race, and ethnicity are associated with CNFD, while patient anthropometric factors are weakly correlated with CNFD.

Treatment of C5 Palsy: An International Survey of Peripheral Nerve Surgeons

STUDY DESIGN

International survey.

OBJECTIVES

C5 palsy (C5P) is a neurological complication affecting 5-10% of patients after cervical decompression surgery. Most cases improve with conservative treatment; however, nearly 20% of patients may be left with residual deficits. Guidelines are lacking on C5P management and timing of surgical intervention. Therefore, we sought to survey peripheral nerve surgeons on their management of C5P.

METHODS

An online survey was distributed centered around a patient with C5P after posterior cervical decompression and fusion. Questions included surgeon demographics, diagnostic modalities, and timing and choice of operation. Responses were summarized and the chi-squared and Kruskal-Wallis H tests were used to examine differences across specialties.

RESULTS

A total of 154 surgeons responded to the survey, of which 59 (38%) indicated that they manage C5P cases. Average time prior to operating was 4.5 ± 2.2 months for complete injuries and 6.6 ± 3.2 months for partial injuries, with neurosurgeons significantly more likely to wait longer periods for complete (P = .01) and partial injuries (P = .03). Foraminotomies were selected by 19% of surgeons, while 92% selected nerve transfers. Transfer of the ulnar nerve to the musculocutaneous nerve was the most common choice (81%), followed by transfer of the radial nerve to the axillary nerve (58%).

CONCLUSION

Consensus exists among peripheral nerve surgeons on the use of nerve transfers for surgical treatment in cases with severe motor weakness failing to improve. Most surgeons advocate for early intervention in complete injuries. Disagreement concerns the type of nerve transfer employed, timing of surgery, and efficacy of foraminotomy.

Neurological Complications and Recovery Rates of Patients With Adult Cervical Deformity Surgeries

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

This study aims to report the incidence, risk factors, and recovery rate of neurological complications (NC) in patients with adult cervical deformity (ACD) who underwent corrective surgery.

METHODS

ACD patients undergoing surgery from 2013 to 2015 were enrolled in a prospective, multicenter database. Patients were separated into 2 groups according to the presence of neurological complications (NC vs no-NC groups). The types, timing, recovery patterns, and interventions for NC were recorded. Patients' demographics, surgical details, radiographic parameters, and health-related quality of life (HRQOL) scores were compared.

RESULTS

106 patients were prospectively included. Average age was 60.8 years with a mean of 18.2 months follow-up. The overall incidence of NC was 18.9%; of these, 68.1% were major complications. Nerve root motor deficit was the most common complication, followed by radiculopathy, sensory deficit, and spinal cord injury. The proportion of complications occurring within 30 days of surgery was 54.5%. The recovery rate from neurological complication was high (90.9%), with most of the recoveries occurring within 6 months and continuing even after 12 months. Only 2 patients (1.9%) had continuous neurological complication. No demographic or preoperative radiographic risk factors could be identified, and anterior corpectomy and posterior foraminotomy were found to be performed less in the NC group. The final HRQOL outcome was not significantly different between the 2 groups.

CONCLUSIONS

Our data is valuable to surgeons and patients to better understand the neurological complications before performing or undergoing complex cervical deformity surgery.

Comparison of laminoplasty and posterior fusion surgery for cervical ossification of posterior longitudinal ligament

This prospective multicenter study, established by the Japanese Ministry of Health, Labour and Welfare and involving 27 institutions, aimed to compare postoperative outcomes between laminoplasty (LM) and posterior fusion (PF) for cervical ossification of the posterior longitudinal ligament (OPLL), in order to address the controversy surrounding the role of instrumented fusion in cases of posterior surgical decompression for OPLL. 478 patients were considered for participation in the study; from among them, 189 (137 and 52 patients with LM and PF, respectively) were included and evaluated using the Japanese Orthopaedic Association (JOA) scores, the JOA Cervical Myelopathy Evaluation Questionnaire (JOACMEQ), and radiographical measurements. Basic demographic and radiographical data were reviewed, and the propensity to choose a surgical procedure was calculated. Preoperatively, there were no significant differences among the participants in terms of patient backgrounds, radiographical measurements (K-line or cervical alignment on X-ray, OPLL occupation ratio on computed tomography, increased signal intensity change on magnetic resonance imaging), or clinical status (JOA score and JOACMEQ) after adjustments. The overall risk of perioperative complications was found to be lower with LM (odds ratio [OR] 0.40, p = 0.006), and the rate of C5 palsy occurrence was significantly lower with LM (OR 0.11, p = 0.0002) than with PF. The range of motion (20.91° ± 1.05° and 9.38° ± 1.24°, p < 0.0001) in patients who had PF was significantly smaller than in those who had LM. However, multivariable logistic regression analysis showed no significant difference among the participants in JOA score, JOA recovery rate, or JOACMEQ improvement at two years. In contrast, OPLL progression was greater in the LM group than in the PF group (OR 2.73, p = 0.0002). Both LM and PF for cervical myelopathy due to OPLL had resulted in comparable postoperative outcomes at 2 years after surgery.

Impact of morphological restoration of the spinal cord from the preoperative to early postoperative periods on C5 palsy development

OBJECTIVE

C5 palsy (C5P) is a known complication of cervical decompression surgery. The tethering effect of the C5 nerve root following the posterior shift of the spinal cord is the most accepted pathologic mechanism for C5P development; however, this mechanism cannot fully explain C5P by itself in clinical practice. Separately, some studies have suggested that preoperative severe spinal cord compression and postoperative morphological changes in the spinal cord affect C5P development; however, no previous study has quantitatively addressed these possibilities. The aim of this study was to examine whether spinal cord morphology and morphological restoration after surgery affect C5P development.

METHODS

The authors reviewed consecutive patients with degenerative cervical myelopathy who underwent laminoplasty including the C3-4 and C4-5 intervertebral disc levels. All participants underwent MRI both preoperatively and within 4 weeks postoperatively. To assess the severity of spinal cord compression, the compression ratio (CR; spinal cord sagittal diameter/transverse diameter) was calculated. As an index of morphological changes in the spinal cord during the early postoperative period, the change rate of CR (CrCR, %) was calculated as CRwithin 4 weeks postoperatively/CRpreoperatively × 100. These measurements were performed at both the C3-4 and C4-5 intervertebral disc levels. The study cohort was divided into C5P and non-C5P (NC5P) groups; then, CR and CrCR, in addition to other radiographic variables associated with C5P development, were compared between the groups.

RESULTS

A total of 114 patients (mean age 67.6 years, 58.8% men) were included in the study, with 5 and 109 patients in the C5P and NC5P groups, respectively. Preoperative CR at both the C3-4 and C4-5 levels was significantly lower in the C5P group than in the NC5P group (0.35 vs 0.44, p = 0.042 and 0.27 vs 0.39, p = 0.021, respectively). Patients with C5P exhibited significantly higher CrCR at the C3-4 level than those without (139.3% vs 119.0%, p = 0.046), but the same finding was not noted for CrCR at the C4-5 level. There were no significant differences in other variables between the groups.

CONCLUSIONS

This study reveals that severe compression of the spinal cord and its greater morphological restoration during the early postoperative period affect C5P development. These findings could support the involvement of segmental cord disorder theory, characterized as the reperfusion phenomenon, in the pathomechanism of C5P, in addition to the tethering effect.

Risk factor analysis of surgery-related complications in primary cervical spine surgery for degenerative diseases using a surgeon-maintained database

AIMS

This study, using a surgeon-maintained database, aimed to explore the risk factors for surgery-related complications in patients undergoing primary cervical spine surgery for degenerative diseases.

METHODS

We studied 5,015 patients with degenerative cervical diseases who underwent primary cervical spine surgery from 2012 to 2018. We investigated the effects of diseases, surgical procedures, and patient demographics on surgery-related complications. As subcategories, the presence of cervical kyphosis ≥ 10°, the presence of ossification of the posterior longitudinal ligament (OPLL) with a canal-occupying ratio ≥ 50%, and foraminotomy were selected. The surgery-related complications examined were postoperative upper limb palsy (ULP) with a manual muscle test (MMT) grade of 0 to 2 or a reduction of two grade or more in the MMT, neurological deficit except ULP, dural tear, dural leakage, surgical-site infection (SSI), and postoperative haematoma. Multivariate logistic regression analysis was performed.

RESULTS

The significant risk factors (p < 0.050) for ULP were OPLL (odds ratio (OR) 1.88, 95% confidence interval (CI) 1.29 to 2.75), foraminotomy (OR 5.38, 95% CI 3.28 to 8.82), old age (per ten years, OR 1.18, 95% CI 1.03 to 1.36), anterior spinal fusion (OR 2.85, 95% CI 1.53 to 5.34), and the number of operated levels (OR 1.25, 95% CI 1.11 to 1.40). OPLL was also a risk factor for neurological deficit except ULP (OR 5.84, 95% CI 2.80 to 12.8), dural tear (OR 1.94, 95% CI 1.11 to 3.39), and dural leakage (OR 3.15, 95% CI 1.48 to 6.68). Among OPLL patients, dural tear and dural leakage were frequently observed in those with a canal-occupying ratio ≥ 50%. Cervical rheumatoid arthritis (RA) was a risk factor for SSI (OR 10.1, 95% CI 2.66 to 38.4).

CONCLUSION

The high risk of ULP, neurological deficit except ULP, dural tear, and dural leak should be acknowledged by clinicians and OPLL patients, especially in those patients with a canal-occupying ratio ≥ 50%. Foraminotomy and RA were dominant risk factors for ULP and SSI, respectively. An awareness of these risks may help surgeons to avoid surgery-related complications in these conditions. Cite this article: Bone Joint J 2021;103-B(1):157-163.

The importance of preoperative T1 slope for determining proper postoperative C2-7 Cobb's angle in patients undergoing cervical reconstruction

BACKGROUND

This study aimed to explore the relationship among different cervical sagittal parameters in asymptomatic volunteers and the correlation between surgical efficacy and difference of presumed and actual postoperative C2-7 Cobbs's angle (C2-7COBB), which was calculated based on preoperative T1 slope (T1S) in patients undergoing cervical reconstruction.

METHODS

In total, 158 inpatients with cervical spondylosis and 274 asymptomatic volunteers were retrospectively reviewed. Cervical sagittal parameters, such as C2-7COBB, T1S, thoracic inlet angle (TIA), and neck tilt (NT), were compared. Then, the correlation among these parameters was analyzed in asymptomatic volunteers, and a regression equation between T1S and C2-7COBB was established and used to analyze the correlation among the Japanese Orthopaedic Association (JOA) score improvement, the sagittal parameters, and the difference between presumed and actual postoperative C2-7COBB in patients after cervical reconstruction.

RESULTS

The mean T1S, C2-7COBB, and TIA were significantly decreased in patients (P < 0.01). T1S and NT had a strong correlation with TIA (P < 0.01). T1S demonstrated a moderate correlation with C2-7COBB in asymptomatic volunteers (r = 0.569, P < 0.01). A regression equation had been established as C2-7COBB = 0.742 × T1S - 0.866. The mean C2-7COBB and JOA score improved significantly (P < 0.05) postoperatively. Moreover, the JOA improvement rate showed a significant negative correlation with the difference in the presumed and actual postoperative C2-7COBB (r = - 0.696, P < 0.01).

CONCLUSION

Our study successfully established a regression equation for calculating postsurgical C2-7COBB based on the correlation between T1S and C2-7COBB in asymptomatic volunteers. The regression equation could be used for guiding surgeons to accomplish an ideal postsurgical C2-7COBB for patients with cervical spondylosis.

Thin Cervical Spinal Cord Between Ossifications of the Ligamentum Flavum and the Posterior Longitudinal Ligament: Case Report and Literature Review

BACKGROUND

Cervical ossification of the ligamentum flavum (OLF) is a rare condition; however, the coexistence of OLF and ossification of the posterior longitudinal ligament (OPLL) is extremely uncommon. These can exist simultaneously and cause thinning of the cervical spinal cord. Sufficient decompression, dural ossification, semispinalis dissection, and postoperative kyphosis were evaluated. We report the successful treatment of coexisting cervical OLF and OPLL.

CASE DESCRIPTION

A 70-year-old man had been experiencing weakness in the left knee and clumsiness in the left hand for 6 months. Hemiparesis was considered; however, magnetic resonance imaging revealed a cervical spinal lesion. Hence a spine surgeon diagnosed the patient with severe stenosis with OLF at the C2-C3 levels and OPLL at the C2-C4 levels. The patient presented with spastic gait and left-hand motor weakness. Computed tomography scan revealed the disappearance of the black line, indicating dural ossification surrounding the OLF. OPLL was observed in 61.5% of the C2 spinal canal. The K-line was (-); however, the alternative K-line between the C1 and C7 level was (+). Posterior laminectomy at the C2-C3 levels and laminoplasty at the C4-C7 levels with muscle preservation resulted in sufficient decompression. The patient's symptoms improved, and cervical alignment was maintained 2 years after surgery.

CONCLUSIONS

An alternative K-line comprised successful treatment for coexisting cervical OLF and OPLL. Surgeons must evaluate the severity of adhesion, damage of the paraspinal muscles, and necessity of posterior corrective surgery along with the patient's comorbidities and possible postoperative complications.

Posterior decompression and fusion versus laminoplasty for cervical ossification of posterior longitudinal ligament: a systematic review and meta-analysis

Both posterior decompression and fusion (PDF) and laminoplasty (LAMP) have been used to treat cervical myelopathy due to multilevel ossification of posterior longitudinal ligament (OPLL). However, considerable controversy exists over the choice of the two surgical strategies. Thus, the aim of this study is to compare clinical outcomes of PDF and LAMP for treatment of cervical myelopathy due to multilevel OPLL. We searched PubMed, EMBASE and Cochrane Central Register of Controlled Trials database to identify relevant clinical studies compared with clinical outcomes of PDF and LAMP for cervical OPLL. The primary outcomes including Japanese Orthopaedic Association (JOA) score and recovery rate of JOA were evaluated, and the secondary outcomes involving visual analogue scale (VAS), cervical curvature, OPLL progression rate, complication rate, reoperation rate and surgical trauma were also evaluated using Stata software. A total of nine studies were included in the current study, involving 324 patients. The current study suggests that compared with LAMP, PDF achieves a lower OPLL progression rate, better postoperative cervical curvature and similar neurological improvement in the treatment of multilevel cervical OPLL. However, PDF has a higher complication rate, more surgical trauma and higher postoperative VAS than LAMP.

Posterior Surgical Techniques for Cervical Spondylotic Myelopathy: WFNS Spine Committee Recommendations

Objective

This study was conducted to determine and recommend the most up-to-date information on the indications, complications, and outcomes of posterior surgical treatments for cervical spondylotic myelopathy (CSM) on the basis of a literature review.

Methods

A comprehensive literature search was performed, using the MEDLINE (PubMed), the Cochrane Register of Controlled Trials, and Web of Science databases, for peer-reviewed articles published in English during the last 10 years.

Results

Posterior techniques, which include laminectomy alone, laminectomy with fusion, and laminoplasty, are often used in patients with involvement of 3 or more levels. Posterior decompression for CSM is effective for improving patients’ neurological function. Complications resulting from posterior cervical spine surgery include injury to the spinal cord and nerve roots, complications related to posterior screw fixation or instrumentation, C5 palsy, spring-back closure of lamina, and postlaminectomy kyphosis.

Conclusion

It is necessary to consider multiple factors when deciding on the appropriate operation for a particular patient. Surgeons need to tailor preoperative discussions to ensure that patients are aware of these facts. Further research is needed on the cost-to-benefit analysis of various surgical approaches, the comparative efficacy of surgical approaches using various techniques, and long-term outcomes, as current knowledge is deficient in this regard.

Perioperative acute neurological deficits in instrumented pediatric cervical spine fusions

OBJECTIVE

Pediatric cervical deformity is a complex disorder often associated with neurological deterioration requiring cervical spine fusion. However, limited literature exists on new perioperative neurological deficits in children. This study describes new perioperative neurological deficits in pediatric cervical spine instrumentation and fusion.

METHODS

A single-center review of pediatric cervical spine instrumentation and fusion during 2002-2018 was performed. Demographics, surgical characteristics, and neurological complications were recorded. Perioperative neurological deficits were defined as the deterioration of preexisting neurological function or the appearance of new neurological symptoms.

RESULTS

A total of 184 cases (160 patients, 57% male) with an average age of 12.6 ± 5.30 years (range 0.2-24.9 years) were included. Deformity (n = 39) and instability (n = 36) were the most frequent indications. Syndromes were present in 39% (n = 71), with Down syndrome (n = 20) and neurofibromatosis (n = 12) the most prevalent. Eighty-seven (48%) children presented with preoperative neurological deficits (16 sensory, 16 motor, and 55 combined deficits).A total of 178 (96.7%) cases improved or remained neurologically stable. New neurological deficits occurred in 6 (3.3%) cases: 3 hemiparesis, 1 hemiplegia, 1 quadriplegia, and 1 quadriparesis. Preoperative neurological compromise was seen in 4 (67%) of these new deficits (3 myelopathy, 1 sensory deficit) and 5 had complex syndromes. Three new deficits were anticipated with intraoperative neuromonitoring changes (p = 0.025).Three (50.0%) patients with new neurological deficits recovered within 6 months and the child with quadriparesis was regaining neurological function at the latest follow-up. Hemiplegia persisted in 1 patient, and 1 child died due a complication related to the tracheostomy. No association was found between neurological deficits and indication (p = 0.96), etiology (p = 0.46), preoperative neurological symptoms (p = 0.65), age (p = 0.56), use of halo vest (p = 0.41), estimated blood loss (p = 0.09), levels fused (p = 0.09), approach (p = 0.07), or fusion location (p = 0.07).

CONCLUSIONS

An improvement of the preexisting neurological deficit or stabilization of neurological function was seen in 96.7% of children after cervical spine fusion. New or progressive neurological deficits occurred in 3.3% of the patients and occurred more frequently in children with preoperative neurological symptoms. Patients with syndromic diagnoses are at higher risk to develop a deficit, probably due to the severity of deformity and the degree of cervical instability. Long-term outcomes of new neurological deficits are favorable, and 50% of patients experienced complete neurological recovery within 6 months.

A Review of the Historical Evolution, Biomechanical Advantage, Clinical Applications, and Safe Insertion Techniques of Cervical Pedicle Screw Fixation

Cervical spine instrumentation is evolving with an aim of stabilizing traumatic and non-traumatic cases of the cervical spine with a beneficial reduction, better biomechanical strength, and a strong construct with minimal intraoperative, as well as immediate and late postoperative complications. The evolution from interspinous wiring till cervical pedicle screws has changed the outlook in treating the cervical spine pathologies with maximum 3D stability, decreasing the duration of postoperative immobilization and hospital stay. Some complications associated with the use of cervical pedicle screw can be catastrophic. This review article discusses the morphometry of cervical pedicle; indications, biomechanical superiority, tricks, and pitfalls of cervical pedicle screw; complications and technical advancements in targeting safe surgery; and future directions of cervical pedicle screw instrumentation.

Acute progressive adolescent idiopathic cervical kyphosis: case report

Acute progressive adolescent idiopathic cervical kyphosis (AICK) is rare, and its treatment strategy is controversial. The authors present a case of AICK successfully treated with preoperative halo-gravity traction, followed by combined anterior-posterior surgery. A 15-year-old girl with no relevant past or family history presented with axial neck pain without any cause. A few months after the development of cervical myelopathy, cervical kyphosis progressed to 71° despite conservative treatment. CT scanning demonstrated osteophyte formation at the anterior aspect of the vertebral body. MRI showed a forward migration of the spinal cord with a ratio (C/M ratio) between the anteroposterior diameter of the medulla-pons junction and the spinal cord at the apex of the kyphosis of 0.27. After 2 weeks of preoperative halo-gravity traction, anterior release and posterior fusion was performed. After surgery, cervical kyphosis was corrected to 0°, and cervical myelopathy improved. One year after surgery, the patient was neurologically intact, and bony union and improved cervical alignment were observed. Preoperative halo-gravity traction followed by combined anterior-posterior surgery led to safe and effective correction. Osteophyte formation at the anterior aspect of the vertebral body and the C/M ratio were useful in predicting the progression of AICK.

Characteristics of deformity surgery in patients with severe and rigid cervical kyphosis (CK): results of the CSRS-Europe multi-centre study project

INTRODUCTION AND PURPOSE

Little information exists on surgical characteristics, complications and outcomes with corrective surgery for rigid cervical kyphosis (CK). To collate the experience of international experts, the CSRS-Europe initiated an international multi-centre retrospective study.

METHODS

Included were patients at all ages with rigid CK. Surgical and patient specific characteristics, complications and outcomes were studied. Radiographic assessment included global and regional sagittal parameters. Cervical sagittal balance was stratified according to the CSRS-Europe classification of sagittal cervical balance (types A-D).

RESULTS

Eighty-eight patients with average age of 58 years were included. CK etiology was ankylosing spondlitis (n = 34), iatrogenic (n = 25), degenerative (n = 9), syndromatic (n = 6), neuromuscular (n = 4), traumatic (n = 5), and RA (n = 5). Blood loss averaged 957 ml and the osteotomy grade 4.CK-correction and blood loss increased with osteotomy grade (r = 0.4/0.6, p < .01). Patients with different preop sagittal balance types had different approaches, preop deformity parameters and postop alignment changes (e.g. C7-slope, C2-7 SVA, translation). Correction of the regional kyphosis angle (RKA) was average 34° (p < .01). CK-correction was increased in patients with osteoporosis and osteoporotic vertebrae (POV, p = .006). 22% of patients experienced a major long-term complication and 14% needed revision surgery. Patients with complications had larger preop RKA (p = .01), RKA-change (p = .005), and postop increase in distal junctional kyphosis angle (p = .02). The POV-Group more often experienced postop complications (p < .0001) and revision surgery (p = .02). Patients with revision surgery had a larger RKA-change (p = .003) and postop translation (p = .04). 21% of patients had a postop segmental motor deficit and the risk was elevated in the POV-Group (p = .001).

CONCLUSIONS

Preop patient specific, radiographic and surgical variables had a significant bearing on alignment changes, outcomes and complication occurrence in the treatment of rigid CK.

An algorithmic strategy of surgical intervention for cervical degenerative kyphosis

PURPOSE

Correction surgery for cervical degenerative kyphosis (CDK) may carry a greater risk of causing neural complications such as spinal cord injury and C5 nerve palsy because spinal canal stenosis, osteoarthritis of the facet, and consequent foraminal stenosis may coexist with CDK. We have produced an algorithmic strategy of surgical intervention for CDK, and report the outcome.

METHODS

Thirty-one patients who underwent correction surgery for CDK, with a kyphotic angle of 20° or more (from 20 to 74) were involved. An algorithmic surgical strategy is shown. Clinical and radiological outcomes were examined amongst the groups.

RESULTS

Recovery rate of the JOA score was a mean of 44%. Preoperative kyphotic angle and correction angle were; 24.4°and 26.5°in P, 38.4°and 41.1°in AP, and 42.0°and 46.9°in PAP respectively. No spinal cord injury was found. Five cases of C5 nerve palsy occurred in P, and one in AP. Four cases of C5 palsy occurred in seven patients in PAP, although prophylactic foraminotomy was performed. All C5 palsy patients recovered fully at follow-up.

CONCLUSIONS

This study showed that our algorithmic surgical strategy for CDK is acceptable because we obtained good outcomes, and no catastrophic complications occurred. Although we did not intend to obtain excessive postoperative lordosis, we still had several incidence of C5 nerve palsy. We have to be aware of this incidence in PAP, which required a massive range of realignment. The incidence occurred even after we performed prophylactic foraminotomy, however, this procedure may lessen the severity of C5 palsy because those were all transient.

Osteotomies in ankylosing spondylitis: where, how many, and how much?

INTRODUCTION

This article presents the current concepts of correction of spinal deformity in ankylosing spondylitis (AS) patients. Untreated AS can be a debilitating disease. In a few patients, disease progression results in severe spinal deformity affecting not only the thoracolumbar, but also the cervical spine. Surgery for correction in AS patients has a long history. With the advent of modern instrumentation, standardization of surgical and anesthesiologic techniques, surgical safety and corrective results could be improved and experiences from lumbar osteotomies could be transferred to the cervical spine.

METHODS

This article presents the current concepts of correction of spinal deformity in AS patients. In particular, questions regarding the localization and number of osteotomies, the optimal surgical target angle as well as planning and prediction of postoperative alignment are discussed.

RESULTS

Insight into recent technical developments, current challenges with correction and geometric analysis of center of rotation (COR) in cervical 3-column osteotomies (3CO) will be presented.

CONCLUSION

The article should encourage readers to improve surgical correction efficacy and provide a better understanding of correction geometry in 3CO for thoracolumbar and cervical spinal deformities.

Diagnostic Accuracy of Somatosensory Evoked Potentials in Evaluating New Neurological Deficits After Posterior Cervical Fusions

STUDY DESIGN

This study examined the diagnostic accuracy of significant changes of somatosensory evoked potentials (SSEPs) to evaluate and predict postoperative neurological deficits after posterior cervical fusions (PCF). Eight hundred forty six eligible patients underwent PCF at the University of Pittsburgh Medical Center (UPMC), from 2010 to 2012.

OBJECTIVE

To assess the specificity and sensitivity of intraoperative monitoring in predicting postoperative neurological deficits during PCF.

SUMMARY OF BACKGROUND DATA

We calculated the predictive value, including sensitivity and specificity, of changes in SSEPs to identify neurological deficits postoperatively. We used a receiver operating characteristic (ROC) curve with SSEP categories as cutoff values to further evaluate the diagnostic accuracy of change in SSEPs and postoperative neurological deficit.

METHODS

All patients had preposition baselines and continuous SSEP monitoring throughout the surgery. Statistical analysis was completed using SPSS version 22 (IBM Corp., Armonk, NY).

RESULTS

Age and sex did not influence outcomes. Obesity affected patient outcome. The SSEP categories of significant changes and loss of responses resulted in a sensitivity/specificity of 0.30/0.96 and 0.16/0.98, respectively. The receiver operating characteristic curve has an area under the curve for significant change in/loss of SSEPs of 0.62/0.65 with a 95% confidence interval of 0.525 to 0.714/0.509 to 0.797.

CONCLUSION

Significant SSEP changes during PCF are a very specific but poorly sensitive indicator of postoperative neurological deficits. The odds ratio for significant changes in SSEPs and loss of waveforms was 9.80 and 11.82, respectively, with a 95% confidence interval of 4.695 to 20.46 and 4.45 to 31.41, respectively.

LEVEL OF EVIDENCE

1.

C5 Palsy After Cervical Spine Surgery: A Multicenter Retrospective Review of 59 Cases

STUDY DESIGN

A multicenter, retrospective review of C5 palsy after cervical spine surgery.

OBJECTIVE

Postoperative C5 palsy is a known complication of cervical decompressive spinal surgery. The goal of this study was to review the incidence, patient characteristics, and outcome of C5 palsy in patients undergoing cervical spine surgery.

METHODS

We conducted a multicenter, retrospective review of 13 946 patients across 21 centers who received cervical spine surgery (levels C2 to C7) between January 1, 2005, and December 31, 2011, inclusive. P values were calculated using 2-sample t test for continuous variables and χ² tests or Fisher exact tests for categorical variables.

RESULTS

Of the 13 946 cases reviewed, 59 patients experienced a postoperative C5 palsy. The incidence rate across the 21 sites ranged from 0% to 2.5%. At most recent follow-up, 32 patients reported complete resolution of symptoms (54.2%), 15 had symptoms resolve with residual effects (25.4%), 10 patients did not recover (17.0%), and 2 were lost to follow-up (3.4%).

CONCLUSION

C5 palsy occurred in all surgical approaches and across a variety of diagnoses. The majority of patients had full recovery or recovery with residual effects. This study represents the largest series of North American patients reviewed to date.

Outcome of posterior decompression with instrumented fusion surgery for K-line (-) cervical ossification of the longitudinal ligament

We investigated the outcome of posterior decompression and instrumented fusion (PDF) surgery for patients with K-line (-) ossification of the posterior longitudinal ligament (OPLL) of the cervical spine, who may have a poor surgical prognosis. We retrospectively analyzed the outcome of a series of 27 patients who underwent PDF without correction of cervical alignment for K-line (-) OPLL and were followed-up for at least 1 year after surgery. We had performed double-door laminoplasty followed by posterior instrumented fusion without excessive correction of cervical spine alignment. The preoperative Japanese Orthopedic Association (JOA) score for cervical myelopathy was 8.0 points and postoperative JOA score was 11.9 points on average. The mean JOA score recovery rate was 43.6%. The average C2-C7 angle was 2.2° preoperatively and 3.1° postoperatively. The average maximum occupation ratio of OPLL was 56.7%. In conclusion, PDF without correcting cervical alignment for patients with K-line (-) OPLL showed moderate neurological recovery, which was acceptable considering K-line (-) predicts poor surgical outcomes. Thus, PDF is a surgical option for such patients with OPLL.

Differences in the time of onset of postoperative upper limb palsy among surgical procedures: a meta-analysis

BACKGROUND CONTEXT

The time of onset of postoperative upper limb palsy (ULP), also referred to as C5 palsy, varies among patients. Although some studies addressed the relationship between the time of onset of ULP and the potential etiologies, no meta-analysis has been conducted regarding the association between the time of onset of ULP and other factors such as surgical procedure type and treated diseases.

PURPOSE

This study aimed to elucidate differences in the time of onset of ULP among spinal surgical procedures and treated diseases to understand its etiology.

STUDY DESIGN

This is a meta-analysis.

OUTCOME MEASURES

The time of onset of ULP after cervical decompression surgery.

METHODS

We conducted a meta-analysis via searches of the PubMed, EMBASE, and Cochrane Library databases. Upper limb palsy within 2 days postoperatively or at 3 days or more postoperatively was defined as early- and late-onset, respectively. We calculated the pooled prevalence of early- and late-onset ULP with regard to surgical procedures and diseases using a random effects model. The proportion of early-onset ULP relative to all ULP was also determined. Surgical procedures were categorized into four procedures: (1) anterior cervical discectomy and fusion (ACDF); (2) anterior cervical corpectomy and fusion (ACCF); (3) laminoplasty or laminectomy (LPN); and (4) posterior spinal fusion with decompression (PSF). Treated diseases were classified as ossification of the posterior longitudinal ligament (OPLL) and non-OPLL.

RESULTS

The pooled prevalence of early-onset ULP was significantly stratified across three groups of surgical procedures (PSF [9.0%]>ACCF [3.7%] and LPN [2.5%]>ACDF [0.6%]). In the pooled analysis of late-onset ULP prevalence, three procedures (PSF [4.3%], ACCF [2.8%], and LPN [2.9%]) were similar, but ACDF (1.0%) was associated with a significantly lower prevalence than LPN. The prevalence of both early- and late-onset ULP was significantly higher with OPLL than without OPLL. However, the proportion of early-onset ULP relative to all ULP was similar between non-OPLL and OPLL (50.8% vs. 49.5%).

CONCLUSIONS

The high prevalence of early-onset ULP in PSF is attributable to a lag correction effect, which is triggered by posterior correction and fusion through comparison with LPN. The combination of our meta-analysis results and previous knowledge facilitates our understanding of the etiology of ULP.

Complications of Anterior and Posterior Cervical Spine Surgery

Cervical spine surgery performed for the correct indications yields good results. However, surgeons need to be mindful of the many possible pitfalls. Complications may occur starting from the anaesthestic procedure and patient positioning to dura exposure and instrumentation. This review examines specific complications related to anterior and posterior cervical spine surgery, discusses their causes and considers methods to prevent or treat them. In general, avoiding complications is best achieved with meticulous preoperative analysis of the pathology, good patient selection for a specific procedure and careful execution of the surgery. Cervical spine surgery is usually effective in treating most pathologies and only a reasonable complication rate exists.

C5 nerve palsy after posterior reconstruction surgery: predictive risk factors of the incidence and critical range of correction for kyphosis

PURPOSE

It has been reported that the incidence of post-operative segmental nerve palsy, such as C5 palsy, is higher in posterior reconstruction surgery than in conventional laminoplasty. Correction of kyphosis may be related to such a complication. The aim of this study was to elucidate the risk factors of the incidence of post-operative C5 palsy, and the critical range of sagittal realignment in posterior instrumentation surgery.

METHODS

Eighty-eight patients (mean age 64.0 years) were involved. The types of the disease were; 33 spondylosis with kyphosis, 27 rheumatoid arthritis, 17 athetoid cerebral palsy and 11 others. The patients were divided into two groups; Group P: patients with post-operative C5 palsy, and Group NP: patients without C5 palsy. The correction angle of kyphosis, and pre-operative diameter of C4/5 foramen on CT were evaluated between the two groups. Multivariate logistic regression analysis was used to determine the critical range of realignment and the risk factors affecting the incidence of post-operative C5 palsy.

RESULTS

Seventeen (19.3 %) of the 88 patients developed C5 palsy. The correction angle of kyphosis in Group P (15.7°) was significantly larger than that in Group NP (4.5°). In Group P, pre-operative diameters of intervertebral foramen at C4/5 (3.2 mm) were significantly smaller than those in Group NP (4.1 mm). The multivariate analysis demonstrated that the risk factors were the correction angle and pre-operative diameter of the C4/5 intervertebral foramen. The logistic regression model showed a correction angle exceeding 20° was critical for developing the palsy when C4/5 foraminal diameter reaches 4.1 mm, and there is a higher risk when the C4/5 foraminal diameter is less than 2.7 mm regardless of any correction.

CONCLUSIONS

This study has indicated the risk factors of post-operative C5 palsy and the critical range of realignment of the cervical spine after posterior instrumented surgery.

Dimensions of the cervical neural foramen in conditions of spinal deformity: an ex vivo biomechanical investigation using specimen-specific CT imaging

PURPOSE

Patients with cervical spondylosis commonly present with neck pain, radiculopathy or myelopathy. As degenerative changes progress, multiple factors including disc height loss, thoracic kyphosis, and facetogenic changes can increase the risk of neural structure compression. This study investigated the impact of cervical deformity including forward head posture (FHP) and upper thoracic kyphosis, on the anatomy of the cervical neural foramen.

METHODS

Postural changes of 13 human cervical spine specimens (Occiput-T1, age 50.6 years; range 21-67) were assessed in response to prescribed cervical sagittal malalignments using a previously reported experimental model. Two characteristics of cervical sagittal deformities, C2-C7 sagittal vertical alignment (SVA) and sagittal angle of the T1 vertebra (T1 tilt), were varied to create various cervical malalignments. The postural changes were documented by measuring vertebral positions and orientations. The vertebral motion data were combined with specimen-specific CT-based anatomical models, which allowed assessments of foraminal areas of subaxial cervical segments as a function of increasing C2-C7 SVA and changing T1 tilt.

RESULTS

Increasing C2-C7 SVA from neutral posture resulted in increased neural foraminal area in the lower cervical spine (largest increase at C4-C5: 13.8 ± 15.7 %, P < 0.01). Increasing SVA from a hyperkyphotic posture (greater T1 tilt) also increased the neural foraminal area in the lower cervical segments (C5-C6 demonstrated the largest increase: 13.4 ± 9.6 %, P < 0.01). The area of the cervical neural foramen decreased with increasing T1 tilt, with greater reduction occurring in the lower cervical spine, specifically at C5-C6 (-8.6 ± 7.0 %, P < 0.01) and C6-C7 (-9.6 ± 5.6 %, P < 0.01).

CONCLUSION

An increase in thoracic kyphosis (T1 tilt) decreased cervical neural foraminal areas. In contrast, an increase in cervical SVA increased the lower cervical neural foraminal areas. Patients with increased upper thoracic kyphosis may respond with increased cervical SVA as a compensatory mechanism to increase their lower cervical neural foraminal area.

Cervical spondylotic myelopathy: posterior decompression and pedicle screw fixation

INTRODUCTION

Posterior decompression by laminoplasty and anterior decompression/fixation have been widely accepted, and they provide sufficient results for cervical spondylotic myelopathy. However, combined procedure of posterior decompression and reconstruction is favorable for some patients accompanying local kyphosis, segmental instability, previously operated conditions on the cervical spine, etc.

DISCUSSION

Among posterior cervical instrumentations, pedicle screw fixation is a strong tool of stabilization of unstable segment and correction of deformities in sagittal and/or coronal planes for the patient with cervical spondylotic myelopathy. On the other hand, neurovascular complications including injury to the vertebral artery and nerve root cannot be completely eliminated. Even after surgeons became familiar with placement of cervical pedicle screws, screw malposition rate by freehand technique is high for patients with severe spondylotic condition. Surgeons must especially be careful for inserting pedicle screw in the cervical spine associating marked degenerative changes by spondylosis, and must obtain preoperatively sufficient anatomical information of the pedicle and surrounding structures.

CONCLUSION

Combined procedure of posterior reconstructive surgery using a pedicle screw fixation provides better clinical outcomes than laminoplasty alone for cervical spondylotic myelopathy accompanying local kyphosis or segmental instability. Further development of supporting tools for cervical pedicle screw insertion including aiming device, navigation system and neuromonitoring procedure are expected for safer screw insertion.

Analysis of correlative risk factors for C5 palsy after anterior cervical decompression and fusion

BACKGROUND

It has been reported that C5 palsy is a potential complication of both anterior and posterior cervical spine surgery, although several mechanisms of C5 palsy following posterior cervical surgery have been proposed, few reports about correlative risk factors have been elaborated on C5 palsy after anterior cervical decompression and fusion (ACDF).

OBJECTIVE

The purpose of this study was to investigate the correlative risk factors of C5 palsy after anterior cervical decompression and fusion.

METHODS

This is a retrospective study. A total of 161 patients (108 males and 53 females) who underwent ACDF between 2007 and 2012 were included in this study. C5 palsy is characterized by deltoid and/or biceps brachii weakness. The patients were divided into two groups: one that had experienced C5 palsy (group A) and the other one had not (group B). In both groups, the age, gender, duration of disease, diagnosis, No. of surgical levels, cervical curvature correction, occupying rate of spinal canal at C4/5, diameter of the C4/5 foramen, intervertebral height variation, decompression width and preoperative high-signal intensity zone (HIZ) of spinal cord in T2-weighted MRI at C4/5 were measured and evaluated. The risk factors of C5 palsy were detected with logistic regression analysis.

RESULTS

There were no significant differences in age, gender, duration of disease, diagnosis, No. of surgical levels, rate of spinal canal at C4/5 and HIZ of spinal cord in T2-weighted MRI at C4/5. Cervical curvature correction, diameter of the C4/5 foramen, intervertebral height variation and decompression width had significant differences between the two groups (P<0.05). Logistic regression analysis revealed that cervical curvature, diameter of the C4/5 foramen, intervertebral height and decompression width were the pivotal risk factors for the incidence of C5 palsy.

CONCLUSION

For patients with ACDF, greater cervical curvature correction, narrow diameter of the C4/5 foramen, improper intervertebral height variation and larger decompression width were the correlative risk factors for C5 palsy after ACDF.

Cervical interfacet spacers and maintenance of cervical lordosis

OBJECT The cervical interfacet spacer (CIS) is a relatively new technology that can increase foraminal height and area by facet distraction. These offer the potential to provide indirect neuroforaminal decompression while simultaneously enhancing fusion potential due to the relatively large osteoconductive surface area and compressive forces exerted on the grafts. These potential benefits, along with the relative ease of implantation during posterior cervical fusion procedures, make the CIS an attractive adjuvant in the management of cervical pathology. One concern with the use of interfacet spacers is the theoretical risk of inducing iatrogenic kyphosis. This work tests the hypothesis that interfacet spacers are associated with loss of cervical lordosis. METHODS Records from patients undergoing posterior cervical fusion at Rush University Medical Center between March 2011 and December 2012 were reviewed. The FacetLift CISs were used in all patients. Preoperative and postoperative radiographic data were reviewed and the Ishihara indices and cervical lordotic angles were measured and recorded. Statistical analyses were performed using STATA software. RESULTS A total of 64 patients were identified in whom 154 cervical levels were implanted with machined allograft interfacet spacers. Of these, 15 patients underwent anterior-posterior fusions, 4 underwent anterior-posterior-anterior fusions, and the remaining 45 patients underwent posterior-only fusions. In the 45 patients with posterior-only fusions, a total of 110 levels were treated with spacers. There were 14 patients (31%) with a single level treated, 16 patients (36%) with two levels treated, 5 patients (11%) with three levels treated, 5 patients (11%) with four levels treated, 1 patient (2%) with five levels treated, and 4 patients (9%) with six levels treated. Complete radiographic data were available in 38 of 45 patients (84%). On average, radiographic follow-up was obtained at 256.9 days (range 48-524 days). There was no significant difference in the Ishihara index (5.76 preoperatively and 6.17 postoperatively, p = 0.8037). The analysis had 80% power to detect a change of 4.25 in the Ishihara index at p = 0.05. There was no significant difference in the preand postoperative cervical lordotic angles (35.6° preoperatively and 33.6° postoperatively, p = 0.2678). The analysis had 80% power to detect a 7° change in the cervical lordotic angle at p = 0.05. The ANOVA of the Ishihara index and cervical lordotic angle did not show a statistically significant difference in degree of change in cervical lordosis among patients with a different number of levels of CIS insertion (p = 0.25 and p = 0.96, respectively). CONCLUSIONS In the authors' experience of placing CISs in more than 100 levels, they found no evidence of significant loss of cervical lordosis. The long-term impacts of these implants on fusion rates and clinical outcomes (particularly radiculopathy and postoperative C-5 palsies) remain active areas of interest and fertile ground for further studies.

Delayed cervical palsy following cervical spine fusion leads to an increase in hospital-related costs

OBJECT

Delayed cervical palsy (DCP) is a known complication following cervical spine surgery. While most DCPs eventually improve, they can result in significant temporary disability. Postoperative complications affect hospital length of stay (LOS) as well as overall hospital cost. The authors sought to determine the hospital cost of DCP after cervical spine fusion operations.

METHODS

A retrospective review of patients undergoing cervical fusion for degenerative disease at the Mayo Clinic from 2008 to 2012 was performed. Patients who developed DCPs not attributable to intraoperative trauma were included. All nonoperative-related costs were compared with similar costs in a control group matched according to age, sex, and surgical approach. All costs and services were reflective of the standard costs for the current year. Raw cost data were presented using ratios due to institutional policy against publishing cost data.

RESULTS

There were 27 patients (18 men, 9 women) who underwent fusion and developed a DCP over the study period. These patients were compared with 24 controls (15 men, 9 women) undergoing fusion in the same time period. There was no difference between patients and controls in mean age (62.4 ± 3.1 years vs. 63.8 ± 2.5 years, respectively; p = 0.74), LOS (4.2 ± 3.3 days vs 3.8 ± 4.5 days, respectively; p = 0.43), or operating room-related costs (1.08 ± 0.09 vs. 1.0 ± 0.07, respectively; p = 0.58). There was a significant difference in nonoperative hospital-related costs between patients and controls (1.67 ± 0.15 vs 1.0 ± 0.09, respectively; p = 0.04). There was a significantly higher utilization of postoperative imaging (CT or MRI) in the DCP group (14/27, 52%) when compared with the matched cohort (4/24, 17%; p = 0.018), and a significantly higher utilization of physiatry services (24/27 [89%] vs 15/24 [63%], respectively; p = 0.046).

CONCLUSIONS

While DCPs did not significantly prolong the length of hospitalization, they did increase hospital-related costs. This method could be further extrapolated to model costs of other complications as well.

Effect of machined interfacet allograft spacers on cervical foraminal height and area

OBJECT

Iatrogenic foraminal stenosis is a well-known complication in cervical spine surgery. Machined interfacet allograft spacers can provide a large surface area, which ensures solid support, and could potentially increase foraminal space. The authors tested the hypothesis that machined interfacet allograft spacers increase cervical foraminal height and area.

METHODS

The C4-5, C5-6, and C6-7 facets of 4 fresh adult cadavers were exposed, and the cartilage was removed from each facet using customized rasps. Machined allograft spacers were tamped into the joints. The spines were scanned with the O-arm surgical imaging system before and after placement of the spacers. Two individuals independently measured foraminal height and area on obliquely angled sagittal images.

RESULTS

Foraminal height and area were significantly greater following placement of the machined interfacet spacers at all levels. The Pearson correlation between the 2 radiographic reviewers was very strong (r = 0.971, p = 0.0001), as was the intraclass correlation coefficient (ICC = 0.907, p = 0.0001). The average increase in foraminal height was 1.38 mm. The average increase in foraminal area was 18.4% (0.097 cm(2)) [corrected].

CONCLUSIONS

Modest distraction of the facets using machined interfacet allograft spacers can increase foraminal height and area and therefore indirectly decompress the exiting nerve roots. This technique can be useful in treating primary foraminal stenosis and also for preventing iatrogenic foraminal stenosis that may occur when the initially nonlordotic spine is placed into lordosis either with repositioning after central canal decompression or with correction using instrumentation. These grafts may be a useful adjunct to the surgical treatment of cervical spine disease.

Non-instrumented correction of cervicothoracic kyphosis in ankylosing spondylitis: a critical analysis on the results of open-wedge osteotomy C7-T1 with gradual Halo-Thoracic-Cast based correction

INTRODUCTION

With progression of cervicothoracic kyphosis (CTK), ankylosing spondylitis (AS) patients suffer functional disability. Surgical correction still poses neurologic risks, while evidence of an ideal technique preventing its complications is weak.

MATERIALS AND METHODS

We report our results with non-instrumented correction in perspective of a review of literature, serving as an important historical control. Database review identified 18 AS patients with CTK correction. After application of a Halo-Thoracic-Cast (HTC) patients underwent posterior non-instrumented open-wedge osteotomy at C7/T1 and osteotomy closure by threaded HTC-rod adjustments. Postoperative gradual HTC correction was continued for 2-4 weeks. Patients were invited for follow-up and medical charts were reviewed for demographics, surgical details, complications and outcomes. The patients' preoperative, postoperative, before HTC removal and follow-up photographs were analyzed for the Chin-Brow-Vertical-Angle (CBVA), radiographs for the CTK angle.

RESULTS

Patients' age was 50 ± 11 years, follow-up was 37 ± 47 months and CBVA correction was 25° ± 9° (p < 0.000001). The final radiographic correction at follow-up was 20° ± 11° (p = 0.00002). At the latest follow-up, three patients judged their outcome as excellent, nine good, three moderate and one poor. Upon invitation, seven patients appeared with follow-up averaging 87 months. Neck-pain disability index was 8 ± 14 %. Two patients died, three were lost, one had revision elsewhere and five just had a routine follow-up. Six patients sustained a minor and ten a major complication. Revisions were indicated in five patients including infection, C8-radiculopathy and neurologic events by translation at the osteotomy. A total of 44 % of patients showed translation at the osteotomy indicating acute surgery with instrumentation twice after osteotomy closure, three patients had a revision posterior decompression and instrumented fusion for sequels related to translation.

CONCLUSION

With the non-instrumented HTC-based technique, average CBVA correction of 25° was achieved and all patients were ambulatory at follow-up. However, regarding translation at the osteotomy, loss of correction, morbidity of the HTC and lack of control at the osteotomy instrumentation-based correction and instrumented fusion seem to be preferable.

Multivariate analysis of C-5 palsy incidence after cervical posterior fusion with instrumentation

Object

Postoperative C-5 palsy is a significant complication resulting from cervical decompression procedures. Moreover, when cervical degenerative diseases are treated with a combination of decompression and posterior instrumented fusion, patients are at increased risk for C-5 palsy. However, the clinical and radiological features of this condition remain unclear. Therefore, the purpose of this study was to clarify the risk factors for developing postoperative C-5 palsy.

Methods

Eighty-four patients (mean age 60.1 years) who had undergone posterior instrumented fusion using cervical pedicle screws to treat nontraumatic lesions were independently reviewed. The authors analyzed the medical records of some of these patients who developed postoperative C-5 palsy, paying particular attention to their plain radiographs, MRI studies, and CT scans. Risk factors for postoperative C-5 palsy were assessed using multivariate logistic regression analysis. The cutoff values for the pre- and postoperative width of the intervertebral foramen (C4–5) were determined by receiver operating characteristic curve analysis.

Results

Ten (11.9%) of 84 patients developed postoperative C-5 palsy. Seven patients recovered fully from the neurological complications. The pre- and postoperative C4–5 angles showed significant kyphosis in the C-5 palsy group. The pre- and postoperative diameters of the C4–5 foramen on the palsy side were significantly smaller than those on the opposite side in the C-5 palsy group and those bilaterally in the non–C5 palsy group. Risk factors identified by multivariate logistic regression analysis were as follows: 1) ossification of the posterior longitudinal ligament (relative risk [RR] 7.22 [95% CI 1.03–50.55]); 2) posterior shift of the spinal cord (C4–5) (RR 1.73 [95% CI 1.00–2.98]); and 3) postoperative width of the C-5 intervertebral foramen (RR 0.33 [95% CI 0.14–0.79]). The cutoff values of the pre- and postoperative widths of the C-5 intervertebral foramen for C-5 palsy were 2.2 and 2.3 mm, respectively.

Conclusions

Patients with preoperative foraminal stenosis, posterior shift of the spinal cord, and additional iatrogenic foraminal stenosis due to cervical alignment correction were more likely to develop postoperative C-5 palsy after posterior instrumentation with fusion. Prophylactic foraminotomy at C4–5 might be useful when preoperative foraminal stenosis is present on CT. Furthermore, it might be useful for treating postoperative C-5 palsy. To prevent excessive posterior shift of the spinal cord, the authors recommend that appropriate kyphosis reduction should be considered carefully.

Neurological complications of cervical spine surgery: C5 palsy and intraoperative monitoring

STUDY DESIGN

Review article.

OBJECTIVE

To review the epidemiology, etiology, risk factors, prevention, and treatment of neurological complications associated with cervical spine surgery. The article focuses on C5 palsy and intraoperative neurophysiological monitoring.

SUMMARY OF BACKGROUND DATA

Neurological problems are the complications most feared by patients and surgeons alike, but, fortunately, spinal cord injury is uncommon. C5 palsy is a less severe but much more common and perplexing problem. Intraoperative monitoring is widely used in cervical spine surgery, but it is unclear how effective it is at preventing spinal cord or nerve root injury.

METHODS

Narrative and review of the literature.

RESULTS

The incidence of new, severe motor weakness in 2 or more extremities occurring within 12 hours of surgery is 0.18%. The rate in the cervical spine is 3 of 1000. The incidence of isolated C5 palsy is much greater; the rate varies between 0% and 30%, depending on how the condition is defined and which patient group is being analyzed. Numerous theories have been postulated to explain the pathogenesis of C5 palsy, and preventative strategies are discussed. Approximately 70% of patients recover completely without treatment. The mean time to full recovery is 4 to 5 months. Recovery is spontaneous; no treatment has been shown to shorten the time to recovery or improve the recovery rate. A systematic review of the literature found a high level of evidence that multimodal intraoperative monitoring is effective at detecting intraoperative neurological injury. The evidence that intraoperative monitoring reduces the rate of new or worsened perioperative neurological deficits is not as strong. Algorithms help surgeons respond to monitoring alerts and manage neurological deficits that are identified postoperatively.

CONCLUSION

The keys to managing neurological complications in cervical spine surgery are prevention through careful planning, appropriate multimodal monitoring, meticulous surgical technique, and decisive action when a problem is identified.

Reconstruction of the subaxial cervical spine using pedicle screw instrumentation

STUDY DESIGN

Review article.

OBJECTIVE

To review the indications, detailed techniques, and complications of cervical pedicle screw fixation procedure.

SUMMARY OF BACKGROUND DATA

Although screw insertion into the cervical pedicles has been considered too risky for the neurovascular structures except C2 and C7, biomechanical studies revealed a superior stabilizing effect of pedicle screw fixation in the cervical spine to other fixation procedures including lateral mass screw fixation. In addition, several investigators reported superior reconstructive results of unstable cervical spine.

METHODS

A literature review and review of the authors' experience in the treatment of the patients with unstable cervical spine and/or cervical spinal deformities using cervical pedicle screw fixation procedure.

RESULTS

Pedicle screw fixation is biomechanically most reliable for reconstruction of the cervical spine in various kinds of disorders. Previously reported articles revealed that pedicle screw fixation is useful for reconstruction of unstable cervical spine and correction of cervical deformities. Neurovascular complication by this procedure cannot be completely eliminated; however, it can be minimized by sufficient preoperative imaging studies and strict control of screw placement during surgery. Modern technology of computer navigation system and newly developing aiming devices can be expected to increase the accuracy of screw placement.

CONCLUSION

Pedicle screw provides excellent 3-dimensional fixations and is a useful procedure for reconstruction of the cervical spine in various kinds of disorders. Possible neurovascular complication can be minimized by sufficient preoperative imaging studies and strict control of screw placement during surgery.

Complications of cervical pedicle screw fixation for nontraumatic lesions: a multicenter study of 84 patients

OBJECT

The cervical pedicle screw (PS) provides strong stabilization but poses a potential risk to the neurovascular system, which may be catastrophic. In particular, vertebrae with degenerative changes complicate the process of screw insertion, and PS misplacement and subsequent complications are more frequent. The purpose of this study was to evaluate the peri- and postoperative complications of PS fixation for nontraumatic lesions and to determine the risk factors of each complication.

METHODS

Eighty-four patients who underwent cervical PS fixation for nontraumatic lesions were independently reviewed to identify associated complications. The mean age of the patients was 60.1 years, and the mean follow-up period was 4.1 years (range 6-168 months). Pedicle screw malpositioning was classified on postoperative CT scans as Grade I (< 50% of the screw outside the pedicle) or Grade II (≥ 50% of the screw outside the pedicle). Risk factors of each complication were evaluated using a multivariate analysis.

RESULTS

Three hundred ninety cervical PSs and 24 lateral mass screws were inserted. The incidence of PS misplacement was 19.5% (76 screws); in terms of malpositioning, 60 screws (15.4%) were classified as Grade I and 16 (4.1%) as Grade II. In total, 33 complications were observed. These included postoperative neurological complications in 11 patients in whom there was no evidence of screw misplacement (C-5 palsy in 10 and C-7 palsy in 1), implant failure in 11 patients (screw loosening in 5, broken screws in 4, and loss of reduction in 2), complications directly attributable to screw insertion in 5 patients (nerve root injury by PS in 3 and vertebral artery injury in 2), and other complications in 6 patients (pseudarthrosis in 2, infection in 1, transient dyspnea in 1, transient dysphagia in 1, and adjacent-segment degeneration in 1). The multivariate analysis showed that a primary diagnosis of cerebral palsy was a risk factor for postoperative implant failure (HR 10.91, p = 0.03) and that the presence of preoperative cervical spinal instability was a risk factor for both Grade I and Grade II screw misplacement (RR 2.12, p = 0.03), while there were no statistically significant risk factors for postoperative neurological complications in the absence of evidence of screw misplacement or complications directly attributable to screw insertion.

CONCLUSIONS

In the present study, misplacement of cervical PSs and associated complications occurred more often than in previous studies. The rates of screw-related neurovascular complications and neurological deterioration unrelated to PSs were high. Insertion of a PS for nontraumatic lesions is surgically more challenging than that for trauma; consequently, experienced surgeons should use PS fixation for nontraumatic cervical lesions only after thorough preoperative evaluation of each patient's cervical anatomy and after considering the risk factors specified in the present study.