Cervical Instrumentation Research Articles

Benefits and pitfalls of iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) imaging in clinical application of the cervical spine MR

To evaluate efficacy of T2-weighted (T2W) iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL)-fast spin echo (FSE) imaging of the cervical spine. The cervical spine of 100 symptomatic patients was imaged using routine magnetic resonance imaging (MRI) versus IDEAL-FSE imaging. The signal-to-noise ratios (SNRs), contrast-to-noise ratios (CNRs), and image quality were analysed. To compare the diagnostic efficiency of degenerative spondylopathy, evaluations of spondylolisthesis, retrolisthesis, disc herniation, myelopathy, disc degeneration, and bone marrow oedema were also performed. IDEAL-FSE showed significantly higher SNRs and CNRs (all p<0.001) than fat-suppressed (FS) T2W-FSE. Sixteen of 100 patients had cervical spine instrumentation; in those patients, IDEAL-FSE provided significantly better uniformity of fat suppression (p<0.001) and fewer metallic artefacts (p<0.001). For patients without instrumentation, FS T2W-FSE showed significantly better overall image quality (p<0.001) and homogeneity of the cerebrospinal fluid (CSF; p<0.001) with fewer motion artefacts (p<0.001). IDEAL-FSE, however, provided significantly better uniformity of fat suppression (p<0.001). There were no significant differences in the diagnoses of spondylolisthesis, retrolisthesis, disc herniation, or myelopathy between IDEAL and FS T2W images. The only significant differences between the IDEAL and FS T2W images were noted when diagnosing degenerative disc disease at the C2-3 and C5-6 disc levels (p=0.019, p=0.002, respectively) and bone marrow oedema at C3 vertebral body (p=0.029). T2W IDEAL-FSE imaging should only be considered as an additional sequence to conventional FS T2W images in patients with poor fat suppression or severe metallic artefacts.

Extruding Cervical Screw: A Rare Cause of Dysphagia

Complications from instrumentation of the cervical spine may affect the esophagus, as it directly overlies the cervical vertebrae; there have been reported cases of perforation, abscess, stricture, and diverticulum formation. While orthopedic surgeons and neurosurgeons are aware of these rare complications, gastroenterologists may not be familiar with them and may not consider these diagnoses when evaluating patients with oropharyngeal issues. We present a case of cervical screw extrusion leading to dysphagia and hoarseness, that underscores the importance of careful endoscopic inspection of the retropharynx during endoscopy and the early use of imaging in evaluation of patients with a history of cervical instrumentation. A 49 year old woman presented with a 4 month history of increasing difficulty and pain swallowing (right side of the throat), and significant hoarseness. Past history was significant for a motor vehicle accident 17 years prior, with cervical spine injury leading to refractory radiculopathy. She subsequently underwent anterior cervical decompression, fusion, and insertion of an integrated cage and plate system. Upper endoscopy showed a normal esophagus. Careful inspection identified a prominent bulge in the right posterior oropharynx, proximal to the piriform sinus with a superficial mucosal erosion, but no perforation (Fig. 1). A follow-up cervical CT scan confirmed a screw extending from the C4-5 level into the posterior esophagus to the right of midline at the level of the piriform sinus (Fig. 2); there was also evidence of instrumented fusion at C4-5 and C4-6 using integrated cage and plate system. The patient was then referred to neurosurgery for urgent operative removal of the screws.1742_A Figure 1. Endoscopic examination identifying a prominent bulge in the right posterior oropharynx, proximal to the piriform sinus.1742_B Figure 2. CT scan confirming a screw extending from the C4-5 level into the posterior esophagus to the right of midline at the level of the piriform sinus.Esophageal complications related to cervical fusion hardware are rare, and may present in the immediate post-operative period or years later. Slow anterior migration of the screw or cage system over time may cause extrinsic compression of the pharyngoesophageal wall leading to pressure necrosis and ultimately erosion or perforation. Gastroenterologists should have a high index of suspicion for this diagnosis when evaluating patients with history of cervical instrumentation presenting with oropharyngeal dysphagia. Endoscopic exam should focus on careful inspection of the oropharynx, as the pertinent findings may be subtle. Follow-up imaging with CT or MRI should be considered in the appropriate setting to confirm the diagnosis.

Patient's Subjective Impression of Cervical Range of Motion: A Mixed-methods Approach.

Mixed-method. To evaluate the association between objective and subjective cervical range of motion (ROM) among patients with neck pain, and to assess the awareness of impairments. Cervical ROM is frequently used to evaluate neck pain, but it is also important to know what a patient expects from treatment, because this can profoundly affect treatment outcomes and patient satisfaction. We used a cervical ROM instrument, the Neck Disability Index (NDI), and a self-administered ROM questionnaire for the neck (S-ROM-Neck). Ten patients took part in semi-structured interviews. Correlations were analyzed using Spearman rank order correlations (rs). Differences between patient and assessor were evaluated by the Mann-Whitney U test. Qualitative data were analyzed by content analysis. Thirty participants (mean age 43.80 years; 21 females) were included. The correlation (rs) for the S-ROM-Neck between patient and assessor was 0.679 [95% confidence interval (95% CI) 0.404-0.884; P = 0.000]. The correlation between the NDI and S-ROM-Neck was 0.178 (95% CI -0.233 to -0.533; P = 346) for the assessor and -0.116 (95% CI -0.475 to -0.219, P = 0.541) for the patient (U = 448, z = -0.030, P = 0.976). Qualitative analysis revealed that patients had general restrictions in daily life and with specific movements, but that they adjusted their behavior to avoid impairment. There was a significant correlation between patient and therapist ratings of cervical spine mobility. Although patients experience restriction while moving and are impaired in specific activities, they adjust their lifestyle to accommodate their limitations. 4.

C5 palsy following posterior decompression and instrumentation in cervical stenosis: Single center experience and review

ObjectiveCausation and avoidance of C5 palsy after laminectomy have proven elusive, with multiple factors incriminated including width of the laminectomy, spinal cord migration, C5 neural foraminal stenosis, or intraoperative C5 root traction. In an attempt to identify risk factors for C5 palsy after decompression in cervical stenosis and myelopathy, the following review was conducted. This report is from a single center with consistent criteria for diagnosis and management of cervical stenosis and myelopathy. Patients and methodsWe retrospectively reviewed 63 patients with cervical stenosis and myelopathy who had been treated with laminectomy with instrumentation at the C4-6 level. Imaging studies reviewed included plain X-ray films, magnetic resonance imaging (MRI), and computed tomography (CT) scans of the cervical spine. Health-related outcomes were assessed before and at follow-up and included Visual Analog Scale (VAS) for pain (1–10), Japanese Orthopedic Association (JOA) score for myelopathy (0–18), and SF-36 physical functioning, energy and fatigue, and general health categories (0–100). ResultsIn 53 patients (control group), decompression and instrumentation was accomplished without incident, but 5 patients developed lasting postoperative C5 palsy. At follow-up, there were overall significant improvements in VAS, JOA, and SF-36 physical functioning and general health domains. Subsequent to surgery, a loss of lordosis of 5° and an increase in C2 sagittal vertical axis (SVA) of 17 mm was significant. There was, however, no significant difference between control and C5 palsy patients in lordosis and C2 SVA, before or after surgery. Postoperative MRI studies were obtained in 15 of the control patients and 6 of the C5 palsy patients. Postoperative width of the laminectomy as well as the caliber of the C5 neural foramina in the control and C5 palsy cohorts were not statistically different. Though the posterior displacement of the cord in the C5 palsy cohort was larger than in controls, this difference was also not significant. ConclusionThe above findings suggest that the cause of C5 palsy remains elusive. Though our incidence of lasting C5 palsy subsequent to laminectomy and instrumentation was 8%, it is probably under-reported. In our experience, laminectomy and instrumentation failed to increase lordosis and, in fact, were associated with an increase in positive cervical balance. Complications with cervical laminectomy and instrumentation are not by any means rare, and need to be emphasized in counselling patients, and selecting the approach.

Comment on "Cervical pedicle screw instrumentation is reliable with O-arm-based 3D navigation: analysis of cervical pedicle screw placement accuracy with O-arm-based 3D navigation" by S. Chachan et al. (Eur Spine J; 2018: doi: 10.1007/s00586-018-5585-1).

Comment on "Cervical pedicle screw instrumentation is reliable with O-arm-based 3D navigation: analysis of cervical pedicle screw placement accuracy with O-arm-based 3D navigation" by S. Chachan et al. (Eur Spine J; 2018: doi: 10.1007/s00586-018-5585-1).

COMPUTER 3D-MODELING OF PATIENT-SPECIFIC NAVIGATIONAL TEMPLATE FOR CERVICAL SCREW INSERTION

Objective. To prove the effectiveness of 3D computer modeling and printing of patient-specific templates for cervical spine screw fixation. Materials and Methods . Based on the MSCT data of three patients, 3D models of cervical vertebrae and guiding templates were produced. The screws were inserted transpedicularly into 3D-printed models of C 2 –C 7 vertebrae and C 1 lateral masses using standard cervical instrumentation. This technology was then clinically tested in a patient with C 2 tumor, in whom posterior stabilization of C 1 –C 3 vertebrae was performed using guiding templates. In the postoperative period, MSCT was performed to monitor the position of screws. Results. When implanting screws into 3D-models, technical difficulties were not revealed. After insertion of screws, a visual assessment of the 3D vertebra model was made. Malpositions in models were not detected. Based on the proven technique, a clinical approbation was performed in a patient with normal cervical spine pattern. MSCT study revealed the deviation of screws relative to the planned trajectory by no more than 2 mm, with no malpositions. Conclusion. The first domestic description of the technique of navigation using guiding templates is presented. Of all the existing methods, this is the most reliable way of screw positioning in the cervical spine. The possible insertion error does not affect the quality of positioning.

Retrospective Study of Postoperative Pulmonary Complications in Patients with Cervical Spine Pathology

Abstract Background Postoperative pulmonary complication (PPC) after cervical spine surgery is known to increase patient morbidity and mortality as well as the hospital and intensive care unit (ICU) stay. However, studies addressing this issue are scarce in the current literature. The aim of this study was to find out the incidence and various factors associated with PPC in patients undergoing cervical spine surgeries. Materials and Methods It is a retrospective study in a tertiary care hospital. Two hundred and seven patients who underwent different cervical spinal surgeries were included in this study. Various perioperative data including demography, history of smoking, associated systemic illness, type and site of lesion, preoperative respiratory status, and signs of involvement of lower cranial nerves were collected. The incidence and the risk factors for PPC were found out. Statistical analysis was done using chi-square/Fisher's exact test/Student's t-test, followed by univariate and multiple logistic regression analysis. Results The incidence of PPC in our study was 39.6%. Various pulmonary complications observed were difficulty in breathing requiring some intervention (19.3%), pneumonia (5.3%), tracheobronchitis (3.9%), arterial desaturation (3.4%), reintubation (3.4%), atelectasis (1.3%), pleural effusion (0.97%), pneumothorax (0.97%), and acute respiratory distress syndrome (ARDS) (0.97%). Preoperative respiratory abnormality, cervical laminectomy and instrumentation surgery and postoperative mechanical ventilation of &gt; 24 hours duration were found to be independent risk factors for occurrence of PPC. Conclusions The patients with cervical spinal cord pathology are at increased risk for PPC. Preoperative respiratory abnormality, postoperative mechanical ventilation of &gt; 24-hour duration, and cervical laminectomy and instrumentation surgery are independent risk factors for PPC.

Correction to: Cervical pedicle screw instrumentation is more reliable with O-arm-based 3D navigation: analysis of cervical pedicle screw placement accuracy with O-arm-based 3D navigation.

Unfortunately, the second author name of the above-mentioned article was incorrectly published in original publication. The complete correct name is given below: Hamid Rahmatullah Bin Abd Razak. The original article has been corrected.

Cervical pedicle screw instrumentation is more reliable with O-arm-based 3D navigation: analysis of cervical pedicle screw placement accuracy with O-arm-based 3D navigation

Despite proven biomechanical superiority and resultant superior clinical outcomes, pedicle instrumentation in cervical spine is not widely practiced due to technical difficulties, steep learning curve, and possible potential catastrophic complications due to screw misplacement. This study was undertaken with the purpose to evaluate the feasibility, accuracy, and complications of cervical pedicle screw instrumentation solely using O-arm-based 3D navigation technology. Prospectively maintained data from a single-surgeon case series were retrospectively analyzed. All the patients had undergone cervical pedicle instrumentation under O-arm 3D navigation. Screw placement accuracy was analyzed and compared among different vertebral levels and also between different patient groups. A total of 241 cervical pedicle screws were inserted in 44 patients. Out of the 241 screws, 197 (81.74%) were inserted at the level of C3-C6 vertebrae with nearly equal distribution among the 4 vertebrae, followed by 32 (13.28%) and 12 (4.98%) screws at C2 and C7 vertebrae, respectively. After the analysis of screw placement as per Gertzbein classification, the overall breach rates were found to be 7.05% (17 screws) with 52.94% (10 screws) Grade I, 47.06% (7 screws) Grade II, and nil Grade III screw breaches. The use of O-arm-based intra-operative 3D scans for navigation can make cervical pedicle screw placement reliable. High accuracy and better intra-operative control can increase surgeon's confidence in using cervical pedicle instrumentation on more regular basis. These slides can be retrieved under Electronic Supplementary Material.

Preparation and Assessment of an Individualized Navigation Template for Lower Cervical Anterior Transpedicular Screw Insertion Using a Three-Dimensional Printing Technique.

Prospective trial. To establish an individualized navigation template for safe and accurate insertion of lower cervical anterior transpedicular screw (ATPS) based on a three-dimensional (3D) printing technique. Conventional screw insertion manually under fluoroscopy easily leading to deviation of ATPS screw channel, cervical instrumentation procedures demand the need for a precise technique for screw placement. Twenty adult cervical spine specimens (10 men and 10 women, with a mean age of 50.29 ± 6.98) were selected for computed tomography pre- and postoperatively. A 3D lower cervical spine model was reconstructed using Mimics software to measure the screw-related parameters and generate a reverse template with optimal screw channel as well as a prototype using 3D printing. Assisted by the navigation template, bilateral ATPS were inserted into the cadavers. The mean outer width and height of pedicle were 5.31 ± 1.23 and 6.78 ± 1.10 mm, respectively. The average length, sagittal, and axial angles of the optimal screw channel obtained through the optimal entry point were 36.34 ± 4.39 mm, 40.67° ± 5.10°, and 93.7° ± 7.96°, respectively. The adjustable safe ranges of sagittal and axial angles were 3.89° ± 1.13° and 5.64° ± 0.97°, respectively. The axial and sagittal accuracies of the 200 screws were 99.5% and 97%, respectively. The average deviations of the actual entry point and the preset opening in the X, Y, and Z axes were 0.39 ± 0.43, 0.21 ± 0.41, and 0.29 ± 0.14 mm, respectively (P > 0.05). An individualized ATPS navigation template was developed using Mimics software and 3D printing prototyping, based on computed tomography, for highly accurate screw insertion. 4.

Comparison of Morphological Characteristics of the Subaxial Cervical Spine between Athetoid Cerebral Palsy and Normal Control.

ObjectiveTo compare the morphometry of subaxial cervical spine between cerebral palsy (CP) and normal control.MethodsWe retrospectively analyzed 72 patients with CP, as well as 72 patients from normal population. The two groups were matched for age, sex, and body mass index. Pedicle, lateral mass (LM), and vertebral foramen were evaluated using computed tomography (CT) imaging. Pedicle diameter, LM height, thickness, width and vertebral foramen asymmetry (VFA) were measured and compared between the two groups. Cervical dynamic motion, disc and facet joint degeneration were investigated. Additionally, we compared the morphology of LM between convex side and concave side with cervical scoliotic CP patients.ResultsLM height was smaller in CP group. LM thickness and width were larger in CP group at mid-cervical level. In 40 CP patients with cervical scoliosis, there were no height and width differences between convex and concave side. Pedicle outer diameter was not statistically different between two groups. Pedicle inner diameter was significantly smaller in CP group. Pedicle sclerosis was more frequent in CP patients. VFA was larger in CP group at C3, C4, and C5. Disc/facet degeneration grade was higher in the CP group. Cervical motion of CP group was smaller than those of the control group.ConclusionLM morphology of CP patients was different from normal population. Sclerotic pedicles and vertebral foramen asymmetry were more commonly identified in CP patients. CP patients were more likely to demonstrate progressive disc/facet degeneration. This data may provide useful information on cervical posterior instrumentation in CP patients.

Cervical Laminectomy with Lateral Mass Screw Fixation in Cervical Spondylotic Myelopathy: Neurological and Sagittal Alignment Outcome: Do We Need Lateral Mass Screws at each Segment?

Background:Anterior cervical decompression and fusion is the standard procedure used for treating patients with cervical myelopathy. However, these procedures are associated with complications such as pseudarthrosis, construct failure, and neurological complications. Posterior cervical laminectomy and instrumentation is an alternative procedure to treat multilevel cervical myelopathy. In this study, we raised questions whether instrumentation is required at all levels and whether stabilizing the spine in neutral or lordotic contour with indirect decompression leads to neurological improvement with radiological evidence of anterior decompression. The results of posterior cervical laminectomy and instrumentation with lateral mass screw in terms of radiological and functional outcome in patients with multilevel cervical myelopathy are prospectively evaluated.Materials and Methods:In this prospective study conducted between June 2006 and December 2015, we have evaluated 112 patients with multilevel cervical myelopathy who underwent multilevel cervical laminectomy and instrumentation with lateral mass screw. All patients were evaluated preoperatively and postoperatively with Nurick's grading and Modified Japanese Orthopaedic Association (mJOA) scale for neurological function. Cooper scale and British Medical Research Council grading system for motor function. Curvature index was used to measure the alignment of cervical spine preoperatively and postoperatively. Alignment of the cervical spine was done preoperatively and postoperatively by calculating the curvature index. Axial MRI was used to calculate the severity of compression preoperatively which was calculated as per Singh's criteria and postoperatively to assess the adequacy of decompression at the operated level.Results:In our study, there were 112 patients including 99 males and 13 females, with mean age of 59.53 years. The mean duration of followup of patients was 33.24 months. In total, cervical laminectomy was performed at 342 levels in 112 patients with an average of 3.05 laminectomies, and in total, 112 lateral mass screws were inserted. On postoperative followup, the mJOA and Nurick's grading showed improvement in all cases as compared to preoperative findings. The mean mJOA improved significantly from 8.56 preoperatively to 13.57 postoperatively (P < 0.001). The mean Nurick's grading also improved significantly from 2.59 preoperatively to 0.66 postoperatively (P < 0.001). The mean Cooper scale also showed significant improvement in both upper and lower limbs postoperatively (P < 0.001). The mean preoperative Cooper scale was 1.75 and postoperative was 0.31 for upper limbs, and the mean Cooper scale was 2.14 preoperatively and 0.56 postoperatively for lower limbs. X-rays done on routine followups showed good alignment of the cervical spine with maintenance of curvature index in all patients. The mean grade of compression as seen on preoperative MRI was 2.46 which reduced significantly postoperatively to 0.16 (P < 0.001).Conclusion:The multilevel cervical laminectomy and instrumentation with lateral mass screw for multilevel cervical myelopathy is a safe technique that provides decompression of the spinal cord, prevents the development of kyphotic spinal deformity and posterior tension band of the spinal cord as associated with laminoplasty or uninstrumented laminectomy.

MODERN TECHNIQUES OF CERVICAL INSTRUMENTATION IN IMMATURE SKELETON: VIABILITY ASSESSMENT

ABSTRACT Objective: This study describes the use of materials for modern cervical instrumentation, evaluating its viability in children and adolescents, and the techniques used in different cases. The efficacy of the techniques was analyzed through improvement of pain, maintenance of cervical range of motion, recovery of craniocervical stability, bone consolidation, and spinal stenosis in the postoperative follow-up. Method: Retrospective study of the clinical and radiological parameters of 27 patients aged two to 16 years with cervical spine diseases. Results: Two patients had chronic dislocation in C1-C2, one had congenital axis spondylolisthesis, two had congenital dislocation in C1-C2, three had tumors, one had kyphosis after laminectomy, one had post-infection kyphosis, one had fracture, 11 were syndromic with instabilities, and five had congenital cervical scoliosis. As to surgical approaches, two patients were transorally operated, three by anterior approach, 15 by posterior approach, two by anterior and posterior approaches, and five were treated in three stages (anterior, posterior and anterior approaches). Regarding the technique of cervical stabilization, seven patients were treated by Goel-Harms technique, two received Goel’s facet distraction, and three, Wright translaminar screws. There were complications in four cases. Two patients in the instrumentation of C1 lateral mass due to poor positioning, one with cerebrospinal fluid fistula and one with surgical wound infection. Conclusion: Modern cervical instrumentation in pediatric patients is a safe and effective technique for the treatment of cervical instability.

Intraoperative Hemorrhage Requiring Emergent Hysterectomy: Failed Conservative Management of a Cervical Placenta Accreta

Background: Emergent peripartum hysterectomy is warranted for a variety of indications, including uterine rupture, uterine atony, retained placenta, and abnormal placentation. Abnormal placentation is an increasingly common phenomenon that can be attributed to disruptions in the endometrial decidua following cesarean delivery, myomectomy, dilation and curettage, endometritis, endometrial ablation, and other operative procedures. Case: At 10 weeks of gestation, a patient with two previous cesarean deliveries and two terminations of pregnancy via dilation and curettage underwent a suction dilation and curettage for a missed abortion. Hemorrhage occurred; she became hemodynamically unstable and underwent an emergent total abdominal hysterectomy (TAH). Results: Surgical pathology testing confirmed an intracervical pregnancy with a placenta accreta. Conclusions: This case highlights the difficulty in differentiating cervical ectopic pregnancy with a spontaneous abortion in process. In order to prevent loss of reproductive function, massive hemorrhage, and possibly maternal mortality, the current authors recommend that, in patients with histories of multiple cervical instrumentations, the risk of cervical ectopic pregnancy and even abnormal cervical placentation must be considered in the preoperative differential. In the unstable patient, the “gold standard” treatment for abnormal placentation—TAH—is warranted when conservative measures, such as balloon tamponade, fail. (J GYNECOL SURG 33:215)

The relationship between cervical lordosis and Nurick scores in patients undergoing circumferential vs. posterior alone cervical decompression, instrumentation and fusion for treatment of cervical spondylotic myelopathy

The loss of regional cervical sagittal alignment and the progressive development of cervical kyphosis is a factor in the advancement of myelopathy. Adequate decompression of the spinal canal along with reestablishment of cervical lordosis are desired objective with regard to the surgical treatment of patients with cervical spondylotic myelopathy. A retrospective chart review was conducted in which patients who underwent either a combined anterior/posterior instrumentation and decompression or a posterior alone instrumentation and decompression for the treatment of CSM at our institution were identified. Any patient undergoing operative intervention for trauma, infection or tumors were excluded. Similarly, patients undergoing posterior instrumentation with constructs extending beyond the level of C2–C7 were similarly excluded from this study. A total of 67 patients met the inclusion criteria for this study. A total of 32 patients underwent posterior alone surgery and the remaining 35 underwent combined anterior/posterior procedure. Radiographic evaluation of patient’s preoperative and postoperative cervical lordosis as measured by the C2–C7 Cobb angle was performed. Each patient’s preoperative and postoperative functional disability as enumerated by the Nurick score was also recorded. Statistical analysis was conducted to determine if there was a significant relationship between improvement in cervical lordosis and improvement in patient’s clinical outcomes as enumerated by the Nurick Score in patients undergoing posterior alone versus combined anterior/posterior decompression, instrumentation and fusion of the cervical spine.

Efficacy of Intraoperative Neurophysiologic Monitoring for Pediatric Cervical Spine Surgery

Clinical case series. To investigate the efficacy of intraoperative neuromonitoring in pediatric cervical spine surgery. Intraoperative neuromonitoring (IONM) consisting of somatosensory-evoked potentials (SSEP) and transcranial motor-evoked potentials (tcMEP) has been shown to effectively prevent permaneny neurologic injury in deformity surgery. The role of IONM during pediatric cervical spine surgery is not well documented. Advances in cervical spine instrumentation have expanded the surgical options in pediatric populations. The goal of this study is to report the ability of IONM to detect neurologic injury during pediatric cervical spine instrumentation. A single institution database was queried for pediatric-aged patients who underwent cervical spine instrumentation and fusion between 2011 and 2014. Age, diagnosis, surgical indication, number of instrumented levels, and a complete IONM were extracted. Sensitivity and specificity for the detection of neurologic deficits were calculated with exact 95% confidence intervals. Positive and negative predictive values were calculated with estimated 95% confidence intervals. Sixty-seven patients who underwent cervical spine instrumentation were identified with a mean age of 11.6 years (range 1-18). Diagnoses included instability (27), congenital (11), kyphosis (8), fracture (7), tumor (7), arthritis (4), and basilar invagination (3). Mean number of vertebral levels fused was 4 (range 2-7). All patients underwent cervical instrumentation with SSEP and tcMEP monitoring. A significant change in tcMEP monitoring was observed in 7 subjects (10%). There were no corresponding SSEP changes in these patients. The sensitivity of combined IONM was 75% [95% CI = 24.9, 98.7] and the specificity was 98.5% [92.7, 99.9]. tcMEP is a more sensitive indicator to spinal cord injury than SSEP, which is consistent with previous studies. IONM changes in 10% of a patient population are significant enough to warrant intraoperative determination if true SCI has occurred or is underway and intervene accordingly. 4.

Blood-saving effect of prophylactic tranexamic acid use in patients undergoing cervical spine surgery

Objective To evaluate the blood-saving effect of prophylactic tranexamic acid(TXA)use in the patients undergoing cervical spine surgery. Methods A total of 100 patients of both sexes, aged 55-75 yr, with body mass index of 19.0-25.0 kg/m2, of American Society of Anesthesiologists physical statusⅠ or Ⅱ, undergoing elective cervical laminectomy and instrumentation, were divided into TXA group and normal saline group(group NS)using a random number table, with 50 patients in each group.TXA 15 mg/kg was intravenously injected at 30 min before skin incision in group TXA, and the equal volume of normal saline was given instead in group NS.Hemoglobin was measured before operation and on postoperative days 1, 3 and 5.The intraoperative, postoperative, total blood loss, hidden blood loss and requirement for blood(allogeneic and autologous blood)transfusion were recorded.The development of complications such as epidural hematoma, deep vein thrombosis and pulmonary embolism was also recorded. Results Compared with group NS, the postoperative blood loss, total blood loss and blood transfusion rate were significantly decreased, the postoperative hemoglobin was increased(P 0.05). No patients developed complications such as epidural hematoma, deep vein thrombosis or pulmonary embolism in the two groups. Conclusion Prophylactic TXA use produces blood-saving effect to some extent in the patients undergoing cervical spine surgery. Key words: Tranexamic acid; Blood loss, surgical; Laminectomy

Management of Esophageal and Pharyngeal Perforation as Complications of Anterior Cervical Spine Surgery.

To describe our experience in treating esophageal and pharyngeal perforation after anterior cervical spine surgery. Six patients with esophageal injury and one patient with pharyngeal injury after anterior cervical spinal surgery, managed at our department between 2000 and 2015, were analyzed retrospectively. During the study period, 7 patients (6 male and 1 female; mean age, 45 years) presented with esophageal perforation. The original anterior cervical spinal surgery was performed due to trauma in 2 patients and because of a degenerative cervical disorder in 5. Early esophageal perforation was diagnosed in 2 patients, and delayed esophageal injury due to chronic irritation with the cervical implants was noted in 5. Three of the five delayed perforation cases were related to cervical instrument displacement. Two patients showed no definite signs of infection, whereas 5 patients had various symptoms, including fever, neck pain, odynophagia, neck swelling, and upper extremity weakness. Two patients with a large defect underwent surgical repair and three with minimal perforation due to chronic irritation from the implants underwent instrument removal without direct repair of defect. Two asymptomatic patients received no intervention. Six patients with infection completely recovered from esophageal injury after treatment for a mean duration of 5.2 weeks (range, 4-8 weeks). One patient died because of postoperative pneumonia and sepsis after implant removal. Esophageal and pharyngeal injury after cervical spinal surgery may occur either directly due to spinal trauma and vigorous intraoperative retraction or due to chronic irritation with cervical implants. In cases of perforation associated with infection, various surgical modalities, including primary closure and reinforcement with a flap, could be considered depending on factors such as esophageal defect size, infection severity, and timing of recognition of injury.

Lateral mass screw stimulation thresholds in posterior cervical instrumentation surgery: a predictor of medial deviation.

OBJECTIVE Normative data exists for stimulus-evoked pedicle screw electromyography (EMG) current thresholds in the lumbar spine, and is routinely referenced during spine surgeries to detect a screw breach, prevent injury of neural elements, and ensure the most biomechanically sound instrumentation construct. To date, similar normative data for cervical lateral mass screws is limited, thus the utility of lateral mass screw testing remains unclear. To address this disparity, in this study the authors describe cumulative lateral mass screw stimulation threshold data in patients undergoing posterior cervical instrumentation with lateral mass screws. These data are correlated with screw placement on postoperative imaging, and a novel correlation is discovered with direct clinical implications. METHODS Using a ball-tip probe, 154 lateral mass screws in 21 patients were electrically tested intraoperatively. In each case, for each screw, the lowest (or threshold) current at which the first polyphasic stimulus-evoked EMG response was reproducibly observed by a neurophysiologist was recorded. All patients underwent postoperative CT. Screw position within the lateral mass was first measured in the axial and sagittal planes for each lateral mass screw using the CT images. Screw placement was also evaluated by 2 independent physicians, blinded to current threshold data, on a binary scale of acceptability. The predictive capacity of screw EMG threshold data was evaluated via multivariable regression analyses and receiver operating characteristic (ROC) analyses. Predictive capacity was examined with respect to screw position within the lateral mass, as well as screw acceptability. RESULTS Lateral mass screw EMG thresholds did not appear to differ significantly for screws considered "acceptable" versus "unacceptable" according to the radiographic criteria. Accordingly, ROC analysis confirmed that EMG current threshold data were of minimal utility in predicting screw radiographic acceptability. However, EMG threshold was significantly predictive of screw medial distance from the spinal canal. A screw stimulating below 7.5 mA correctly identified a screw as being within 2 mm of the spinal canal with 75% sensitivity and 92% specificity (positive predictive value 20%, negative predictive value 99.3%), independent of its distance relative to other lateral mass landmarks. EMG current threshold was not significantly predictive of screw deviation in the superior or inferior directions, and was inversely predictive of screw deviations in the lateral direction. CONCLUSIONS In the context of uncertainty regarding the utility of cervical lateral mass EMG current threshold data, this study found that EMG current thresholds correspond significantly, and exclusively, with screw distance from the spinal canal. This association appears independent of other criteria for screw misplacement. As such, the authors recommend that EMG current thresholds be referenced in the case of a suspected medial breach as an effective means to rule out screw placement too medial to the spinal canal.

A novel classification of screw placement accuracy in the cervical spine.

Goal of this study is to present an easily reproducible and reliable measurement to evaluate accuracy of screw placement in cervical spine. Accuracy of cervical screw position was assessed in 52 patients treated with 163 screws. Each patient receiving pedicle, transarticular C1/2, lateral mass, or laminar screws and postoperative CT scan was included. Placement position was categorized in 5 grades: Grade 1 is ideal with pedicle wall perforation < 1 mm, grade 2 < 2 mm, grade 3 < 3 mm, and grade 4 < 4 mm. Grade 5 > 4 mm and/or obstruction of transverse foramen by more than half a screw diameter. Intraclass correlation coefficient (ICC) values were assessed for inter- and intraobserver reliability. The mode of individual evaluations was calculated to assign a single value to each screw. This yielded 89 grade 1 (54.6%), 48 grade 2 (29.4%), 14 grade 3 (8.6%), 3 grade 4 (1.8%), and 9 grade 5 (5.5%) screws. Intraobserver reliability ICC was 0.966 and 0.959 for measurements. Interobserver reliability ICC was 0.938. This study introduces a reliable classification of cervical spine instrumentation with various screw types. This should enable the use of a uniform and reproducible, and thus comparable classification for screw position in cervical spine.