Monchai Ruangchainikom

Prevalence and motion characteristics of degenerative cervical spondylolisthesis in the symptomatic adult.

Study Design. Retrospective analysis of kinetic magnetic resonance images. Objective. To define the prevalence of degenerative cervical spondylolisthesis in symptomatic patients and to analyze the motion characteristics and influence on the spinal canal at the affected level. Summary of Background Data. When compared with lumbar spondylolisthesis, there are few studies evaluating cervical spondylolisthesis, and the prevalence and motion characteristics of cervical spondylolisthesis are not well defined. Methods. Four hundred sixty-eight symptomatic patients underwent upright cervical kinetic magnetic resonance images in neutral, flexion, and extension positions. Segmental displacement and intervertebral angles were measured in 3 positions using computer analysis software. Spondylolisthesis was defined as the vertebral displacement more than 2 mm, and graded based on the magnitude into 2 groups at each level: grade 1 (2–3 mm), grade 2 (>3 mm). Instability was defined as segmental translational motion exceeding 3 mm. Results. Grade 1 and 2 spondylolisthesis at a minimum of 1 level were observed with a prevalence of 16.4% and 3.4% of all patients, respectively. The most affected levels were C4–C5 (6.2%) and C5–C6 (6.0%) followed by C3–C4 (3.6%) and C6–C7 (3.0%). Translational motion was greater in levels with grade 1 as compared with segments without spondylolisthesis, but there was no difference in angular motion between the 3 groups. Translational instability was observed with a prevalence of 16.7% in grade 2, 4.3% in grade 1, and 3.4% in segments without spondylolisthesis. Space available for the cord at the affected level was decreased and spinal cord compression grade was higher in grade 1 and grade 2 as compared with levels without spondylolisthesis. Conclusion. Cervical spondylolisthesis of at least 2 mm was observed in 20% of patients and was most common at C4–C5 and C5–C6. The presence of spondylolisthesis was associated with increased translational motion and decreased segmental spinal canal diameter. Level of Evidence: N/A

Effect of cervical kyphotic deformity type on the motion characteristics and dynamic spinal cord compression.

Study Design. Retrospective analysis of kinematic magnetic resonance images. Objective. To provide baseline data on the segmental angular and translational motion of the degenerated cervical spine by subtype of kyphotic cervical deformity and to elucidate the relationship between motion and degree of spinal cord compression. Summary of Background Data. Kyphotic deformities of the cervical spine are relatively common and are classified as either global or focal. Nevertheless, the effects of kyphotic subtype on cervical segmental motion and degree of spinal cord compression are unknown. Methods. A total of 1171 symptomatic patients (618 females, 553 males) underwent cervical kinematic magnetic resonance imaging in the neutral, flexion, and extension positions. Cervical spines demonstrating kyphosis were included and classified into 3 groups: (1) “global kyphotic deformity” (C-type) (n = 54); (2) “sigmoid deformity” (S-type) with kyphotic upper and lordotic lower cervical segments (n = 29); and (3) “reverse sigmoid deformity” (R-type) with lordotic upper and kyphotic lower cervical segments (n = 39). Translational motion, angular motion, and degree of spinal cord compression were evaluated for each cervical level along with the changes associated with flexion and extension. Results. In the C- and R-types, angular motion with extension was increased in the upper cervical spine, where there was kyphosis; when compared with the S-type, in which there was lordosis in the upper segments. The results were opposite for flexion angular motion. R-type displayed more translational motion at C3–C4 and C5–C6. Degree of static spinal cord compression of R-type was higher than the others at C3–C4. The dynamic spinal cord compression increased in extension more than flexion in all subtypes. Conclusion. Cervical spine studies that aim to investigate kyphotic deformities should make efforts to discern the different subtypes of kyphotic deformities to more accurately characterize and study the effects that the sagittal alignment has on the kinematics of the spine and the degree of spinal cord compression. Level of Evidence: 3

Risk factors for missed dynamic canal stenosis in the cervical spine.

Study Design. Retrospective analysis of kinematic magnetic resonance (MR) images. Objective. To elucidate the distribution and risk factors associated with missed dynamic stenosis in cervical spine. Summary of Background Data. Motion of the cervical spine is widely accepted to be associated with cervical spondylotic myelopathy; however, the distribution and the risk factors for dynamic spinal stenosis are not well understood. Methods. A total of 435 symptomatic patients (2610 cervical segments) obtained upright kinematic MR images in neutral, flexion, and extension postures. Spinal cord compression (SCC), spondylolisthesis, disc bulging, angular motion, translational motion, disc degeneration grade, Modic changes, segmental alignment, and developmental stenosis were all evaluated. Cervical segments C2–C3 to C7–T1 were divided into 2 groups, determined by the presence of SCC. After excluding segments with SCC in the neutral position, a multivariate logistic regression model was used to evaluate for associated risk factors of SCC in flexion and extension that were not present in the neutral position. Results. SCC in neutral position was observed in 5.3% (139/2610) of segments. After excluding these segments, missed dynamic stenosis was found in 8.3% (204/2471) of segments in extension and 1.6% (40/2471) in flexion. Missed dynamic stenosis in both extension and flexion was most frequent at C5–C6. Multivariate logistic regression analysis for dynamic stenosis in extension revealed that disc bulge greater than 2.4 mm, angular motion greater than 4.8°, moderate and severe disc degeneration, segmental kyphosis, and developmental stenosis were significant risk factors. In flexion, significant risk factors were a disc bulge of 1.9 mm or greater, moderate to severe disc degeneration, and segmental kyphosis. Conclusion. Dynamic cord compression was most common at the C5–C6 segment. Cervical segments with greater disc bulge, more severe disc degeneration, greater angular motion, segmental kyphosis, and developmental stenosis may be at risk for missed dynamic stenosis. Level of Evidence: 2

Chronic spinal cord injury treated with transplanted autologous bone marrow-derived mesenchymal stem cells tracked by magnetic resonance imaging: a case report

IntroductionIntrathecal transplantation is a minimally invasive method for the delivery of stem cells, however, whether the cells migrate from the lumbar to the injured cervical spinal cord has not been proved in humans. We describe an attempt to track bone marrow-derived mesenchymal stem cells in a patient with a chronic cervical spinal cord injury.Case presentationA 33-year-old Thai man who sustained an incomplete spinal cord injury from the atlanto-axial subluxation was enrolled into a pilot study aiming to track bone marrow-derived mesenchymal stem cells, labeled with superparamagnetic iron oxide nanoparticles, from intrathecal transplantation in chronic cervical spinal cord injury. He had been dependent on respiratory support since 2005. There had been no improvement in his neurological function for the past 54 months. Bone marrow-derived mesenchymal stem cells were retrieved from his iliac crest and repopulated to the target number. One half of the total cells were labeled with superparamagnetic iron oxide nanoparticles before transplantation to the intrathecal space between L4 and L5. Magnetic resonance imaging studies were performed immediately after the transplantation and at 48 hours, two weeks, one month and seven months after the transplantation. His magnetic resonance imaging scan performed immediately after the transplantation showed hyposignal intensity of paramagnetic substance tagged stem cells in the subarachnoid space at the lumbar spine area. This phenomenon was observed at the surface around his cervical spinal cord at 48 hours. A focal hyposignal intensity of tagged bone marrow-derived stem cells was detected at his cervical spinal cord with magnetic resonance imaging at 48 hours, which faded after two weeks, and then disappeared after one month. No clinical improvement of the neurological function had occurred at the end of this study. However, at 48 hours after the transplantation, he presented with a fever, headache, myalgia and worsening of his motor function (by one grade of all key muscles by the American Spinal Injury Association impairment scale), which lasted for 48 hours.ConclusionIntrathecal injection of bone marrow-derived stem cells at the lumbar spine level could deliver the cells to the injured cervical spinal cord. Transient complications should be observed closely in the first 48 hours after transplantation. Further study should be carried out to evaluate the result of the treatment.

Growth-Factor Nanocapsules That Enable Tunable Controlled Release for Bone Regeneration.

Growth factors are of great potential in regenerative medicine. However, their clinical applications are largely limited by the short in vivo half-lives and the narrow therapeutic window. Thus, a robust controlled release system remains an unmet medical need for growth-factor-based therapies. In this research, a nanoscale controlled release system (degradable protein nanocapsule) is established via in situ polymerization on growth factor. The release rate can be finely tuned by engineering the surface polymer composition. Improved therapeutic outcomes can be achieved with growth factor nanocapsules, as illustrated in spinal cord fusion mediated by bone morphogenetic protein-2 nanocapsules.

BMP-2 adverse reactions treated with human dose equivalent dexamethasone in a rodent model of soft-tissue inflammation.

Study Design. Basic science rodent model of bone morphogenetic protein-2 (BMP-2) soft-tissue inflammation. Objective. This study investigated the anti-inflammatory effect of human dose equivalent (HDE) dexamethasone (DM) for treatment of BMP-2-related soft-tissue inflammation in a rodent model and suggests an appropriate dose for utilization in the clinical practice of spine surgeons. Summary of Background Data. BMP-2 is frequently used in spinal surgery to augment fusion. Yet, side effects of soft-tissue inflammation have been observed. DM decreases proinflammatory cytokine production and cellular immune response. However, the anti-inflammatory effects of HDE DM in a rodent model of BMP-2-associated soft-tissue inflammation have not been reported. Methods. Five, 10, and 15 mg of HDE DM were administered 3 times perioperatively to rodent cohorts receiving BMP-2 paraspinal implants and compared against BMP-2 only positive controls and phosphate buffer negative controls (n = 6 subjects per group). Histopathology, magnetic resonance imaging, and gross dissection were used as measures of cellular, edematous, and exudative inflammatory response. Serial killings were made on day 2 and day 7 postoperatively. Results. Magnetic resonance imaging volume rendering demonstrated inflammatory edema decreased by 49% from 605.4 mm3 to 304.03 mm3 in subjects treated with 5, 10, or 15 mg of HDE DM (P < 0.05). Histopathological analysis demonstrated inflammatory cross-sectional area decreased 28.8% from 1.84 mm2 to 1.31 mm2 in subjects treated with 5, 10 or 15 mg of HDE DM (P < 0.05). Immune cellular infiltration depth decreased 38.5% from 0.26 mm to 0.16 in subjects treated with 15 mg of HDE DM (P < 0.05). Gross anatomical inflammatory exudates were prevented in 100% of subjects treated with 10 or 15 mg of HDE DM (P < 0.05). Conclusion. Low-dose DM administration is effective in controlling the cellular inflammation and edema resulting from BMP-2. Ten or 15 mg of DM might be considered by spine surgeons for controlling the inflammation and edema seen in spine surgery with BMP-2.

The Compensatory Relationship of Upper and Subaxial Cervical Motion in the Presence of Cervical Spondylosis.

Study Design:This study was an in vivo kinematic magnetic resonance imaging analysis of cervical spinal motion in human subjects. Objective:The objective of the study was to identify associations between disk degeneration in the subaxial cervical spine and upper cervical spinal motion in patients with general age-related cervical spondylosis. Summary of Background Data:The kinematic relationship between the occipital-atlantoaxial complex and subaxial cervical spine in patients with cervical spondylosis and decreased cervical motion is not well understood. Methods:A total of 446 symptomatic patients who had neck pain with and without neurogenic symptoms were included in this study. Kinematic magnetic resonance imaging was performed with dynamic motion of the cervical spine in upright, weight-bearing neutral, flexion, and extension positions. Intervertebral disk degeneration for each segment from C2–3 to C7–T1 and sagittal angular motion between flexion and extension for each segment from Oc–C1 to C7–T1 was evaluated. Depending on the amount of sagittal subaxial angular motion, the patients were classified into 3 groups by sagittal angular motion using cutoff points based on tertile (<36-degree group: 149 cases; 36–47-degree group: 148 cases; and >47-degree group: 149 cases). Results:A significant correlation was found between subaxial angular motion and intervertebral disk degeneration, indicating that the subaxial motion decreases according to the degree of disk degeneration. Mean angular motion of the occipital-atlantoaxial complex, especially of Oc–C1, was significantly higher in the <36-degree and 36–47-degree group than in the >47-degree group, whereas no significant difference was found at C1–C2. Conclusions:Our study demonstrates that decreased subaxial cervical spinal motion is associated with intervertebral disk degeneration in a symptomatic population. This decrease in mobility at the subaxial cervical spine is compensated for by an increase in angular mobility of the upper cervical spine at the occipital-atlantoaxial complex, especially at Oc–C1.

Magnetic Resonance Classification System of Cervical Intervertebral Disc Degeneration -Its Validity and Meaning.

Study Design: Retrospective analysis of kinetic magnetic resonance images (kMRIs). Objective: (1) To analyze the changes seen on MRI related to disk degeneration and to develop a new grading system for cervical disk degeneration. (2) To evaluate the reliability and validity of the grading system. Summary of Background Data: Few have studied the relationship between changes seen on MRI with cervical disk degeneration and the chronological order of disk degeneration. A few grading systems for cervical disk degeneration have been reported; however, there have been problems related to subjectivity and lack of a clear, reliable algorithm. Methods: A total of 300 cervical intervertebral disks were graded for nucleus color, structure, disk bulge, and disk height. On the basis of the analysis, a new grading system consisting of 4 grades (grade 0–III) and algorithm were developed. Intraobserver and interobserver reliabilities were assessed. A total of 2802 intervertebral disks were then evaluated using the grading system to correlate disk degeneration grades with patient age and function and to evaluate the validity of the new system. Results: On the basis of cross-table analysis, disk degeneration presents in the following order: (1) decrease and/or change of nucleus intensity; (2) loss of distinction between nucleus and annulus; (3) positive disk bulge; and (4) disk height decrease. The &kgr;-coefficients for intraobserver and interobserver agreements were 0.96 and 0.90, respectively. Severe disk degeneration is most common at C5/C6 followed by C6/C7 and C4/C5, and total disk degeneration grade is correlated with age (R=0.467). There was a decrease of angular motion in grades I–III and an increase in translational motion and decrease of space available for the cord in grades II–III. Conclusions: We developed a new classification system of cervical disk degeneration based on analysis of the changes seen on MRI. Reliability tests indicated high reproducibility of this system, and further analysis confirmed its validity and clinical significance.

Effects of sagittal endplate shape on lumbar segmental mobility as evaluated by kinetic magnetic resonance imaging.

Study Design. Retrospective analysis using kinetic magnetic resonance imaging. Objective. To investigate relationships between vertebral endplate remodeling, Modic changes, disc degeneration, and lumbar segmental mobility. Summary of Background Data. Previous studies have shown that disc degeneration and vertebral endplate Modic changes are associated with differences in spinal motion, however, the effects of vertebral endplate morphology on lumbar segmental motion have not been fully investigated. Methods. A total of 420 patients underwent kinetic magnetic resonance imaging of 2100 lumbar motion segments. Sagittal endplate shapes (concave, flat, irregular), Modic changes (types, 0–3), and disc degeneration (grade, I–V) were assessed along with translational and angular motion of vertebral segments in flexion, extension, and neutral positions. Results. The most common findings were concave endplate shape (63.24%), type 2 Modic change (71.79%), and grade II disc degeneration (40.33%). Flat, irregular endplates were more common at L1–L2, L4–L5, and L5–S1 than L2–L3 and L3–L4. Types 1, 2, and 3 Modic changes increased in frequency according to endplate shape: concave less than flat less than irregular. Type 0 was observed to decrease with the change of endplate shape from flat to concave to irregular. Vertebral levels with irregular endplates had more disc generation than those with flat; levels with flat endplates had significantly more disc degeneration than those with concave. Translational motion of the lumbar segment was greatest at levels with irregular endplates and decreased at those with flat and then concaves endplates. Angular motion was least at levels with irregular endplates and increased at levels with flat, then concave endplates. Conclusion. The degree of pathogenic lumbar segmental motion is associated with remodeling of the sagittal endplate. Endplate remodeling may occur as an adaptation to restrain abnormal movement of the lumbar segment. Level of Evidence: N/A

Dynamic Evaluation of the Cervical Spine and the Spinal Cord of Symptomatic Patients Using a Kinetic Magnetic Resonance Imaging Technique.

Purpose: The purpose of this study was to examine the movement of the spinal cord and its relationship to the spinal canal in patients with mild spondylosis using kinetic magnetic resonance imaging (kMRI). Methods: Weight-bearing, multiposition kMRI was performed on symptomatic patients through a full range of flexion-extension. A total of 52 study patients were selected based on the C2–C7 Cobb angle of sagittal alignment: lordotic (from 30 to 45 degrees). We evaluated dynamic changes in different parameters from flexion-extension: spinal canal diameter (CD), spinal cord diameter (SCD), space available for the cord, anterior space available for the cord (ASAC), posterior space available for the cord (PSAC), average distance between the anterior canal and the cord (d-value), and global angle for the spinal canal and cord. Results: The CD tended to decrease from flexion to extension from C3/C4 to C6/C7, however, there were no significant differences at the proximal and distal levels, C2/C3 and C7/T1. There were no significant differences of SCD between different postures. The SCD tended to decrease from C2/C3 to C7/T1. The ASAC followed the same pattern as CD-values. The ASAC was narrowest at C4/C5 and C5/C6. The PSAC tended to increase from C2/C3 to C7/T1. The spinal cord shifted anteriorly with extension and posteriorly with flexion. In addition, the spinal cord maintained its curve with the movement. Conclusions: The kinematics of spinal cord motion may be associated with the pathogenesis of cervical spondylotic myelopathy. However, the spinal cord maintains its curve with position changes. Consequently, different motions of the cervical spine may affect spinal cord migration and cause changes in ASAC and PSAC.