The dosage and administration of long-term intrathecal baclofen therapy for severe spasticity of spinal origin.

STUDY DESIGN: Retrospective chart audit. OBJECTIVE: To indicate the appropriate baclofen dosage to control severe spasticity of spinal origin and to develop the optimal administration protocol for long-term intrathecal baclofen (ITB) therapy. SETTING: Department of Orthopaedic Surgery, Spinal Injuries Center, Japan. METHODS: Thirty-four people with spasticity of various spinal origins who were consistently treated at our hospital were included. The median follow-up period was 6 years and 11 months. Measures of Ashworth score were taken before and after surgical implant of baclofen pump. We decided not to increase the baclofen dosage after the Ashworth score reached 1. We recorded the control of spasticity, changes in the baclofen dose, and the incidence of complications. RESULTS: The average Ashworth score was 3.31 (1.75-4.0) before implant surgery, 1.38 (1.0-2.25) after implant surgery, and 1.39 (1.0-2.25) at the final follow-up, while the average baclofen dose (therapeutic/optimal dose) was 230.6 µg/day (50-450). The incidence of each complication was as follows: 8.8% (n = 3) catheter-related, 2.9% (n = 1) pump-related and 5.9% (n = 2) drug tolerance. No patients experienced withdrawal syndrome. Dose fluctuation with changes in the pathology of the original disease was observed in three cases. CONCLUSIONS: The usage of the Ashworth score as a guide for dose adjustment was found to be a good objective indicator for ITB therapy. The administration based on this objective indicator made it possible to effectively manage patients with a relatively low dose of baclofen and a low rate of drug-related complications.

Sequential neurological improvements after conservative treatment in patients with complete motor paralysis caused by cervical spinal cord injury without bone and disc injury.

OBJECTIVE This study investigated neurological improvements after conservative treatment in patients with complete motor paralysis caused by acute cervical spinal cord injury (SCI) without bone and disc injury. METHODS This study was retrospective. The authors evaluated neurological outcomes after conservative treatment of 62 patients with complete motor paralysis caused by cervical SCI without bone and disc injury within 72 hours after trauma. The sequential changes in their American Spinal Injury Association Impairment Scale (AIS) grades were reviewed at follow-up 24-72 hours, 1 week, and 1, 3, and 6 months after treatment. RESULTS Of the 31 patients with a baseline AIS grade of A, 2 (6.5%) patients improved to grade B, 5 (16.1%) improved to grade C, and 2 (6.5%) improved to grade D by the 6-month follow-up. The 22 (71.0%) patients who remained at AIS grade A 1 month after injury showed no neurological improvement at the 6-month follow-up. Of the 31 patients with a baseline AIS grade of B, 12 (38.7%) patients showed at least a 1-grade improvement at the 1-month follow-up; 11 (35.5%) patients improved to grade C and 16 (51.6%) patients improved to grade D at the 6-month follow-up. CONCLUSIONS Even in patients with complete motor paralysis caused by cervical SCI without bone and disc injury within 72 hours after trauma, approximately 30% of the patients with an AIS grade of A and 85% of the patients with an AIS grade B improved neurologically after conservative treatment. It is very important to recognize the extent of neurological improvement possible with conservative treatment, even for severe complete motor paralysis.

Normative data for parameters of sagittal spinal alignment in healthy subjects: an analysis of gender specific differences and changes with aging in 626 asymptomatic individuals.

PURPOSE: This study aims to establish normative data for parameters of spino-pelvic and spinal sagittal alignment, gender related differences and age-related changes in asymptomatic subjects. METHODS: A total of 626 asymptomatic volunteers from Japanese population were enrolled in this study, including 50 subjects at least for each gender and each decade from 3rd to 8th. Full length, free-standing spine radiographs were obtained. Cervical lordosis (CL; C3-7), thoracic kyphosis (TK; T1-12), lumbar lordosis (LL; T12-S1), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS) and sagittal vertical axis (SVA) were measured. RESULTS: The average values (degrees) are 4.1 ± 11.7 for CL, 36.0 ± 10.1 for TK, 49.7 ± 11.2 for LL, 53.7 ± 10.9 for PI, 14.5 ± 8.4 for PT, and 39.4 ± 8.0 for SS. Mean SVA is 3.1 ± 12.6 mm. Advancing age caused an increase in CL, PT and SVA, and a decrease in LL and SS. There was a significant gender difference in CL, TK, LL, PI, PT and SVA. From 7th decade to 8th decade, remarkable decrease of LL & TK and increase of PT were seen. A large increase of SVA was also seen between 60' and 70'. CONCLUSION: Standard values of spino-pelvic sagittal alignment were established in each gender and each decade from 20' to 70'. A remarkable change of spino-pelvic sagittal alignment was seen from 7th decade to 8th decade in asymptomatic subjects.

Sensitivity and specificity of the 'knee-up test' for estimation of the American Spinal Injury Association Impairment Scale in patients with acute motor incomplete cervical spinal cord injury.

STUDY DESIGN: A retrospective study. OBJECTIVE: Precise classification of the neurological state of patients with acute cervical spinal cord injury (CSCI) can be challenging. This study proposed a useful and simple clinical method to help classify patients with incomplete CSCI. SETTING: Spinal Injuries Centre, Japan. METHODS: The sensitivity and specificity of the 'knee-up test' were evaluated in patients with acute CSCI classified as American Spinal Injury Association Impairment Scale (AIS) C or D. The result is positive if the patient can lift the knee in one or both legs to an upright position, whereas the result is negative if the patient is unable to lift the knee in either leg to an upright position. The AIS of these patients was classified according to a strict computerised algorithm designed by Walden et al., and the knee-up test was tested by non-expert examiners. RESULTS: Among the 200 patients, 95 and 105 were classified as AIS C and AIS D, respectively. Overall, 126 and 74 patients demonstrated positive and negative results, respectively, when evaluated using the knee-up test. A total of 104 patients with positive results and 73 patients with negative results were classified as AIS D and AIS C, respectively. The sensitivity, specificity, positive predictive and negative predictive values of this test for all patients were 99.1, 76.8, 82.5 and 98.7, respectively. CONCLUSIONS: The knee-up test may allow easy and highly accurate estimation, without the need for special skills, of AIS classification for patients with incomplete CSCI.

A Safe Surgical Procedure for Old Distractive Flexion Injuries of the Subaxial Cervical Spine.

STUDY DESIGN: Retrospective review. PURPOSE: To describe a safe and effective surgical procedure for old distractive flexion (DF) injuries of the subaxial cervical spine. OVERVIEW OF LITERATURE: Surgical treatment is required in old cases when a progression of the kyphotic deformity and/or persistent neck pain and/or the appearance of new neurological symptoms are observed. Since surgical treatment is more complicated and dangerous in old cases than in acute distractive-flexion cases, the indications for surgery and the selection of the surgical procedure must be carefully conducted. METHODS: To identify a safe and effective surgical procedure, the procedure selected, reason(s) for its selection, and associated neurological complications were investigated in 13 patients with old cervical DF injuries. RESULTS: No neurological complications were observed in nine patients (DF stage 2 or 3) who underwent the anterior-posterior-anterior (A-P-A) method and two patients (DF stage 1) who underwent the posterior method. It was initially planned that two patients (DF stage 2) who underwent the P-A method would be treated using the Posterior method alone; however, anterior discectomy was added to the procedure after the development of a severe spinal cord disorder. CONCLUSIONS: The A-P-A method (anterior discectomy, posterior release and/or partial facetectomy, reduction and instrumentation, anterior bone grafting) is considered to be a suitable surgical procedure for old cervical DF injuries.

Can the acute magnetic resonance imaging features reflect neurologic prognosis in patients with cervical spinal cord injury?

BACKGROUND CONTEXT: Several prognostic studies looked for an association between the degree of spinal cord injury (SCI), as depicted by primary magnetic resonance imaging (MRI) within 72 hours of injury, and neurologic outcome. It was not clearly demonstrated whether the MRI at any time correlates with neurologic prognosis. PURPOSE: The purpose of the present study was to investigate the relationship between acute MRI features and neurologic prognosis, especially walking ability of patients with cervical spinal cord injury (CSCI). Moreover, at any point, MRI was clearly correlated with the patient's prognosis. STUDY DESIGN: Retrospective image study. PATIENT SAMPLE: From January 2010 to October 2015, 102 patients with CSCI were treated in our hospital. Patients who were admitted to our hospital within 3 days after injury were included in this study. The diagnosis was 78 patients for CSCI with no or minor bony injury and 24 patients for CSCI with fracture or dislocation. A total of 88 men and 14 women were recruited, and the mean patient age was 62.6 years (range, 16-86 years). Paralysis at the time of admission was graded as A in 32, B in 15, C in 42, and D in 13 patients on the basis of the American Spinal Injury Association (ASIA) impairment scale. Patients with CSCI with fracture or dislocation were treated with fixation surgery and those with CSCI with no or minor bony injury were treated conservatively. Patients were followed up for an average of 168 days (range, 25-496 days). OUTCOME MEASURES: Neurologic evaluation was performed using the ASIA motor score and the modified Frankel grade at the time of admission and discharge. METHODS: Magnetic resonance imaging was performed for all patients at admission. Using the MRI sagittal images, we measured the vertical diameter of intramedullary high-intensity changed area with T2-weighted images at the injured segment. We studied separately the patients divided into two groups: 0-1 day admission after injury, and 2-3 days admission after injury. We evaluated the relationship between the vertical diameter of T2 high-intensity changed area in MR images and neurologic outcome in these two groups. This study does not contain any conflict of interest. RESULTS: In the group admitted at 0-1 day after injury, there was a relationship between the vertical diameter of T2 high-intensity area in MR image and the ASIA motor score at admission and at discharge, but correlation coefficient was low (0.3766 at admission and 0.4239 at discharge). On the other hand, in the group admitted at 2-3 days after injury, there was a significant relationship between the vertical diameter of T2 high-intensity area in MR image and the ASIA motor score at admission and at discharge, and correlation coefficient was very high (0.6840 at admission and 0.5293 at discharge). In the group admitted at 2-3 days after injury, a total of 17 patients (68%) recovered to walk with or without a cane. Receiver operating characteristic (ROC) curve analysis demonstrated that the optimal vertical diameter of T2 high-intensity area cutoffvalue for patients who were able to walk at discharge was 45.8 mm. If the vertical diameter of T2 high-intensity area cutoff value was 45 mm, there was a significant positive correlation with being able to walk at discharge (p<.0001). CONCLUSIONS: From our study, 2-3 days after injury, a significant relationship was observed between the vertical diameter of T2 high-intensity area and the neurologic prognosis at discharge. Zero to 1 day after injury, the relationship between the vertical diameter of T2 high-intensity area and the neurologic prognosis at discharge was weak. Neurologic prognosis is more correlated with MRI after 2-3 days after the injury. If the vertical diameter of T2 high-intensity area was <45 mm, the patients were able to walk with or without a cane at discharge. T2 high-intensity changed area can reflect the neurologic prognosis in patients with CSCI.

Morphologic Evaluation of Lumbosacral Nerve Roots in the Vertebral Foramen: Measurement of Local Pressure of the Intervertebral Foramen.

STUDY DESIGN: The prospective cohort study. OBJECTIVE OF THE STUDY: The objective was to evaluate the relationships between local pressure changes of the intervertebral foramen during lumbar spine extension and lumbar foraminal morphology. SUMMARY OF BACKGROUND DATA: The physiological states of lumbosacral nerve roots in the vertebral foramen remain controversial. METHODS: We evaluated 56 lumbosacral vertebral foramens in 21 patients with L4-degenerative spondylolisthesis. All patients underwent L4-5 posterolateral fusion (PLF). The local pressure of the intervertebral foramen was measured intraoperatively, and measurement was performed before and after L4-5 PLF. We defined the changes in the ratio of local pressure between lumbar flexion to extension as percent pressure. The sagittal angular motion, distance between the inferior cortex of the cranial pedicle and superior cortex of the caudal pedicle, posterosuperior margin of the superior vertebral body and superior articular facet, posteroinferior edge of the superior vertebral body and inferior articular facet, and the intervertebral disc height were measured using preoperative functional plain radiographs and CT images. RESULTS: The average local pressure of the intervertebral foramen significantly increased during lumbar extension. However, the L4-5 vertebral foraminal pressure after PLF were nearly identical. There was no significant correlation between percent pressure and lumbar range of motion. Furthermore, there were no significant correlations between percent pressure and each morphologic parameter of the lumbar foramen. CONCLUSIONS: There were no significant relationships between the lumbar foraminal morphology and intervertebral foraminal pressure changes during lumbar extension, and L4-5 vertebral foraminal pressure was not affected by the lumbar posture after L4-5 posterior fusion. On the basis of the results, the external dynamic stresses on the nerve roots in the vertebral foramen might be improved by lumbar posterior fusion using instrumentation without direct decompression of the vertebral foramen.

"Knee-up test" for easy detection of postoperative motor deficits following spinal surgery.

BACKGROUND CONTEXT: Neurologic motor deficit is a serious complication of spinal surgery. Early diagnosis of complications by neurologic examination immediately after spinal surgery is mandatory. However, patients cannot always cooperate with the physician in the very early stages of recovery. PURPOSE: The aim of the present study is to prospectively investigate the usefulness of the "knee-up test" for easy detection of postoperative motor deficits. STUDY DESIGN: A prospective clinical study was carried out. PATIENT SAMPLE: Patients with spinal disorder operated upon at a single institute were administered the knee-up test after an anesthesiologist had judged that endotracheal extubation was possible. OUTCOME MEASURES: The outcome measures were preoperative and postoperative Manual Muscle Testing. METHODS: A simple yet reliable method known as the "knee-up test" was developed to easily assess postoperative deficits before endotracheal extubation. When the patient's knee is passively lifted up and the patient is able to maintain this position in both legs, the result is negative, whereas when the patient is unable to maintain the knee in an upright position for one or both legs, the result is positive. The presently accepted criterion for a new-onset postoperative neurologic motor deficit is motor weakness leading to a decrease in function of at least two grades in more than one muscle function within 12 hours of spinal surgery, as evaluated by the Manual Muscle Testing. The association between the presence of new-onset motor deficits and the results of the knee-up test was prospectively investigated. RESULTS: Seventeen patients exhibited positive results when evaluated using the knee-up test, whereas 521 patients exhibited negative results. Sixteen of the patients with positive results were determined to have new-onset motor deficits, whereas no new-onset motor deficits were observed in the remaining patient. Of the 521 patients with negative knee-up test results, only 2 were determined to have new-onset motor deficits, whereas no new-onset motor deficits were observed in the remaining 519 patients. The sensitivity, specificity, positive predictive value, and negative predictive value were 88.9, 99.8, 94.1, and 99.6, respectively. CONCLUSIONS: The knee-up test may allow for early and easy detection of postoperative motor deficits with high probability in very early stages.

Clinical Influence of Cervical Spinal Canal Stenosis on Neurological Outcome after Traumatic Cervical Spinal Cord Injury without Major Fracture or Dislocation.

STUDY DESIGN: Retrospective case series. PURPOSE: To clarify the influence of cervical spinal canal stenosis (CSCS) on neurological functional recovery after traumatic cervical spinal cord injury (CSCI) without major fracture or dislocation. OVERVIEW OF LITERATURE: The biomechanical etiology of traumatic CSCI remains under discussion and its relationship with CSCS is one of the most controversial issues in the clinical management of traumatic CSCI. METHODS: To obtain a relatively uniform background, patients non-surgically treated for an acute C3-4 level CSCI without major fracture or dislocation were selected. We analyzed 58 subjects with traumatic CSCI using T2-weighted mid-sagittal magnetic resonance imaging. The sagittal diameter of the cerebrospinal fluid (CSF) column, degree of canal stenosis, and neurologic outcomes in motor function, including improvement rate, were assessed. RESULTS: There were no significant relationships between sagittal diameter of the CSF column at the C3-4 segment and their American Spinal Injury Association motor scores at both admission and discharge. Moreover, no significant relationships were observed between the sagittal diameter of the CSF column at the C3-4 segment and their neurological recovery during the following period. CONCLUSIONS: No relationships between pre-existing CSCS and neurological outcomes were evident after traumatic CSCI. These results suggest that decompression surgery might not be recommended for traumatic CSCI without major fracture or dislocation despite pre-existing CSCS.

Narrow cervical canal in 1211 asymptomatic healthy subjects: the relationship with spinal cord compression on MRI.

PURPOSE: Narrow cervical canal (NCC) has been a suspected risk factor for later development of cervical myelopathy. However, few studies have evaluated the prevalence in asymptomatic subjects. The purpose of this study was to investigate the prevalence of NCC in a large cohort of asymptomatic volunteers. METHODS: This study was a cross-sectional study of 1211 asymptomatic volunteers. Approximately 100 men and 100 women representing each decade of life from the 20s to the 70s were included in this study. Cervical canal anteroposterior diameters at C5 midvertebral level on X-rays, and the prevalence of spinal cord compression (SCC) and increased signal intensity (ISI) changes on MRI were evaluated. Receiver operating characteristic analysis was performed to determine the cut-off value of the severity of canal stenosis resulting in SCC. RESULTS: NCC (<14 mm) was observed in 123 (10.2 %) subjects. SCC and ISI were found in 64 (5.3 %) and 28 (2.3 %) subjects, respectively. The prevalence of NCC was significantly higher in females and older subjects, but the occurrence of severe NCC (<12 mm) did not increase with age. The canal size in subjects with SCC or ISI was significantly smaller than in those without SCC (p < 0.0001). The cut-off values of cervical canal stenosis resulting in SCC were 14.8 and 13.9 mm in males and females, respectively. CONCLUSIONS: The prevalence of NCC was considerably lower among asymptomatic healthy volunteers; the cervical canal diameter in subjects with SCC or ISI was significantly smaller than in asymptomatic subjects; NCC is a risk factor for SCC.

Morphology of the injured posterior wall causing spinal canal encroachment in osteoporotic vertebral fractures.

BACKGROUND CONTEXT: The relationship between fractured posterior vertebral wall patterns and the protrusion of bony fragments into the spinal canal is not clear. PURPOSE: We sought to elucidate the effects of fracture patterns of the injured posterior wall on posterior wall instability and spinal canal encroachment using computed tomography myelography (CTM) in two different positions. STUDY DESIGN/SETTING: This is a prospective analysis of CTM in both supine and semi-sitting positions. PATIENT SAMPLE: The sample includes 36 consecutive elderly patients with delayed neurologic disorders due to insufficient bone union at the posterior vertebral wall after vertebral fracture. OUTCOME MEASURES: Radiological parameters, including the rates of dural compression and of occupation by bony fragments (OBFr) and the posterior vertebral body height ratio (PVBHr), were used. METHODS: All patients were examined using CTM in both supine and semi-sitting positions. According to fracture patterns of the posterior vertebral wall, we classified injured posterior walls with one fragment as the simple type and those with two or more fragments as the comminuted type. RESULTS: The simple type was found in 19 of 36 cases, whereas the comminuted type was found in 17 of 36 cases. A significant correlation was identified between changes in OBFr and PVBHr in both the simple and comminuted types. The mean change of PVBHr between the two positions in the comminuted type was significantly larger (9.2%) than that in the simple type (4.8%). Likewise, the mean change in OBFr in the comminuted type (14.0%) was significantly larger than that in the simple type (8.2%), indicating that the injured posterior vertebral wall with the comminuted type would be more likely to collapse and protrude into the spinal canal. CONCLUSIONS: Both simple and comminuted fracture types could cause protrusion of vertebral fragments into the spinal canal because of a collapsing non-united posterior vertebral wall; however, the comminuted type showed more severe spinal canal encroachment, with axial loading. The morphology of the injured posterior wall is thus important for estimating instability.

Risk factors for adjacent segment pathology requiring additional surgery after single-level spinal fusion: impact of pre-existing spinal stenosis demonstrated by preoperative myelography.

PURPOSE: We determined the incidence of and risk factors for clinical adjacent segment pathology (C-ASP) requiring additional surgeries among patients previously treated with one-segment lumbar decompression and fusion surgery. METHODS: We retrospectively analysed 161 consecutive patients who underwent one-segment lumbar decompression and fusion surgery for L4 degenerative spondylolisthesis. Patient age, sex, body mass index (BMI), facet orientation and tropism, laminar inclination angle, spinal canal stenosis ratio [on myelography and magnetic resonance imaging (MRI)], preoperative adjacent segment instability, arthrodesis type, pseudarthrosis, segmental lordosis at L4-5, and the present L4 slip were evaluated by a log-rank test using the Kaplan-Meier method. A multivariate Cox proportional-hazards model was used to analyse all factors found significant by the log-rank test. RESULTS: Of 161 patients, 22 patients (13.7 %) had additional surgeries at cranial segments located adjacent to the index surgery's location. Pre-existing canal stenosis ≥47 % at the adjacent segment on myelography, greater facet tropism, and high BMI were significant risk factors for C-ASP. The estimated incidences at 10 years postoperatively for each of these factors were 51.3, 39.6, and 32.5 %, and the risks for C-ASP were 4.9, 3.7, and, 3.1 times higher than their counterparts, respectively. Notably, spinal canal stenosis on myelography, but not on MRI, was found to be a significant risk factor for C-ASP (log-rank test P < 0.0001 and 0.299, respectively). CONCLUSIONS: Pre-existing spinal stenosis, greater facet tropism, and higher BMI significantly increased C-ASP risk. Myelography is a more accurate method for detecting latent spinal canal stenosis as a risk factor for C-ASP.

Relatively Large Cervical Spinal Cord for Spinal Canal is a Risk factor for Development of Cervical Spinal Cord Compression: A Cross-Sectional Study of 1211 Subjects.

STUDY DESIGN: A cross-sectional study. OBJECTIVE: This study aims to investigate the correlation of the cervical canal and spinal cord size, and evaluate whether the size of the spinal cord relative to the spinal canal is a risk factor for development of cervical spinal cord compression (SCC). SUMMARY OF BACKGROUND DATA: There is little knowledge regarding the relationship between cervical bony canal and spinal cord diameters. Although developmental canal stenosis has been recognized as a risk factor for SCC, the size of the spinal cord relative to the spinal canal has not been similarly discussed. METHODS: Cervical canal anteroposterior (AP) diameters on X-rays and AP diameters and cross-sectional areas of dural sacs and spinal cords on magnetic resonance imaging (MRI) were measured in 1211 healthy volunteers. Correlation between cervical canal diameter on X-rays and AP diameter and cross-sectional area of dural sacs and spinal cords on MRI were assessed. The ratio of the AP diameter of the spinal cord/dural sac was compared between subjects with and without SCC. RESULTS: Spinal canal diameters were not highly correlated with spinal cord AP diameters and cross-sectional areas, although spinal canal diameters were significantly correlated with dural sac AP diameters. The individual difference in the ratio of the AP diameter of the spinal cord/dural sac was large (35%-93%), and the ratio was significantly larger in the subjects with SCC. An AP diameter ratio more than 62% at the C2 to C3 disc level is a risk factor for developing SCC. CONCLUSION: The spinal cord diameter was independent of the spinal canal diameter and the relative size of a spinal cord and spinal canal differed on an individual basis. In addition, the ratio of spinal cord/dural sac in subjects with SCC was significantly larger. Therefore, a relatively large spinal cord could be a risk factor for SCC.

D-dimer screening for deep venous thrombosis in traumatic cervical spinal injuries.

BACKGROUND CONTEXT: Deep venous thrombosis (DVT) in spinal cord injury (SCI) patients is a life-threatening comorbidity. Despite its seriousness, prophylaxis and screening for DVT in SCI patients are still not sophisticated. PURPOSE: This study aimed to define the epidemiology and incidence of DVT in acute traumatic cervical SCI in a Japanese population, determine the best timing for DVT screening, and determine the optimal D-dimer threshold level for use as an easy and minimally invasive screening tool. STUDY DESIGN: This is a prospective clinical study. PATIENT SAMPLE: The patient sample included acute traumatic cervical SCI patients who were admitted to our facility within 2 weeks after injury. OUTCOME MEASURE: Multivariate logistic regression was performed for outcome measure. METHODS: We enrolled 268 patients (223 men and 45 women), from April 2007 to December 2012. After excluding early drop-out patients, 211 patients remained. Assessment for neurological status and blood chemistry, especially blood coagulation levels (prothrombin time, prothrombin time-international normalized ratio, activated partial thromboplastin time, and serum D-dimer), was performed every week until 1 month after injury. Ultrasonography was performed for DVT detection every 2 weeks. RESULTS: Deep venous thromboses were detected in 22 patients (10.4% of patients studied). All DVT-positive patients demonstrated severe paralysis classified as C or greater on the American Spinal Injury Association (ASIA) Impairment Scale. Multivariate logistic regression of clinical and laboratory parameters revealed that only the D-dimer level at 2 weeks after injury was an accurate predictor of DVT formation. The optimal threshold of D-dimer for prediction was determined to be 16 µg/dL. The sensitivity and specificity for detecting DVT were 77.3% and 69.2%, respectively. CONCLUSIONS: D-dimer levels may be used to predict the likelihood of DVT development in patients with acute cervical SCI. Furthermore, the optimal timing for screening test by D-dimer is 2 weeks after injury, and optimal threshold level for D-dimer for diagnosing DVT is 16 µg/dL. Such a screening test would be cost-efficient and simple to administer and could then be followed with additional investigations, such as ultrasonography or venography.

Cervical Disc Protrusion Correlates With the Severity of Cervical Disc Degeneration: A Cross-Sectional Study of 1211 Relatively Healthy Volunteers.

STUDY DESIGN: Cross-sectional study. OBJECTIVE: The purposes of this study were (1) to investigate the frequency and degree of cervical disc degeneration and protrusion on cervical spine magnetic resonance (MR) images and (2) to analyze the correlation between the severity of disc degeneration and disc protrusion. SUMMARY OF BACKGROUND DATA: Cervical disc degenerative changes or protrusion is commonly observed on MR images in healthy subjects. However, there are few large-scale studies, and the frequency and range of these findings in healthy subjects have not been clarified. Moreover, there are no reports regarding the correlation between cervical disc degeneration and disc protrusion. METHODS: Cervical disc degeneration and protrusion were prospectively measured using magnetic resonance imaging in 1211 relatively healthy volunteers. These included at least 100 males and 100 females in each decade of life between the 20s and the 70s. Cervical disc degeneration was defined according to the modified Pfirrmann classification system, and the amount of disc protrusion was evaluated using the anteroposterior diameter of disc protrusion on sagittal MR image. RESULTS: Mild disc degeneration was very common, including 98.0% of both sexes in their 20s. The severity of cervical disc degeneration significantly increased with age in both sexes at every level. The disc degeneration predominantly occurred at C5-C6 and C6-C7. The difference between sexes was not significant except for individuals in their 50s. The average anteroposterior diameter of disc protrusion increased with aging, especially from the 20s to the 40s. The anteroposterior diameter of disc protrusion increased with a progression in the disc degeneration grade. CONCLUSION: Cervical disc degeneration and protrusion were frequently observed in healthy subjects even in their 20s and deteriorated with age. Cervical disc protrusion was significantly correlated with cervical disc degeneration, and spatial cervical disc protrusion was affected by biochemical degenerative changes as observed on MR images. LEVEL OF EVIDENCE: 2.

Abnormal findings on magnetic resonance images of the cervical spines in 1211 asymptomatic subjects.

STUDY DESIGN: Cross-sectional study. OBJECTIVE: The purpose of this study was to determine the prevalence and distribution of abnormal findings on cervical spine magnetic resonance image (MRI). SUMMARY OF BACKGROUND DATA: Neurological symptoms and abnormal findings on MR images are keys to diagnose the spinal diseases. To determine the significance of MRI abnormalities, we must take into account the (1) frequency and (2) spectrum of structural abnormalities, which may be asymptomatic. However, no large-scale study has documented abnormal findings of the cervical spine on MR image in asymptomatic subjects. METHODS: MR images were analyzed for the anteroposterior spinal cord diameter, disc bulging diameter, and axial cross-sectional area of the spinal cord in 1211 healthy volunteers. The age of healthy volunteers prospectively enrolled in this study ranged from 20 to 70 years, with approximately 100 individuals per decade, per sex. These data were used to determine the spectrum and degree of disc bulging, spinal cord compression (SCC), and increased signal intensity changes in the spinal cord. RESULTS: Most subjects presented with disc bulging (87.6%), which significantly increased with age in terms of frequency, severity, and number of levels. Even most subjects in their 20s had bulging discs, with 73.3% and 78.0% of males and females, respectively. In contrast, few asymptomatic subjects were diagnosed with SCC (5.3%) or increased signal intensity (2.3%). These numbers increased with age, particularly after age 50 years. SCC mainly involved 1 level (58%) or 2 levels (38%), and predominantly occurred at C5-C6 (41%) and C6-C7 (27%). CONCLUSION: Disc bulging was frequently observed in asymptomatic subjects, even including those in their 20s. The number of patients with minor disc bulging increased from age 20 to 50 years. In contrast, the frequency of SCC and increased signal intensity increased after age 50 years, and this was accompanied by increased severity of disc bulging. LEVEL OF EVIDENCE: 2.

Effect of preservation of the C-6 spinous process and its paraspinal muscular attachment on the prevention of postoperative axial neck pain in C3-6 laminoplasty.

OBJECT: Axial neck pain after C3-6 laminoplasty has been reported to be significantly lesser than that after C3-7 laminoplasty because of the preservation of the C-7 spinous process and the attachment of nuchal muscles such as the trapezius and rhomboideus minor, which are connected to the scapula. The C-6 spinous process is the second longest spinous process after that of C-7, and it serves as an attachment point for these muscles. The effect of preserving the C-6 spinous process and its muscular attachment, in addition to preservation of the C-7 spinous process, on the prevention of axial neck pain is not well understood. The purpose of the current study was to clarify whether preservation of the paraspinal muscles of the C-6 spinous process reduces postoperative axial neck pain compared to that after using nonpreservation techniques. METHODS: The authors studied 60 patients who underwent C3-6 double-door laminoplasty for the treatment of cervical spondylotic myelopathy or cervical ossification of the posterior longitudinal ligament; the minimum follow-up period was 1 year. Twenty-five patients underwent a C-6 paraspinal muscle preservation technique, and 35 underwent a C-6 nonpreservation technique. A visual analog scale (VAS) and VAS grading (Grades I-IV) were used to assess axial neck pain 1-3 months after surgery and at the final follow-up examination. Axial neck pain was classified as being 1 of 5 types, and its location was divided into 5 areas. The potential correlation between the C-6/C-7 spinous process length ratio and axial neck pain was examined. RESULTS: The mean VAS scores (± SD) for axial neck pain were comparable between the C6-preservation group and the C6-nonpreservation group in both the early and late postoperative stages (4.1 ± 3.1 vs 4.0 ± 3.2 and 3.8 ± 2.9 vs 3.6 ± 3.0, respectively). The distribution of VAS grades was comparable in the 2 groups in both postoperative stages. Stiffness was the most prevalent complaint in both groups (64.0% and 54.5%, respectively), and the suprascapular region was the most common site in both groups (60.0% and 57.1%, respectively). The types and locations of axial neck pain were also similar between the groups. The C-6/C-7 spinous process length ratios were similar in the groups, and they did not correlate with axial neck pain. The reductions of range of motion and changes in sagittal alignment after surgery were also similar. CONCLUSIONS: The C-6 paraspinal muscle preservation technique was not superior to the C6-nonpreservation technique for preventing postoperative axial neck pain.

Pathophysiological effects of lumbar instrumentation surgery on lumbosacral nerve roots in the vertebral foramen: measurement of local pressure of intervertebral foramen.

STUDY DESIGN: Measurement of local pressure of the intervertebral foramina. OBJECTIVE: To evaluate the pathophysiological effects of lumbar instrumentation surgery on lumbosacral nerve roots in the vertebral foramen. SUMMARY OF BACKGROUND DATA: The physiological states of lumbosacral nerve roots in the vertebral foramen remain controversial. METHODS: From 2000 to 2012, 11 of 710 patients with L4 degenerative spondylolisthesis failed to develop postoperative radiculopathy because of intraoperative pedicle screw malposition (L5: 10, L4: 1). We prospectively evaluated the local pressure at the L4-L5 and L5-LS vertebral foramina in 18 patients with L4 degenerative spondylolisthesis. All patients underwent L4-L5 posterolateral fusion (PLF) with L3-L4-L5 laminotomy. Intraoperatively, local pressure of the intervertebral foramen was measured using a catheter pressure transducer while changing the lumbar spine posture, and the measurement was performed before and after L4-L5 PLF. RESULTS: The local pressures at the L4-L5 vertebral foramen were 29.74 ± 16.26 and 51.57 ± 23.18 mm Hg (before fixation), and 39.13 ± 17.69 and 41.71 ± 17.94 mm Hg (after fixation) in the lumbar spine neutral and extension postures, respectively. The local pressure before fixation increased significantly during lumbar spine extension (P < 0.001), although the value after fixation was almost identical. The local pressures at the L5-LS vertebral foramen were 26.91 ± 18.16 and 54.36 ± 26.67 mm Hg (before fixation), and 24.82 ± 17.1 and 58.46 ± 32.78 mm Hg (after fixation) in the lumbar spine neutral and extension postures, respectively. The local pressure before and after fixation increased significantly during lumbar spine extension (P < 0.001), and the values after fixation were higher than those before fixation. CONCLUSION: The local pressure at the L4-L5 vertebral foramen did not change during lumbar extension after L4-L5 PLF, whereas the local pressure at the L5-LS vertebral foramen was significantly increased during lumbar extension after L4-L5 PLF. Our results suggested that the nerve roots caudal to the fixed segments may be exposed to higher external dynamic stresses after lumbar instrumentation surgery. LEVEL OF EVIDENCE: 4.

Influence of spinal cord compression and traumatic force on the severity of cervical spinal cord injury associated with ossification of the posterior longitudinal ligament.

STUDY DESIGN: Retrospective review. OBJECTIVE: To evaluate the influence of static compression factors and dynamic factors based on the various degrees of traumatic force on the cervical spinal cord injury (SCI) in patients with ossification of the posterior longitudinal ligament. SUMMARY OF BACKGROUND DATA: Spinal cord disorder occurs as a result of various factors, including static factors and traumatic force. Discussions about the severity of paralysis resulting from SCI must therefore focus on dynamic factors based on the traumatic force as well as on static compression factors. However, the past reports did not describe the influence of traumatic force in detail. METHODS: Fifty patients presenting with cervical SCI associated with ossification of the posterior longitudinal ligament were included in this study. The American Spinal Injury Association motor score 3 days after injury, the degree of the traumatic force, and the spinal cord compression rate were investigated, and the relationships among these factors were investigated. RESULTS: Paralysis at the time of injury was not determined by static factors alone or by traumatic force alone. The severity of paralysis at the time of injury was determined on the basis of a combination of both the static factors and the degree of traumatic force. CONCLUSION: Both the degree of spinal cord compression and the degree of traumatic force were found to be important factors associated with the severity of cervical SCI in patients with ossification of the posterior longitudinal ligament. LEVEL OF EVIDENCE: 4.