Is the “snake-eye” MRI sign correlated to anterior spinal artery occlusion on CT angiography in cervical spondylotic myelopathy and amyotrophy?

Objective

The goal of this study was to identify anterior spinal artery (ASA) occlusion by CT angiography in cervical spondylotic myelopathy (CSM) and amyotrophy (CSA) with T2-weighted hyperintensity of MR image of documented small intramedullary high signal intensity known as “snake-eye appearance” (SEA).

Method

One hundred and six patients with CSM were admitted to the investigator group between June 2010 and June 2013. Intramedullary high signal intensity was found in 42 cases and was divided into two types, SEA and non-SEA. SEA was observed in 10 patients, including seven CSM patients and three CSA patients. All SEA patients were performed CT angiography of ASA after admission.

Results

The ASA was visualized in all 10 patients. ASA incomplete occlusion was found in one CSA patient and one CSM patient. No ASA occlusion was found in other CSA and CSM patients with SEA.

Conclusion

ASA occlusion is not commonly seen in CSM and CSA patients with SEA. Pathological changes about SEA in CSM and CSA have no close correlation with ASA occlusion, but may be with anterior radiculomedullary arteries.     

Cervical extension magnetic resonance imaging in evaluating cervical spondylotic myelopathy

Background

Cervical spondylotic myelopathy (CSM) may be caused by static and dynamic spinal cord compression, particularly during neck extension. Dynamic compression may be better evaluated with dynamic magnetic resonance (MR) images. We performed a retrospective study to determine the clinical indication for dynamic MR imaging, and conducted a survey regarding image interpretation by clinicians.

Method

A total of 32 patients (M:F?=?20:12, 60.1?±?10.7 years) who had undergone neutral/extension cervical MR imaging were included. The study population consisted of 22 patients with signs of cervical myelopathy (M group) and 10 patients without signs of myelopathy (NM group). The number of compression levels (complete obliteration of the anterior and posterior subarachnoid space) was assessed at each level in mid-sagittal, T2-weighted, neutral and extension MR images. Reproduced images from 22 patients in the M group were randomly arranged, and four experienced spine surgeons at four different institutes interpreted them to reach a clinicians’ agreement. The agreements were then assessed with inter-rater correlation coefficients (ICC).

Results

Analysis with extension MR images found an increased number of compression levels in 23/32 (72 %) of patients; 20/22 in the M group and 3/10 in the NM group (p?<?0.01, chi-squared test), as compared to findings of the neutral MR images. Clinical factors for increased compression levels in extension MR images were age (p?<?0.01, 63.3?±?10.0 years vs. 51.9?±?8.1) and signs of myelopathy (p?<?0.01, odds ratio, 23.33). Clinician agreement was improved with extension MR images; ICC was 0.67 with neutral and 0.81 with extension MR images.

Conclusions

The evaluation of CSM may be improved with dynamic MR images. Dynamic MR scanning may be considered for elderly patients with signs of myelopathy, but an interpretation for asymptomatic spinal compression based exclusively on extension MR image should be made with caution.     

Measurement of volume-occupying rate of cervical spinal canal and its role in cervical spondylotic myelopathy

Purpose

To compare volume-occupying rate of cervical spinal canal between patients with cervical spondylotic myelopathy (CSM) and normal subjects, and to investigate its significance in cervical spine disease.

Methods

Spiral computed tomography (CT) scan (C4–C6 cervical spine unit) was performed in 20 normal subjects and 36 cases of CSM at a neutral position, and data were transferred to the Advantage Workstation Version 4.2 for assessment. Bony canal area and fibrous canal area in each cross section, and sagittal diameters of cervical spinal canal and cervical spinal body were measured. Volume-occupying rate of cervical spinal canal was calculated using MATLAB. Cervical spinal canal ratio and effective cervical spinal canal ratio were calculated, and Japanese Orthopaedic Association score was used to assess cervical spinal cord function.

Results

Volume-occupying rate of cervical spinal canal at a neutral position was significantly higher in CSM patients as compared to normal subjects (P < 0.01). There was no correlation between cervical spinal canal ratio and JOA score in CSM patients, with a Pearson’s correlation coefficient of 0.171 (P > 0.05). However, sagittal diameter of secondary cervical spinal canal, effective cervical spinal canal ratio and volume-occupying rate of cervical spinal canal were significantly associated to JOA score, with Pearson’s coefficient correlations of 0.439 (P < 0.05), 0.491 (P < 0.05) and ?0.613 (P < 0.01), respectively.

Conclusions

Volume-occupying rate of cervical spinal canal is an objective reflection of compression on cervical spine and spinal cord, and it is associated with cervical spinal cord function. These suggest that it may play a significant role in predicting the development of CSM.     

脊髓型颈椎病脊髓前动脉CT血管造影观察

目的通过颈脊髓前动脉CT血管造影观察脊髓型颈椎病患者的颈脊髓前动脉。方法 2009年2月~2012年8月,采用64排螺旋CT机对17例脊髓型颈椎病患者行脊髓前动脉造影,观察脊髓前动脉阻塞和梗阻,以及MRI T2高信号与脊髓前动脉的关系。结果 2例脊髓型颈椎病并发脊髓前动脉综合征患者脊髓前动脉造影显示颈脊髓前动脉于病变部位中断;其余15例脊髓型颈椎病患者CT脊髓前动脉造影均显影,未见明显中断。结论 64排CT脊髓前动脉造影术可以显像脊髓型颈椎病的颈脊髓前动脉。脊髓型颈椎病脊髓前动脉不易被压迫中断。脊髓型颈椎病MRI图像T2高信号与颈脊髓前动脉无直接关系。     

Spine MR imaging features of subacute combined degeneration patients

Background and purpose

Subacute combined degeneration (SCD) is a potentially reversible neurological complication of a vitamin B12 deficiency; therefore, timely diagnosis and appropriate treatment are of great importance. The study was to evaluate the spine MR imaging features of SCD in a series of patients.

Materials and methods

Eight patients diagnosed with SCD from 2008 to 2010 comprised the study population. Spine MRIs were available for all eight patients, and three of them had follow-up MRIs after vitamin B12 treatment. Two radiologists evaluated the prevalence of signal intensity abnormality of spinal cord and analyzed the distribution and pattern of the signal change in consensus. And they also evaluated post-treatment MRI to find interval change.

Results

Seven of eight patients showed abnormal hyperintensity within posterior aspect of spinal cord on T2-weighted images. The spinal cord abnormalities were seen at cervical spine in five patients (62.5 %) and at thoracic spine in the other two patients (25 %). For patients with cervical spinal cord abnormalities, axial T2-weighted images showed symmetric linear T2-hyperintensity as an “inverted V” at cervical spinal cord. For patients with thoracic spinal cord abnormalities, the abnormal signal intensity looked bilateral paired nodular T2-hyperintensity as “dumbbell” or “binoculars” at thoracic spinal cord. Follow-up MRIs after vitamin B12 treatment showed interval resolution of the areas of abnormal T2-hyperintensity in all.

Conclusion

Symmetric T2-hyperintensity within dorsal column of spinal cord is commonly seen in SCD patients with a linear pattern in the cervical spine and a nodular pattern in the thoracic spine.     

Is the anterior spinal artery occluded in severe cervical compressive myelopathy?

Purpose: The goal of this study was to identify whether the anterior spinal artery (ASA) is occluded in severe cervical compressive myelopathy (CCM) according to computed tomography angiography (CTA); occlusion was defined as spinal canal sagittal diameter compression of more than 80%.Study design: A retrospective study.Setting: Xinqiao Hospital, Chongqing, China.Participants: The sample comprised 11 patients with spinal canal sagittal diameter compression of more than 80%.Interventions: The patient underwent CTA of the ASA after admission. Covisualization of the ASA and the artery of Adamkiewicz was used to identify the ASA.Outcome Measures: Spinal cord compression and decompression were determined with 1.5-Tesla magnetic resonance imaging. The neurologic status was evaluated according to the classification of the American Spinal Injury Association (ASIA).Results: No ASA occlusion was found in all 11 severe CCM patients who presented with chronic or acute onset. All patients demonstrated improved neurological status after the anterior cervical decompression and fusion procedure.Conclusion: ASA occlusion was not observed in CCM patients with spinal canal sagittal diameter compression of more than 80%.     

Usefulness of diffusion tensor MR imaging in the assessment of intramedullary changes of the cervical spinal cord in different stages of degenerative spine disease

Purpose

The aim of this study was to evaluate the usefulness of diffusion tensor imaging (DTI) in the detection of cervical spinal cord integrity alterations in different stages of degenerative spine disease, as well as to compare DTI parameters with selected cervical spinal stenosis measurements.

Methods

One hundred and thirty-two symptomatic patients (mean age 53.58 years) with different stages of cervical spondylosis and twenty-five control subjects (mean age 45.78 years) were enrolled in the study. DTI was performed with a 1.5 T MR scanner. Three hundred and forty-nine spine segments from C2/C3 to C5/C6 were evaluated and divided into five groups according to the degree of spinal cord compression. The values of fractional anisotropy (FA) and apparent diffusion coefficient at each level were calculated and their correlations with the degree of stenosis were analyzed.

Results

FA values differed significantly (p < 0.0001) at all levels between the control group and patients with cervical degenerative disease, including subjects without spinal cord compression visible on plain MR images. A significant (p < 0.01) positive correlation between the mean FA values and anteroposterior diameter of the spinal canal as well as space available for the spinal cord index was demonstrated at all investigated levels.

Conclusion

DTI is capable of revealing impairment of the cervical spinal cord microstructure at the very early stage of degenerative spine disease, even prior to spinal cord compression visible on plain MR. Anteroposterior spinal canal diameter as well as space available for the cord index is well related to spinal cord tissue integrity defined by DTI.     

Effect of Modic changes on spinal canal stenosis and segmental motion in cervical spine

Purpose

Few studies have reported the characteristics of Modic changes (MCs) in the cervical spine in contrast to the lumbar spine. The purpose of this study was to identify the prevalence of MCs in the cervical spine and to elucidate the relationship of MCs with spinal canal stenosis and angular motion.

Methods

437 consecutive, symptomatic patients with neck pain with or without neurogenic symptoms were included in this study. MRI in multiple positions was performed with dynamic motion of the cervical spine in upright, weight-bearing neutral, flexion and extension positions. Type of MC, intervertebral disc degeneration grade, spinal cord compression grade and sagittal angular motion between flexion and extension for each segment from C2–3 to C6–7 were evaluated.

Results

MCs were observed in 84 out of 437 patients (19.2 %) and in 109 out of 2,185 motion segments (5.0 %) with type 2 changes predominating. Disc degeneration grades and spinal cord compression grades of segments with MCs were significantly higher than those without MCs. Sagittal angular motion of segments with MCs were significantly lower than those without MCs. Multiple logistic regression analysis revealed that significantly elevated odds ratios for MCs were observed in segments with severe disc degeneration, severe spinal canal compression and less angular motion.

Conclusion

The cervical segments with MCs were significantly more likely to have disc degeneration and spinal canal stenosis. In addition, the segments with MCs had significantly less angular motion, which suggests MCs may correlate with loss of mobility.     

Risk factors for a poor outcome following surgical treatment of cervical spondylotic amyotrophy: a multicenter study

Introduction

Cervical spondylotic amyotrophy (CSA) is characterized by muscle atrophy in the upper extremities without gait disturbance. However, the indications and outcomes of surgical treatment for CSA have not been clarified. The purpose of this study was to determine the risk factors for a poor outcome following surgical treatment of CSA.

Materials and methods

We performed a retrospective review of CSA in patients from 1991 to 2010 through a multicenter study. We collected information regarding age, type of muscle atrophy, preoperative manual muscle test (MMT), duration of symptoms, high-intensity areas on T2-weighted MR images, low-intensity areas on T1-weighted MR images, levels of spinal canal stenosis, cervical kyphosis and surgical procedures (laminoplasty, anterior cervical discectomy and fusion and posterior spinal fusion), and calculated overall risk factors related to a poor outcome following surgery. Univariate analyses and multivariate logistic regression analysis were performed to identify correlates of a poor outcome.

Results

Fifty-nine patients, 95 % male (56 patients), were included in our analysis with a mean age of 59 years (range 32–78 years). Eighteen patients did not improve after surgery. Symptom duration (OR = 1.263), preoperative MMT grade (OR = 0.169) and distal type of CSA (OR = 9.223) were all associated with an increased risk of a poor surgical outcome.

Conclusion

Early surgery is recommended for CSA patients in whom conservative treatment has not been successful. We also recommend surgery for patients who have severe preoperative muscle weakness or have the distal type of CSA.     

Magnetic resonance imaging evaluation after implantation of a titanium cervical disc prosthesis: a comparison of 1.5 and 3 Tesla magnet strength

Purpose

Cervical disc prostheses induce significant amount of artifact in magnetic resonance imaging which may complicate radiologic follow-up after surgery. The purpose of this study was to investigate as to what extent the artifact, induced by the frequently used Discover^® cervical disc prosthesis, impedes interpretation of the MR images at operated and adjacent levels in 1.5 and 3 Tesla MR.

Methods

Ten subsequent patients were investigated in both 1.5 and 3 Tesla MR with standard image sequences one year following anterior cervical discectomy with arthroplasty.

Outcome measures

Two neuroradiologists evaluated the images by consensus. Emphasis was made on signal changes in medulla at all levels and visualization of root canals at operated and adjacent levels. A “blur artifact ratio” was calculated and defined as the height of the artifact on T1 sagittal images related to the operated level.

Results

The artifacts induced in 1.5 and 3 Tesla MR were of entirely different character and evaluation of the spinal cord at operated level was impossible in both magnets. Artifacts also made the root canals difficult to assess at operated level and more pronounced in the 3 Tesla MR. At the adjacent levels however, the spinal cord and root canals were completely visualized in all patients. The “blur artifact” induced at operated level was also more pronounced in the 3 Tesla MR.

Conclusions

The artifact induced by the Discover^® titanium disc prosthesis in both 1.5 and 3 Tesla MR, makes interpretation of the spinal cord impossible and visualization of the root canals difficult at operated level. Adjusting the MR sequences to produce the least amount of artifact is important.     

Preoperative assessment of hemifacial spasm by the coronal heavily T2-weighted MR cisternography

Background

Microvascular decompression (MVD) has become a well-established surgical procedure for hemifacial spasm (HFS). Before surgery, it is essential to evaluate any possible deformity of the brainstem and establish the precise location of the offending vessels. In the present study of HFS patients we examined coronal sections taken by heavily T2-weighted MR cisternography in addition to routine axial sections, and assessed the usefulness of these images through comparison with intraoperative findings.

Methods

Eighty patients with HFS underwent preoperative coronal heavily T2-weighted MR cisternography before microvascular decompression surgery. Three neurosurgeons examined the preoperative axial and coronal MR images and evaluated vessel invagination into the brainstem. The usefulness of coronal sections was assessed statistically by the Mann-Whitney U test.

Results

Invagination of the offending vessel into the brainstem was observed in 24 cases (30.0%). In 19 patients, it was predicted preoperatively that compression of the flocculus and brainstem would be required in order to approach the offending vessels. Coronal MR cisternography was significantly more useful in cases with vessel invagination into the brainstem than in cases without invagination.

Conclusions

Coronal sections obtained by MR cisternography are able to demonstrate the severity of vessel invagination into the brainstem as well as revealing the presence of the offending vessel. This information is helpful for planning a suitable approach to the root exit zone.     

Increased spinal cord movements in cervical spondylotic myelopathy

Background context

Magnetic resonance imaging (MRI) is a very useful diagnostic test for cervical spondylotic myelopathy (CSM) because it can identify degenerative changes within the spinal cord (SC), disclose the extent, localization, and the kind of SC compression, and help rule out other SC disorders. However, the relationships between changes in cerebrospinal fluid (CSF) flow, cord motion, the extent and severity of spinal canal stenosis, and the development of CSM symptoms are not well understood.

Purpose

To evaluate if changes in the velocity of CSF and SC movements provide additional insight into the pathophysiological mechanisms underlying CSM beyond MRI observations of cord compression.

Study design

Prospective radiologic study of recruited patients.

Patient sample

Thirteen CSM subjects and 15 age and gender matched controls.

Outcome measures

Magnetic resonance imaging measures included CSF and SC movement. Cervical cord condition was assessed by the Japanese Orthopaedic Association (JOA) score, compression ratio (CR), and somatosensory evoked potentials (SSEPs) of the tibial and ulnar nerves.

Methods

Phase-contrast imaging at the level of stenosis for patients and at C5 for controls and T₂-weighted images were compared with clinical findings.

Results

Cerebrospinal fluid velocity was significantly reduced in CSM subjects as compared with controls and was related to cord CR. Changes in CSF velocity and cord compression were not correlated with clinical measures (JOA scores, SSEP) or the presence of T₂ hyperintensities. Spinal cord movements, that is, cord displacement and velocity in the craniocaudal axis, were increased in CSM patients. Increased SC movements (ie, total cord displacement) both in the controls and CSM subjects were associated with altered spinal conduction as assessed by SSEP.

Conclusions

This study revealed rather unexpected increased cord movements in the craniocaudal axis in CSM patients that may contribute to myelopathic deteriorations in combination with spinal canal compression. Understanding the relevance of cord movements with respect to supporting the clinical CSM diagnosis or disease monitoring requires further long-term follow-up studies.     

Does the type of T2-weighted hyperintensity influence surgical outcome in patients with cervical spondylotic myelopathy? A review

Purpose

To review the literature on different classifications of T2-weighted (T2W) increased signal intensity (ISI) on preoperative magnetic resonance (MR) images of patients with cervical spondylotic myelopathy (CSM).

Methods

The authors searched the databases of PubMed and Cochrane for studies that used a categorization of T2W ISI to predict the functional outcome after decompressive surgery for CSM. Selected studies were analyzed for the type of ISI classification used, patient selection, methodology and results. The level of evidence provided by each study was determined.

Results

Twenty-two studies fulfilled our search criteria. There were 11 prospective studies and a total of 1,508 patients were studied. The majority of studies classified ISI based on either the longitudinal extent (12 studies) or the qualitative features of the ISI (10 studies). Three studies used both parameters to classify T2W ISI. Other classifications were based on the position of ISI (1 study), presence of snake-eye appearance on axial MR images (1 study) and signal intensity ratio (SIR) (1 study). Poorer functional outcomes correlated with sharp, intense ISI (6 studies) and multisegmental ISI (5 studies) (Class II evidence). Five of ten studies reported that the regression of ISI postoperatively was associated with better neurological outcomes (Class II evidence).

Conclusions

Methodological variations in previous studies made it difficult to compare studies and results. Both multisegmental T2W ISI and sharp, intense T2W ISI are associated with poorer surgical outcome (Class II evidence). The regression of T2W ISI postoperatively correlates with better functional outcomes (Class II). Future studies on the significance of ISI should ensure use of a uniform grading system, standardized outcome measures and multivariate analyses to control for other preoperative variables.     

Clinical relationship between cervical spinal canal stenosis and traumatic cervical spinal cord injury without major fracture or dislocation

Purpose

The purpose of the study was to evaluate the clinical relationship between cervical spinal canal stenosis (CSCS) and incidence of traumatic cervical spinal cord injury (CSCI) without major fracture or dislocation, and to discuss the clinical management of traumatic CSCI.

Methods

Forty-seven patients with traumatic CSCI without major fracture or dislocation (30 out of 47 subjects; 63.83 %, had an injury at the C3–4 segment) and 607 healthy volunteers were measured the sagittal cerebrospinal fluid (CSF) column diameter at five pedicle and five intervertebral disc levels using T2-weighted midsagittal magnetic resonance imaging. We defined the sagittal CSF column diameter of less than 8 mm as CSCS based on the previous paper. We evaluated the relative and absolute risks for the incidence of traumatic CSCI related with CSCS.

Results

Using data from the Spinal Injury Network of Fukuoka, Japan, the relative risk for the incidence of traumatic CSCI at the C3–4 segment with CSCS was calculated as 124.5:1. Moreover, the absolute risk for the incidence of traumatic CSCI at the C3–4 segment with CSCS was calculated as 0.00017.

Conclusions

In our results, the relative risk for the incidence of traumatic CSCI with CSCS was 124.5 times higher than that for the incidence without CSCS. However, only 0.017 % of subjects with CSCS may be able to avoid developing traumatic CSCI if they undergo decompression surgery before trauma. Our results suggest that prophylactic surgical management for CSCS might not significantly affect the incidence of traumatic CSCI.     

A novel MRI classification system for congenital functional lumbar spinal stenosis predicts the risk for tandem cervical spinal stenosis

Purpose

The purpose of this study was to develop a simple and clinically useful morphological classification system for congenital lumbar spinal stenosis using sagittal MRI, allowing clinicians to recognize patterns of lumbar congenital stenosis quickly and be able to screen these patients for tandem cervical stenosis.

Methods

Forty-four subjects with an MRI of both the cervical and lumbar spine were included. On the lumbar spine MRI, the sagittal canal morphology was classified as one of three types: Type I normal, Type II partially narrow, Type III globally narrow. For the cervical spine, the Torg-Pavlov ratio on X-ray and the cervical spinal canal width on MRI were measured. Kruskal–Wallis analysis was done to determine if there was a relationship between the sagittal morphology of the lumbar spinal canal and the presence of cervical spinal stenosis.

Results

Subjects with a type III globally narrow lumbar spinal canal had a significantly lower cervical Torg-Pavlov ratio and smaller cervical spinal canal width than those with a type I normal lumbar spinal canal.

Conclusion

A type III lumbar spinal canal is a globally narrow canal characterized by a lack of spinal fluid around the conus. This was defined as “functional lumbar spinal stenosis” and is associated with an increased incidence of tandem cervical spinal stenosis.

     

Die zervikale spondylotische Myelopathie

Background

The pathogenesis of cervical spondylotic myelopathy (CSM) is often multifactorial. Hence, the treatment of this disease requires a differentiated surgical approach in order to adequately address the underlying pathology.

Purpose

The aim of this review is to identify factors that influence the choice of treatment strategy and to summarize them in an algorithm that serves as a decision aid in choosing the optimal indication for surgical treatment. An attempt is made to define the threshold values for the indication of surgical treatment and to discuss the ideal timing for performing surgery.

Materials and methods

On the basis of the published data, the influencing factors on the prognosis of CSM, as well as surgical approaches are discussed.

Results

Circumferential spinal cord compression, a sharply defined myelopathy signal in the T2-weighted MRI sequence, and segmental instability at the level of the myelopathy signal mean an unfavorable prognosis for the worsening of CSM. The most important factors that influence the choice of the surgical access point are the sagittal profile of the cervical spine, the extent of myelopathy, the extent of stenosis, and the location of the myelopathy-inducing pathology. Previously existing neck pain and prior cervical surgery must also be considered.

Discussion

On the basis of the research carried out, we developed an algorithm that could serve as an aid in choosing the right treatment in the setting of cervical spondylotic myelopathy.

     

Prognostic relevance of the postoperative evolution of intramedullary spinal cord changes in signal intensity on magnetic resonance imaging after anterior decompression for cervical spondylotic myelopathy

OBJECT: Areas of intramedullary signal intensity changes (hypointensity on T1-weighted magnetic resonance [MR] images and hyperintensity on T2-weighted MR images) in patients with cervical spondylotic myelopathy (CSM) have been described by several investigators. The role of postoperative evolution of these alterations is still not well known. METHODS: A total of 47 patients underwent MR imaging before and at the end of the surgical procedure (intraoperative MR imaging [iMRI]) for cervical spine decompression and fusion using an anterior approach. Imaging was performed with a 1.5-tesla scanner integrated with the operative room (BrainSuite). Patients were followed clinically and evaluated using the Japanese Orthopaedic Association (JOA) and Nurick scales and also underwent MR imaging 3 and 6 months after surgery. RESULTS: Preoperative MR imaging showed an alteration (from the normal) of the intramedullary signal in 37 (78.7%) of 47 cases. In 23 cases, signal changes were altered on both T1- and T2-weighted images, and in 14 cases only on T2-weighted images. In 12 (52.2%) of the 23 cases, regression of hyperintensity on T2-weighted imaging was observed postoperatively. In 4 (17.4%) of these 23 cases, regression of hyperintensity was observed during the iMRI at the end of surgery. Residual compression on postoperative iMRI was not detected in any patients. A nonsignificant correlation was observed between postoperative expansion of the transverse diameter of the spinal cord at the level of maximal compression and the postoperative JOA score and Nurick grade. A statistically significant correlation was observed between the surgical result and the length of a patient's clinical history. A significant correlation was also observed according to the preoperative presence of intramedullary signal alteration. The best results were found in patients without spinal cord changes of signal, acceptable results were observed in the presence of changes on T2-weighted imaging only, and the worst results were observed in patients with spinal cord signal changes on both Tl- and T2-weighted imaging. Finally, a statistically significant correlation was observed between patients with postoperative spinal cord signal change regression and better outcomes. CONCLUSIONS: Intramedullary spinal cord changes in signal intensity in patients with CSM can be reversible (hyperintensity on T2-weighted imaging) or nonreversible (hypointensity on T1-weighted imaging). The regression of areas of hyperintensity on T2-weighted imaging is associated with a better prognosis, whereas the T1-weighted hypointensity is an expression of irreversible damage and, therefore, the worst prognosis. The preliminary experience with this patient series appears to exclude a relationship between the time of signal intensity recovery and outcome of CSM.     

Clinical applicability of magnetic resonance imaging in acute spinal cord trauma

Purpose

To assess the clinical application of magnetic resonance imaging (MRI) in patients with acute spinal cord trauma (SCT) according to the type, extension, and severity of injury and the clinical–radiological correlation.

Methods

Diagnostic imaging [computed tomography (CT) and MRI] tests of 98 patients with acute SCT were analyzed to assess their clinical diagnostic value. The following radiological findings of SCT were investigated: vertebral compression fractures, bursts and dislocations, posterior element fractures, C1 and C2 lesions, vertebral listhesis, bone swelling, spinal canal compression, disk herniation, extradural hematoma, spinal cord contusions, spinal cord swelling, and posterior ligamentous complex (PLC) injuries.

Results

The radiological findings were better visualized using MRI, except for the posterior elements (p = 0.001), which were better identified with CT. A total of 271 lesions were diagnosed as follows: 217 using MRI, 154 using CT, and 100 (36.9 %) using both MRI and CT. MRI detected 117 more lesions than CT.

Conclusion

MRI was significantly superior to CT in the diagnosis of bone swelling, PLC injury, disk herniation, spinal canal compression, spinal cord contusion and swelling present in SCT. MRI detected a larger number of lesions than CT and is highly useful for the diagnosis of soft tissue and intrathecal injuries.     

Surgical results and prognostic factors for thoracic myelopathy caused by ossification of ligamentum flavum: posterior surgery by laminectomy

Background

Thoracic ossification of ligamentum flavum (TOLF) of the spine is characterized by a heterotopic bone formation in the thoracic ligamentum flavum, which causes slowly progressing spinal cord injury. Surgical decompression is the most common treatment of choice for patients with compressive myelopathy due to TOLF. However, the surgical outcome is not always satisfactory.

Methods

To identify the predictors of surgical outcome, we retrospectively studied the associations between various clinical and radiological parameters and postoperative recovery in 78 patients who underwent decompressive laminectomy for thoracic myelopathy due to TOLF between October 1998 and June 2011. Surgical outcomes were assessed using modified Japanese Orthopedic Association (mJOA) recovery rate (RR)/outcome scores.

Results

At a minimum of 1 year after surgery for TOLF treatment, the postoperative clinical scores showed statistically significant changes with improvement in the JOA scores. The results indicated that a longer duration of preoperative symptoms, fused-type TOLF, and the degree of compression of the anteroposterior diameter and ossified region (middle thoracic OLF) was related to poor prognosis.

Conclusion

Early diagnosis and sufficient surgical decompression improved the functional outcomes of TOLF patients. The surgical risk is relatively higher due to the tenuous blood supply of the spinal cord and the limited spinal canal volume of the middle thoracic spine extending from T4 to T9.     

Range of motion of thoracic spine in sagittal plane

Study design

Imaging study of thoracic spine.

Objective

The purpose of this study was to investigate dynamic alignment and range of motion (ROM) at all segmental levels of thoracic spine.

Summary of background data

Thoracic spine is considered to have restricted ROM because of restriction by the rib cage. However, angular movements of thoracic spine can induce thoracic compressive myelopathy in some patients. Although few previous studies have reported segmental ROM with regard to sagittal plane, these were based on cadaver specimens. No study has reported normal functional ROM of thoracic spine.

Methods

Fifty patients with cervical or lumbar spinal disease but neither thoracic spinal disease nor compression fracture were enrolled prospectively in this study (34 males, 16 females; mean age 55.4 ± 14.7 years; range 27–81 years). After preoperative myelography, multidetector-row computed tomography scanning was performed at passive maximum flexion and extension position. Total and segmental thoracic kyphotic angles were measured and ROM calculated.

Results

Total kyphotic angle (T1/L1) was 40.2° ± 11.4° and 8.5° ± 12.8° in flexion and extension, respectively (P < 0.0001). The apex of the kyphotic angle was at T6/7 in flexion. Total ROM (T1/L1) was 31.7° ± 11.3°. Segmental ROM decreased from T1/2 to T4/5 but increased gradually from T4/5 to T12/L1. Maximum ROM was at T12/L1 (4.2° ± 2.1°) and minimum at T4/5 (0.9° ± 3.0°).

Conclusions

Thoracic spine showed ROM in sagittal plane, despite being considered a stable region. These findings offer useful information in the diagnosis and selection of surgical intervention in thoracic spinal disease.