Acute spinal trauma: prognostic value of MRI appearances at 0.5 T

Quantifying Intraparenchymal Hemorrhage after Traumatic Spinal Cord Injury: A Review of Methodology

Intraparenchymal hemorrhage (IPH) after a traumatic injury has been associated with poor neurological outcomes. Although IPH may result from the initial mechanical trauma, the blood and its breakdown products have potentially deleterious effects. Further, the degree of IPH has been correlated with injury severity and the extent of subsequent recovery. Therefore, accurate evaluation and quantification of IPH following traumatic spinal cord injury (SCI) is important to define treatments' effects on IPH progression and secondary neuronal injury. Imaging modalities, such as magnetic resonance imaging (MRI) and ultrasound (US), have been explored by researchers for the detection and quantification of IPH following SCI. Both quantitative and semiquantitative MRI and US measurements have been applied to objectively assess IPH following SCI, but the optimal methods for doing so are not well established. Studies in animal SCI models (rodent and porcine) have explored US and histological techniques in evaluating SCI and have demonstrated the potential to detect and quantify IPH. Newer techniques using machine learning algorithms (such as convolutional neural networks [CNN]) have also been studied to calculate IPH volume and have yielded promising results. Despite long-standing recognition of the potential pathological significance of IPH within the spinal cord, quantifying IPH with MRI or US is a relatively new area of research. Further studies are warranted to investigate their potential use. Here, we review the different and emerging quantitative MRI, US, and histological approaches used to detect and quantify IPH following SCI.

Spinal cord stimulation: the types of neurostimulation devices currently being used, and what radiologists need to know when evaluating their appearance on imaging

Neural stimulation is increasingly used as a treatment for chronic pain. Common indications for spinal cord stimulation include chronic neuropathic and oncological pain, intractable angina, or chronic pain secondary to vascular disease. It is estimated that up to 4 million patients may be candidates for the therapy. Therefore, it is likely that an increasing number of patients will have spinal neurostimulation devices implanted over the coming years. Because radiography and computed tomography are the primary imaging modalities used to evaluate the proper positioning of these devices, radiologists should be familiar with their appearance. The purpose of this article is to discuss the types of neurostimulation devices currently being used and to demonstrate their respective imaging appearances.

A quantitative and reproducible method to assess cord compression and canal stenosis after cervical spine trauma: a study of interrater and intrarater reliability

STUDY DESIGN

Reliability study.

OBJECTIVE

To assess the intrarater and interrater reliability of a recently described technique to measure of maximum canal compromise (MCC) and maximum spinal cord compression (MSCC) using digitized and magnified images in the setting of traumatic cervical spinal cord injury (SCI).

SUMMARY OF BACKGROUND DATA

The extent of MCC and MSCC is of clinical and prognostic value in the setting of traumatic cervical SCI. However, concerns remain regarding the accuracy of measurements based on hard copy images. We hypothesized that the interrater and intrarater reliability of these assessments would be enhanced using magnified digitized images and software-based measurement tools.

METHODS

Midsagittal MRI and CT images of cervical spine were selected from 5 individuals with acute traumatic cervical SCI. Measurements of MCC using CT scan and T1-weighted MRI and measurements of MSCC based on T2-weighted MR images were independently estimated by 13 raters on 10 occasions.

RESULTS

The intrarater reliability for CT-MCC, T1-weighted MRI-MCC and T2-weighted MRI-MSCC was high in the 10 rounds in each patient. In addition, the mean intrarater interclass correlation coefficient was 0.72 +/- 0.05 for the CT-MCC, 0.70 +/- 0.07 for the T1-weighted MRI-MCC, and 0.68 +/- 0.11 for the T2-weighted MRI-MSCC. The mean interrater interclass correlation coefficients were 0.43 +/- 0.02 for the CT-MCC, 0.61 +/- 0.03 for the T1-weighted MRI-MCC, and 0.55 +/- 0.05 for the evaluation of T2-weighted MRI-MSCC.

CONCLUSION

Our study has demonstrated that the intrarater reliability for the instrument to assess MCC and MSCC in the setting of traumatic SCI was high. The interrater ICCs at a moderate level of reliability combined with our results using analysis of variance with post hoc tests indicate that the measurements of MCC and MSCC are reproducible, which supports the use of these radiologic parameters in the clinical and research settings.

Acute cervical traumatic spinal cord injury: MR imaging findings correlated with neurologic outcome--prospective study with 100 consecutive patients

PURPOSE

To prospectively evaluate whether quantitative and qualitative magnetic resonance (MR) imaging assessments after spinal cord injury (SCI) correlate with patient neurologic status and are predictive of outcome at long-term follow-up.

MATERIALS AND METHODS

The study included 100 patients (79 male, 21 female; mean age, 45 years; age range, 17-96 years) with traumatic cervical SCI. Ethics committee approval and informed consent were obtained. The American Spinal Injury Association (ASIA) motor score was used as the outcome measure at admission and follow-up. The ASIA impairment scale was used to classify patients according to injury severity. Three quantitative (maximum spinal cord compression [MSCC], maximum canal compromise [MCC], and lesion length) and six qualitative (intramedullary hemorrhage, edema, cord swelling, soft-tissue injury [STI], canal stenosis, and disk herniation) imaging parameters were studied. Data were analyzed by using the Fisher exact test, the Mantel-Haenszel chi(2) test, analysis of variance, analysis of covariance, and stepwise multivariable linear regression.

RESULTS

Patients with complete motor and sensory SCIs had more substantial MCC (P=.005), MSCC (P=.002), and lesion length (P=.005) than did patients with incomplete SCIs and those with no SCIs. Patients with complete SCIs also had higher frequencies of hemorrhage (P<.001), edema (P<.001), cord swelling (P=.001), stenosis (P=.01), and STI (P=.001). MCC (P=.012), MSCC (P=.014), and cord swelling (P<.001) correlated with baseline ASIA motor scores. MSCC (P=.028), hemorrhage (P<.001), and cord swelling (P=.029) were predictive of the neurologic outcome at follow-up. Hemorrhage (P<.001) and cord swelling (P=.002) correlated significantly with follow-up ASIA score after controlling for the baseline neurologic assessment.

CONCLUSION

MSCC, spinal cord hemorrhage, and cord swelling are associated with a poor prognosis for neurologic recovery. Extent of MSCC is more reliable than presence of canal stenosis for predicting the neurologic outcome after SCI.

Interobserver and intraobserver reliability of maximum canal compromise and spinal cord compression for evaluation of acute traumatic cervical spinal cord injury

STUDY DESIGN

Prospective, blinded validation study of an objective, quantitative measure to assess maximum canal compromise (MCC) and maximum spinal cord compression (MSCC) in individuals with acute cervical spinal cord injury (SCI).

OBJECTIVE

To examine the intraobserver and interobserver reliability of MCC and MSCC in individuals with acute traumatic cervical SCI.

SUMMARY OF BACKGROUND DATA

To date, few quantitative reliable radiologic methods for assessing the extent of spinal cord compression in the setting of acute SCI have been reported. MCC and MSCC, as assessed on mid-sagittal CT and T2-weighted MR images, respectively, appear to have potential clinical and prognostic value. To date, the validation of these assessment tools has been limited to a small number of observers at a single institution. However, to date no study has focused on the reliability of these radiologic parameters among a large cohort of spine surgeons from North America and abroad. This type of validation is critical to allow the broader use of these outcome measures in research studies and in clinical practice.

METHODS

Mid-sagittal MRI and CT images of cervical spine were selected from 10 individuals with acute traumatic cervical SCI. A total of 28 spine surgeons independently estimated CT MCC, T1-weighted MRI MCC, and T2-weighted MRI MSCC on two occasions using a calibrated ruler. In the first round of measurements, the observers estimated the radiologic parameters using only written instructions. The second measurement set was obtained after an interactive teaching session on the methodology. The order of the images was altered for the second set of measurements.

RESULTS

Analysis using parametric and nonparametric statistics indicated high intraobserver reliability for CT MCC, T1-weighted MRI MCC, and T2-weighted MSCC with interclass correlation coefficients (ICCs) of 0.92, 0.95, and 0.97, respectively. The interobserver reliability for all three radiologic parameters was considered moderate with ICCs ranging from 0.35 to 0.56.

CONCLUSION

Our results indicate that the intraobserver reliability for the MCC and MSCC was high. Although the interobserver reliability for all three radiologic parameters in the present study was below 0.75, the observed differences were small and largely accounted for by the limitations in the precision of the calibrated ruler. For cases with minimal cord compression, the measurement of canal stenosis (MCC) proved more accurate. In contrast, in cases with severe cord compression, the assessment of MSCC was more accurate. It is anticipated that the use of digital imaging technologies will further enhance the precision of these outcome measures.

Neurologic recovery according to early magnetic resonance imaging findings in traumatic cervical spinal cord injuries

The aim of this study was to determine the usefulness of early magnetic resonance imaging findings in predicting neurologic recovery at or below the injured level in traumatic cervical spinal cord injuries. Thirty patients with traumatic cervical spinal cord injuries were included. All of the patients received a magnetic resonance imaging and a neurologic examination in the emergency room, within 7 days of injury and at 6 months following the injury. To quantify neurologic recovery below the injured level, we modified clinical scales, particularly the motor ratio and the sensory ratio. We used the neurologic level to quantify recovery around the injured level. We assessed neurologic recovery according to MRI patterns and lesion extents. The pure hemorrhagic MRI pattern was not observed. In edematous and mixed types, the improvement of neurologic levels was not significantly different. The motor ratio and sensory ratio improved significantly more in edematous type patients than in mixed type patients. Based on MRI lesion extent, the improvement of neurologic levels was not significantly different, and motor ratio and sensory ratio improved significantly more in those with one or two segments involved than in those with more than two segments involved. In conclusion, early MRI pattern and lesion extent after traumatic cervical spinal cord injury may provide important information to help predict neurologic recovery, especially below the injured level.

Cervical spine clearance: a review

Ethical concerns have hindered any randomised control blinded studies on the imaging required to assess the cervical spine in an unconscious trauma patient. The issue has been contentious for many years and has resulted in burgeoning but inconclusive guidance. MRI and multislice CT technology have made rapid advances, but the literature is slower to catch up. Never the less there appears to be an emerging consensus for the multiply injured patient. The rapid primary clinical survey should be followed by lateral cervical spine, chest and pelvic radiographs. If a patient is unconscious then CT of the brain and at least down to C3 (and in the USA down to D1) has now become routine. The cranio-cervical scans should be a maximum of 2 mm thickness, and probably less, as undisplaced type II peg fractures, can be invisible even on 1 mm slices with reconstructions. If the lateral cervical radiograph and the CT scan are negative, then MRI is the investigation of choice to exclude instability. Patients with focal neurological signs, evidence of cord or disc injury, and patients whose surgery require pre-operative cord assessment should be imaged by MRI. It is also the investigation of choice for evaluating the complications and late sequela of trauma. If the patient is to have an MRI scan, the MR unit must be able to at least do a sagittal STIR sequence of the entire vertebral column to exclude non-contiguous injuries, which, since the advent of MRI, are now known to be relatively common. Any areas of oedema or collapse then require detailed CT evaluation. It is important that cases are handled by a suitably skilled multidisciplinary team, and avoid repeat imaging due to technical inadequacies. The aim of this review is to re-examine the role of cervical spine imaging in the context of new guidelines and technical advances in imaging techniques.

Nervous Tissue Damage Markers in Cerebrospinal Fluid after Cervical Spine Injuries and Whiplash Trauma

Clinical examination is the only tool available to assess the extent of the nerve tissue damage after a spinal cord injury, and it is well known that the reliability of classification based on clinical examination is not satisfactory, especially in cases with incomplete motor injuries. There is a need to evaluate new methods in order to improve the possibilities of classifying and prognosticating spinal cord injuries. Methods for assessing central nervous system (CNS) damage using markers in cerebrospinal fluid (CSF) have recently been developed. Previous studies have reported glial fibrillary acidic protein (GFAp) and neurofilament protein (NFL) levels in non-traumatic diseases in the central nervous system. The present study is the first report of GFAp and NFL levels in CSF after trauma to the cervical spine. Six cases with cord damage and pronounced neurological deficit showed significantly increased concentrations of both GFAp and NFL in the CSF. Patients with tetrapareses showed higher values than those with incomplete injuries. Three of the 17 whiplash cases had increased levels of NFL, but normal GFAp. Assessment of nervous tissue markers in CSF will probably improve possibilities to classify and prognosticate spinal cord injuries and also to evaluate pharmacological intervention. The increased levels of NFL in three whiplash cases indicate neural damage in a proportion of the cases with neurological deficit. Neurological examinations are presently the only tools for grading and prognostication of spinal cord injuries. Assessment of nervous tissue markers in CSF makes it possible to quantify the degree of nerve cell damage after different types of cervical spine injury ranging from spinal cord lesions to whiplash injuries.

Magnetic resonance imaging of the cervical ligaments in the absence of trauma

STUDY DESIGN

Prospective study of cervical spine magnetic resonance imaging.

OBJECTIVES

To determine the frequency of nonvisualization of the cervical spinal ligaments in patients who have not suffered acute spinal trauma.

SUMMARY OF BACKGROUND DATA

The cervical ligaments appear on magnetic resonance studies as a thin hypointense line, the "black stripe." Discontinuity of this "black stripe" is considered a reliable sign of ligament rupture following acute spinal trauma.

METHODS

Twenty patients (13 female and 7 male, mean age 45.5 years, range 28-58 years) undergoing magnetic resonance imaging for cervical degenerative disc disease were examined using sagittal T1- and T2-weighted fast spin echo sequences. The status of the anterior longitudinal ligaments and posterior longitudinal ligaments was assessed on T1-weighted images from C2 to T1 (total of 120 levels), the ligamentum flavum from C1 to T1 (140 levels), and the apical ligament on both T1 and T2 weighted images (20 levels). The presence and sites of degenerative change were also noted.

RESULTS

On the T1-weighted images, only 74-79% of anterior longitudinal ligaments, 36-74% of posterior longitudinal ligaments, 63-65% of ligamentum flavums, and 35-60% of apical ligaments were visualized. On T2-weighted images, all the apical ligaments were seen. An association was identified between nonvisualization of the anterior longitudinal ligaments on T1 and the presence of anterior osteophytes.

CONCLUSION

Discontinuity of the "black stripe" on a T1-weighted sequence cannot be used as a reliable isolated sign of ligament rupture in the setting of acute spinal trauma, because the spinal ligaments are commonly not visualized.

Neurovascular injuries of the spinal cord

Neurovascular spinal cord injuries are very prevalent and in a busy trauma center radiology practice these injuries are commonly seen. Imaging neurovascular injuries has been greatly facilitated by magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA). The histopathological changes that occur with spinal cord trauma have been found to correlate well with what is seen on MRI examinations. The MRI findings in spinal cord trauma have also been found to be useful in determining patient prognosis. Spinal cord infarcts due to arterial injury from trauma are relatively rare, but it has been shown by imaging that vertebral artery injuries are not an unusual occurrence. The specific findings associated with neurovascular injuries will be described with an emphasis on the findings on MRI and MRA examinations. MRI and MRA techniques have become the procedure of choice for evaluating neurovascular injuries because of their proven accuracy and because they are non-invasive. Conventional angiography, although, does remain quite useful for evaluating arterial injuries.

Magnetic resonance imaging in the diagnosis and treatment of a canine spinal cord injury

A nine-year-old female crossbred dog was presented with tetraplegia following a fall. No vertebral abnormalities were detectable on plain radiographs of the cervical spine. Magnetic resonance imaging scans revealed absence of extraparenchymal compression and an area of oedema within the cervical spinal cord, suggesting a favourable prognosis. Following nursing care and physiotherapy, the dog recovered the ability to walk, although mild neurological deficits persisted in the left limbs.

Central cord injury complicating acute cervical disc herniation in trauma

STUDY DESIGN

A retrospective study on 24 patients with acute central cervical cord injury caused by traumatic disc herniation.

OBJECTIVES

To determine the correlation of disc herniation with central cord injury and to evaluate the role of anterior cervical decompression and interbody fusion in management of this injury.

SUMMARY OF BACKGROUND DATA

Acute cervical disc herniation has been documented as a causative factor in spinal cord injury but has been infrequently reported with central cord syndrome.

METHODS

Between 1989 and 1994, 24 patients with acute cervical disc herniation and central cord syndrome were studied. These patients underwent anterior decompression and fusion, and were followed for 2 to 7 years, with an average follow-up period of 3 years and 8 months. The degree of disc herniation and neurologic scores were rated.

RESULTS

During follow-up period, the American Spinal Injury Association motor score in 24 patients was increased to 86.46 +/- 10.22 from 47.79 +/- 19.66. The age of the patients was very negatively correlated with recovery rate (P < 0.01), but no correlation was observed between severity of cord compression and neurologic scores (P > 0.05). Postoperative neurologic improvement in patients with fracture or dislocation was very significantly slower (P < 0.01) than in those without these injuries.

CONCLUSIONS

Far more common than previously expected, acute disc herniation in cervical spine injury is the one of principal cause for central cord syndrome. Magnetic resonance imaging assessment and surgical intervention are required.

The optimal radiologic method for assessing spinal canal compromise and cord compression in patients with cervical spinal cord injury. Part I: An evidence-based analysis of the published literature

STUDY DESIGN

An evidence-based analysis of published radiologic criteria for assessing spinal canal compromise and cord compression in patients with acute cervical spinal cord injury.

OBJECTIVES

This study was conducted to determine whether literature-based guidelines could be established for accurate and objective assessment of spinal canal compromise and spinal cord compression after cervical spinal cord injury.

SUMMARY OF BACKGROUND DATA

Before conducting multicenter trials to determine the efficacy of surgical decompression in cervical spinal cord injury, reliable and objective radiographic criteria to define and quantify spinal cord compression must be established.

METHODS

A computer-based search of the published English, German, and French language literature from 1966 through 1997 was performed using MEDLINE (U.S. National Library of Medicine database) to identify studies in which cervical spinal canal and cord size were radiographically assessed in a quantitative manner. Thirty-seven references were included for critical analysis.

RESULTS

Most studies dealt with degenerative disease, spondylosis, and stenosis; only 13 included patients with acute cervical spinal cord injury. Standard lateral radiographs were the most frequent imaging method used (23 studies). T1- and T2-weighted magnetic resonance imaging were used to assess spinal cord compression in only 7 and 4 studies, respectively. Spinal cord size or compression were not precisely measured in any of the cervical trauma studies. Interobserver or intraobserver reliability of the radiologic measurements was assessed in only 7 (19%) of the 37 studies.

CONCLUSIONS

To date, there are few quantitative, reliable radiologic outcome measures for assessing spinal canal compromise or cord compression in patients with acute cervical spinal cord injury.

Predicting neurologic recovery in traumatic cervical spinal cord injury

OBJECTIVE

Traumatic spinal cord injury (SCI) affects 8,000 to 10,000 individuals per year in the United States. One of the most difficult tasks confronting the clinician is the discussion of neurologic recovery and prognosis with the patient and/or family. Our objective is to provide a guide for practitioners to accurately predict neurologic outcome in acute traumatic cervical SCI (tetraplegia).

DATA SOURCE

Published reports obtained through MEDLINE search, texts, and studies presented at national conferences.

STUDY SELECTION

Peer reviewed studies, in English language, that discussed prognosis after traumatic SCI.

CONCLUSION

A comprehensive physical examination of the acute SCI patient is essential in determining the initial level and classification of the injury and is the most accurate method to predict neurologic recovery. Other diagnostic tests, including somatosensory evoked potentials, magnetic resonance imaging, and transcranial magnetic stimulation, may be helpful in further determining outcome when used in association with the clinical examination. The understanding of neurologic recovery should help predict ultimate functional capability and potential needs.

Use of magnetic resonance imaging in spinal trauma: indications, techniques, and utility

Magnetic resonance (MR) imaging of acute spinal injury provides excellent visualization of neurologic and soft-tissue structures in a noninvasive format. Advances in imaging-sequence techniques have made possible more rapid acquisition of images with greater spatial resolution. Appropriate selection of imaging sequences allows improved imaging and contrast of the pathologic processes involved in acute spinal trauma, including spinal cord, soft-tissue, and ligamentous injury. Three patterns of spinal cord injury have been identified. Type I is representative of acute cord hemorrhage. Type II represents spinal cord edema. Type III is a mixed hemorrhagic-edematous presentation. Correlation of MR findings with experimental and clinical spinal cord injury has given a relative predictive value to spinal cord injury patterns on MR images indicative of long-term neurologic outcome. Magnetic resonance imaging is useful in delineating soft-tissue injuries associated with spinal column trauma. Despite the improved spatial resolution of MR imaging, plain radiography and computed tomography remain the standard modalities for visualizing spinal fractures.

The value of current developments in radiology to the accident and emergency department--a pictorial review

Images

Magnetic resonance imaging: utilization in the management of central nervous system trauma

OBJECTIVE

To determine the availability, use, and perceived value of magnetic resonance imaging (MR) in the management of acute central nervous system (CNS) trauma in United States Level I (or equivalent) trauma centers (TCs).

DESIGN, MATERIALS, AND METHODS

One hundred sixty-nine American College of Surgeons, state or locally designated Level I (or equivalent) TCs were identified using compiled lists and telephone contacts. Surveys about MR use in CNS trauma were mailed to each institution. Follow-up telephone calls were made to nonresponding institutions. Data were analyzed using frequency distribution.

MEASUREMENTS

Using returned questionnaires from trauma directors and follow-up telephone contacts, data on the physical location, technologist availability, and patient monitoring capabilities were accrued. The questionnaire addressed the perceived value and cost-effectiveness of MR for acute CNS trauma in general, distinguishing between spinal cord and traumatic brain injury, using a Likert-type rating scale.

MAIN RESULTS

One hundred nine (65%) of identified TCs responded by mail. Sixty (33%) required contact by telephone. One hundred fifty-two (93%) reported MR scanners "on site." Five of seven TCs without on-site MR had facilities within 5 miles. No TC reported the inability to obtain MR scans. Seventy-four percent of TCs reported MR angiography capabilities. Ninety-seven percent of MR facilities were staffed 24 hours per day, 83% by on-call, out-of-hospital technologists at night and on weekends. TCs reported patient monitoring capabilities including cardiac monitoring (83%) and pulse oximetry (91%). Seventy-one percent reported the ability to scan intubated patients. Forty-five percent of TCs "rarely" use MR, 51% report "occasional" use, and 4% "frequently" use MR for acute trauma. Ninety-four percent of trauma directors agreed or strongly agreed that MR directed management and was cost-effective for spinal cord trauma. Fifty-four percent agreed or strongly agreed that MR directed management and was cost-effective for traumatic brain injury. No correlation existed between perceptions of MR applicability in CNS trauma and the number of trauma admissions or on-site availability.

CONCLUSIONS

Most trauma directors consider MR important in the acute evaluation of spinal trauma and, to a lesser extent, for traumatic brain injury. Despite these opinions, the vast majority of these centers reported only "rare" to "occasional" use of MR in the setting of acute CNS trauma. Our results show that most TCs have on-site and continuously available MR facilities capable of cardiac and pulmonary monitoring. Other factors such as the higher relative cost of MR may be responsible for the discrepancy between the perceived value and the actual utilization of MR imaging in the setting of CNS trauma.