Prognosis of cervical spinal cord injury in correlation with magnetic resonance imaging

Quantitative Analysis in Cervical Spinal Cord Injury Patients Using Diffusion Tensor Imaging and Tractography

Objective

To investigate the clinical usefulness of diffusion tensor imaging (DTI) and tractography in the prediction of outcomes after traumatic cervical spinal cord injury (SCI) and to assess whether the predictability is different between DTI and tractography administered before and after surgery.

Methods

Sixty-one subjects with traumatic cervical SCI were randomly assigned to preop or postop groups and received DTI accordingly. Among the patients who had DTI before surgery, we assigned 10 patients who had received repeated DTI examinations at 8 weeks after injury to the follow-up group. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were obtained from DTI, and imaginary fiber and crossing fiber numbers were calculated from the tractography. Neurological status and functional status were assessed at 4 and 8 weeks after SCI.

Results

The neurologic and functional statuses of both groups improved after 4 weeks. Out of the initial 61 patients who were enrolled in the study, the failure rate of DTI image analysis was significantly higher in the postop group (n=17, 41.5%) than in the preop group (n=6, 20%). The FA values and fiber numbers in the preop group tended to be higher than those in the postop group, whereas ADC values were lower in the preop group. When comparing the tractographic findings in the follow-up group, imaginary fiber numbers at the C6 and C7 levels and crossing fiber numbers from the C3 to C6 levels were significantly decreased after surgery. Several DTI and tractographic parameters (especially the ADC value at the C4 level and imaginary fiber numbers at the C6 level) showed significant correlations with neurologic and functional statuses in both the preop and postop groups. These findings were most prominent when DTI and physical examination were simultaneously performed.

Conclusion

Preoperative DTI and tractography demonstrated better FA and ADC values with lower interpretation failure rates than those obtained after surgery, whereas postoperative data significantly reflected the patient’s clinical state at the time of evaluation. Therefore, DTI and tractography could be useful in predicting clinical outcomes after traumatic cervical SCI and should be interpreted separately before and after spine surgery.

Who is going to walk? A review of the factors influencing walking recovery after spinal cord injury

The recovery of walking function is considered of extreme relevance both by patients and physicians. Consequently, in the recent years, recovery of locomotion become a major objective of new pharmacological and rehabilitative interventions. In the last decade, several pharmacological treatment and rehabilitative approaches have been initiated to enhance locomotion capacity of SCI patients. Basic science advances in regeneration of the central nervous system hold promise of further neurological and functional recovery to be studied in clinical trials. Therefore, a precise knowledge of the natural course of walking recovery after SCI and of the factors affecting the prognosis for recovery has become mandatory. In the present work we reviewed the prognostic factors for walking recovery, with particular attention paid to the clinical ones (neurological examination at admission, age, etiology gender, time course of recovery). The prognostic value of some instrumental examinations has also been reviewed. Based on these factors we suggest that a reliable prognosis for walking recovery is possible. Instrumental examinations, in particular evoked potentials could be useful to improve the prognosis.

Clinical diagnosis and prognosis following spinal cord injury

Spinal cord injury (SCI) is a sudden, life-altering event. Injury severity and accompanying recovery vary considerably from individual to individual. The most important determinant of prognosis is whether an injury is clinically complete or incomplete. While approximately 10-20% of complete injuries convert to incomplete during the first year post-injury, the magnitude of motor recovery following complete SCI is limited or absent. Robust functional motor recovery (e.g., weight-bearing, ambulation) distal to the zone of injury is rare. Recovery following incomplete SCI is particularly variable, and anywhere from 20% to 75% of individuals will recover some degree of walking capacity by 1 year post-injury. This is related to presenting injury severity (American Spinal Injury Association Impairment Scale grade); however, even 20-50% of individuals who present as motor complete, sensory incomplete will walk in some capacity by 1 year post-injury. Regardless, for both complete and incomplete injuries, the majority of recovery is observed during the initial 9-12 months, with a relative plateau reached by 12-18 months post-injury. Magnetic resonance imaging (MRI) provides valuable adjunct information when a bedside clinical assessment cannot be completed. The presence of intramedullary hemorrhage and extended segments of edema have been associated with clinically complete SCI.

Neuroimaging in traumatic spinal cord injury: an evidence-based review for clinical practice and research

OBJECTIVE

To perform an evidence-based review of the literature on neuroimaging techniques utilized in spinal cord injury clinical practice and research.

METHODS

A search of the medical literature for articles on specific neuroimaging techniques used in SCI resulted in 2,302 published reports. Review at the abstract and full report level yielded 99 clinical and preclinical articles that were evaluated in detail. Sixty nine were clinical research studies subjected to quality of evidence grading. Twenty-three articles were drawn from the pre-clinical animal model literature and used for supportive evidence. Seven review articles were included to add an element of previous syntheses of current thinking on neuroimaging topics to the committee process (the review articles were not graded for quality of evidence). A list of clinical and research questions that might be answered on a variety of neuroimaging topics was created for use in article review. Recommendations on the use of neuroimaging in spinal cord injury treatment and research were made based on the quality of evidence.

RESULTS

Of the 69 original clinical research articles covering a range of neuroimaging questions, only one was judged to provide Class I evidence, 22 provided Class II evidence, 17 Class III evidence, and 29 Class IV evidence.

RECOMMENDATIONS

MRI should be used as the imaging modality of choice for evaluation of the spinal cord after injury. CT and plain radiography should be used to assess the bony anatomy of the spine in patients with SCI. MRI may be used to identify the location of spinal cord injury. MRI may be used to demonstrate the degree of spinal cord compression after SCI. MRI findings of parenchymal hemorrhage/ contusion, edema, and spinal cord disruption in acute and subacute SCI may contribute to the understanding of severity of injury and prognosis for neurological improvement. MRI-Diffusion Weighted Imaging may be useful in quantifying the extent of axonal loss after spinal cord injury. Functional MRI may be useful in measuring the anatomic functional/metabolic correlates of sensory-motor activities in persons with SCI. MR Spectroscopy may be used to measure the biochemical characteristics of the brain and spinal cord following SCI. Intraoperative Spinal Sonography may be used to identify spinal and spinal cord anatomy and gross pathology during surgical procedures. Further research in these areas is warranted to improve the strength of evidence supporting the use of neuroimaging modalities. Positron Emission Tomography may be used to assess metabolic activity of CNS tissue (brain and spinal cord) in patients with SCI.

Traumatic cervical cord injury at C3-4 without radiographic abnormalities: correlation of magnetic resonance findings with clinical features and outcome

PURPOSE

Clinical features and outcomes of 43 patients at the Department of Orthopaedic Surgery, Okayama Rosai Hospital, Okayama, were studied prospectively. These patients were not found to have radiographic abnormalities but magnetic resonance images showed acute cervical spinal cord trauma at the C3-4 disc level.

METHODS

Magnetic resonance images were analysed at presentation (immediately after the injury) and subsequent follow-up visits (at subacute and chronic stages, respectively) in an attempt to correlate imaging findings to clinical features and outcomes, respectively.

RESULTS

The injury mechanism was usually a hyperextension of the cervical spine. The level of neurological involvement was assessed in 9 patients with complete tetraplegia: the motor level was C5 in 6 patients and C4 in 3, whereas the sensory level was C5 in 7 patients, C4 in one, and C3 in one. Respiratory dysfunction in patients with severe paralysis, or numb and clumsy hands in patients with incomplete paralysis were the characteristic clinical features of cervical spinal cord injury at these lesions. Three patterns of signal change on magnetic resonance images were observed in patients with spinal cord injury at C3-4. A low-intensity area on T2-weighted images in the acute stage indicated a poor prognosis, while a high-intensity area at 2 to 3 weeks after injury indicated some degree of permanent paralysis.

CONCLUSION

The serial signal changes of magnetic resonance images and the clinical severity or outcome seemed to be well correlated.

Emergency magnetic resonance imaging of cervical spinal cord injuries: clinical correlation and prognosis

OBJECTIVE

The goal of this study was to determine the prognostic and clinical value of magnetic resonance imaging (MRI) performed within hours after cervical spinal cord injuries in human patients.

METHODS

Fifty-five patients with acute cervical vertebral column and spinal cord injuries underwent MRI as part of their initial treatment at the University of Michigan Medical Center. All images were obtained within 21 hours after injury (mean, 7.8 h) and were interpreted by an attending neuroradiologist who was blinded to the clinical status of the patients. Neurological function at presentation and in long-term follow-up examinations was compared with MRI characteristics assessed immediately after the injury.

RESULTS

The presence and rostrocaudal length of intra-axial hematoma, the rostrocaudal length of spinal cord edema, the presence of spinal cord compression, and spinal cord compression by extra-axial hematoma were each significantly associated with poor neurological function at presentation and in long-term follow-up examinations. Although the best single predictor of long-term improvement in neurological function was the neurological function at presentation, four MRI characteristics, i.e., the presence of intra-axial hematoma, the extent of spinal cord hematoma, the extent of spinal cord edema, and spinal cord compression by extra-axial hematoma, provided significant additional prognostic information. MRI data demonstrated spinal cord compression for 27 of 55 patients (49%), leading to emergency surgery. Among patients who underwent imaging after restoration of normal vertebral alignment using closed cervical traction, 13 of 26 (50%) underwent emergency surgery for treatment of persistent, MRI-demonstrated, spinal cord compression.

CONCLUSION

Emergency MRI after spinal cord injury provides accurate prognostic information regarding neurological function and aids in the diagnosis and treatment of persistent spinal cord compression after vertebral realignment.

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.