Article
Prognostic relevance of spinal cord morphology as revealed by 3 Tesla MRI imaging and timing of treatment in an experimental rabbit spinal cord compression model
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Published: | May 20, 2009 |
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Objective: To determine the prognostic significance of changes of spinal cord (SC) morphology and timing of decompressive treatment in an experimental rabbit SC compression model.
Methods: An established rabbit model of SC compression was used which allows for a gradual 270° compression of the SC (n=20). Neurological deficits were graded on a scale from 0 to 5. Once neurological deficits had developed the SC was decompressed by removal of the compressing silicone band. Total SC compression time, time from start of compression to onset of neurological deficits, and time from onset of neurological deficits to decompression were recorded. MRI imaging was carried out at 3 time points: preoperatively, after development of neurological deficits, and after SC decompression. The animals underwent a T2 weighted sequence of the thoracic spine at 3 Tesla. Images were analyzed using the Dicom Works software (Version 1.3.5). Sagittal and transverse SC and spinal canal diameters, as well as transverse SC and spinal canal areas were measured at the epicenter. Furthermore, SC compression ratios and their differences between the examination time points were calculated. According to the grade of neurological deficit at the end of follow-up, outcome was dichotomized (good/poor).
Results: Significant differences were found for the outcome groups for the ratio sagittal SC diameter/SC transverse diameter at epicenter in the first postoperative MRI (40.8% ± 13.8% (good) vs. 29.5% ± 7.1% (poor), p<0.05). Furthermore, significant differences were found for the variable time between onset of compression and onset of neurological deficits (5.6 ± 4.4 vs. 1.2 ± 2.2 days, p=0.021). The good outcome group showed the shortest intervals between onset of neurological deficits and decompression (5.6 ± 7.3 days) and the longest total SC compression times (11.4 ± 4.7 days) compared to the poor outcome group (1.2 ± 2.2 days and 9.8 ± 5.9 days respectively).
Conclusions: Morphological changes of the spinal cord under compression have a significant impact on recovery and outcome; however, the clinical acuity of spinal cord compression seems to be the most important factor, even more important than a fast spinal cord decompression.