Spine
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Appropriate application of an oncologic staging system is required to evaluate the relationship among histologic types, management, and outcome of primary bone tumors. A commonly accepted terminology for surgical procedures and for definition of tumor extent is needed for surgical planning and clinical reviews. The principles of the Enneking system for classifying stages of tumors are emphasized and applied to the spine using a practical approach for surgical staging.
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Rabbits were used as an experimental model in the study of motor-evoked potentials. ⋯ Intraoperative monitoring of descending pathways by means of motor-evoked potentials during anesthesia of the rabbits based on nitrous oxide is feasible when neural activity is evaluated. Higher doses of nitrous oxide, however, are not compatible with recording of muscular activity.
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Using human cadaver spines, the authors compared the effect of using a combination of pedicle screw and laminar hook on the same vertebra with that of using a pedicle screw alone in reference to bone mineral density of the vertebra under nondestructive cyclic loading. ⋯ Instrumentation stiffness obtained by the combination method was significantly greater than that obtained by the use of pedicle screw alone. There was no significant correlation between the improvement ratio by the combination method and bone mineral density. These results suggest that the combination method is valuable irrespective of the presence of spinal osteoporosis.
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This study was designed to examine the possibility of a new spinal cord monitoring method using measurement of the refractory period to monitor spinal cord function. ⋯ The change of the responses elicited by the paired stimuli is more sensitive than those elicited by the single stimulus in the spinal cord evoked potentials. The absolute refractory periods and the recovery rate during 50% attenuation of the precompression amplitude is the critical alarm level in spinal cord monitoring.