Study on the safe range of shortening of the spinal cord in canine models

Abstract

Study design: Experimental dog model of spinal cord shortening. Objectives: To clarify the relationship between the amount of shortening of the spinal cord and the degree of injury it may induce, and to determine the safe range of the shortening. Setting: Xi'an Jiaotong University, China. Methods: Thirty adult dogs were randomly allocated to five groups. Dogs in Group A (sham operation control) underwent spondylectomy to have two-thirds of the thirteenth thoracic segment (T13) resected, without bone-to-bone contact of the adjacent vertebral bodies. Those in Group B, C, D and E had one-third, half, two-thirds and total of their T13 resected, respectively, with boneto-bone contact. Somatosensory-evoked potentials (SEP) and spinal cord blood flow (SCBF) were detected. The histopathologic changes of spinal cord tissue were observed by hematoxylin and eosin stain and electron microscope. Results: The shortening of the spinal cord o half of a vertebral segment height caused a reversible change of SEP. Whereas, the changes resulted from the shortening of more than two-thirds of a vertebral segment height did not return to the normal level. SCBF increased temporarily when the shortening was within two-thirds of a vertebral segment height; whereas, it decreased progressively when the length of the shortening was equal to one vertebral segment height. More serious hemorrhage occurred as the shortening increased. INTRODUCTIONVertebrectomy is commonly performed in treating spinal deformity, tumors of the spinal column and other abnormal spinal conditions. [1][2][3] In this process, spinal shortening is a basic and commonly performed operation for the correction of spinal deformity and the fusion of osteotomy surface. 2,4,5 However, there exists the risk of neurologic complications induced by spinal cord injury (SCI) due to overshortened spinal cord. 2 These complications can be catastrophic for the patients and are very costly. Therefore, it is of great importance to clarify the pathophysiological changes of spinal cord shortening and determine the safe range of the shortening so as to prevent SCI.However, the safe range of shortening of the spinal column is still in debate. Two previous studies recognized the association between SCI and the range of spinal column shortening, but reached different conclusions in the safe range. 6,7 It seems that further research is necessary to confirm the safe shortening range. Besides, we have found no report about the serial changes of somatosensory-evoked potentials (SEP) and spinal cord blood flow (SCBF) over time with different amount of spinal shortening. The present study was therefore conducted, in which a modified animal model was used and detailed variations of SCBF and SEP were quantitatively recorded over a longer period of time at each stage of shortening. The obtained

A preliminary study of spinal cord blood flow during PVCR with spinal column shortening

“…For non-deformity spinal column, Kawahara and other researchers also indicated that a proper spinal column shortening could not injure the spinal cord and could increase the SCBF in animal experiment. [ 19 , 20 ] In this study, the SCBF could maintain at a satisfaction level to avoid SCI and proved its protection effect of blood flow, although the SCBF did not continued to increase during repeated shortening. The reason is that the correction operation might be harmful to the SCBF and it partially counteracted the benefit of the shortening.…”

“…The author also found that more than 2/3 vertebral segment height shortening can cause an irreversible SCI. [ 20 ]…”

Clinical Efficacy and Safety of Controlled Distraction-Compression Technique Using Expandable Titanium Cage in Correction of Posttraumatic Kyphosis

“…Some animal studies reported that SCI occurred from a spinal shortening of more than one-half to two-thirds 10,15,17) or 73.8% of the vertebral body height (VBH) 25) . However, a clinical study by Bourghli et al 3) reported that 10 patients treated with modified closing-opening wedge osteotomy at the TL junction and underwent shortening of the VBH by 35% and 38% showed transient neurological deficits postoperatively.…”

“…These techniques use posterior spinal shortening as a basic mechanism for a large correction angle. Therefore, over-shorting and redundancy of spinal cord are likely to occur, resulting in neurological deficits 3,15) .…”

Posterior Injured Vertebra Column Resection and Spinal Shortening for Thoracolumbar Fracture Associated with Severe Spinal Cord Injury: A Retrospective Case-Control Observational Study

“…Proper range of spinal shortening brings about vasodilation of the arteries of the spinal cord, which could result in the concomitant reduction of resistance to blood flow and increase the diameter of the anterior spinal artery by 138% compared to base line. Moreover, SCBF could be increased by 111%-160% compared to the base line before shortening [ 19 , 23 , 25 ]. Based on the abovementioned studies, the spinal shortening could reduce the spinal tension and increase SCBF, which are critical for the neurological recovery in sSCI.…”