The Experimental Study Of Spinal Cord Ischemia Caused By Cervical Anterior Spinal Artery Injury

The Experimental Study of Spinal Cord Ischemia Caused by Cervical Anterior Spinal Artery Injury PURPOSE The first purpose of this experimental study was to design a large animal model tat could simulate the ischemic condition caused by cervical anterior spinal artery injury. Then confirmed on the degree and range of spinal cord ischemia, observed the histomorphological outcome of medullary ischemia, researched the pathologic mechanism of spinal cord ischemic injury. Observed dynamically MB] change of spinal cord ischemia, determined any MRI characteristics tat may be useful for the diagnosis of spinal cord ischemia in clinic. MATERIAL AND METHODS The model of spinal cord ischemia caused by cervical anterior spinal artery injury was established in canines. Made anterocervial incision and window in cervical vertebrae, and injured cervical anterior spinal artery. Evaluated the stabilization of cervical vertebra by X rays, observed the characteristics of anterior spinal artery, and determined quantitatively the quantity of radicular arteries. All canines myodynamia in this study were evaluated according to the Tarlov抯 criteria. Estimated spinal cord function by the latency of the motor evoked potential (MEP). The animals were sacrificed in due time periods, the pathology of corresponding segment of each cord was observed grossly and under light microscope as well as transmission electron microscope. Observed dynamically MRI outcome of spinal cord postischemia, confirmed on any MRI characteristics in difference period of spinal cord ischemia. RESULTS Anatomy of spinal artery of canines was found to have a closed resemblance to the human. The supplying blood vessels of spinal cord are anterior and posterior spinal arteries running longitudinally along the cord and radicular arteries running 3 circuniferentially. Those canines with cervical anterior spinal artery injury showed incomplete paraplegia of the hind legs postoperatively, but the myodynamia restored to I degree within 3 days. The latency of the motor evoked potential (MEP) delayed after cervical anterior spinal artery injury, but came back incompletly within 3 days. Demonstrated spine stabilization postoperation by X rays After cervical anterior spinal artery injury, the spinal cord underwent sequential pathological changes including hematomyelia, edema, axonal and motor neurons degeneration or necrosis, and demyelination. The evolution of these pathological changes developed gradually. Within 2 hours of anterior spinal artery injury, axonal and motor neurons degeneration, petechial hemorrhages occurred in spinal cord. Edema and demyelination was observed distinctly in spinal cord at 24 hours postischemia, however, motor neurons necrosis and hematomyelia worsened with time so that by 7 days after ischemia, there were motor neurons necrosis and distinct hemorrhages. The pathological changes involved primarily only the ventricolunina, funiculus anterior and funiculus lateralis of spinal cord, however, pathological findings also showed that motor neurons necrosis spreads into adjacent segments of the cord, extend more prominently to the caudal side spinal cord. Showed by electron microscopy by 2 hours after ischemia, some axonal and chondriosome changes were apparent. The pathologic changes worsened with time, there were disrupted myelin...