Abstract： Objective To further investigate the impact of impaired microvasculature of spinal cord and its physiological compensation on postoperative morbidity after intramedullary microsurgery.Methods In 120 cats, the segmental anterior longitudinal spinal arteries (ALSA), the posterior longitudinal spinal arteries (PLSA), and the unilateral radiculomedullary arteries (RMA) were selectively coagulated in different patterns. Hydrogen electrode technique was used to detect the changes of regional blood flow of the spinal cord at different segments. Benzidine dihydrochloride (BDHC) staining was used to observe the microvascular pattern of the spinal cord, tetrazolium chloride (TTC) staining was applied to morphometric analysis of the ischemic area, and hematoxylin-eosin staining was applied to histologic examination.Results When the segmental ALSA was injured, the blood flow of the gray matter and white matter decreased greatly. Since the central arteries were the terminal blood supply arteries, no compensation occurred after the injury. The blood flow of the segment below the impaired segment hardly changed, indicating that the direction of the blood flow in ALSA altered to adapt the changes of the microvasculature. Injury to the unilateral PLSA and RMA at both cervical and lumbar area only caused a minor decrease in the regional blood flow, unless the perimedullary arterial system was considerably injured. In the thoracic medullary segment, the sparse microvasculature was the main cause for the segment vulnerable to ischemia and infarction. This was caused by not only the rarity of RMA as an anatomic factor, but also the small number and low activity of the neurons at this area. After microsurgery, the impairment and decompensation of the microvasculature were closely related to the ischemic volume of and pathological changes in the spinal cord. Conclusion The impairment and decompensation of microvasculature after microsurgery are the rudimentary causes of spinal cord ischemia. During operation, one should protect the terminal arteries to decrease the severity of injury to the perimedullary system, and do the best to avoid disturbance of microvasculature to accelerate the recovery of postoperative ischemia and neurological dysfunction of the spinal cord.