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    Caracterização morfofuncional da isquemia medular após pinçamento da aorta torácica descendente em ratos
    (Universidade Federal de São Paulo (UNIFESP), 2014-09-29) Prestes, Osias Martins [UNIFESP]; Miranda Junior, Fausto Miranda Junior [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Background: Paraplegia is a devastating complication of surgical repair of thoracoabdominal aortic aneurysms. Ischemic injury of spinal axons is an important determinant of neurological deficits. We assessed motor deficits and their correspondent density of motor neurons in an experimental model of spinal cord ischemia in rats. Objective: To evaluate whether motor deficits caused by transient cross-clamping of the descending thoracic aorta in rats are related to the density of motor neurons in the ventral horn of the thoraco-lumbar spinal cord. Methods: Twenty-five rats were randomized into 5 groups of 5 animals each. Four groups of animals had their descending aorta crossclamped for different periods of time (15, 20, 25 and 30 minutes), before reperfusion. Control group wasn?t submitted to ischemia. All animals were assessed for neurological deficit in their hind limbs by the Tarlov scale 60 minutes following reperfusion. The animals were then sacrificed and had their spinal cord removed. Density of motor neurons in the ventral horn of the thoraco-lumbar spinal cord was assessed by immunohystochemical quantitative analysis using the ImageJ image processing program. Other evaluated parameters included: neurological assessment, body temperature, heart rate and mean proximal arterial blood pressure, arterial blood gas, hemoglobin and hematocrit levels and serum concentration of sodium, potassium and lactate. Results: Post-operative serum lactate, bicarbonate and pH values were significantly different from pre-operative values in all groups of study. Animals submitted to 30 minutes of aortic cross-clamping had significantly lower levels of bicarbonate and pH than the control group. Tarlov scores in the 30-minute ischemia group were significantly lower than the other groups. In all animals, the density of motor neurons was directly related to the neurological score and inversely related to the duration of ischemia. Conclusion: Motor deficits caused by the occlusion of the descending thoracic aorta in rats are related to the density of motor neurons in the ventral horn of the thoraco-lumbar spinal cord.