Modification of a model for cerebral ischemia in the cat: a new method to occlude the middle cerebral artery

A modified method of occluding the middle cerebral artery (MCA) by inserting a tiny copper wire into the lumen of the vessel to make a model for cerebral ischemia in the cat is described. Of 22 rats, 4 were controls and the remaining 18 were divided into two groups. Bipolar electrocoagulation was used in 9 cats and copper wire insertion was used in the other 9 to occlude the MCA through a transorbital approach. Two cats died after surgery and were excluded from this study. Of the 16 cats in two experimental groups, 13 of 14 showed hemiplegia and the other 2 were killed under anesthesia. Typical ischemic changes can be seen in the territory of the occluded MCA. Increased water content and decreased amplitude of somatosensory evoked potentials can be found in the ischemic hemisphere. Histochemical fluorescence study demonstrated that the sympathetic nerve fibers normally existing on the MCA can be completely destroyed by electrocoagulation but may remain intact with the copper wire method. This new method may have less influence on the vascular regulative function of the autonomic nervous system and be more similar to the pathological changes of cerebral infarction in man. We think our method can be useful for further research in cerebral ischemic disease and the regulative effects of the nervous system on brain vessels.