Focal brain ischemia induced in rats by occlusion of middle cerebral artery (MCA) is a widely used paradigm of human brain infarct. The purpose of this study is to establish chronic stroke model by MCA occlusion using intraluminal filament in rats.

A total 44 rats were operated by modified Longa's method. The surgical procedure consisted of introducing an intraluminal filament into the internal carotid artery and advancing it intracranially to block blood flow for 60 minutes into MCA. After this procedure motor and postural change were assessed using a 0~5 point grading scale consisted of forelimb, hindlimb and circling test. Behavioral tests such as rotarod, stepping and cylinder tests were examined in the survived rats after MCA occlusion up to 14 weeks post-ischemia. Autopsy was done to evaluate the cerebral infarct volume.

Thirteen rats were survived up to 14 weeks post-ischemia and for the severely paralyzed subjects by acute neurological severity scoring were examined with behavioral tests once a week for 14 weeks. Although rotarod test have not shown any specific changes during 14 weeks, stepping and cylinder tests have shown stabilizing pattern since 4 weeks after the procedure.

MCA occlusion using intraluminal filament could be reliable method to make stroke model in rats. We concluded that 4 weeks post-ischemia by this method in rats might be regarded as chronic model.