Immediate effects of cerebral ischemia: evolution and resolution of neurological deficits after experimental occlusion of one middle cerebral artery in conscious cats.

Acute occlusion of the left middle cerebral artery (MCA) was accomplished without anesthesia and inside an intact cranium containing cerebrospinal fluid (CSF) in ten cats five to nine days after implantation of an occlusive device through the orbit. Immediate neurological deficits included forced ambuxlation, circling, and tonic deviation of the head and neck toward the side of the occluded artery; weakness of the opposite limbs; and an apathetic or akinetic state. Two cats died within 24 hours. The other eight cats improved but secondary deficits developed in two, causing death. In two of the remaining six cats no deficits were apparent seven days later. The cerbral infarcts regularly involved the basal ganglia, internal capsule, and cortical regions, and were larger and less variable than those produced by MCA occlusion through and open optic foramen or craniectomy with cranial decompression by drainage of CSF. This model of acute focal cerebral ischemia may be of value for studies of physiological and biochemical factors uninfluenced by sedatives, anesthesia, or recent surgical procedures.