My cat suddenly developed weakness on his right side and now walks funny. The veterinarian said the cat had a cerebrovascular accident. What is this?
A cerebrovascular accident (CVA), sometimes called stroke, occurs when normal blood flow to the brain is acutely disrupted, which results in sudden deficiencies in neurological function. The disruption may arise from spontaneous bleeding or occlusion of a blood vessel within the brain. The neurological signs typically occur acutely or peracutely (very sudden onset), and are nonprogressive. The manifestations of CVA may be focal or very generalized. Seizures may occur. Hemiparesis (partial paralysis), or circling, where the affected cat moves in circles toward the side of the damaged brain tissue, may result from focal damage to the brain. Generalized tissue destruction may produce ataxia (general muscle incoordination), coma or even death. The brain damage that ensues may be reversible, but this varies from case to case.
Stroke-producing hemorrhage, or bleeding, is frequently associated with trauma, certain infections that cause bleeding disorders, warfarin-based medications, rodenticides or other toxins, vascular anomalies and cancer. Malignant tumor impingement on an artery can cause it to rupture. Cancer and trauma may be the most common causes with no other identifiable clinical signs. Most cat patients with bleeding disorders, or that have been exposed to or have ingested toxins will show other systemic signs of bleeding, either before or concurrently with the cerebrovascular accident.
Infarction, or blockage, of an artery in the brain occurs most commonly with migrating bacteria or tumor cells that clump together to produce the blocking embolus. Emboli with air, fat or clots may form after surgery in any part of the body and subsequently travel in the blood stream to lodge in an artery in the brain. Although blood clots associated with increased thrombotic tendency, or clotting disorders, may cause CVA, these thrombi have more impact in the lungs.
Idiopathic feline cerebral infarction, also called feline ischemic encephalopathy, is a specific form of CVA in the cat. Its cause is unknown. One specific artery in the brain is frequently affected. Depending on the extent of brain damage, clinical signs may include behavioral changes, seizures, circling, blindness, partial facial paralysis or contracture.
Emergency treatment may aid in the reduction of secondary brain swelling and the brain damage that results when the swollen brain is compressed against the cranium (skull). Patients may need oxygen and other respiratory support. Additionally, they may require intensive nursing care, both in the acute phase of stroke and for supportive care of chronic neurological problems. Preventing recurrence by correction of the underlying disease, if known, is a major goal of treatment.
07/10/03
