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Cerebrovascular disease

ISSN 2398-2950

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Introduction

  • Reports of cerebrovascular diseases (CVDs) in cats are scarce, although they are increasingly recognized with the advance of neuro-imaging.
  • The term feline ischemic encephalopathy Feline ischemic encephalopathy has been used to describe cases of peracute onset of clinical signs consistent with a unilateral cerebral or brainstem problem caused by ischemia.
  • Cerebrovascular accident (stroke) is the most common clinical presentation of CVDs.
  • CVDs can be divided in ischemic stroke or hemorrhagic stroke.
  • Cause: obstruction or rupture of blood vessels in brain.
  • Signs: acute onset (lateralizing) neurological signs improving with time.
  • Diagnosis: clinical signs, neuroimaging.
  • Treatment: supportive care and management of underlying disease.
  • Prognosis: generally good but varies according to location, severity and underlying cause. Print off the Factsheet on Stroke (cerebrovascular accident) to give to your clients.

Presenting signs

  • Seizures Seizures, depression, circling, head tilt or head turn, hemiparesis or tetraparesis.
  • Ataxia, stupor, unilateral menace response deficit, anisocoria.
  • Cranial nerves involvement other than CN I and VIII.

Acute presentation

  • The hallmarks of CVD are acute or peracute onset of (lateralizing) neurological signs that are non-progressive (usually past the 24 hours time window after the onset) or improve with time.
  • As opposed to ischemic stroke, neurological signs associated with intracranial hemorrhage Intracranial hemorrhage are largely related to raised intracranial pressure which could be associated with progressive worsening over a short period of time.

Age predisposition

  • In man there is an increasing incidence of CVD with age. There is no known age predisposition in cats with CVDs.

Cost considerations

Pathogenesis

Etiology

  • Cerebrovascular diseases (CVDs) divided into hemorrhagic and ischemic disease:
    • Obstruction of the blood vessels   →    ischemia, with or without infarction.
    • Rupture of the blood vessel wall   →    hemorrhage.
  • Pathologic processes of the blood vessel responsible for CVD include:
    • Occlusion of the lumen by thrombus or embolus.
    • Rupture of the vessel.
    • Any lesion or altered permeability of the vessel wall.
    • Increased viscosity or other change in the quality of the blood.
  • CVDs are the underlying cause of cerebrovascular accidents.
  • The common mode of presentation of CVD is a stroke.

Predisposing factors

General

  • Hemorrhagic stroke has been reported in cats in association with:
    • Rupture of congenital vascular abnormalities.
    • Hemorrhage into primary and secondary brain tumors Brain neoplasia.
    • Inflammatory disease of the arteries and veins.
    • Intravascular lymphoma.
    • Brain infarction (hemorrhagic infarction).
    • Impaired coagulation Hemostatic disorders: acquired.

Specific

  • Sepsis Shock: septic.
  • Vascular malformations.
  • Chronic kidney disease.
  • Primary or metastatic brain tumors.
  • Parasite migration (Cuterebra).

Pathophysiology

Ischemic stroke

  • The brain requires a continuous supply of glucose and oxygen to maintain ionic pump function.
  • Supply requires adequate ventilation, hemoglobin concentration and saturation, glucose concentration, vascular patency, cardiac output, systemic blood pressure and cerebrovascular auto-regulation.
  • When perfusion pressure falls to critical levels, ischemia develops progressing to infarction if it persists long enough or is severe enough.

Infarction

  • Focal occlusion of one or more blood vessels compromises brain parenchyma and results in infarction.
  • Occlusion due to:
    • Vascular obstruction developing within the occluded vessels (thrombosis) or
    • Obstructive material originating from another vascular bed traveling to the brain (thromboembolism).
  •  The pathogenesis of vascular occlusions of large and medium-sized arteries differs from that of small arteries.
  • Arterial disease that involves a small penetrating branch of a large artery results in a small, deep infarct also called a lacunar infarct.
  • Ischemic disease of the cerebral cortex is secondary to involvement of the rostral, middle or caudal cerebral artery. In man, this type of stroke is mainly due to atherosclerosis which is considered rare in cats. This stroke may also be due to embolic infarction (cardioembolic or artery-to-artery embolism).

Hemorrhagic stroke

  • In hemorrhagic stroke, blood leaks from the vessel directly into the brain, forming a hematoma in the brain parenchyma, or into the sub-arachnoid space.  The mass of clotted blood causes physical disruption of the tissue and pressure on the surrounding brain.
  • This alters CNS volume/pressure relationships with the possibility of increasing intracranial pressure Intracranial pressure measurement and decreasing cerebral blood flow.
  • Intracerebral hemorrhage resulting from spontaneous rupture of vessels is considered rare in cats.
  • Infarct of an individual brain region is associated with specific clinical signs that reflect the loss of function of that specific region.
  • The clinical presentation of hemorrhagic stroke is different from ischemic disease as the hemorrhage usually involves the territory of more than one artery and pressure effects cause secondary signs. Neurological signs are largely related to increasing intracranial pressure, which gives rise to non-specific signs of forebrain or brainstem disease.

Timecourse

  • Peracute onset of neurological signs.
  • Signs usually improving over several weeks.

Epidemiology

  • Reports of ischemic strokes in cats are scarce. Most reports are based on post-mortem results and probably skew the perceived severity and incidence of the disease.
  • The true incidence in the cat population is unknown but since the wider availability of non-invasive imaging, ie MRI it has become apparent that CVD, whilst not common, does occur.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Garosi L (2010) Cerebrovascular disease in dogs and cats. Vet Clin Small Anim 40 (1), 65-79 PubMed.
  • Cherubini G B, Rusbridge C, Singh B P et al (2007) Rostral cerebellar arterial infarct in two cats. J Feline Med Surg (3), 246-253 PubMed.
  • Glass E N, Cornetta A M, deLahunta A et al (1998) Clinical and clinicopathologic features in 11 cats with Cuterebra larvae myasis of the central nervous system. J Vet Intern Med 12 (5), 365-368 PubMed.
  • Williams K J, Summers B B A, de Lahunta A (1998) Cerebrospinal cuterebriasis in cats and its association with feline ischemic encephalopathy. Vet Pathol 35 (5), 330-43 PubMed.

Other sources of information

  • Garosi L & Platt S R (2009) Treatment of cerebrovascular accident. Current Veterinary Therapy XIV, Bongura & Twedt, pp 1074-1077.