Stroke in Surgical Patients: A Narrative Review

Phillip E. Vlisides, M.D.; Laurel E. Moore, M.D.

Disclosures

Anesthesiology. 2021;134(3):480-492. 

In This Article

Definition, Etiology, and Pathophysiology

Stroke is defined as brain cell death attributable to ischemia, based on neuropathological, neuroimaging, and/or clinical evidence of permanent injury.[23] Such an injury may result in considerable clinical deficits. Alternatively, small infarcts may be clinically unrecognizable (i.e., covert stroke), and a transient ischemic attack reflects a temporary period of cerebral ischemia without permanent infarction. For surgical patients, perioperative stroke will be defined as brain infarction that occurs within 30 days of surgery.[24]

The major causes of ischemic stroke include embolism, thrombosis, and decreased perfusion.[25] In this context, classification systems have been created with the objective of categorizing acute ischemic stroke based on etiology and anatomy. The Trial of Org 10172 in Acute Stroke Treatment (TOAST) offers a system for coherently defining stroke subtypes across clinical trials.[26] This system classifies ischemic stroke into large-vessel or small-vessel categories, and cardioembolic causes are differentiated from atherothrombosis. The Oxfordshire Community Stroke Project provides a classification system based on anatomical location and natural history of acute stroke.[27] One advantage to the TOAST system is a more precise classification of etiology, because the Oxfordshire criteria focus more on anatomical location. The Oxfordshire system does, however, provide additional anatomical detail (e.g., anterior, partial anterior, posterior) compared to the TOAST System (Table 1).

These classification systems have been applied to perioperative stroke. The majority of perioperative strokes occur in large-vessel territories, with cardioembolism and thrombotic events causing large-vessel occlusion and subsequent stroke.[7–10] In the case of cardioembolism, interruption of anticoagulation therapy increases risk for cerebral embolism formation. Similarly, interruption of antithrombotic medications (e.g., aspirin) can contribute to cerebral thrombosis, particularly given that surgery induces a prothrombotic state,[28] and cessation of antithrombotic therapy can produce rebound hypercoagulability perioperatively.[29] Indeed, risk of perioperative stroke appears highest within the first 3 days after surgery,[8] when anticoagulation and antithrombotic medications are often just being restarted. Although cerebral hypoperfusion may also lead to perioperative stroke, thromboembolic stroke appears to occur more commonly.[8,9] Lastly, etiology remains undetermined in approximately 30% of perioperative stroke cases based on medical record review.[8,9]

Overall, perioperative stroke most often occurs within the first few days after surgery, in large-vessel territories, due to major thromboembolic events. Etiology frequently nonetheless remains unclassifiable, which impedes pathophysiological understanding.

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