Perioperative Stroke

Perioperative stroke is an acute cerebral infarct or haemorrhage occurring during surgery or within 30 days after. Many strokes are covert (silent infarcts on MRI) and are linked to cognitive decline.

Epidemiology. Overt stroke occurs in 0.1% to 1% of non-cardiac, non-neurological surgery, about 2% to 10% after cardiac surgery (higher with valve surgery and aortic arch surgery), and up to 5% after carotid surgery. Mortality is about 20% to 25%. Covert strokes affect about 7% of older patients.

Risk factors. Atrial fibrillation, prior stroke or transient ischaemic attack, carotid stenosis, age over 70 years, hypertension, diabetes, renal disease, heart failure, myocardial infarction, anticoagulant interruption, aortic atheroma, hypotension, and cardiac or vascular surgery.

Mechanisms. Embolic (cardiac source, aortic atheroma, paradoxical), hypoperfusion (watershed infarction), thrombotic (hypercoagulable state), and haemorrhagic (anticoagulation, hypertension).

Pathophysiology.

Surgery provokes hypercoagulability, inflammation and haemodynamic swings. Interruption of anticoagulation and antiplatelet therapy, atrial fibrillation, hypotension and aortic manipulation lead to cerebral embolism or hypoperfusion.

Focal weakness, facial droop, speech disturbance, visual loss, confusion, delayed awakening, seizures, or reduced consciousness. Recognition is often delayed by sedation and analgesia.

Red flags.

• New focal deficit.
• Failure to wake.
• Sudden severe headache.
• Seizure.

Time of last known well, glucose, then emergency CT head to exclude haemorrhage, followed by CT angiography of head and neck (large vessel occlusion) and perfusion imaging or MRI with diffusion. Send ECG, troponin, coagulation, blood count and creatinine. Echocardiography and rhythm monitoring for source.

Differential diagnosis.

• Hypoglycaemia.
• Seizure with Todd paralysis.
• Residual anaesthetic or block.
• Intracranial haemorrhage.
• Air embolism.
• Hyponatraemia.
• Hypoperfusion.

Call the stroke team at once, check airway, breathing and circulation, and treat glucose (target 4 to 10 mmol/L). Keep oxygen saturation at 94% to 98% and avoid hypotension (mean arterial pressure at 65 mmHg or more, and systolic pressure 140 to 180 mmHg or more as needed for perfusion).

• Alteplase (ischaemic stroke within 4.5 hours of onset, if no contraindication): 0.9 mg/kg IV (maximum 90 mg), 10% as bolus over 1 minute and the rest over 60 minutes; monitor blood pressure (under 185/110 mmHg before and under 180/105 mmHg for 24 hours) and neurological state every 15 minutes; contraindicated by major surgery in the previous 14 days in many settings, active bleeding, recent intracranial surgery and coagulopathy. Weigh risk and benefit with the surgeon, because major surgery is a relative contraindication. Tenecteplase 0.25 mg/kg IV single bolus (maximum 25 mg) is an alternative.
• Mechanical thrombectomy for large vessel occlusion up to 24 hours from onset (selected by imaging), and often possible after major surgery.
• Aspirin: 300 mg orally or rectally once if thrombolysis is not given and haemorrhage excluded, then 75 mg daily; maximum 300 mg daily; start 24 hours after thrombolysis; monitor bleeding.
• Anticoagulation for atrial fibrillation is deferred for 3 to 14 days depending on infarct size, by specialist decision.
• Statin: atorvastatin 40 to 80 mg orally at night; maximum 80 mg daily; monitor liver enzymes and muscle symptoms; reduce with hepatic impairment.

Intracerebral haemorrhage: reverse anticoagulation (prothrombin complex concentrate 25 to 50 units/kg with vitamin K 5 to 10 mg IV), lower systolic blood pressure to 130 to 140 mmHg, and consult neurosurgery.

Prevention. Continue antiplatelet and statin therapy, bridge or resume anticoagulation early, avoid hypotension and atrial fibrillation with rate control, and treat carotid disease before elective surgery in symptomatic patients.

Monitoring. Neurological observation every 15 minutes initially, ECG rhythm, blood pressure, glucose and temperature (treat over 37.5 C).

Referral and escalation. Stroke team, neurology and neurosurgery urgently. Rehabilitation.