What is the diagnosis for a patient with no movement in the left arm and initial limited movement in the left leg, now with improved leg movement, after a mitral valve repair, maze procedure, and atrial appendage surgery, with a normal CT (Computed Tomography) head scan with contrast?

Postoperative Stroke Following Cardiac Surgery

This patient has suffered a perioperative stroke, specifically involving the right middle cerebral artery territory, causing left hemiparesis with differential recovery between upper and lower extremity. The complete absence of left arm movement with improving left leg function, combined with a negative CT head with contrast, strongly suggests an acute ischemic stroke that is either too early to visualize on CT or involves a small vessel territory 1.

Diagnostic Reasoning

Why Stroke is the Primary Diagnosis

• Anatomic correlation: The pattern of left arm plegia with partial leg involvement indicates right hemisphere cortical or subcortical involvement, most consistent with right middle cerebral artery (MCA) territory infarction where the arm representation in the motor homunculus is more extensively affected than the leg 1

• Timing of CT imaging: Non-contrast CT head has poor sensitivity for acute ischemic stroke in the first 6-12 hours, and even CT with contrast may not reveal early infarction due to cytotoxic edema without blood-brain barrier breakdown 1

• High-risk surgical context: Mitral valve repair combined with maze procedure and atrial appendage surgery carries significant embolic stroke risk from multiple sources: air embolism during left atrial opening, thrombus from atrial manipulation, particulate matter from valve repair, and perioperative atrial fibrillation 1

Stroke Risk Factors in This Case

• Atrial fibrillation history: The maze procedure indicates chronic AF was present preoperatively, which independently increases stroke risk even after surgical ablation 1

• Left atrial appendage surgery: While LAA closure/ligation reduces long-term stroke risk, the surgical manipulation itself can dislodge existing thrombus 1, 2

• Cardiopulmonary bypass: CPB is associated with microemboli (air, fat, platelet aggregates) and hypoperfusion injury, particularly in watershed territories 1

Immediate Management Algorithm

Urgent Neuroimaging

• MRI with diffusion-weighted imaging (DWI) is the gold standard and should be obtained emergently as it can detect acute ischemic changes within minutes of symptom onset, unlike CT which may remain normal for 12-24 hours 1

• CT angiography of head and neck should be performed to evaluate for large vessel occlusion that might be amenable to mechanical thrombectomy, though the time window post-cardiac surgery may complicate intervention decisions 1

• Repeat non-contrast CT if MRI unavailable, as hemorrhagic transformation must be excluded before any anticoagulation decisions 1

Anticoagulation Considerations

• Critical timing dilemma: Postoperative hemorrhage risk must be balanced against stroke extension risk 1, 2

• If no hemorrhage on imaging: Consider therapeutic anticoagulation with unfractionated heparin (aPTT 1.5-2.0 times control) after consultation with cardiac surgery, typically safe 24-48 hours post-mitral valve repair if hemostasis is secure 2

• Transition to warfarin: Target INR 2.0-3.0 for bioprosthetic valve (if used) or for AF, continuing for minimum 3 months, likely lifelong given AF history 2

Neurological Monitoring

• Serial neurological examinations every 2-4 hours to detect extension or hemorrhagic transformation 1

• Blood pressure management: Permissive hypertension (SBP 140-180 mmHg) in acute ischemic stroke to maintain cerebral perfusion, but avoid excessive hypertension that could cause surgical site bleeding 1

Common Pitfalls to Avoid

• Assuming negative CT excludes stroke: This is the most dangerous error—CT sensitivity for acute ischemic stroke in first 6 hours is only 30-40% 1

• Delaying MRI: Every minute counts in stroke diagnosis; MRI should be obtained emergently, not as an outpatient follow-up 1

• Attributing symptoms to anesthesia: While prolonged emergence from anesthesia can cause focal deficits, unilateral motor deficits persisting beyond 2-4 hours post-extubation are stroke until proven otherwise 1

• Withholding anticoagulation indefinitely: While immediate postoperative period requires caution, prolonged withholding of anticoagulation in AF patients with stroke dramatically increases risk of recurrent stroke 1, 2

Prognosis and Recovery

• Differential limb recovery: The improving leg function with persistent arm plegia suggests cortical rather than subcortical stroke, as leg motor cortex is more medial and may have better collateral flow 1

• Rehabilitation: Early mobilization and intensive physical/occupational therapy should begin immediately, as neuroplasticity is greatest in first 3 months 1

• Long-term anticoagulation: Given AF history and stroke, lifelong warfarin (INR 2.0-3.0) or direct oral anticoagulant is mandatory unless contraindicated 1, 2