What is the cause of progressive worsening of right-sided weakness in a patient with a thrombosed pericallosal part of the right Anterior Cerebral Artery (ACA) despite being on single antiplatelet therapy?

Management of Progressive Stroke in a Patient with Right Anterior Cerebral Artery Thrombosis

Cause of Progressive Deterioration

The progressive worsening of right-sided weakness in this patient is most likely due to ongoing thrombosis or extension of the existing thrombus in the pericallosal branch of the right anterior cerebral artery (ACA), with inadequate antithrombotic therapy on single antiplatelet treatment alone. 1

Recommended Management

Antithrombotic Therapy

1. Intensify antithrombotic therapy by adding low-dose rivaroxaban (2.5 mg twice daily) to the current antiplatelet therapy to reduce the risk of further major adverse cardiovascular events (MACE) and major adverse limb events (MALE). 1

   • Single antiplatelet therapy is insufficient for this patient with progressive neurological deterioration
   • The combination of low-dose rivaroxaban and antiplatelet therapy has shown superior efficacy in reducing thrombotic events in patients with symptomatic arterial disease

2. Consider switching from single to dual antiplatelet therapy if rivaroxaban cannot be used:

   • Add clopidogrel 75 mg daily to the current regimen
   • Duration: at least 1-6 months 1

Blood Pressure Management

• Continue current antihypertensive regimen targeting BP <130 mmHg
• Ensure consistent blood pressure control to prevent further neurological deterioration

Lipid Management

• Continue high-intensity statin therapy (zocor 40 mg)
• Consider adding ezetimibe if LDL-C remains ≥70 mg/dL 1

Neurological Monitoring

• Implement close neurological monitoring with serial assessments
• Document National Institutes of Health Stroke Scale (NIHSS) scores every 4-6 hours to detect further deterioration

Pathophysiology of Progressive Deterioration

The progressive worsening of right-sided weakness despite single antiplatelet therapy suggests:

1. Ongoing thrombosis: The initial single antiplatelet therapy was insufficient to prevent thrombus propagation in the pericallosal branch of the right ACA

2. Hemodynamic compromise: The thrombosed vessel may be causing progressive hemodynamic compromise to the watershed areas

3. Inflammatory response: Post-stroke inflammatory cascade may be contributing to secondary neuronal injury and clinical deterioration

4. Inadequate collateral circulation: Poor collateral blood flow to the affected territory may be exacerbating the ischemic injury

Additional Considerations

Imaging

• Repeat brain MRI with diffusion-weighted imaging to assess for extension of infarct
• Consider CT angiography or MR angiography to evaluate the extent of thrombosis and collateral circulation

Rehabilitation

• Early initiation of physical and occupational therapy
• Positioning to prevent contractures given the severe right-sided weakness

Pitfalls and Caveats

1. Avoid full-intensity oral anticoagulation (such as therapeutic warfarin) without a specific indication (e.g., atrial fibrillation), as this has been shown to be harmful in patients with arterial thrombosis without other indications 1

2. Monitor for bleeding risk when intensifying antithrombotic therapy, especially in the setting of recent stroke

3. Do not delay intensification of antithrombotic therapy as the patient is showing progressive neurological deterioration despite current management

4. Consider underlying causes of hypercoagulability if not already evaluated (thrombophilia workup may be warranted)

5. Avoid excessive blood pressure lowering which could worsen cerebral perfusion in the setting of large vessel occlusion

The progressive deterioration despite standard therapy necessitates prompt intensification of antithrombotic treatment to prevent further neurological decline and improve outcomes.