When can antiplatelet therapy be initiated after a patient sustains a traumatic subarachnoid hemorrhage and subdural hematoma from a fall?

When to Restart Antiplatelet Therapy After Traumatic Subarachnoid and Subdural Hemorrhage

Antiplatelet therapy should be withheld until the intracranial hemorrhage has completely resolved on repeat imaging, which typically requires waiting 4-8 weeks or longer after the initial trauma. 1

Immediate Management: Complete Cessation

• Discontinue all antiplatelet agents immediately upon diagnosis of traumatic subarachnoid hemorrhage (SAH) and subdural hematoma (SDH). 1
• Active intracranial hemorrhage constitutes an absolute contraindication to any antiplatelet therapy, regardless of the indication for which it was originally prescribed. 2
• The FDA labeling for clopidogrel explicitly lists intracranial hemorrhage as a contraindication to use. 2

Acute Phase: VTE Prophylaxis Without Antiplatelets

• Use mechanical thromboprophylaxis exclusively during the first 24-48 hours after traumatic intracranial hemorrhage, including intermittent pneumatic compression devices and anti-embolic stockings. 3
• Pharmacological VTE prophylaxis (low-molecular-weight heparin at prophylactic doses, NOT antiplatelet agents) may be considered only after bleeding has been controlled and documented stable on repeat CT imaging, typically after 24-48 hours. 3
• This distinction is critical: VTE prophylaxis uses anticoagulants at prophylactic doses, not antiplatelet agents, which serve a different purpose. 3

Timing of Antiplatelet Resumption: The Evidence

For Traumatic Subdural Hematoma Specifically

• Wait until complete radiographic resolution of the subdural hematoma before restarting antiplatelet therapy. 4
• In a study of 95 patients with traumatic SDH requiring anticoagulation/antiplatelet therapy, anticoagulation was held for a median of 67 days, with 82.1% waiting until complete SDH resolution. 4
• Restarting antiplatelets with residual SDH present carries a 41.2% risk of re-hemorrhage, rising to 62.5% if the residual hematoma is large. 4
• Among patients who restarted therapy with residual SDH, 17.6% required surgical intervention for re-hemorrhage. 4

For Subarachnoid Hemorrhage

• A minimum waiting period of 4 weeks with documented hemorrhage stability on repeat imaging is recommended before considering antiplatelet resumption, extrapolating from guidelines for other intracranial hemorrhages. 1
• European Heart Rhythm Association guidelines state that if SAH occurs in a patient already receiving antiplatelet therapy without a remediable cause, it may be prudent not to re-initiate therapy at all. 1

Practical Algorithm for Decision-Making

Step 1: Confirm Hemorrhage Stability (Weeks 2-4)

• Obtain repeat head CT at 2-4 weeks post-injury to assess for hemorrhage stability or progression. 5
• If hemorrhage has expanded or new bleeding is present, continue withholding antiplatelets and repeat imaging in 2-4 weeks. 5

Step 2: Document Complete Resolution (Weeks 4-8+)

• Optimal approach: Wait for complete radiographic resolution of both SAH and SDH before considering antiplatelet resumption. 4
• For SDH specifically, this typically requires 8-12 weeks or longer depending on initial hematoma size. 4

Step 3: Risk-Benefit Assessment

• If the indication for antiplatelet therapy is recent coronary stent (within 12 months), the thrombotic risk may warrant earlier resumption, but only after minimum 4 weeks and documented stability. 1, 6
• If the indication is secondary stroke prevention or stable coronary disease, waiting for complete resolution is strongly preferred given the high re-hemorrhage risk. 4
• Consider alternative strategies such as left atrial appendage closure for atrial fibrillation if long-term antiplatelet therapy is deemed unsafe. 1

Step 4: Restart Protocol

• When restarting, use single antiplatelet therapy (aspirin 81-100mg or clopidogrel 75mg daily) rather than dual antiplatelet therapy to minimize bleeding risk. 7
• Avoid loading doses when restarting after intracranial hemorrhage. 2
• Obtain repeat head CT 1-2 weeks after restarting to confirm no re-hemorrhage. 5

Critical Pitfalls to Avoid

• Do not restart antiplatelets based solely on time elapsed (e.g., "it's been 2 weeks") without repeat imaging confirmation of stability or resolution. 4
• Do not assume dual antiplatelet therapy is necessary even if the patient was on it before; single agent therapy substantially reduces bleeding risk. 7
• Do not confuse VTE prophylaxis with antiplatelet therapy—these serve different purposes and have different risk profiles in the setting of intracranial hemorrhage. 3
• Do not restart therapy with any residual subdural hematoma present unless the thrombotic risk is immediately life-threatening (e.g., acute stent thrombosis), as re-hemorrhage risk exceeds 40%. 4
• Avoid bridging strategies or temporary use of other antiplatelet agents, as these markedly increase bleeding risk without proven benefit. 1

Special Consideration: Thromboembolic Events During Waiting Period

• The risk of thromboembolic events while holding antiplatelet therapy is low (1.1% in one series of 95 patients). 4
• If a thromboembolic event occurs while antiplatelets are contraindicated, consider IVC filter placement for venous thromboembolism rather than restarting antiplatelets prematurely. 3, 1
• For arterial events (e.g., acute coronary syndrome), this represents a true emergency requiring multidisciplinary discussion between neurosurgery, cardiology, and neurology, but generally the presence of active or recent intracranial hemorrhage still contraindicates antiplatelet use. 2