What is the recommended duration of heparin therapy for a patient with cranial sinus thrombosis?

Duration of Heparin Therapy for Cranial Sinus Thrombosis

For cerebral venous sinus thrombosis, therapeutic anticoagulation with heparin (either unfractionated heparin or low-molecular-weight heparin) should be continued for a minimum of 3 months, with the specific duration determined by the underlying etiology: 3-6 months for provoked cases with transient risk factors, 6-12 months for unprovoked cases or mild thrombophilia, and indefinite anticoagulation for severe thrombophilia or recurrent thrombosis. 1, 2

Initial Heparin Phase (Acute Treatment)

The acute phase involves therapeutic anticoagulation with either:

• Intravenous unfractionated heparin (dose-adjusted to maintain aPTT at 1.5-2.5 times baseline) 1, 2
• Subcutaneous low-molecular-weight heparin (body weight-adjusted: enoxaparin 1.0 mg/kg twice daily or 1.5 mg/kg once daily; dalteparin 200 U/kg once daily) 2, 3, 4

This initial heparin therapy typically continues for 5-10 days until transition to oral anticoagulation is achieved, specifically continuing parenteral anticoagulation for a minimum of 5 days and until INR is ≥2.0 for at least 24 hours if transitioning to warfarin. 2

Minimum Treatment Duration: 3 Months

All patients with cerebral venous sinus thrombosis require anticoagulation for at least 3 months (the "treatment phase"), regardless of the presence of intracranial hemorrhage. 1, 2 This represents the absolute minimum duration supported by the strongest evidence from the American College of Chest Physicians and American Heart Association guidelines. 1

Duration Based on Underlying Etiology

Provoked CVST with Transient Risk Factors (3-6 months)

For CVST secondary to clearly identifiable, reversible risk factors (such as oral contraceptive use, pregnancy, infection, or trauma), anticoagulation should continue for 3-6 months. 1, 2, 3, 4 This follows the same principles established for extracranial deep vein thrombosis with transient risk factors. 1

Unprovoked CVST or Mild Thrombophilia (6-12 months)

For idiopathic CVST without identifiable risk factors, or in patients with mild hereditary thrombophilia (heterozygous factor V Leiden, prothrombin G20210A mutation, or elevated factor VIII), anticoagulation should continue for 6-12 months. 3, 4 The American Heart Association guidelines support this extended duration for unprovoked first-time events. 1

Severe Thrombophilia or Recurrent CVST (Indefinite)

Indefinite (lifelong) anticoagulation is recommended for: 1, 2, 3, 4

• Patients with recurrent episodes of CVST
• Severe thrombophilia including antithrombin deficiency, protein C or S deficiency, homozygous factor V Leiden or prothrombin G20210A mutation, antiphospholipid antibodies, or combined thrombophilic abnormalities
• Antiphospholipid syndrome 2

Cancer-Associated CVST

For CVST associated with active malignancy, anticoagulation should continue as long as anti-cancer treatment is given, following the same principles as cancer-associated thrombosis in other locations. 2

Transition to Oral Anticoagulation

After the initial heparin phase, transition to oral anticoagulation occurs with:

• Warfarin with target INR 2.0-3.0 (target 2.5) 2
• Direct oral anticoagulants may be considered, though warfarin is preferred in patients with mechanical heart valves, antiphospholipid syndrome, or severe renal impairment 2

The oral anticoagulant should be started early during the heparin phase, with overlap continuing until therapeutic INR is achieved for at least 24 hours. 2

Critical Clinical Pitfall

The presence of intracranial hemorrhage related to CVST is explicitly NOT a contraindication to anticoagulation. 1, 5, 2, 3, 4, 6, 7, 8 This represents the most common and dangerous error in CVST management. The hemorrhagic venous infarction occurs due to venous congestion from the thrombosis itself, and anticoagulation prevents thrombus propagation which would worsen outcomes. Two randomized controlled trials and multiple observational studies confirm the safety of anticoagulation even with baseline intracranial hemorrhage. 1, 7, 8

Monitoring and Follow-Up

• Perform follow-up MR venography or CT venography at 3-6 months after diagnosis to assess recanalization in stable patients 2, 9
• Regular neurological assessment is necessary to detect clinical deterioration requiring escalation of care 2
• Complete prothrombotic workup during hospitalization to guide duration decisions, including factor V Leiden, prothrombin G20210A mutation, antiphospholipid antibodies, protein C, protein S, and antithrombin III levels 9