Written by Meghan Breed
Cerebral venous thromboses can occur in the dural (superior sagittal sinus & transverse sinuses) and cortical (surface of cortex) venous systems. Thrombi most commonly originate in the dural sinus. Depending on the location of the occlusion, clinical presentations will vary. CT or MRI with contrast-enhanced venography is the preferred method of diagnosis.
Why does this matter?
Cerebral venous thrombosis is an uncommon diagnosis but will be missed if not considered as part of the differential diagnosis for patients presenting with headache, particularly since neurologic examination is often normal.
Brain clot = bad
Dural venous sinus thrombosis most commonly presents with a headache; headache characteristics vary from patient-to-patient. If cortical infarction occurs, seizures and neurologic deficits can develop. Cavernous sinus thrombosis usually causes a headache that localizes to the periorbital and forehead region, chemosis, often with involvement of cranial nerves III, IV, V or VI, as these nerves course through the cavernous sinus. Cortical vein thrombosis more commonly presents with focal neurologic deficits; however, isolated cortical vein thromboses are exceedingly rare. Most commonly, these form from the propagation of dural sinus thromboses.
Diagnosis relies on cranial imaging. Ideally, a CT or MRI includes contrast-enhanced venography which will reveal a segment of vein or sinus without blood flow. The classic “empty delta” sign occurs when the dural wall of the sagittal sinus enhances without intrasinus enhancement. If venous phase imaging is not available, a noncontrasted CT scan may reveal a hyperdensity if the thrombus is acute. It is important to remember that venous strokes do not correspond to arterial territories.
Risk factors include hypercoagulable states (heparin-induced thrombocytopenia (HIT), factor V Leiden, protein S and C deficiency), direct cranial trauma, neurosurgical procedures, bacterial meningitis, oral contraceptives, cancer therapies, and rarely COVID-19 adenoviral vector vaccinations or COVID-19 infection. Anticoagulation is the mainstay of treatment; however, robust evidence as to which class of anticoagulant is lacking. Generally heparin or low-molecular-weight-heparin (LMWH) is preferred; European Stroke Organization recommends initiating LMWH as soon as safely possible (this excludes patients diagnosed with HIT). In general, anticonvulsant medications are not prophylactically administered. Endovascular treatment (thrombectomy) of dural sinus thrombosis has been reported and remains an avenue for future research.
Cerebral Venous Thrombosis. N Engl J Med. 2021 Jul 1;385(1):59-64. doi: 10.1056/NEJMra2106545.