A Case of Cerebral Venous Sinus Thrombosis Followed by Subdural Hematoma in a Pregnant Woman

Introduction Cerebral venous sinus thrombosis (CVST) is an uncommon cause of stroke and accounts for 0.5-1% of all strokes. The most common clinical manifestations are intracranial hypertension and hemorrhagic infarctions [1,2]. Nontraumatic subdural hematomas can occur secondary to various types of cerebrovascular lesions, such as ruptured aneurysms [3,4] or arteriovenous malformations [3], spontaneous intracerebral hemorrhages [4], or thrombosis of a cerebral vein or dural sinus [5]. Among these lesions, subdural hematoma associated with cerebral venous thrombosis has been rarely reported. A case in which thrombosis of the left transverse sinus was followed by a frontoparietal subdural hematoma has been observed.


Introduction
Cerebral venous sinus thrombosis (CVST) is an uncommon cause of stroke and accounts for 0.5-1% of all strokes.The most common clinical manifestations are intracranial hypertension and hemorrhagic infarctions [1,2].Nontraumatic subdural hematomas can occur secondary to various types of cerebrovascular lesions, such as ruptured aneurysms [3,4] or arteriovenous malformations [3], spontaneous intracerebral hemorrhages [4], or thrombosis of a cerebral vein or dural sinus [5].Among these lesions, subdural hematoma associated with cerebral venous thrombosis has been rarely reported.A case in which thrombosis of the left transverse sinus was followed by a frontoparietal subdural hematoma has been observed.

Case Presentation
A 23-year-old woman who was 33 weeks pregnant presented with a new onset, unilateral, non-throbbing right temporoparietal headache, associated with nausea and vomiting, which had started 5 days prior to admission.There was no history of trauma, drug abuse, smoking, or alcohol use.There was no family history of coagulopathy or thrombophilia.

Discussion
The pathological changes described in the early stages of thrombosis of the cerebral veins and dural sinuses include cerebral edema, petechial hemorrhages, hemorrhagic infarction, subarachnoid hemorrhage (SAH), and intracerebral hematoma.In the acute stage of thrombosis, dilated cerebral veins are prone to rupture, causing subdural, subarachnoid, or intracerebral hemorrhage [6,7].However, subdural hematoma with cerebral venous sinus thrombosis are rarely reported in conjunction.Most patients with CVST are younger than 50 years.Systemic conditions which increase the risk of CVST include pregnancy, puerperium, hormone consumption, genetic coagulopathy, malignancy, polycythemia vera and anemia, myeloproliferative disorders, and dehydration.
Mechanical factors which reduce blood flow in the cerebral sinuses and cause thrombosis include adjacent infections (such as mastoiditis), neoplastic invasion of the sinus, trauma, and neurosurgical procedures.About one-third of patients with CVST do not have thrombophilia or other predisposing conditions [2].The use of magnetic resonance imaging (MRI), MR venography (MRV) and computed tomography (CT) venography has improved the ability to detect other clinical manifestations of CVST, including subdural hematoma (SDH) [8] and cortical SAH [9].Diagnosis of CVST is challenging due to the variability in presenting symptoms and signs.It is accepted that CVST may present with elevated intracranial pressure (ICP) and hemorrhagic venous infarcts [2].There is increasing evidence that CVST can cause SDH and focal cortical SAH [9].
Many patients with SDH following CVST had underlying hypercoagulable states.The presence of thrombophilia is generally established based on personal and family history, as well as from selective laboratory testing.Our patient was at risk due to pregnancy.An evaluation of risk factors for cerebral venous sinus thrombosis should include screening for thrombophilia, including medications such as oral contraceptives, deficiencies in protein C, protein S, antithrombin III, genetic mutations in the prothrombin gene (G20210A mutation) and the Factor V gene (Leiden mutation), anticardiolipin, beta-2-glycoprotein, lupus anticoagulant, anti-dsDNA antibodies, ANA, homocysteinemia related to mutations in the methyltetrahydrofolate reductase gene (C677T and A1298C mutations), and hemoglobinopathies such as sickle cell disease [10].The proposed mechanism of SDH following CVST is venous hypertension and associated venous engorgement, after which venous bleeding occurs.Treatment must be individualized.Once CVST is identified and treated using anticoagulants, satisfactory recovery occurs.The use of anticoagulation in patients with hemorrhagic infarct and CVST has gained acceptance [2].In patients with small SDHs (with or without associated intracerebral hemorrhage), there are no clear guidelines for patient management.The patient in this case was successfully managed with systemic anticoagulation as well as frequent laboratory and imaging monitoring.
It is important to recognize that SDH and CVST may both arise as a rare complication of intracranial hypotension [8,11].Our patient had neither a clinical history nor a radiologic finding of intracranial hypotension.

Conclusion
Cerebral venous sinus thrombosis may present with spontaneous SDH and with or without associated hemorrhagic infarction.With easy to use MR and CT venography, the diagnosis of CVST complicated by SDH and cortical SAH will improve.The management of patients with SDH complicating CVST is complex, as a result of contraindications for anticoagulation in patients with symptomatic SDH.

Figure 1 .
Figure 1.(A)T2 weighted brain MRI revealed high signal intensity at left frontal lobe of subdural hematoma .(B) Brain MR venography shows a .(filling defect in favor of left transverse sinus thrombosis A B