Introduction
Cerebral Venous Thrombosis (CVT) is a rare but serious condition, accounting for approximately 0.5% of all stroke cases. While less common than arterial stroke, CVT is a critical diagnosis for automotive repair experts, particularly when considering the health and well-being of clients and understanding potential underlying medical conditions that could impact driving ability or overall health. Unlike arterial strokes, CVT disproportionately affects younger adults and children and is three times more prevalent in females than males, although this gender gap narrows after age 60.
The primary issue in CVT is the formation of a thrombus in the cerebral veins, often starting at the junction of these veins and larger sinuses. The superficial cerebral venous system, including cortical veins, anastomotic veins of Trollard and Labbe, and the superficial middle cerebral vein, drains into the superior sagittal sinus, transverse sinus, and cavernous sinus, respectively. Deep brain structures are drained by the basal vein of Rosenthal, vein of Galen, and transcerebral venous system, forming the inferior sagittal sinus and straight sinus.
Thrombus formation in these veins can extend to occlude major draining venous sinuses. This occlusion increases venous system pressure, potentially leading to cerebral edema, infarction, and hemorrhage. Dural sinus thrombosis may also impair cerebrospinal fluid absorption, elevating intracranial pressure (ICP). Historically, Cvt Diagnosis was often post-mortem. However, advancements in neuroimaging and increased clinical awareness have made ante-mortem diagnosis the norm. Early CVT diagnosis and management are crucial to prevent thrombus propagation and complications. While management protocols can vary, awareness of current guidelines is paramount. The prognosis for CVT is generally favorable, with most patients achieving full recovery; however, a significant minority experiences death or severe disability.
Clinical Features of CVT: Recognizing the Signs
The clinical presentation of CVT is highly variable, making cvt diagnosis challenging. Symptoms can be categorized into three broad groups: signs of raised intracranial pressure (ICP), focal neurological deficits indicative of a brain lesion, or a combination of both. The onset can be acute (stroke-like within 48 hours in up to 40% of patients), subacute (within a month in over 50%), or chronic (symptoms lasting over a month in about 7%). The non-specific nature of many symptoms means patients may initially present to various medical specialists, including those in acute medicine, stroke, neurology, and neurosurgery.
Presenting symptoms are influenced by the thrombus location and the degree of raised ICP, whether due to venous pressure alone or significant parenchymal damage (See Table 1). Headache is the most frequent symptom, occurring in approximately 90% of cases, and is the sole symptom in 25% of patients. Headaches can arise from any cerebral venous occlusion but are most pronounced in larger sinus thromboses like sagittal or straight sinus thrombosis. The headache presentation can range from migraine-like to severe ICP features, potentially including papilledema detectable via fundoscopy. Given the lower incidence of headache in arterial stroke (25–30%), severe headache alongside stroke-like symptoms should raise suspicion for CVT. Beyond headache, craniofacial pain can occur. Ear or mastoid pain, possibly with discharge, may indicate transverse sinus thrombosis secondary to mastoiditis. Seizures are also more common in CVT than arterial stroke (40% vs 6%). Focal neurological symptoms, such as motor weakness (up to 40% of patients), visual field loss, sensory issues, inattention, or neglect, are also frequent. These suggest focal lesions, ranging from cortical vein occlusion with edema to larger vessel occlusion with extensive infarction or hemorrhage. Rapid cognitive decline leading to drowsiness or coma may indicate deep venous occlusion with thalamic infarction.
Table 1. Signs and Symptoms of CVT and Probable Lesion Location
| Signs and Symptoms | Probable Lesion |
|---|---|
| Headache | Migraine / Any venous occlusion/focal lesion |
| Raised ICP | Large venous or sinus occlusion/large mass lesion |
| Thunderclap headache | Any venous occlusion/subarachnoid hemorrhage |
| Ear/mastoid pain | Transverse sinus with/without infection |
| Focal neurological deficits (Hemiparesis, Cranial nerve palsy) | Infarction/hemorrhage/venous edema |
| Cranial nerve III, IV palsy | Cavernous sinus |
| Cranial nerve V palsy | Cavernous sinus/superior petrosal sinus |
| Cranial nerve VI palsy | Cavernous sinus/inferior petrosal sinuses/raised ICP |
| Cranial nerve VII palsy | Transverse/sigmoid sinus |
| Cranial nerve VIII palsy | Transverse/sigmoid sinus/raised ICP |
| Cranial nerve IX, X, XI palsy | Posterior cavernous sinus/internal jugular vein/deep venous system |
| Aphasia | Focal infarction/hemorrhage/superficial or deep venous system |
| Sensory disturbance | Focal infarction/hemorrhage/superficial or deep venous system |
| Inattention/neglect | Focal infarction/hemorrhage/superficial venous system |
| Ataxia | Cerebellar veins/raised ICP |
| Seizures (Focal or Generalized) | Focal infarction/hemorrhage/severely raised ICP |
| Visual disturbance (Reduced acuity, Reduced/altered visual field, Diplopia) | Raised ICP/Posterior infarction/hemorrhage/raised ICP (false localizing sign) / Cavernous sinus/petrosal sinus/raised ICP |
| Papilledema | Raised ICP |
| Meningism (Neck pain/stiffness, Photophobia) | Suggests infectious or inflammatory etiology |
| Reduced consciousness (Drowsiness, Stupor, Coma) | Deep venous system/straight sinus/raised ICP/non-convulsive status epilepticus |
| Cognitive impairment (Encephalopathy, Disorientation, Reduced concentration, Amnesia) | Deep venous system/temporal-parietal lesion (vein of Labbe)/seizures |
Risk Factors for CVT: Identifying Predisposing Conditions
CVT can be either provoked or unprovoked, with patients often presenting multiple risk factors (Table 2). Up to 90% of CVT patients have at least one risk factor for venous thromboembolism (VTE), and thrombophilias (genetic or acquired) are found in over 30%. Female-specific risk factors like estrogen-containing contraceptives, pregnancy, and the puerperium are more significant in younger women, while malignancy is more prevalent in older adults. The presence of these risk factors should heighten suspicion for CVT, and their identification is crucial for guiding long-term treatment decisions.
Table 2. Risk Factors for Cerebral Venous Thrombosis
| Category | Specific Risk Factors |
|---|---|
| Thrombophilias | Genetic (e.g., Factor V Leiden) / Acquired (e.g., antiphospholipid syndrome) |
| Infection | Intracranial / Regional (e.g., ear, nose, throat, head, neck) / Systemic |
| Trauma | Head injury / Cranial surgery / Lumbar puncture / Endovascular intervention |
| Reproductive | Pregnancy / Puerperium |
| Malignancy | Intracranial / Extracranial |
| Medications | Oral contraceptives / Steroids / Anti-neoplastic drugs (particularly L-asparaginase) |
| Inflammatory Conditions | Vasculitis (e.g., Behçet’s disease) / Systemic lupus erythematosus / Inflammatory bowel disease / Sarcoidosis |
| Hematological Conditions | Iron deficiency anemia / Polycythemia |
| Endocrine Conditions | Hyperthyroidism |
| Systemic Conditions | Dehydration / Sepsis |
| Intracranial Abnormalities | Dural fistulae / Venous anomalies / Arteriovenous malformations |
Radiological Diagnosis of CVT: Imaging Techniques and Interpretation
Radiological investigation is essential for cvt diagnosis. Collaboration with radiologists to select the most appropriate imaging techniques is critical. In most emergency settings, brain Computed Tomography (CT) is readily available and is the primary initial imaging modality for suspected stroke. CT effectively identifies subacute ischemia and acute hemorrhage (parenchymal or subarachnoid) (Fig 1a,b). Specific features of parenchymal lesions suggestive of CVT include bilateral or parasagittal lesions (Fig 1c), lesions crossing arterial territories, and juxtacortical lesions. In some instances, thrombus within cerebral venous sinuses may appear hyperdense on plain CT (Fig 1d). CT’s advantage lies in the easy addition of a CT venography (CT-V) protocol, which reliably demonstrates occlusive disease in major cerebral veins and sinuses (Fig 1e).
Magnetic Resonance Imaging (MRI) and Magnetic Resonance Venography (MR-V) are also highly sensitive for cvt diagnosis. MRI is superior for detecting alternative pathologies and subtle brain lesions and avoids ionizing radiation. However, MR-V is more susceptible to motion and low-flow artifacts, and thrombus appearance can vary with age. In chronic cases, Gradient Echo (GRE) or Susceptibility-Weighted Imaging (SWI) can effectively show low signal in thrombosed sinuses. Catheter angiography is occasionally useful when anatomical clarity is needed, but its accessibility is limited to specialized neuroscience centers due to the requirement for highly skilled operators.
Management of CVT: Treatment Strategies and Prognosis
CVT management focuses on prompt cvt diagnosis and treatment. Anticoagulation is the primary treatment to prevent thrombus propagation and reduce pulmonary embolism risk. Poor prognostic factors include large parenchymal lesions, age over 37, Glasgow Coma Scale (GCS) below 9/15, seizures, posterior fossa lesions, intracranial hemorrhages, or malignancy. Patients with these factors are at higher risk of deterioration and require acute management.
Both the American Heart Association/American Stroke Association (AHA/ASA) and the European Federation of Neurological Societies (EFNS) recommend anticoagulation even in the presence of hemorrhage. This recommendation is based on limited evidence from two small Randomized Controlled Trials (RCTs) using unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH). These RCTs showed improved clinical outcomes and reduced mortality with anticoagulation compared to controls, without increased intracranial hemorrhage risk. A meta-analysis suggested a 13% absolute reduction in mortality or dependency with anticoagulation, although not statistically significant. The optimal anticoagulation method remains debated. Studies in systemic VTE suggest LMWH is superior to UFH in prevention and thrombus reduction, but its applicability to CVT is unclear. However, a recent single-center RCT showed significantly lower mortality with LMWH compared to UFH. Current recommendations favor immediate therapeutic LMWH or UFH. Alongside anticoagulation, underlying etiologies should be investigated and managed. Reversible risk factors like prothrombotic drugs, dehydration, and infections should be addressed (Table 2). Screening for prothrombotic and genetic factors may be considered later, often with hematology consultation. If infection or inflammation is suspected, especially in the head and neck, lumbar puncture (LP) should be considered if no contraindications exist (e.g., large infarction/hemorrhage). Ideally, LP should precede anticoagulation.
For patients who deteriorate despite anticoagulation (9–13% of CVT cases), endovascular thrombolysis or mechanical thrombectomy might be considered, although evidence is limited. Steroids are not generally recommended and may worsen prognosis unless indicated for underlying conditions like meningitis or malignancy. Prophylactic antiepileptic drugs are not advised but should be promptly initiated if seizures occur. Decompressive craniectomy may benefit patients with rapid neurological decline due to impending herniation.
Long-term management post-acute CVT involves vitamin K antagonists like warfarin, targeting an INR of 2–3. Anticoagulation duration depends on etiology. AHA/ASA guidelines recommend 3–6 months for provoked CVT, 6–12 months for unprovoked CVT, and potentially lifelong for recurrent CVT, VTE post-CVT, or CVT with severe thrombophilias. More recent guidelines suggest 3 months for provoked VTE, with annual review for unprovoked cases after 3 months, considering bleeding risk. Recanalization does not correlate with clinical outcome and should not guide anticoagulation duration. Direct Oral Anticoagulants (DOACs) are being explored as alternatives to warfarin, but current evidence for CVT is limited, making them a potential option when warfarin is unsuitable but not a first-line recommendation.
Conclusion
Cerebral Venous Thrombosis is a rare, potentially life-threatening condition with varied presentations. Accurate cvt diagnosis requires clinical suspicion and close collaboration between clinical and radiological teams. Heparin is the cornerstone of acute CVT treatment, with long-term anticoagulation duration guided by etiology and risk factors. Awareness of potential complications and adherence to available guidelines are crucial due to limited evidence supporting specific treatment strategies.
Declaration of Interests
The authors declare no competing interests.
