Abstract
Cerebral venous thrombosis occurs when a thrombus develops within the intracranial venous system. The overall incidence is estimated to be 0.3–0.5 per 100,000 person-years and can affect patients of any age. The most common risk factor for cerebral venous thrombosis is the presence of a prothrombotic condition. The clinical presentation is variable but often manifests as a headache, focal neurologic deficits, seizures, or disturbances in level of consciousness. Diagnosis can be delayed or missed due to the variability and nonspecificity of clinical manifestations. Radiologic imaging is the mainstay for diagnosis, and magnetic resonance venography is the most sensitive method to confirm the diagnosis and is considered the current gold standard. Treatment consists of anticoagulation and symptomatic treatment. Mortality from cerebral venous thrombosis has decreased due to improvements in diagnostic techniques and earlier institution of treatment.
Keywords
Anticoagulants, Cerebral vein thrombosis, Headache, Hypercoagulability, Infarct, Intracranial hemorrhage, Pregnancy, Seizure, Sinus thrombosis, Stroke
Venous Anatomy
Venous drainage of the brain is illustrated in Fig. 41.1 . Blood is drained from the brain by two major types of vessels. Cerebral veins are thin-walled, valveless vessels, whereas dural venous sinuses are endothelium-lined spaces contained between the periosteal and meningeal layers of the dura mater. Cerebral veins drain the brain parenchyma and are tributaries of the dural venous sinuses that eventually drain into the internal jugular veins or pterygoid venous plexus. The venous system of the brain is unique in that veins do not necessarily run in parallel with the arterial circulation. Thus occlusion of venous outflow from the brain results in injury to different parenchymal regions of the brain than those observed following impairment of arterial inflow. This difference can be important for distinguishing between an arterial or venous origin of stroke as will be discussed in detail later.
Incidence of Cerebral Venous Thrombosis
The overall incidence of CVT is estimated to be 0.3–0.5 per 100,000 person-years, but more 2012 data suggest that the incidence can be as high as 1.32 per 100,000 person-years in the general population. The increased incidence may be related to an increased awareness of CVT and improved imaging techniques leading to more frequent CVT diagnosis. Rates of CVT in adults stratified by age and gender are illustrated in Fig. 41.2 . Rates of CVT among males and females are similar in the elderly and pediatric populations, but CVT occurs 3 times more frequently in young and middle-aged women compared to men. The difference is attributed to oral contraceptives and pregnancy. For example, the incidence of CVT in pregnancy occurs on an average of 10–20 cases per 100,000 deliveries. In the pediatric population, the incidence is at least 0.67 per 100,000 children per year.
Risk Factors
Three mechanisms contribute to the development of CVT: a prothrombotic state, inflammation, and mechanical factors that affect the intracranial venous system. One or more of these pathophysiologic mechanisms are present in the setting of each specific risk factor or disease state known to be associated with increased risk for CVT, as summarized in Table 41.1 . At least one condition noted in Table 41.1 can be identified in 85% of patients and multiple conditions can be found in almost half of patients with CVT. The presence of a prothrombotic condition is the most common factor contributing to CVT. The presence of a mutation leading to a prothrombotic state in isolation often does not lead to CVT, but an additional cause is often also present. Therefore, the identification of one risk factor should not discourage further workup for other contributing causes.
| Prothrombotic States |
| Anticardiolipin antibodies |
| Antiphospholipid syndrome |
| Anti–thrombin III deficiency |
| Factor V Leiden mutation |
| G20 210A mutation |
| Hyperhomocysteinemia |
| Protein C deficiency |
| Protein S deficiency |
| Pregnancy and Puerperium |
| Surgery and Perisurgical Period |
| Malignancies |
| Central nervous system tumors |
| Solid tumors outside of the central nervous system |
| Hematological cancers |
| Infections |
| Central nervous system (e.g., meningitis, abscess) |
| Head and neck (e.g., otitis, mastoiditis, sinusitis) |
| Systemic infections (e.g., sepsis, endocarditis, tuberculosis, malaria, human immunodeficiency virus) |
| Drugs |
| Steroidal drugs (e.g., oral contraceptives, hormone replacement therapy) |
| Cytotoxic drugs |
| Hematological Disorders |
| Polycythemia |
| Thrombocytosis |
| Anemia |
| Inflammatory Diseases |
| Systemic lupus erythematosus |
| Behçet disease |
| Rheumatoid arthritis |
| Thromboangiitis obliterans |
| Wegener granulomatosis |
| Sjögren syndrome |
| Inflammatory bowel disease |
| Sarcoidosis |
| Temporal arteritis |
| Autoimmune thyroiditis |
| Central Nervous System Disorders |
| Traumatic brain injury |
| Arteriovenous malformation |
| Dural arteriovenous fistulae |
| Venous anomalies |
| Perineurosurgical period |
| Other Mechanical Precipitants |
| Lumbar puncture |
| Jugular venous catheter occlusion |
| Other Disease States |
| Dehydration |
| Diabetic ketoacidosis |
Risk factors in women of child-bearing age, children, and the elderly deserve special comment. The hypercoagulable state that results from oral contraceptive use and that occurs during pregnancy makes women of child-bearing age the highest risk demographic group for CVT. Oral contraceptives increase the odds for CVT by 5.59. The rate of CVT in pregnant and postpartum women is 12 per 100,000 cases or 30–40 times greater than that of the general population. In pregnant patients, most instances of CVT occur in the third trimester. However, CVT occurring in the immediate postpartum period accounts for the majority of CVT associated with pregnancy. Risk of CVT associated with pregnancy and puerperium increases with the presence of a congenital prothrombotic state, increasing maternal age, cesarean delivery, hypertension, infections, and hyperemesis gravidarum.
Risk factors for children with CVT are age dependent and differ from those for adults. In neonates younger than 1 month, CVT is more common in those with perinatal complications such as hypoxic encephalopathy. Head and neck infections such as mastoiditis, otitis media, and sinusitis are common risk factors in preschool-aged children. Older children with CVT are more likely to have chronic diseases such as connective tissue disorders. In children, as in adults, prothrombotic states are also risk factors for CVT.
The most common risk factors for elderly patients include genetic or acquired thrombophilia, malignancies, and polycythemia. Of interest, elderly patients were more likely to have an identified risk factor compared to the general population.
Pathophysiology
CVT can lead to clinical manifestations by multiple mechanisms, as illustrated in Fig. 41.3 . In patients with thrombosis in a cortical vein or in a venous sinus, CVT leads to increased capillary pressure in vessels that are tributaries to the affected venous structure. The increased capillary pressure can result in capillary or proximal venous rupture, disruption of the blood–brain barrier (BBB), and decreased capillary perfusion. Capillary or venular rupture results in parenchymal hemorrhage. Disruption of the BBB causes vasogenic edema. Decreased capillary perfusion leads to decreased cerebral perfusion resulting in ischemic injury and subsequent cytotoxic edema. A major route of cerebrospinal fluid (CSF) reabsorption is the arachnoid granulations where CSF is absorbed into the blood at the major dural venous sinuses. In patients with a thrombosis of a dural venous sinus, impairment of CSF absorption can also contribute to hydrocephalus, further exacerbating the clinical manifestations.
Clinical Manifestations
The clinical presentation of CVT is highly variable, and the symptoms may be nonspecific. The clinical presentation is affected by age, sex, location of CVT (as illustrated in Table 41.2 ), and degree of parenchymal involvement. Presentation also depends on the degree of cerebral edema that is present, intracranial pressure, and whether or not hemorrhage or cerebral ischemia is present. CVT can manifest clinically as (1) headache due to intracranial hypertension, (2) focal neurologic deficits, (3) seizures, or (4) disturbances in the level of consciousness.
| Superior sagittal sinus | Motor deficits |
| Seizures | |
| Inferior sagittal sinus | Motor deficits |
| Seizures | |
| Straight sinus | Motor deficits |
| Mental status changes | |
| Transverse sinus | Intracranial hypertension (headache) |
| Tinnitus | |
| Cranial nerve palsies | |
| Aphasia (if left-sided) | |
| Cavernous sinus | Orbital pain |
| Chemosis | |
| Proptosis | |
| Cranial nerve palsies (III–VI) | |
| Deep cerebral venous system | Akinetic mutism |
| Coma | |
| Mental deficits | |
| Decerebration | |
| Internal jugular vein | Neck pain |
| Tinnitus | |
| Cranial nerve palsies |
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