Cerebral venous sinus thrombosis overview

# Overview
Cerebral venous thrombosis(CVT)is thrombosis of cerebral veins, a rare form of stroke which is different from arterial strokes. CVT incidence is 1.3 in per 1,00,000/year in developed countries. Young children and women especially pregnant/puerperium have a higher frequency of CVT. Due to the wide spectrum of clinical features, CVT frequently gets misdiagnosed as other strokes. Commonly known risk factors and causes of cerebral venous thrombosis are venous thromboembolism, thrombophilia (especially antithrombin deficiency, protein C and S deficiency and factor V Leiden mutation), pregnancy, oestrogen therapy/oral contraceptives, hypercoagulability as part of inflammatory disease, head trauma, local infections and underlying cancer. Pathophysiology of CVT includes two mechanisms including thrombosis of cerebral veins creating local edema and venous infarction; intracranial hypertension created by increased venous pressure and decreased absorption of CSF. Clinical presentations of CVT can be categorized into 4 categories as isolated intracranial hypertension, neurological deficits, encephalopathy and seizure. Symptoms related to increased intracranial hypertension are headache, diplopia, papilledema, sixth nerve palsy and decreased consciousness; focal neurological deficits present as motor and sensory impairments, aphasia. Though in 90% of patients with CVT , headache is the most common symptom, followed by seizures in 40% patients and 20 % patients with seizure.
Superior sagittal sinus is the most commonly involved sinus approximately 62% of patients and transverse sinus is the next common site (40-45%). Internal cerebral vein and straight sinus are less commonly involved in CVT but associated with worse outcomes. Diagnosis of CVT is based on clinical findings and neuroimaging. D-dimer level is more than 500 g/L in most of the patients with CVT. Per recommendation of American Heart Association (AMA) and the European Federation of Neurological Societies (EFNS), MRI/MRV is preferred 
for brain imaging. But CT can be considered if MRI is unavailable. Treatment of CVT includes early initiation of anticoagulant therapy and treatment of other underlying causes as sepsis, dehydration, discontinuation of prothrombotic medications; seizure and intracranial hypertension management.
CVT has good prognosis in 75% of patients with full functional recovery while in 15% of patients die or become dependent. Male sex, older age, confusion or coma, intracranial hemorrhage, deep vein involvement, infection and malignancy are the risk factors for poor outcomes.

# Historical Perspective
Cerebral venous sinus thrombosis (CVT) as first described by a French physician Ribes in 1825. But till the second half of 20th century, CVT was a diagnosis after death as it was frequently misdiagnosed due to overlapping of clinical symptoms and physical findings overlapping with other strokes. In 1951, introduction of venography made a drastic change in diagnosis of CVT.

# Classification
There is no classification of cerebral venous thrombosis (CVT).

# Pathophysiology
Imbalance in prothrombotic and fibrinolysis processes are the main pathophysiologic mechanisms leading to cerebral venous sinus thrombosis. Hypercoagulability is the main cause of cerebral venous thrombosis.

# Causes
Genetic or acquired conditions causing thrombosis are considered as risk factors for developing cerebral venous sinus thrombosis. Some of the common causes are thrombophilia due to factor V Leiden mutation, protein C and S deficiency, pregnancy, puerperium, oral contraceptive use, Nephrotic syndrome and other related factors.

# Differentiating Venous sinus thrombosis from Other Diseases
Cerebral venous sinus thrombosis is often get misdiagnosed due to the overlapping of symptoms with other neurological conditions

# Epidemiology and Demographics
Cerebral venous sinus thrombosis is a rare disease that mostly occurs in children and women. Mostly common in Asia, Middle East.

# Risk Factors
Any prothrombotic event acquired or genetic is considered a risk factor for cerebral venous sinus thrombosis.

# Screening
There is no screening test for cerebral venous thrombosis.

# Natural History, Complications, and Prognosis
Common complications of cerebral venous thrombosis are death, coma, neurological impairments, visual impairment, seizure and encephalopathy. The prognosis of CVT is favorable than other strokes. Complete functional recovery has been reported in 75% of patients but 15% of patients die or become dependent. Study showed women has better prognosis than men. 81% of women recovered completely while only 71 % of men had so. Recurrent thrombosis is a common complication in CVT, around 6.5% per year but mostly in patients who are not on anticoagulants.

# Diagnosis

## Diagnostic Study of Choice
MRI venography is the confirmatory test for cerebral venous thrombosis (CVT). CT scan can be an alternative choice where MRI is not available. To detect smaller blood clots cerebral angiography is more helpful.

## History and Symptoms
Symptoms of cerebral venous sinus thrombosis often overlap with the clinical presentations of other strokes. Headache is the most common presenting symptom followed by seizure, unconsciousness, cognitive impairments.

## Physical Examination
Physical examination in cerebral venous thrombosis is mostly related to intracranial hypertension as papilledema, hypertension. Weakness of muscles in single side of the body might be found.

## Laboratory Findings
No specific lab finding is related to diagnose cerebral venous sinus thrombosis. MRI venography is the confirmatory brain imaging to diagnose cerebral venous sinus thrombosis.

## CT scan
CT scan is helpful to rule out space occupying brain lesions and CT venogram rules out any thrombosis in cerebral veins.

## MRI
MRI venography of the brain is considered the most confirmatory test in cerebral venous sinus thrombosis. MRV in association with MRI shows non visualization of vessels, flow defect and collateral vessels near the occluded vessels.

## Other Imaging Findings
There are no other imaging findings associated with cerebral venous thrombosis.

## Other Diagnostic Studies
There are no other diagnostic studies associated with cerebral venous thrombosis.

# Treatment

## Medical Therapy
Pharmacologic therapy is indicated in cerebral venous sinus thrombosis. Medical therapy includes anticoagulants, acetazolamide, and anticonvulsants. Empiric antimicrobial therapy is required and generally includes the combination of Metronidazole, a penicillinase-resistant penicillin, and a third generation cephalosporin.

## Interventions

## Surgery
Surgical decompression or surgical thrombectomy is required in the treatment of cerebral venous thrombosis with life-threatening intracranial hypertension.

## Primary Prevention
Primary prevention of cerebral venous thrombosis is focussed on preventing or reducing the risk of systemic thrombosis.

## Secondary Prevention
For patients with cerebral venous thrombosis, a long-term anticoagulant is highly recommended to prevent future events.