Although a rare cause of stroke, cerebral venous thrombosis (CVT) is increasingly diagnosed because of greater clinical awareness, more sensitive neuroimaging techniques, and the survival of patients with previously lethal diseases that confer a predisposition to CVT. The incidence of CVT in adults was investigated in two Dutch provinces, serving 3.1 million people, and was found to be 1.32 per 100 000 person years (95% CI 1.06â1.61) with an incidence of 2.78 (95% CI 1.98â3.82) among women between the ages of 31 and 50 years (Coutinho et al., 2012). The most common condition associated with CVT in women is pregnancy/puerperium, with an incidence of around 10 in 100 000 deliveries in highâincome countries, accounting for 5â20% of all CVT (Bousser and Crassard, 2012). The incidence in Canadian children was estimated at 0.67 per 100 000 (95% CI 0.55â0.76), but is likely higher in developing countries due to infective diseases (deVeber et al., 2001).
Aetiology
There are multiple predisposing factors of CVT, which are very similar to those causing extracerebral venous thrombosis, except for a number of local causes. In about 15% of patients, no cause of CVT can be found, but followâup may detect an underlying disease up to several months later (Ferro et al., 2004). Oral hormonal contraception remains the sole predisposing factor in about 10%, but is also frequently found in combination with coagulation disorders. Coagulation disorders are common causes of CVT, in particular the FactorâVâLeiden mutation, with APC resistance accounting for 10â25% of cases (Dentali et al., 2006; Pai et al., 2012).
Other coagulopathies associated with CVT include: prothrombin mutation G 20210 A; antithrombin III deficiency; protein C and protein S deficiency; antiphospholipid antibody syndrome; plasminogen deficiency; hyperhomocysteinaemia; dysfibrinogenaemia; disseminated intravasal coagulation; heparinâinduced thrombocytopenia type 2 (Kenet et al., 2010; Saposnik et al., 2011). Additional causes include malignancies (meningeoma, carcinoma, lymphoma, carcinoid, leukaemia), haematological disorders (polycythaemia, sickle cell disease, paroxysmal nocturnal haemoglobinuria, immuneâmediated haemolytic diseases, thrombocytaemia), collagenosis (systemic lupus erythematodes, Sjögrenâs syndrome) and vasculitis (Behcetâs disease, Wegenerâs granulomatosis, sarcoidosis) (Saposnik et al., 2011).
Other rare causes of CVT include: intracranial hypotension; cerebral concussion; neurosurgical interventions; obstructive hydrocephalus; impaired venous drainage (central venous catheter, dural arteriovenous malformation, strangulation); medication poisoning (asparaginase, other chemotherapeutics, steroids, erythropoietin, drugs, vitamin A overdose); metabolic disorders (diabetes, thyrotoxicosis, uraemia, nephrotic syndrome); gastrointestinal disorders (liver cirrhosis, chronic inflammatory bowel disease); and heart disease (heart failure, cardiomyopathy). Septic CVT can be found in up to 18% of all cases in developing countries (Khealani et al., 2008), and is associated with localised infections such as mastoiditis, otitis media, sinusitis, tonsillitis, retropharyngeal abscess with thrombosis of adjacent jugular vein, oral or cerebral abscess, and meningitis. Potential generalised infectious causes include bacterial septicaemia, endocarditis, hepatitis, encephalitis, measles, tuberculosis, typhus, malaria, and aspergillosis.
Clinical Presentation
CVT may often remain asymptomatic, due to numerous ways of venous drainage and reversal of venous flow. Headache is the initial symptom in more than 70%, and remains the only symptom in about 16% (Gameiro et al., 2012). It can be associated with other common symptoms, such as nausea/vomiting, seizures, reduced consciousness or confusional state and focal neurological deficits (Ferro et al., 2004). Papilledema can be found in about 40%, mainly in patients with a chronic course or delayed diagnosis. Initial presentation with focal or generalised epileptic seizures occurs in 30â40% of cases. Other less frequent symptoms include thunderclap headache, subarachnoid haemorrhage, cranial nerve palsy, transient ischemic attacks, migraine with aura, psychiatric disturbances and tinnitus.
Neurological findings and type of focal seizures are determined by the localisation of CVT and the associated lesions. The common thrombosis of the superior sagittal sinus (60% of cases) causes headache, papilledema, seizures, motor deficits and impaired consciousness, whereas thrombosis of the cavernosus sinus is associated with ocular nerve palsies and ipsilateral ocular affection (chemosis, proptosis, papilledema). Patients with isolated thrombosis of the lateral sinus present mostly as isolated intracranial hypertension or aphasia, if the left transverse sinus is occluded. Occlusion of the deep cerebral venous system more likely causes coma, motor deficits or aphasia. Bilateral venous congestion of the thalamic region causes decreased consciousness as a major finding, and minor transient cognitive impairment, rather than...
