BACKGROUND AND PURPOSE: Cerebellar venous infarction or hemorrhage due to isolated venous thrombosis of the posterior fossa is a rare form of intracranial vein thrombosis that can be unsuspected in clinical practice. METHODS: We studied 230 patients with intracranial vein thrombosis, identifying 9 (3.9%: 7 women, mean age 34 years) with neuroimaging or histopathologic evidence of localized posterior fossa vein thrombosis causing parenchymal injury limited exclusively to the cerebellum. RESULTS: All patients had an insidious presentation suggesting other diagnoses. Intracranial hypertension (n=6) and cerebellar (n=4) syndromes were the main clinical presentations. Intracranial vein thrombosis was idiopathic in 3 patients; associated with puerperium in 3; and with contraceptives, protein C deficiency, and dehydration in 1 case each. CT was abnormal but not diagnostic in 5 patients, showing a cerebellar hypodensity with fourth ventricle compression and variable hydrocephalus in 5 patients, and cerebellar hemorrhage in 2. Conventional MRI provided diagnosis in 6 cases, showing the causal thrombosis and cerebellar involvement; angiography was practiced in 2 of them, confirming the findings identified by MRI. In the other 3 patients, diagnosis was reached by histopathology. Thromboses were localized at the straight sinus (n=4), lateral sinuses (n=3), and superior petrosal vein (n=2). The acute case fatality rate was 22.2% (n=2), 1 (11.1%) patient was discharged in a vegetative state, 1 (11.1%) was severely disabled, and 5 (55.6%) were moderately disabled. CONCLUSIONS: Isolated venous thrombosis of the posterior fossa is infrequent and implies a challenging diagnosis. Risk factors for intracranial vein thrombosis and atypical cerebellar findings on CT should lead to further MRI assessment.
BACKGROUND AND PURPOSE:Cerebellar venous infarction or hemorrhage due to isolated venous thrombosis of the posterior fossa is a rare form of intracranial vein thrombosis that can be unsuspected in clinical practice. METHODS: We studied 230 patients with intracranial vein thrombosis, identifying 9 (3.9%: 7 women, mean age 34 years) with neuroimaging or histopathologic evidence of localized posterior fossa vein thrombosis causing parenchymal injury limited exclusively to the cerebellum. RESULTS: All patients had an insidious presentation suggesting other diagnoses. Intracranial hypertension (n=6) and cerebellar (n=4) syndromes were the main clinical presentations. Intracranial vein thrombosis was idiopathic in 3 patients; associated with puerperium in 3; and with contraceptives, protein C deficiency, and dehydration in 1 case each. CT was abnormal but not diagnostic in 5 patients, showing a cerebellar hypodensity with fourth ventricle compression and variable hydrocephalus in 5 patients, and cerebellar hemorrhage in 2. Conventional MRI provided diagnosis in 6 cases, showing the causal thrombosis and cerebellar involvement; angiography was practiced in 2 of them, confirming the findings identified by MRI. In the other 3 patients, diagnosis was reached by histopathology. Thromboses were localized at the straight sinus (n=4), lateral sinuses (n=3), and superior petrosal vein (n=2). The acute case fatality rate was 22.2% (n=2), 1 (11.1%) patient was discharged in a vegetative state, 1 (11.1%) was severely disabled, and 5 (55.6%) were moderately disabled. CONCLUSIONS: Isolated venous thrombosis of the posterior fossa is infrequent and implies a challenging diagnosis. Risk factors for intracranial vein thrombosis and atypical cerebellar findings on CT should lead to further MRI assessment.