<P> Papilledema, or the swelling of the optic disc, can be a reliable sign that ICP is elevated . Unlike other conditions that may result in the swelling of the optic disc, it is in the case of papilledema that vision may go largely unaffected . </P> <P> Causes of increased intracranial pressure can be classified by the mechanism in which ICP is increased: </P> <Ul> <Li> mass effect such as brain tumor, infarction with edema, contusions, subdural or epidural hematoma, or abscesses all tend to deform the adjacent brain . </Li> <Li> generalized brain swelling can occur in ischemic - anoxia states, acute liver failure, hypertensive encephalopathy, hypercarbia (hypercapnia), and Reye hepatocerebral syndrome . These conditions tend to decrease the cerebral perfusion pressure but with minimal tissue shifts . </Li> <Li> increase in venous pressure can be due to venous sinus thrombosis, heart failure, or obstruction of superior mediastinal or jugular veins . </Li> <Li> obstruction to CSF flow and / or absorption can occur in hydrocephalus (blockage in ventricles or subarachnoid space at base of brain, e.g., by Arnold - Chiari malformation), extensive meningeal disease (e.g., infection, carcinoma, granuloma, or hemorrhage), or obstruction in cerebral convexities and superior sagittal sinus (decreased absorption). </Li> </Ul> <Li> mass effect such as brain tumor, infarction with edema, contusions, subdural or epidural hematoma, or abscesses all tend to deform the adjacent brain . </Li>

What causes stage 1 of intracranial hypertension stage 1 intracranial hypertension is caused by the
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