Acquired hydrocephalus develops after birth as a result of neurological conditions such as head trauma, brain tumor, cyst, intraventricular hemorrhage (brain bleed) or infection of the central nervous system.
Common Causes of Acquired Hydrocephalus
Head injury – A head injury or repeated head trauma can damage the brain’s tissues, nerves, or blood vessels. Blood from ruptured vessels may enter the CSF pathway, causing inflammation. Sites of CSF absorption might then be blocked by scarred membranes – meninges – or by blood cells.
The CSF flow is restricted, and hydrocephalus develops. Severe head injuries can cause structural changes to the brain, resulting in the inability for fluid to pass freely through the ventricular system and causing hydrocephalus.
Brain tumors – In children, brain tumors most commonly occur in the back of the brain which is referred to as the posterior fossa. As a tumor grows, it may fill or compress the fourth ventricle, blocking the flow of CSF and causing hydrocephalus. A tumor somewhere else in the brain might also block or compress the ventricular system.
Please see the National Institute of Neurological Disorders and Stroke (NINDS) for more information on brain tumors.
Intraventricular hemorrhage – An intraventricular hemorrhage, which most frequently affects premature newborns, may cause an acquired form of hydrocephalus. When small blood vessels alongside the ventricular lining rupture, blood may block or scar the ventricles or plug the arachnoid villi, which allow CSF to be absorbed. When the CSF can’t be absorbed, hydrocephalus results.
Meningitis – Meningitis is an inflammation of the membranes of the brain and spinal cord. Caused by a bacterial or (less frequently) viral infection, meningitis can scar the delicate membranes called meninges that line the CSF pathway. An acquired form of hydrocephalus may develop if this scarring obstructs the flow of CSF as it passes through the narrow ventricles or over the surfaces of the brain in the subarachnoid space.
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