What complication can arise due to the proximity of medulloblastoma to the fourth ventricle?

The complication that can arise due to the proximity of medulloblastoma to the fourth ventricle is hydrocephalus. Medulloblastomas are typically located in the posterior fossa, near the fourth ventricle, which is crucial for the flow of cerebrospinal fluid (CSF). When a tumor obstructs the normal pathways of CSF drainage, it can lead to an accumulation of cerebrospinal fluid in the ventricles of the brain, resulting in hydrocephalus.

Hydrocephalus is characterized by an increased volume of CSF, which stretches the ventricles and can lead to increased intracranial pressure. However, it is the obstruction of CSF flow that is directly linked to the presence of the tumor and not simply the resulting pressure increase that defines this specific complication.

While increased intracranial pressure can indeed result from hydrocephalus, hydrocephalus as a direct result of the medulloblastoma's location is the primary consideration in this context. Therefore, the close relationship of the tumor to the fourth ventricle makes hydrocephalus a significant and direct complication of medulloblastoma.