How can brain tumors contribute to elevated ICP?

Brain tumors can contribute to elevated intracranial pressure (ICP) primarily by taking up space within the skull. The skull is a rigid structure that does not allow for expansion. When a tumor grows, it increases the volume of the contents inside the cranial cavity. This additional volume disrupts the delicate balance of intracranial components, which include brain tissue, blood, and cerebrospinal fluid (CSF).

As the tumor expands, it can lead to displacement of these components, resulting in increased pressure throughout the cranial cavity. The accumulation of excessive mass from the tumor causes the surrounding brain tissue and CSF to be compressed, leading to a rise in ICP. This phenomenon can result in symptoms such as headaches, nausea, vomiting, and vision changes, and can potentially lead to serious complications if not properly managed.

The other choices relate to processes that either do not lead to an increase in ICP or are not direct contributors to the effect caused by a growing tumor.