Any brain tumor is inherently serious and life-threatening because of its invasive and infiltrative character in the limited space of the intracranial cavity.
From the en.wikipedia.org
Because the brain is well protected by the skull, the early detection of a brain tumor occurs only when diagnostic tools are directed at the intracranial cavity.
From the en.wikipedia.org
In the cranial cavity, they found loose bone fragments that were not covered with the intracranial solidified embalming material.
From the sciencedaily.com
Increased intracranial pressure can cause parts of the brain to herniate through narrowed portions of the cranial cavity or through the foramen magnum.