A meningioma is a tumor that arises from the meninges, the protective layers of tissue covering the brain and spinal cord. It is the most common primary tumor originating in the central nervous system, accounting for approximately 37.6% of all cases. While the vast majority are non-cancerous and grow slowly, their potential for causing death is a real, though uncommon, risk. A person can die from a meningioma, but the probability depends heavily on its grade and physical location within the skull.
The Spectrum of Meningioma Severity
The biological aggressiveness of a meningioma is systematically classified using the World Health Organization (WHO) grading system, which directly correlates with the risk of recurrence and overall survival. This system divides meningiomas into three distinct grades based on cellular appearance and mitotic activity.
Grade I meningiomas are the most common, representing about 80% to 90% of all cases. They are considered benign because they grow slowly and have distinct borders. These tumors rarely pose an immediate, life-threatening risk unless they are situated in a highly sensitive area.
Grade II, or atypical meningiomas, make up about 15% to 18% of cases and exhibit a faster growth rate with a higher likelihood of returning after treatment. These tumors are considered intermediate in behavior, falling between benign and malignant classifications.
The highest risk of mortality comes from Grade III, or anaplastic meningiomas. These malignant tumors constitute the rarest type, accounting for only 1% to 4% of diagnoses. Grade III tumors are highly aggressive, characterized by rapid cell division and the potential to invade adjacent brain tissue. They are significantly more resistant to standard therapies, elevating the risk of death compared to lower-grade tumors.
How Meningiomas Cause Critical Complications
A meningioma, even if benign, can become life-threatening by exerting physical pressure on the brain, a mechanism known as mass effect. Since the skull is a fixed, rigid container, any growth within this space increases the intracranial pressure (ICP). This pressure can severely compromise brain function and blood flow.
Sustained high intracranial pressure can ultimately lead to brain herniation, which is often the fatal event. Herniation occurs when pressure forces brain tissue to shift and squeeze under rigid structures inside the skull, such as the tentorium or the foramen magnum. This process compresses the brainstem, which controls life-sustaining functions like breathing and heart rate, leading to rapid neurological decline and death.
The location of the tumor dictates the level of risk, independent of its grade or size. A small tumor near a highly sensitive structure, such as the brainstem or major blood vessels, poses a greater danger than a much larger tumor in an accessible area. These delicate locations make complete removal challenging without causing severe neurological deficits.
Some meningiomas cause significant swelling in the surrounding brain tissue, known as peritumoral edema. This swelling contributes substantially to the dangerous rise in intracranial pressure. The edema is vasogenic, meaning it results from increased permeability of blood vessels, which allows fluid and serum proteins to leak into the brain tissue. This additional volume further compresses the brain, accelerating the risk of herniation and neurological deficit.
Treatment Outcomes and Long-Term Prognosis
The prognosis is heavily influenced by the tumor’s WHO grade and the success of the initial treatment. For asymptomatic Grade I tumors, active observation with regular imaging may be appropriate. Symptomatic or higher-grade tumors require aggressive management, typically involving surgical removal.
The aim of surgery is to achieve a complete removal of the tumor, known as gross total resection, as the extent of removal is a strong predictor of long-term outcome and recurrence risk. For tumors that cannot be fully resected due to their location near sensitive structures, or for higher-grade tumors, radiation therapy is often used to target any remaining tumor cells. Radiation reduces the risk of regrowth and can significantly improve the long-term survival rate, especially when combined with surgery.
The statistical outlook for meningioma patients is generally favorable, reflecting the high percentage of benign tumors. For Grade I meningiomas, the five-year survival rate is very high, often exceeding 90%, with many patients having a near-normal life expectancy.
The survival rates decline with increasing grade, highlighting the direct impact of the tumor’s biological behavior on mortality. For Grade II atypical meningiomas, the five-year survival rate typically falls within the 70% to 80% range. Grade III anaplastic meningiomas carry the poorest prognosis, with five-year survival rates often ranging between 50% and 70%. Furthermore, the risk of the tumor returning significantly elevates the long-term mortality risk, with Grade II and Grade III tumors having much higher recurrence rates than the slow-growing Grade I tumors.