Meningioma is a type of tumor that originates from the meninges, which are the protective membranes covering the brain and spinal cord. These tumors are generally slow-growing and most often benign, meaning they are not cancerous. However, their growth can cause problems by pressing on the brain or spinal cord, leading to various neurological symptoms.
The exact cause of meningioma is not fully understood, but it is believed to arise from specific cells in the meninges, particularly the dural border cells or arachnoid barrier cells. These cells normally form part of the protective layers around the brain, but when they undergo certain changes, they can start to grow uncontrollably, forming a tumor. These changes often involve alterations in the DNA of the cells, which disrupt the normal instructions that regulate cell growth and death. Instead of dying when they should, these cells multiply excessively, leading to the formation of a mass[2].
Several factors may contribute to the development of meningiomas. One important factor is exposure to ionizing radiation, especially to the head. People who have undergone radiation therapy for other conditions or have been exposed to radiation through environmental or occupational sources have a higher risk of developing meningiomas. This is because radiation can damage the DNA in cells, increasing the likelihood of mutations that lead to tumor growth.
Hormonal influences also appear to play a role. Meningiomas are more common in women than men, and they often express receptors for hormones such as progesterone. This suggests that hormones might stimulate the growth of these tumors. For example, the use of certain hormonal medications, like Depo-Provera (a synthetic form of progesterone), has been linked to an increased risk of meningioma development. Women using this medication have been found to have a significantly higher chance of developing these tumors, possibly due to the hormone-like effects promoting tumor cell growth[5].
Genetic factors may also contribute. While most meningiomas occur sporadically without a clear inherited pattern, some genetic conditions increase the risk. For example, people with neurofibromatosis type 2 (NF2), a hereditary disorder, often develop multiple meningiomas. This condition involves mutations in a gene that normally suppresses tumor formation, so when it is defective, cells can grow unchecked.
The immune environment of the meninges might influence meningioma behavior as well. The meninges are not just passive coverings; they contain immune cells and a lymphatic network that interact with the tumor cells. These interactions can affect how the tumor grows and how symptoms develop, although this area is still under research[2].
In summary, meningiomas arise from the meninges due to a combination of genetic mutations, environmental exposures like radiation, and hormonal influences. The tumor cells grow slowly but can cause symptoms by pressing on nearby brain structures. Understanding these causes helps guide treatment and prevention strategies, although much remains to be learned about the precise mechanisms behind meningioma formation.
