Meninges are the three membrane layers that envelop the brain and spinal cord. The (outermost) of these thin layers is the dura mater, the second layer is the arachnoid, and the third layer is the pia mater.
A meningioma is a primary intracranial tumor of the meninges. Primary means that this type of brain tumor develops and stays in the brain. Meningiomas are classified into three grades. Meningiomas are also usually benign, meaning that they grow slowly, but if they are not discovered on a timely basis, they can interfere with the brain's normal functioning. In certain locations, they can be severely disabling and even life threatening if they become large enough. Usually patients develop only a single meningioma; however, several meningiomas may simultaneously grow in other parts of the brain or spinal cord.
Grade 1 is Benign Meningioma, which has the lowest rate of growth and recurrence risk. Grade 2 is Atypical Meningioma, which is more aggressive in terms of growth and recurrence risk. Grade 3 is Malignant (Anaplastic) Meningioma, which has the most aggressive rate of grow and highest risk of recurring.
A tumor is an abnormal growth caused by abnormal cell multiplication that does not serve any physiological function. Cell division is regulated by the tumor suppressor genes. These genes also help to repair any damage caused to the DNA. Tumor suppressor genes are constantly at war against the cancer-causing genes called oncogenes. When tumor suppressor genes fail to function properly due to mutations that affect protein encoding, unregulated cell division and growth can occur and cause the development of a tumor.
The body's natural defense system should optimally detect the abnormal cells and kill them. But tumors may produce substances that obstruct the immune system from recognizing the abnormality of tumor cells and eventually the tumor cells may overpower all internal and external checks to their growth.
Certain types of radiation exposure and genetic disorders have been linked with meningiomas. Although some environmental factors are suspected of contributing to the development of tumors, doctors do not know many of the risk factors of many types of tumors yet.
The symptoms of meningiomas usually become noticeable only when the tumor has grown quite large. Symptoms do not show up in the early stages due to the benign nature of this tumor. Some meningiomas may never exhibit symptoms during a patient's lifetime. Symptoms will vary depending on the size and location of the tumor. Some common symptoms of meningiomas may include:
Since meningiomas may not exhibit any symptoms, they might be detected unexpectedly when a patient has a brain scan for unrelated symptoms.
If a person is suspected of having a meningioma, a neurological exam will be done. This involves checking the function of eyes, ears, nose, and muscles. Sensation, balance and coordination are also tested. Mental state and memory are also assessed.
Diagnostic imaging tests may be ordered, including computerized tomography, or CT, scans or magnetic resonance imaging, or MRI, scans. The results from these imaging studies can help to determine the size, location, and type of tumor. The diagnosis may also be confirmed by examining a tissue sample taken from the tumor in a procedure called a biopsy.
Observation and less invasive treatment options may be chosen if:
Surgery is generally the standard treatment option for meningiomas. Surgery is often successful in treating meningiomas because they are a benign tumor with defined boundaries.
Surgery involves removal of the affected cells. Surgery is scheduled soon after the initial diagnosis. Surgery may not be the only treatment. It is often complemented with other techniques, like radiation therapy if complete removal of all affected cells is not possible or if the tumor is recurrent.