Neurosurgeons diagnose and treat various disorders of the central and peripheral nervous system including vascular disorders, infections, degenerative diseases of the brain or spine, tumors and more. Meningioma is one of many types of brain tumors that Penn Medicine neurosurgeons specialize in treating.
John Y.K. Lee, MD, MSCE, is an Associate Professor of Otorhinolaryngology and Neurosurgery at the Pennsylvania Hospital and the Medical Director of the Gamma Knife Center at Penn Medicine. Below he discusses the need-to-know facts about meningioma, one of the most commonly diagnosed brain tumors in adults.
What is meningioma?
A meningioma is a slow-growing tumor that forms on the meninges— a group of tissues that surround the brain and spinal cord. It is the most common brain tumor found in adults, but fortunately most are benign, non-cancerous tumors (WHO grade I). Roughly 10% of patients are diagnosed with atypical variants (WHO grade II), and only a minority <1% are diagnosed with the more aggressive, malignant grade of meningioma (WHO grade III).
Who is most likely to be diagnosed with meningioma?
Meningioma is most frequently found in older adults. Meningioma is two to three times more common in women than in men, but when men are diagnosed with meningioma, they tend to have a more aggressive form of the disease. Exposure to radiation as a child does result in a six times higher risk of developing a meningioma. In addition, there are rare genetic diseases that predispose you to developing a meningioma such as neurofibromatosis type two.
What causes meningioma?
It’s not well understood what causes meningioma. It is typically seen in older patients, but that could be because meningiomas grow so slowly that they are only diagnosed at later ages. With increasingly frequent use of MRI scans, incidental small meningiomas are identified earlier and earlier.
Because meningiomas are more common in women, there was a lot of interest in examining the effect of estrogen and progesterone receptors on meningioma growth. Epidemiologic studies have yielded mixed results. For example, studies to determine whether women who took birth control or who underwent hormone replacement after menopause were more likely to have meningioma have been pretty equivocal; some have shown some association, others have not. Researchers are still working to figure this out.
What are the treatment options for meningioma?
Meningiomas can be easy to cure with surgery if the tumor is located on the front or surface convexity of the brain. Patients may have almost no symptoms at all until the tumor has grown to be very large. In contrast, some patients come in with a small tumor and say they’ve started to notice symptoms. Depending on the location of the tumor, meningioma can cause seizures, headaches, or changes in vision, smell or hearing.
For the majority of patients we see for meningioma, especially those whose tumors are asymptomatic, the first step is to monitor the tumor with periodic MRI scans. Serial imaging with MRI is very reasonable if the tumor is small and the patient has no symptoms. In contrast, if the tumor is causing symptoms such as double vision, weakness in the limbs, blindness, paralysis or a seizure, then neurosurgeons need to determine whether surgery is an option. Ideally, surgical removal of meningioma entails removal of a one-centimeter margin all the way around the tumor. However, this type of resection is not always possible, especially in the skull base. These deep-seated tumors in the skull base require referral to a skull base neurosurgeon.
For patients who are not good candidates for surgery, have recurring tumors, or have requested it, we offer radiosurgery as a second option. Gamma Knife stereotactic radiosurgery is the most accurate radiosurgery system available—and when you’re delivering such a high dose of radiation to the brain, you want to be as accurate as possible. In contrast to surgery, Gamma Knife stereotactic radiosurgery does not remove a tumor in the same way that surgery does; rather, radiosurgery inactivates the tumor and stops it from growing. Hence, the patient will need frequent serial MRI scans to monitor tumor growth or lack thereof.
In rare cases, surgery, Gamma Knife radiosurgery, and even conventional fractionated radiation therapy are not enough to control meningiomas, and novel techniques are necessary.
What are the advantages of coming to Penn Medicine for meningioma treatment?
Meningiomas present in so many different ways, and some of the atypical and malignant meningiomas can be very challenging to treat. That’s why it’s important to have many different tools available for treatment, so if one option doesn’t work for a patient, there are other options available to try.
Some hospitals might only have one treatment option available, or they might only offer surgery when that might not be the best option for a particular patient. At Penn Medicine, we have many different treatment options. If Gamma Knife is not an option, we might consider Cyber Knife, or we might consider using proton radiation therapy. In addition to traditional surgery, Dr. Lee and the Penn neurosurgery department are well-versed in minimally invasive endoscopic techniques such as purely endonasal means of removing specific skull base tumors. Penn Medicine’s Center for Precision Surgery enables us to offer a unique surgery using a fluorescent dye that makes tumor cells glow to help ensure the entire tumor is removed. After a meningioma is removed, physicians in the Penn Center for Personalized Diagnostics can analyze the tumor for specific targetable mutations that we may be able to treat with a targetable medication.
So, one advantage to coming to Penn Medicine is that we have many treatment options, including traditional surgery, intraoperative molecular imaging with fluorescent dyes during surgery, endoscopic minimally invasive surgery, Gamma Knife radiosurgery, Cyber Knife robotic radiosurgery, proton therapy or targeted therapy. Another advantage is that Penn practitioners have a lot of experience treating meningioma. Some of the most difficult meningomas are located at the base of the skull; these are very difficult to remove and require a high level of experience and expertise. Penn Medicine is able to offer some very good minimally invasive options to remove a tumor that other hospitals may not be experienced with.