Meningiomas: Prominent Expert's Q&A on the Most Common Brain Tumor

Meningiomasrepresent about 1 out of 3 primary brain and spinal cord tumors. They are themost commonly diagnosed primary brain tumors in adults. And although theyevolve in the meninges, the layers of tissue that surround the outer part ofthe brain and spinal cord, they are referred to as brain tumors

The vastmajority of meningiomas are benign, but these tumors can grow slowly and, ifleft undiscovered, can be severely disabling and life-threatening depending ontheir location. About 10 to 15 percent of meningiomas are malignant, orcancerous.

Michael McDermott, M.D.., a neurosurgeon and the chief medical executive of Miami Neuroscience Institute, is a world-renowned leader in neurosciences, with a clinical expertise in the field of meningioma surgery.

“I would say that the greatest proportion of meningiomas are discovered by chance,” explains Dr. McDermott. “Because of the wide availability of modern imaging, particularly with magnetic resonance imaging (MRI), studies are done for other reasons. That’s why these tumors are frequently discovered.”

Dr.McDermott is the editor of two books that were recently published: Handbookof Clinical Neurology: Meningiomas, Part 1, Vol. 169 (2020); and Part 2,Vol. 170 (2020).

Mostmeningiomas are usually discovered after an MRI or CT scan that someone mayundergo after complaining of headaches or seizures, or possibly after a headinjury. Since meningiomas are commonly slow-growing tumors, they often do notcause noticeable symptoms until they grow to certain size. In extreme cases, thesetumors can alter a person’s behavior and mood.

In thefollowing Q&A, Dr. McDermott provides more insight into meningiomas,including symptoms, risk factors and treatments.

Whatshould people know about meningiomas?

Dr. McDermott:
“Meningiomas are the most common primary brain tumor in adults from over the age of 35 until death. Approximately 70 percent of these are low-grade and benign-behaving tumors. About 25 percent are a slightly higher grade, more aggressive and they need radiation therapy. They’re a very common tumor. They’re found frequently incidentally. For example, after a concussion, a CT scan is done for other reasons — and lo and behold — there’s a tumor and it’s a meningioma.

“Mostof the meningiomas diagnosed do not require treatment. So, if the patient isasymptomatic, they don’t have symptoms specific to the tumor site and there’sno documented growth, then there’s no role for intervention. The patient can besafely observed.”

What arecommon symptoms associated with meningiomas?

Dr.McDermott:

“Themost common symptoms for an adult patient with a brain tumor of any type areheadaches, seizures, and progressive focal neurologic deficit. What does thatmean? If the tumor overlies your motor cortex, you develop weakness on theother side. If it’s over your sensory cortex, you develop sensory symptoms. Ifit’s over your visual cortex, you develop visual symptoms. And then the otherone is changing personality or behavior. That relates to the fact that thefrontal lobe and temporal lobe are large parts of the brain and they controlmood, insight, judgment, personality and behavior.

“So, ifyou have a big tumor pressing on your frontal lobe, you’ll have the so-calledfrontal lobe syndrome, which can encompass an apathetic and demotivationalstate, and depressed mood. Those are the kind of symptom complexes that thepatients show. Every headache is not a brain tumor. But a headache that’spresent for two weeks, is worse in the morning than the evening, and isassociated with nausea and vomiting — that’s not normal.” 

What arethe top risk factors for meningiomas?

Dr.McDermott:

“Overwhelming,the majority, 90 percent or greater, are sporadic — meaning we don’t know whythey occur. As I mentioned before, the majority are benign. But there are riskfactors, such as prior radiation therapy exposure. With childhood leukemias,where the children are radiated prophylactically between the ages of three toseven. Now, there’s a national registry for those patients … understandingthat there’s a 25-fold risk increase for the later development of meningioma.

“Thereare other associations with certain genetic syndromes, like neurofibromatosis(a genetic disorder that causes tumors to form on nerve tissue); non-causativelinks like breast cancer.  Breast cancersare very common, and meningiomas are much less common. But they have similargenetic abnormalities. That doesn’t mean if you have breast cancer, you goingto develop a meningioma, or vice versa.

“There’s anassociation with thyroid tumors; an association with fertility treatments; andan and an association with a family history — like two first-degree relativeswith meningiomas — that might put you at a higher risk later in life for beingdiagnosed with one.”

What isthe most common misconception that people may have about meningiomas?

Dr. McDermott:
“When you tell a patient that they have a benign tumor, they think that surgical treatment will be curative. But that’s not always the case and we have options for treatment. So, if we’re following a patient who’s asymptomatic, and they either become symptomatic or we have documented radiographic growth, then there’s a consideration for intervention or treatment.

“Thedifferent forms of treatment include surgery, radiation therapy or radiosurgeryat diagnosis. And each of those forms of treatment has a different riskprofile. Even 50 percent of benign tumors that are totally excised will recur25 years after diagnosis. So, the key thing is that if you treat a patient witha benign tumor, they have to be followed essentially for their lifetime to ruleout recurrence.”