Meningiomas are benign tumors that come from meninges.
The meninges line the brain. Most meningiomas are benign, meaning that they do not aggressively invade surrounding tissues or metastasize to distant organs. A small percentage are atypical or malignant, less than 1 out of 10.
Where Is the Tumor Located?
Meningiomas may be located anywhere in the brain or spinal cord.
A meningioma may arise anywhere there are meninges. The location impacts the management strategy a great deal. At Dallas Ear, we are involved with mengiomas of the ear structures and lateral skull base. Relevant meningiomas typically arise in and around the corridors for the cranial nerves involved with facial sensation (Vth), hearing and balance (VIIth), and swallowing and speaking (IXth-XIth).
What Are the Symptoms of a Meningioma?
Symptoms reflect impairment of nearby cranial nerves.
If the meningioma grows near the fifth cranial nerve facial numbness or trigeminal neuralgia like symptoms occur. Similarly if near the eighth nerve hearing loss, tinnitus, or imbalance, may occur. If near the lower cranial nerves hoarseness and difficulty swallowing can result. Large menigiomas may cause headache, blurry vision, and nausea of hydrocephalus (excess build up of brain fluid) occurs.
How Does My Doctor Test for a Meningioma?
Magnetic resonance imaging (MRI) is ordered if neurological symptoms create concern for meningioma.
Often, an MRI has been ordered by another physician before you visit Dallas Ear. Other tests may be helpful depending on the type of meningioma. For example, a hearing test can show if the mengioma is causing hearing loss.
What Are the Risk Factors for a Meningioma?
Most meningiomas are sporadic.
This means that they occur in patients with no family history or other known risk factors. They are most likely to occur between ages 40-70. They are more common in women than men.
How Is a Meningioma Treated?
There are three options to manage meningomas: observation, radiation, and surgery.
Because meningiomas are typically benign, some may need no treatment at all. These are observed with serial MRI. If they are growing the may require treatment.
They type of treatment is determined by factors such as the age/health of the patient, status of cranial nerves, and size/location of tumor.
What Type of Surgical Treatments Are Available?
Microsurgery refers to removal of mengioma with aid of the operating microscope.
This is important to preserve the surrounding nerves when possible. There are two approaches used to address these tumors: transpetrosal and retrosigmoid.
The transpetrosal approach involves navigating the anatomy of the temporal bone, posterior fossa, and middle fossa. It allows a wide view of meningiomas deep in the skull base. It is useful to address tumors near the trigeminal or fifth cranial nerve. It is also useful for tumors that involve both the middle fossa and posterior fossa. Tumors that occupy a space at the top of the spinal column near the brainstem called the petroclival junction can be addressed by this approach as well.
The retrosigmoid approach involves navigating the anatomy of the posterior fossa from behind the temporal bone. It is useful to address meningiomas of the lower cranial nerves and of the corridor where the eighth cranial travels through. This is called the cerebellopontine angle. Tumors that arise in the CP angle may also be approached using the transpetrosal route. The choice is complex and depends on tumor factors such as size and location.
Risks that are common to both approaches include intracranial bleeding, hearing loss, facial weakness or paralysis, hoarseness, difficulty swallowing, double vision, CSF leak, stroke, and meningitis.
How Is Radiation Used to Treat Meningiomas?
The goal of radiation is to arrest tumor growth.
Radiation is delivered in a single dose. It is given through a planned number of shots that converge on the tumor. This is called stereotactic radiosurgery. A three-dimensional dose delivery plan is constructed from CT and MRI scans of the tumor. By converging many small shots on a central location, tissue surrounding the tumor is spared while the tumor receives a high dose of radiation.
If successful, the tumor stops growing, and may occasionally shrink. However, the tumor must be monitored for growth in the future. If radiation fails, surgical options for treatment are revisited.
Which Treatment Is Best for Me?
The decision about proper treatment is complex and is best made by a skull base team.
It should be made by a team that includes both a neurotologist and a neurosurgeon. Many factors must be considered. Tumor factors include size and location. Patient factors include age, health, cranial nerve status, and tumor anatomy. The team approach will decide whether observation, radiation, or microsurgery is best for you.