Meningioma: what is considered large, growth and treatment

There is no single size at which every meningioma counts as large. Doctors judge size together with location, growth over time and symptoms: a small meningioma pressing on the optic nerves can matter more than a bigger one in a roomier part of the skull. Most meningiomas are benign, slow-growing grade 1 tumors, and many are small and found by chance on a scan done for another reason.

What is a meningioma?

A meningioma is a tumor that grows from the meninges, the thin layers of tissue that cover the brain and spinal cord. Because it starts in these coverings rather than in the brain itself, it usually pushes on the brain from the outside instead of growing into it.

Meningiomas can form almost anywhere along the meninges: over the surface of the brain, along the midline between the two halves, at the skull base, or around the spinal cord.

How common is meningioma?

Meningioma is the most common primary brain tumor, meaning the most common tumor that starts in or around the brain rather than spreading there from elsewhere. It is more common in women than in men and becomes more common with age, with most people diagnosed in middle age or later. It is uncommon in children.

Because brain scans are now done so often, many meningiomas are discovered incidentally in people who have no symptoms at all.

What type of cancer is meningioma?

Most meningiomas are not cancer. The World Health Organization grades them from 1 to 3:

WHO grade	Name often used	How it behaves
Grade 1	Benign	Slow-growing; by far the most common
Grade 2	Atypical	Grows faster and is more likely to come back after treatment
Grade 3	Anaplastic or malignant	Rare; grows quickly and behaves like a cancer

The grade is usually confirmed by examining tissue after surgery. Even grade 1 tumors are watched carefully, because a benign tumor inside the skull can still cause problems by pressing on nearby structures.

What is considered a large meningioma?

Whether a meningioma is considered large depends mostly on where it is and what it is touching, not on a fixed number. Doctors look at:

• Location. Some areas, such as the skull base or near the optic nerves, have very little spare room.
• Effect on the brain. Swelling (edema) in the nearby brain or pressure that shifts brain tissue suggests the tumor is causing harm.
• Symptoms. A tumor causing seizures, weakness or vision loss is treated differently from one causing none.
• Growth. A tumor that is steadily enlarging on repeat scans raises more concern than one that has stayed the same.

A good example is a tuberculum sellae meningioma, which grows just in front of the pituitary gland, right beneath the optic nerves and the point where they cross. Even a fairly small tumor here can press on these nerves and cause gradual vision loss, often first noticed as blurring or loss of side vision.

How long does a meningioma take to grow?

Most meningiomas grow slowly, often over many years, and some barely change at all on repeat scans. Many have probably been present for years before they are found.

Growth rates vary a lot between people and between grades. Grade 2 and grade 3 tumors usually grow faster. This variability is the reason doctors often repeat MRI scans after a new diagnosis: comparing scans over time is the most reliable way to learn how a particular tumor is behaving.

What are the symptoms of meningioma?

Many meningiomas cause no symptoms. When they do, symptoms depend on location and develop gradually. They can include:

• Headaches, often worse in the morning
• Seizures
• Weakness or numbness in an arm or leg
• Changes in personality, memory or concentration, especially with tumors at the front of the brain
• Vision problems, such as blurred vision, double vision or loss of side vision
• Loss of smell, with tumors along the floor of the front of the skull
• Hearing loss or ringing in the ear, with tumors near the hearing nerve
• Back pain or leg weakness, with meningiomas of the spine

These symptoms have many other, more common causes. New seizures, steadily worsening vision or new weakness should always be checked promptly.

How is meningioma treated?

Treatment depends on the tumor's size, location, grade, growth and symptoms, as well as the person's age and overall health. There are three main approaches.

Watch and wait

Small meningiomas that cause no symptoms are often monitored with regular MRI scans instead of being treated right away. This is called active surveillance. Many such tumors never need treatment. If the tumor grows or starts causing symptoms, treatment can be considered at that point.

Surgery

Surgery is the main treatment for meningiomas that are causing symptoms, growing, or pressing on important structures. The aim is usually to remove the tumor along with its attachment to the meninges when it is safe to do so. How completely the tumor is removed, called the extent of resection, is one of the strongest predictors of whether it comes back.

Most meningiomas are removed through an opening in the skull (craniotomy). Some skull base tumors, including certain tuberculum sellae meningiomas, can be removed through the nose using an endoscopic endonasal approach. The best route depends on the tumor's shape and its relationship to nerves and blood vessels.

When a tumor is wrapped around nerves or arteries, surgeons may deliberately leave a small piece behind to protect function, and then watch or treat that remnant.

Radiation and radiosurgery

Stereotactic radiosurgery delivers a precise, high dose of radiation in one or a few sessions. It is generally used for smaller meningiomas, tumors in places that are hard to reach surgically, or pieces left after surgery. It aims to stop the tumor from growing rather than make it disappear.

Conventional (fractionated) radiation therapy, given in smaller doses over several weeks, is often recommended after surgery for grade 2 and grade 3 meningiomas, or for tumors that keep coming back.

Meningioma surgery: what to expect

Recovery after meningioma surgery varies with the location and size of the tumor. Many people spend a few days in the hospital and return to normal activities over several weeks. Follow-up MRI scans continue for years, because even benign meningiomas can occasionally return.

For tumors near the optic nerves, vision often improves after the pressure is relieved, especially when the loss has not been present for too long. Some research tools now estimate how likely vision is to improve under different surgical plans, such as this tuberculum sellae meningioma model.

Frequently asked questions

What causes meningioma?

In most people, no clear cause is found. The best-established risk factors are previous radiation to the head (especially in childhood), the inherited condition neurofibromatosis type 2, older age and female sex. Hormones appear to play a role, and certain high-dose progestin medications have been linked to meningioma, which is why doctors sometimes review these medicines after a diagnosis.

What should you avoid with a meningioma?

No specific foods or activities have been proven to cause meningiomas to grow. People are generally advised to avoid unnecessary radiation to the head and to discuss any hormone treatments with their doctor. Anyone who has had seizures should follow their doctor's advice on driving and other safety precautions.

What doctor should I see for a meningioma?

A neurosurgeon is usually the main specialist, often working with a neurologist and a radiation oncologist. For tumors affecting vision, a neuro-ophthalmologist may test vision in detail. Many people are first referred by their primary care doctor after a scan.

Can a meningioma come back after treatment?

Yes, it can. The chance is lower for grade 1 tumors that were completely removed, and higher for grade 2 and grade 3 tumors or when part of the tumor was left behind. Regular follow-up scans help catch any regrowth early.