Meningioma

What is Meningioma?

Meningioma is the most common type of primary tumor found in the central nervous system, which includes the brain and spinal cord. It makes up about 37.6% of these kinds of tumors and around half of all benign, or non-cancerous, brain tumors. The tumors start in the layers of protective tissue around the brain or spinal cord, known as the meninges. The World Health Organization (WHO) has classified them into three grades based on their severity. The majority of meningiomas are benign and are considered grade 1. However, around 1 to 3% could turn into malignant, or cancerous, tumors. The survival rate five years after diagnosis for these malignant tumors is between 32% to 64%. Several factors can increase the risk of developing a meningioma, including genetic disorders like neurofibromatosis type 2, exposure to radiation, hormonal therapy, and family history.

The symptoms a person experiences depend on the size and location of the tumor. As a result, some people might not have any symptoms, while others may experience neurological deficits or issues with their nervous system function. A brain MRI, or magnetic resonance imaging scan, is the preferred method for diagnosing a meningioma and gives the most accurate results. If the meningioma is not causing any symptoms and is growing slowly, doctors usually suggest regular observation and imaging. However, if the tumor is growing quickly, is large, or is causing symptoms, surgery is usually the best option for treatment. This specifically applies to meningiomas that are found within the cranium, which houses the brain.

What Causes Meningioma?

Meningiomas, a type of brain tumor, mostly occur by chance, but certain factors can increase the risk of developing them. These can include lifestyle factors like obesity and alcohol consumption, as well as exposure to radiation or hormones. Examples of hormone exposure include hormone replacement therapy, use of birth control pills, and having a history of breast cancer.

Meningiomas have been found to have receptors for progesterone, estrogen, and androgen hormones on their cell surfaces. Progesterone receptors are especially common, found in as many as 72% of these tumors. These receptors make the tumors responsive to hormone levels in the body, that’s why they can occasionally change in size during pregnancy or certain phases of the menstrual cycle. This could explain why meningiomas are more common in women.

Your risk of developing a meningioma may also be higher if you have a close relative (like a parent or sibling) with one, or if you have certain genetic conditions. These include neurofibromatosis type 2, von Hippel Lindau disease, multiple endocrine neoplasia type 1, Li-Fraumeni syndromes, Cowden disease, and Gorlin syndrome.

Risk Factors and Frequency for Meningioma

Primary brain tumors are increasing around the world, impacting around 10.82 in every 100,000 people each year as of 2015. The average age of diagnosis is 66, and it occurs more often in women than men, with a ratio of 2.3 to 1. These tumors are particularly common in African Americans, again with a higher ratio in women than men.

Meningiomas, a specific type of brain tumor, make up 37.6% of all primary central nervous system tumors and 50% of all non-cancerous ones. This condition affects between 1.8 and 13 in every 100,000 people per year. In the United States, there are around 170,000 people diagnosed with meningioma out of a population of around 100,000. Meningiomas are more prevalent in adults than children, being most common in the 75 to 84 age group.

About 1% of all meningiomas are linked to Neurofibromatosis type 2, a genetic disorder.
According to the World Health Organization:

• 80-81% are typical or grade 1 meningiomas.
• 17-18% are atypical or grade 2.
• 1.7% are anaplastic or grade 3 meningiomas.

Recurrence rates vary depending on the grade of the tumor, with higher-grade meningiomas recurring more frequently. After ten years, up to 20% of meningiomas can reappear. Specifically, in grade 3 tumors, the recurrence rate could be as high as 94%, while in grades 1 and 2, it ranges from 7% to 52%.

Spinal meningiomas are also quite common, accounting for 30.7% to 38.8% of all primary spinal tumors in adults aged 20 and above in the United States. Women tend to have them more, accounting for 80.3% of the patient group.

Signs and Symptoms of Meningioma

Intracranial meningioma, or a tumor in the brain’s protective layers, can show different symptoms based on where it’s located. The majority of these tumors are found in the upper part of the brain. Common areas where they occur are on or near the brain’s surface, along the ridge of the sphenoid bone, within the brain’s folds, or in the olfactory groove – the area responsible for smell. They’ve also been found above the pituitary gland, in the back part of the skull, inside the ventricles (fluid-filled spaces in the brain), and around the eye.

• Upper body muscle stiffness or uncontrollable muscle contractions
• Excessive reflex reactions
• Unusual foot sign (Babinski sign) and hand sign (Hoffman sign)
• Weakness or inability to move
• Loss of sense of smell (anosmia)
• Headaches
• Dizziness
• Problems with vision
• Seizures
• Swelling of the optic disk due to increased intracranial pressure (papilledema)
• Changes in behavior

Depending on the specific location of the tumor, further symptoms may include weakness or paralysis of the limb on the opposite side, cranial nerve problems with associated seizures, or Foster-Kennedy syndrome which involves loss of smell, swelling of the optic nerve on one side and wasting away of the optic nerve on the other.

Tumors in other areas may cause issues with cranial nerves controlling eyesight, eye movement, face sensation, and facial muscle movement. In the brain’s frontal area, meningiomas can cause mental, cognitive, and behavioral changes. If located in the lower part of the brain or near the large hole at the base of the skull (foramen magnum), the tumor could result in ‘bulbar palsy’ – a host of neurological symptoms, disturbance in balance, muscle weakness, facial paralysis, hearing loss, and neck pain. A meningioma in the brain’s ventricles can result in a blockage of the brain’s fluid pathways, causing ‘obstructive hydrocephalus’, a condition characterized by an accumulation of fluid in the brain. Tumors in the areas around the pituitary gland, eye socket, or in the cavernous sinus (a blood-filled space located on either side of the pituitary gland) can lead to vision loss and an outward displacement of the eyeball.

When meningiomas occur in the spine, the usual symptoms are pain and a damaged or irritated nerve, followed by other possible nervous system issues. These disturbances could relate to upper motor neurons (nerves located in the brain and spinal cord) or lower motor neurons (nerves found outside the brain and spinal cord), hinging on the location of the tumor and which nerve roots are being compressed. Symptoms from lower motor neuron damage include weakness, reduction in muscle tone, muscle twitches, and reduced reflexes. Physical examination might also reveal local spine tenderness.

Testing for Meningioma

Diagnosing meningioma, a type of tumor that occurs in the brain and spinal cord, involves a few stages. These include reviewing your medical history, carrying out a physical examination, and conducting radiological investigations.

A head CT scan, which is a type of X-ray, can be useful for patients who cannot have an MRI for any reason. This can help to see changes in the bone, or in cases of meningiomas that have become hard like bone. Without a contrast dye, meningiomas often appear as dense or same-density lesions that grow along the dura – the membrane that covers the brain. In contrast-enhanced head CT scans, most meningiomas appear as uniformly dense enhanced lesions, sometimes with evidence of brain swelling. The scan can also better show the presence of tumor calcifications and bone changes that can be associated with certain types of meningioma.

The best tool to diagnose meningioma is a contrast-enhanced brain MRI. This can help to differentiate between tumors that are outside the brain (extra-axial) from those inside the brain (intra-axial). These MRIs provide good detail and can show features associated with meningiomas, such as a ‘dural tail’. Brain MRI is also useful in evaluating involvement of brain veins and detection of cyst-like formations.
On a non-contrast brain MRI, meningiomas usually appear darker (hypointense) on T1-weighted images and brighter (hyperintense) on T2-weighted images. Some meningiomas could appear the same in both T1 and T2 weighted images.

Along with this, MRI can show brain swelling due to a leakage of fluid from the blood vessels into the brain tissues. This swelling is usually seen as bright areas on T2 weighted images. What causes this swelling isn’t fully understood. Still, it’s believed to be influenced by several factors such as absence of an arachnoid plane – a protective layer of brain tissue, high levels of Ki-67 antigen – a protein associated with cell growth, and irregular tumor margins. Tumors may also release a specific growth factor that affects the tumor-brain barrier and cause swelling.

Another useful feature to distinguish an extra-axial lesion from an intra-axial lesion is the ‘white matter buckling sign’. This is an inward compression of the white matter that can be seen on both head CT scan or brain MRI, usually associated with extra-axial lesions like meningiomas.

MRI spectroscopy can be used to detect aggressive meningiomas by comparing the biochemical components of healthy brain tissue with the tumor.

Digital subtraction angiography (DSA) is a procedure that provides pictures of the blood vessels. It can help show the blood vessels supplying blood to a tumor and distinguish the type of blood supply.

Positron emission tomography (PET) scans are another method that can help in surgical planning and follow-up after surgery by marking out and defining the blood supply and the interface between the tumor and the brain.

Cytogenetic abnormalities can also be detected through genetic karyotyping studies. Some examples of genetic changes present in some cases of meningiomas include mutations in chromosome 22, and loss of copies in chromosomes 1, 10, and 14.

Finally, there’s an indicator called the ‘ginkgo leaf sign’ that can differentiate spinal meningiomas from schwannomas. This sign is typically seen with a contrast-enhanced MRI. It gives an image of the spinal cord being pushed to one side by the meningioma, stretching the denticulate ligament.

Treatment Options for Meningioma

Observation is a suitable approach for people with small, asymptomatic brain tumors, as well as those with cavernous sinus meningiomas, a type of tumor situated near the eyes. These patients are monitored closely, typically on a yearly or bi-yearly basis. Regular check-ups involve taking MRI scans of the brain to detect any changes or growth in the tumor.

If the tumor is causing symptoms or is growing quickly, the primary treatment is usually surgery, aiming to remove as much of the tumor as possible. Successfully removing the tumor through surgery can potentially offer a 90% chance of remaining cancer-free for 5 years. The amount of the tumor removed during surgery significantly impacts whether the tumor may reappear. The Simpson grading system helps measure the chance of recurrence, depending on how much of the tumor was removed. The grading system ranges from grade 1, where all of the visible tumor, as well as the attached tissues and any impacted bone, is removed, to grade 5, where only a small amount of the tumor is removed or a sample is taken for biopsy purposes. For those with radiation-induced meningiomas, it’s generally safer and more effective to remove the entire tumor. Risk factors for severe complications after surgery include lengthy surgeries (more than 4 hours long), being over 70 years old, and poor health status.

After the surgical removal of the tumor, radiation therapy may be beneficial, especially for grade II and III meningiomas. This therapy uses high-energy beams, such as X-rays or protons, to kill the remaining tumor cells. This not only can enhance the survival rates of affected individuals but can also lower the chances of the tumor coming back, thus improving disease control in these patients.

Stereotactic radiosurgery (SRS) is another option, which is often used when the patient isn’t a good candidate for surgery. SRS works by using multiple beams of radiation to deliver a highly focused form of radiation directly to the tumor. However, it’s generally not recommended for certain situations, such as when the tumor is large, neighboring critical parts of the brain, or causing swelling or clotting of the brain’s veins. SRS has a promising survival rate, with 95% of patients living for at least 3 years after treatment, and 90% living for 5 years or more. However, the outcomes are usually not as favorable for aggressive types of meningiomas, even when treated with high doses of radiation.

Chemotherapy might be needed in some cases to help prevent the tumor from growing back, especially when the tumor could not be entirely removed during surgery or for malignant tumors. An example of such a drug used in treatment is bevacizumab, which targets specific molecules in the tumor cells to stop their growth. This drug has shown promising results, with successful decreases in tumor size following its use.

What else can Meningioma be?

When a doctor is diagnosing a meningioma, which is a type of tumor that occurs in the brain and spinal cord, there are several other conditions that could show similar symptoms and need to be ruled out. These include:

• Central Nervous System Solitary Fibrous Tumors: These occur in any organ and at any age, originating from the dural mesenchyme. They appear as well-defined lesions on brain scans.
• Intracranial Hemangiopericytoma: Very aggressive tumors that often recur and metastasize. They appear as various types of lesions with different degrees of enhancement on brain scans.
• Gliosarcoma: Rare tumors composed of anaplastic astrocytes or glial cells with sarcomatous elements. They are usually considered to be a variant of glioblastoma multiform and can metastasize.
• Leiomyosarcoma: This is one of the rarest central nervous system tumors and is often seen in people with compromised immune systems, such as those with HIV.
• Dural Metastatic Tumors: These are typically metastatic tumors that originate from the breast, prostate, lung adenocarcinoma, and renal cell carcinoma.
• Intracranial Hodgkin Lymphoma: These tumors can spread to the scalp, epidural space, and subcutaneous tissue. They are usually seen in later stages of the disease.
• Plasmacytoma: These are tumors that usually arise from the plasma cells. They often appear as intense homogeneous lesions with an enhanced dural tail sign.
• Rosai-Dorfman Disease or Sinus Histiocytosis: This is a benign condition that originates from the proliferation of histocytes in the lymph nodes.
• Neurosarcoidosis: This affects approximately 5% of patients with systemic sarcoidosis. These tumors are dural-based lesions.
• Melanocytic Tumors: These tumors can be malignant or benign. They often have leptomeningeal involvement.
• Plasma Cell Granuloma: This is described as an inflammatory pseudotumor, the cause of which is still unknown. They often originate from the dura or the leptomeninges.

Each of these conditions can appear differently on scans and have different symptoms, making careful examination and diagnosis crucial.

What to expect with Meningioma

Meningioma, a type of tumor, has different survival rates that often depend on the grade of the tumor. For instance, the likelihood of remaining cancer-free for the next 5 years is 95.7% if you have a grade 1 tumor, 81.8% for a grade 2, and 46.7% for a grade 3. If we extend this to a 10-year period, 90.4% of patients with a grade 1 tumor and 69.4% of those with a grade 2 tumor remain cancer-free.

Another important concept is the ‘progression-free survival’, which refers to the length of time during and after treatment that a patient lives without the disease getting worse. Certain factors can improve the chances of progression-free survival, such as the completeness of the tumor removal, a mitotic index less than 5% (meaning the cancerous cells are not dividing and growing rapidly), a lower grade of the tumor, small tumor size (less than 6 cm), being afflicted with only one tumor, and depending on where the tumor is located.

In terms of recurrence, which means the return of the cancer, grade 1 has a 4.9% chance, grade 2 has 18.4%, and grade 3 has a 27.3% chance. Nevertheless, the decline in the mortality rate for malignant meningiomas over a 10-year period is a positive sign, and is partly due to the advances in treatment options. Partial removal of the tumor can offer an 85% 5-year survival rate with benign meningioma; however this drops significantly to 58% for malign tumors.

In relation to Meningioma patients who have undergone radiation treatment after surgery, tumor grade is considered a key predictor of survival rates. Higher survival rates were observed in patients with grade 1 and 2 tumors. Specifically, the 5-year survival rate after using radiation therapy is about 81% for patients with grade 1 tumors, as compared to about 53% for patients with grade 2 and 3 tumors.

Interestingly, the recurrence rate of meningioma correlates with the extent of surgical removal. Here ‘extent’ means how much of the tumor they managed to remove. Using the original Simpson grading system, which is a method to measure the level of surgical removal, the recurrence rates for grades 1, 2, 3, and 4 are respectively 9%, 19%, 29%, and 40%. Thus, the less of the tumor present after surgery, the less chance it has to come back. For complete removal of the tumor along with the associated tissues, lower recurrence rates have been reported. A study carried out in 2017 showed very similar recurrence rates. The 5-year survival rates for patients with atypical and malignant meningioma also depend on how much of the tumor can be removed. With full removal, the survival rate is 91.3% for atypical meningioma and 64.5% for malignant meningioma. This decreases to 78.2% for atypical meningioma and 41.1% with partial removal for malignant meningioma.

Possible Complications When Diagnosed with Meningioma

There can be different complications depending on the type of treatment for meningiomas, which are typically benign tumors in the brain:

1. Non-surgical treatments can result in increased tumor size, faster growth, and the risk of the tumor coming back. Meningiomas can also become hardened, progress to grade 2 or 3, with a possibility of turning cancerous, invading the brain, and in rare cases, spreading to other parts of the body.

Common Non-Surgical Complications:

• Risk of the tumor returning
• Increase in tumor size
• Accelerated tumor growth
• Potential for the tumor to harden
• Risk of the tumor escalating to grade 2 or 3
• Possibility of turning cancerous and invading the brain
• Rare chance of spreading to other parts of the body

2. Surgical and medical treatments also have their own complications including bruising, infections, blood clots in the veins, fluid leakage from the brain and spine, risk of harming nearby anatomical structures, and worsening of any existing neurological issues. Additional medical complications can be lung infection due to inhalation of food particles, blood clot in the deep veins, clot in the lungs, lack of blood supply to the heart, or stroke.

Common Surgical and Medical Complications:

• Bruising
• Infections
• Blood clots in the veins
• Fluid leakage from the brain and spine
• Risk of harming nearby anatomical structures
• Worsening of existing neurological problems
• Lung infection due to inhalation of food particles
• Blood clot in the deep veins
• Clot in the lungs
• Lack of blood supply to the heart
• Stroke

3. Post-radiosurgery risks include cranial nerve deficits such as optic nerve damage in intracranial meningiomas caused by radiotherapy.

Common Post-Radiosurgery Complications:

• Visual impairment due to optic nerve damage
• Other cranial nerve defects
• Toxicity due to radiotherapy

Preventing Meningioma

Meningioma is a type of tumor growing in the protective layers called the meninges, which safeguard the brain and spinal cord. The majority of these tumors are benign, basically harmless and non-cancerous. Many meningiomas produce no symptoms, so they’re often discovered randomly during brain scans. Head CT scans or brain MRIs are used to check for meningiomas. Depending on where the tumor is located in the brain, a patient may endure headaches, dizziness, vision problems, muscle weakness, seizures, or changes in speech or personality.

So far, no specific causes of meningioma have been identified, but there are certain risk factors that can increase the chances of developing this condition. For example, during pregnancy, these tumors may grow bigger due to the influence of female hormones. Radiation exposure, oral contraceptive use, hormone replacement therapy, and previous occurrences of some types of cancer, like breast cancer, have also been associated with meningioma. Certain genetic diseases, like neurofibromatosis and Cowden disease among others, may also increase meningioma risk. It’s essential to note that having risk factors does not necessarily cause meningioma; it just increases its probability.

If a meningioma is small and causes no symptoms, it can be often managed by regular monitoring, which involves routine brain scans. On the other hand, larger, symptomatic, or rapidly growing meningiomas generally require surgical removal by a neurosurgeon. The likelihood of the meningioma reappearing after surgery depends on the specifics of that tumor and how much of it was removed. Radiation therapy is another treatment option that can slow the tumor growth or even decrease its size.

As yet, no primary prevention methods have been found for meningiomas. While anyone can develop a meningioma, some people may be at higher risk due to their medical history or genetic makeup. For such individuals, it is essential to have regular check-ups and paid special attention to the possible risk factors like long-term estrogen therapy, radiation exposure, or a family history of meningioma. Physicians will help these patients understand their risk and the need for regular monitoring if a meningioma is discovered but causing no symptoms.

One preventable risk factor of meningioma is obesity. Research suggests a link between a higher body mass index (more specifically, a BMI of 30 or more) or increased waist size, and the likelihood of developing meningioma. Therefore, maintaining a healthy weight through regular exercise and a balanced diet could help prevent this condition. Extreme body weight can affect the levels of various hormones and proteins in the body, which may be associated with meningioma development. And while no direct link has been established between meningioma and changes in the immune system, individuals with this condition have been found to have altered levels of certain immune markers. Assessing these markers may offer a way for early detection and prevention of this disease.