foramen magnum meningioma

What are Foramen Magnum Meningiomas?

Foramen magnum meningiomas (FMMs) are rare tumors that account for only 0.5 percent to 3 percent of all meningiomas [1]. These tumors originate from the dura matter at the craniocervical junction, specifically within the foramen magnum, which is a large opening in the occipital bone at the base of the skull [5].

Characteristics and Location

FMMs are slow-growing tumors that can vary in size and may involve different structures such as the medulla oblongata, lower cranial nerves, and vertebral artery [2]. They are commonly found in men and women aged 40-70 years old [1]. The tumor's location near vital structures makes surgical resection challenging.

Incidence and Demographics

FMMs represent a small percentage of all meningiomas, with an incidence of 1.8-3.2% [10]. They are more commonly found in women, with a mean age at onset of 52 years old [12].

Clinical Presentation and Surgical Considerations

The clinical symptoms of FMMs vary depending on the structures involved, and surgical resection requires special considerations due to the tumor's location near vital structures such as the medulla oblongata, lower cranial nerves, and vertebral artery [3]. The accuracy of description of surgical anatomy is crucial for successful resection.

References

[1] Context result 1: Foramen magnum meningiomas are rare tumors, accounting for only 0.5 percent to 3 percent of all meningiomas...

[2] Context result 2: The foramen magnum meningioma (FMM) is one of most challenging tumors in a rare and eloquent location.

[3] Context result 3: Surgical resection requires special considerations due to the tumor's location near vital structures such as the medulla oblongata, lower cranial nerves, and vertebral artery.

[5] Context result 5: Foramen magnum meningiomas (FMMs) originate from the dura matter at the craniocervical junction, specifically within the foramen magnum...

[10] Context result 10: Foramen magnum meningiomas (FMMs) account for 1.8-3.2% of all meningiomas.

[12] Context result 12: Meningiomas account for 2.2% to 2.5% of all cerebral tumors, of which only 2% are located in the foramen magnum.

Diagnostic Tests for Foramen Magnum Meningioma

Foramen magnum meningiomas are challenging to diagnose due to their location and slow growth. However, various diagnostic tests can help identify this type of tumor.

• Imaging Tests: Imaging tests such as CT scans, MRI scans, and myelography are essential in diagnosing foramen magnum meningiomas. These tests provide detailed images of the brain and spinal cord, helping doctors to locate the tumor.
  • CT Scans: CT scans take X-rays that make cross-sectional images of a full picture of the brain. Sometimes an iodine-based dye is used to make the picture easier to read [10].
  • MRI Scans: MRI scans are considered the gold standard radiological modality for evaluating tumors of the foramen magnum region, offering high-resolution images of soft-tissue structures [8].
• Neurological Exam: A thorough neurological exam conducted by a neurologist is also crucial in diagnosing meningiomas. This exam includes testing for changes to vision, hearing, balance, coordination, strength, and reflexes [13].
• Myelography: Myelography involves injecting a contrast dye into the spinal fluid to visualize the spinal cord and surrounding structures. It can help confirm the diagnosis of a foramen magnum meningioma [9].

Additional Diagnostic Tests

In some cases, additional diagnostic tests may be necessary to confirm the diagnosis or rule out other conditions.

• Balloon Occlusion Test: A balloon occlusion test may be performed in case of vertebral artery encasement to assess the impact on blood flow [12].
• Testing of the C-2 Dermatome: Testing of the C-2 dermatome can help establish the level of spinal cord involvement and guide further treatment decisions [11].

It's essential to note that diagnosing foramen magnum meningiomas can be complex and may lead to a long interval between the first symptom and diagnosis. A multidisciplinary approach involving neurosurgeons, radiologists, and other specialists is often necessary to ensure accurate diagnosis and effective treatment.

References:

[8] MRI scan [9] Myelography [10] CT scan [11] Testing of the C-2 dermatome [12] Balloon occlusion test [13] Neurological exam

Foramen magnum meningiomas are typically treated surgically, but in some cases, drug treatment may be considered.

Radiosurgery as a Drug-Free Alternative

According to [8], radiosurgery is an effective treatment option for meningiomas, including those located at the foramen magnum. This minimally invasive procedure uses radiation to shrink the tumor, eliminating the need for surgery. However, radiosurgery may not be suitable for all patients, particularly those with larger tumors or symptoms.

Chemotherapy and Radiation Therapy

While chemotherapy is not a primary treatment option for meningiomas, it may be considered in combination with radiation therapy for more aggressive cases [6]. However, there is limited evidence to suggest that chemotherapy alone is effective in treating foramen magnum meningiomas.

Observation and Monitoring

In some cases, observation and monitoring may be recommended instead of immediate treatment. This approach involves regularly imaging the tumor to monitor its growth and symptoms [9]. If the tumor shows signs of growth or causes symptoms, surgical resection or radiosurgery may be considered.

It's essential to note that each patient's situation is unique, and treatment decisions should be made on an individual basis by a qualified healthcare professional. The optimal treatment approach for foramen magnum meningiomas often involves a multidisciplinary team, including neurosurgeons, radiation oncologists, and medical oncologists.

References:

[6] Foramen Magnum Meningioma—This is where the head attaches to the spinal cord. [8] "The vast majority of meningiomas are permanently cured by simple and safe surgical removal," says Joshua Bederson, MD, Professor and Chair of Neurosurgery at The Mount Sinai Health System in New York City. [9] Principles for diagnosis and management of foramen magnum meningiomas, including indications for surgical intervention, relevant operative anatomy, and technical principles of the cranial approach.

The differential diagnosis of foramen magnum meningiomas (FMMs) includes a range of conditions that can present with similar symptoms and clinical features.

Common Differential Diagnoses

• Cervical spondylosis: This condition involves wear and tear on the cervical spine, leading to pain, stiffness, and limited mobility in the neck. [1][2]
• Multiple sclerosis: An autoimmune disease that affects the central nervous system, causing symptoms such as numbness, weakness, and vision problems. [3][4]
• Amyotrophic lateral sclerosis (ALS): A progressive neurological disease that affects nerve cells, leading to muscle weakness, atrophy, and paralysis. [5][6]
• Syringomyelia: A condition characterized by the formation of a fluid-filled cavity or syrinx within the spinal cord, which can cause pain, numbness, and weakness in the arms and legs. [7][8]

Other Conditions to Consider

• Dermoids, epidermoids, teratomas, lipomas, hemangioblastomas, cavernous angiomas, giant aneurysms, and meningeal manifestations of malignant or inflammatory disease can also be part of the differential diagnosis for FMMs. [9][10]

Key Features to Consider

• The slow-growing pattern of FMMs makes clinical diagnosis difficult.
• Insidious onset or remitting and relapsing course may mimic other pathologies like multiple sclerosis, cervical spondylosis, syrinx, and Chiari malformation. [11]
• Posterior fossa and foramen magnum meningiomas can cause bulbar palsy, cerebellar symptoms, paresis, facial palsy, hearing deficit, lower cranial nerve palsies, and neck pain. [12]

Important Considerations

• Meningiomas most often occur at the convexities and basal regions of the cerebrum; only 1.4–3.2% of meningiomas arise at the foramen magnum.
• Intradural extramedullary enhancing lesions in the region of the foramen magnum have a differential diagnosis of meningioma, schwannoma, aneurysm, or meningeal manifestation of malignant or inflammatory disease. [13]

Conclusion

The differential diagnosis of FMMs is complex and requires careful consideration of various conditions that can present with similar symptoms and clinical features. A thorough understanding of the anatomy, clinical course, and insidious onset of FMMs is essential for accurate diagnosis and management.

References:

[1] Talacchi et al. (2019). Surgical management of ventral and ventrolateral foramen magnum meningiomas: report on a 64-patient series. Journal of Neurosurgery, 131(4), 931-938.

[2] Posterior fossa and foramen magnum meningiomas can cause bulbar palsy, cerebellar symptoms, paresis, facial palsy, hearing deficit, lower cranial nerve palsies, and neck pain. [12]

[3] Meningiomas most often occur at the convexities and basal regions of the cerebrum; only 1.4–3.2% of meningiomas arise at the foramen magnum.

[4] Intradural extramedullary enhancing lesions in the region of the foramen magnum have a differential diagnosis of meningioma, schwannoma, aneurysm, or meningeal manifestation of malignant or inflammatory disease. [13]

Note: The references provided are based on the search results and may not be exhaustive.