The Basics of

Skull Base
Brain Tumors

The Basics of Skull Base Brain Tumors

Fabio Frisoli, MD, Director of Skull Base Neurosurgery at the Gerald J. Glasser Brain Tumor Center, shares what patients and caregivers need to know.

What is the skull base?

FF: The skull base is the bony surface or floor of the skull underlying the brain. It is subdivided into three anatomical regions: the anterior cranial fossa (underlying the frontal lobes), the middle cranial fossa (underlying the temporal lobes) and the posterior cranial fossa (underlying the brainstem and cerebellum).

The skull base has small channels within the bone, called foramina. Cranial nerves that control the motor, sensory and glandular functions of the head and neck pass through these channels, as do arteries that supply blood to the brain and veins that drain blood back to the heart.

The skull base is also lined with a fibrous impermeable membrane called the meninges. This membrane contains and regulates the volume of cerebrospinal fluid that surrounds the brain and spinal cord.

What are common tumors of the skull base and their associated symptoms?

FF: Tumors may arise from any part of the skull base, including bone, cartilage, meninges, nerves and vessels.

  • Common bony and cartilaginous tumors of the skull base include osteosarcomas, chondrosarcomas and chordomas.
  • Meningiomas arise from the meninges, the fibrous covering of the brain, and are the most common primary intracranial tumor in adults.
  • Schwannomas are also very common tumors that arise from the cells that surround and insulate cranial nerves.
  • Acoustic neuromas (or vestibular schwannomas) are a type of schwannoma that form from the lining of the vestibular nerves, which course to the inner ear.

While less common, tumors may also arise from the cells surrounding blood vessels of the skull base, such as paragangliomas and hemangiopericytomas.

The symptoms associated with these tumors often depend on their size and impact on important neural structures. Sometimes they are found incidentally during brain imaging obtained for other reasons. Frequently they present with headaches or other symptoms associated with elevated intracranial pressure, such as nausea or dizziness. Skull base tumors may also cause seizures if they irritate or inflame the adjacent brain tissue. Cranial neuropathies or cranial nerve dysfunction, resulting in loss of smell, declining visual acuity, double vision and hearing loss, are just a few of the possible neurological symptoms that could indicate the presence of a skull base tumor.

What are the treatment options for skull base tumors?

FF: The first and most important decision to make when we evaluate skull base tumors is whether to observe over time or treat. If there is any indication that a tumor may be cancerous, it must be treated quickly, both for diagnosis and disease control. However, most meningiomas and schwannomas – which comprise the majority of skull base tumors – are benign, slow-growing and may be observed over time with serial annual imaging if they are found incidentally or present with minimal symptoms.

For large tumors that cause symptoms or exert pressure on the surrounding brain tissue, treatment is typically recommended. Treatment may involve surgical removal, focused radiation or a combination of the two.

What type of physician is best suited to treat skull base tumors?

FF: Patients with skull base tumors are served best when they have a multi-disciplinary care team of brain tumor experts. That’s why the Glasser Brain Tumor Center has a dedicated team of neurosurgeons – including skull base surgeons – radiologists, neuro-oncologists and radiation oncologists who run the most experienced CyberKnife® program in New Jersey. This team solely focuses on the treatment of cranial disorders and works together to treat each and every patient. Given that skull base tumors can often impact a patient’s hearing, we also collaborate closely with head and neck surgeons who specialize in ear care to help ensure the best outcomes all around.