A skull base tumor forms under the brain, or between the brain and skull. Most of these tumors are non-cancerous, but their location near the spinal cord and brain can make them serious health problems.
The symptoms of a skull base tumor vary based on its size and location. Early stage symptoms may include headaches, dizziness, and changes in hearing or vision. More serious symptoms develop if the tumor pushes into nerves or the brain. Serious skull base tumor symptoms can include double vision, total loss of hearing or vision, difficulty swallowing, cognitive changes, facial paralysis, and compression of the brain. It is important to be evaluated by your ear, nose and throat doctor if you have these symptoms.
A glomus tumor develops behind the tympanic membrane or jugular vein. It grows slowly but has the potential to destroy the inner ear, ear bones, and parts of the brain. This tumor results in difficulty with speaking and swallowing and may cause a person to hear a persistent whooshing sound. Nerve deficits and gradual hearing loss can also occur. If the tumor has advanced into the brain or neck, it can impact the voice, swallowing, facial movements, and hearing. Radiosurgery is the treatment of choice. If the tumor is small, it may be surgically removed.
A meningioma originates in the meninges, or brain lining. These tumors can be benign or malignant. Malignant tumors are classified based on the World Health Organization’s levels of aggressiveness of cancers. Most meningiomas are benign and are grade 1. Meningiomas in the elderly may not grow at all. Grade II and III tumors grow more quickly and may spread.
Schwannomas, also called neuromas, originate in nerve coverings. They occur most often in the vestibular nerve, which is responsible for balance. They also grow in the trigeminal nerve that transmits facial sensations. They sometimes involve cranial nerves nine and ten and can cause facial paralysis.
Chordomas are most common in men ages 20 to 40 years. They grow outside of the brain’s dural covering and grow from remnant embryonic cells. Their location near the brain stem makes treatment difficult and complex.
Chondrosarcomas affect the temporal bone. They grow slowly. These rare tumors involve bony skull base structures.
Diagnosis and Treatment
Computed tomography (CT) and magnetic resonance imaging (MRI) are used to identify and grade skull base tumors. Some patients need additional vision, hearing, and balance tests. Technology allows for the use of minimally invasive techniques to treat many skull base tumors. Computer-assisted navigation facilitates visualization of tumors in three dimensions. Endoscopic surgery allows surgeons to use a minimally invasive approach, which shortens the operation time and incision size.
Intra-operative MRIs allow doctors to obtain detailed images during the surgery. These images ensure that doctors remove the entire tumor. Radiosurgery is used on certain types of tumors, with proprietary systems such as GammaKnife and CyberKnife that direct concentrated radiation at the tumor from many directions. The surrounding tissue is relatively protected.