Tumors of the skull base occupy an area inside the head that forms the floor of the cranium and the roof of the sinus cavities.
The skull base is a critical and complex area. The anatomy is a complicated landscape of depressions, prominences and irregularities that support the brain. It has networks of nerves and blood vessels that enter or leave the skull. Critical nerves that pass through the skull base include the optic nerves, and facial, olfactory and auditory nerves.
Most skull-base tumors are diagnosed at an advanced stage, after the tumor enlarges and puts pressure on adjacent structures or obstructs respiration, and usually require surgical treatment.
The highly skilled OSUCCC – James skull-base team uses one of two approaches: a newer, minimally invasive technique that they helped pioneer called endoscopic endonasal surgery (EES), or the more traditional open craniotomy approach. An open craniotomy may be required for treating certain skull-base tumors due to their location or size. Whenever possible, however, the OSUCCC – James neurosurgeons who specialize in the treatment of skull-base tumors use the endoscopic endonasal surgery, which avoids the need for an open craniotomy.
When tumor size and anatomical location require it, the OSUCCC – James skull-base team use a technique called the open craniotomy procedure. This is an “upstairs-downstairs” approach that is performed by a highly skilled and experienced neurosurgeon and an otolaryngologist. If the treatment involves the eye, the team will include a third surgeon, an ophthalmologist. A neurosurgeon performs an open craniotomy to access the tumor from above, and an otolaryngologist approaches it from below, through facial incisions.
To expose the brain, an open craniotomy begins by temporarily removing a piece of the skull. To access the tumor, the brain is retracted to a degree that is determined by where the tumor is located, whether toward the front, center or posterior region of the skull base. If facial incisions are needed, their location will likewise depend on the position of the tumor.
The procedure is concluded by carefully replacing the bone plate that was removed from the skull when the surgery began. The initial skin incision is hidden behind the hairline to achieve an excellent outcome and natural appearance.
Endoscopic Endonasal Surgery
Endoscopic endonasal surgery (EES) is a minimally invasive approach to skull-base tumors. The procedure removes tumors through the nose and typically avoids the need for an open craniotomy. EES is the procedure of choice for the James Cancer Hospital skull-base team, which considers it one of the most important advances in the field of skull-base surgery. In addition, Ohio State is at the forefront of EES worldwide and is known for training surgeons in the technique.
The OSUCCC – James EES team consists of highly trained otolaryngologists, neurosurgeons and ophthalmologists who specialize in the approach.
The otolaryngologist often begins the procedure by first creating a space in the nasal cavity for two surgeons to work using an endoscopic device that involves two tubes, one with a light and camera and one with surgical instruments.
The endoscope’s light and high-definition camera can angulate to look around corners, offering a better view of the tumor and surrounding tissue than is usually possible during open-field surgery. The camera’s images are displayed on a monitor in the operating room. The surgeons can closely inspect the surgical area and more readily distinguish tumor from normal tissues, allowing them to preserve normal tissue to a higher degree.
Working together, the otolaryngologist and neurosurgeon expose the skull-base lesion. The neurosurgeon removes the tumor that is adjacent to the brain or on its dural covering, while the head and neck surgeon removes tumor in the sinuses and skull base itself. Tumors larger than the nasal cavity are either collapsed or removed piecemeal. If the eye is involved, the team will include a third surgeon, an ophthalmologist.
EES has several important advantages for patients:
- It avoids scars from facial or scalp incisions.
- It avoids the need for a craniotomy and retracting the brain to reach the tumor, which reduces the risk of tissue swelling and of cognitive or personality changes that sometimes follow traditional skull-base surgery.
- Patients typically recover faster and have shorter hospital stays.
Radiation therapy uses high-energy radiation – X-rays and gamma rays, and alpha and beta particles – to kill cancer cells. The most common type of radiation used to treat cancer is called external-beam radiation because it is delivered to the body from the outside. Another type of radiation therapy, called brachytherapy, delivers radiation from inside the body.
External Beam Radiation Therapy
A large machine called a linear accelerator, shown below, produces high-energy X-rays that are directed at the patient’s tumor. The beam can treat large areas of the body, and its size and shape it can be adjusted to conform to the shape of the tumor, which reduces damage to surrounding healthy tissues. Radiation therapy uses high-energy particles or waves, such as x-rays, gamma rays, electron beams, or protons, to kill or damage cancer cells. Cancer cells grow and divide faster than most normal cells, so radiation therapy affects them at a higher rate by causing more breaks in the DNA of the cancer cells. These breaks keep cancer cells from growing and dividing, causing them to die.
External-beam radiation: Advanced technology allows the beam to be more tightly focused and to better conform to the shape of the tumor. This allows almost ‘pinpoint’ therapy, helps avoid damage to normal tissue and decreases toxicity.
Intensity modulated radiation therapy (IMRT): This is a highly precise way to deliver radiation that maximizes the radiation dose to a tumor or to parts of a tumor while minimizing the exposure of nearby healthy tissue. IMRT is frequently used to treat skull-base tumors located near sensitive, crucial healthy tissues such as the optic nerve or the eye.
Volumetric modulated arc therapy (VMAT): This newer form of IMRT delivers varying doses of radiation while moving in an arc around the patient, exposing the tumor to higher doses while protecting healthy tissue. This circular manner of treatment allows the beam to strike the tumor from many angles. The bean itself can be shaped sometimes within a fraction of an inch of the tumor, enabling precise adjustment of the radiation dose and better protection of healthy tissues.
Intra-operative radiation therapy (IORT): This is radiation that is given during surgery. It can be delivered by external beam or sometimes by brachytherapy. It is used when a tumor is close to sensitive structures or organs that must be shielded from the radiation beam.
Pre-operative or neoadjuvant radiation therapy: This refers to radiation given before surgery. The purpose is to shrink a tumor to facilitate its complete removal at the time of surgery and prevent its recurrence.
Adjuvant radiation therapy: This is radiation given after surgery in an attempt to kill any hidden clusters of cancer cells that might cause the cancer to return.
Brachytherapy delivers radiation to a tumor from inside the body. It involves implanting tiny radioactive seeds that are about the size of an uncooked grain of rice into a tumor. Needles, catheters, or special applicators are used to place the seeds into the tissue. The seeds can deliver high doses or low doses of radiation.
Palliative Radiation Therapy
Radiation therapy can also be used to provide palliative care. The goal of palliative care is to relieve symptoms and improve the quality of life. Palliative therapy is given in cases of certain advanced cancers or cancers located so close to vital organs that they cannot be surgically removed. Palliative radiation therapy might be used, for example, to shrink a brain tumor that is pressing against the skull and causing pain or to help with tumors in the spine that are pressing on nerves and may be causing weakness or pain.
Additionally, the OSUCCC – James has highly specialized, palliative-care support teams that provide expert symptom management and quality-of-life care, along with spiritual, emotional, psychological and nutritional counseling. They can also help guide patients through complex treatment choices and navigate the healthcare system.
These highly experienced teams work directly with OSUCCC – James radiation oncologists and are part of the OSUCCC – James Palliative Care Center. They include physicians, advanced practice nurses, psychologists, clergy members and other experts who specialize in providing emotional, psychological and spiritual support.
Team physicians are all board certified in palliative medicine and other team members have advanced certifications in pain and symptom management.
Chemotherapy refers to the use of specialized drugs to stop the growth of cancer cells, either by destroying the cells or by preventing them from making new cells. Chemotherapy is rarely used in the treatment of skull-base tumors, but exceptions do occur. NOTE: Chemotherapy is used exclusively to treat malignant (cancerous) tumors; it is never used to treat benign tumors.
The way chemotherapy is given depends on the type of drug and the type and grade of the cancer being treated. Many chemotherapy drugs are unable to reach a tumor in the brain because they are unable to cross the blood-brain barrier, a biological mechanism that protects the brain from chemicals. Thus, some chemotherapy drugs are chosen because they can cross this barrier, or the drug is placed or injected directly into the brain during surgery.
Chemotherapy treatment usually takes place in an outpatient part of the hospital, at the doctor's office or in the home. Some people may need to stay in the hospital for treatment.
The OSUCCC – James has a highly specialized, coordinated support team that provides additional care, also called palliative care, to chemotherapy patients. The goal of palliative care is to relieve symptoms and improve the quality of life. Along with expert symptom management, the palliative care team also provides spiritual, emotional, psychological and nutritional counseling. It also can guide patients through complex treatment choices and help them navigate the healthcare system.
The palliative care team works directly with OSUCCC – James medical oncologists, and they are part of the OSUCCC – James Palliative Care Center. They include physicians, advanced practice nurses, psychologists, clergy members and other experts who specialize in providing emotional, psychological and spiritual support.
Team physicians are board certified in palliative medicine and other team members have advanced certifications in pain and symptom management.