Endonasal Skull-Base Surgery
The OSUCCC – James Comprehensive Skull Base Surgery Center offers an endoscopic approach and comprehensive care for tumors of the skull base, paranasal sinuses, spine and brain.
BY KENDALL POWELL
Tumors of the skull base are rare, but when they arise, they occupy an area of the body that few people know exists—the area inside the head that forms the floor of the cranium and the roof of the sinus cavities. It is an anatomical terrain that is dense, complex and delicate.
“Skull-base anatomy presents a complicated network of nerves and blood vessels residing in a tricky landscape of depressions, prominences and irregularities,” says Ted Teknos, MD, director of Head and Neck Oncologic Surgery at The Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute (OSUCCC – James). “The optic nerves, facial, olfactory, auditory and other small nerves leave the brain from the skull base, and the carotid arteries are always close by.”
Skull-base neoplasms include pituitary gland tumors, meningiomas, chordomas, and sinus and olfactory endothelium tumors. Most are diagnosed at an advanced stage, when they press on adjacent structures or obstruct respiration. To treat these difficult lesions, the OSUCCC – James earlier this year began a Comprehensive Cranial Base Surgery Program spearheaded by the recruitment of two internationally renowned leaders in the field: otolaryngologist Ricardo Carrau, MD, and neurosurgeon Daniel Prevedello, MD. Working together, Prevedello and Carrau played a leading role in revolutionizing the surgical treatment of skull-base tumors. They now form a team with Bradley Otto, MD, an otolaryngologist and endoscopic skull base surgeon, and Matthew Old, MD, a head and neck and skull base surgeon.
“This is high-price real estate; the anatomy is dense—there are no parts to spare,” says Carrau, a head and neck surgeon and director of the Cranial Base Surgery Program of the Otolaryngology-Head and Neck Surgery Department. “We want to save critical blood vessels and nerves; the trick is doing the surgery without producing a problem that is worse than the tumor itself.”
A New Strategy
Typically, skull base tumor surgery involves an “upstairs-downstairs” approach. A neurosurgeon performs a craniotomy and comes at the tumor from above, and an otolaryngologist comes in from below, through facial incisions.
In the 1990s, Carrau was at the University of Pittsburgh, where he and a small group of physicians developed a less invasive, endoscopic means of removing skull base lesions. Prevedello also joined the group and has become one of the premier endoscopic neurosurgeons in the world. The “endoscopic endonasal approach” they developed removes tumors through the nose, a technique that 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 skull base traditional surgery.
- Patients typically recover faster and have shorter hospital stays.
Also, the endoscope’s light and high-definition camera, which can angulate to look around corners, offers 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, enabling close inspection of the surgical area. “Our visualization enables us to better distinguish tumor from normal tissues, allowing us to preserve normal tissue to a higher degree,” Teknos notes.
Experience and Teamwork
“Skull base anatomy presents a complicated network of nerves and blood vessels, and it takes incredible knowledge of the anatomy to cut around a structure such as a tumor,” Teknos says, “Drs. Prevedello and Carrau have tremendous experience in that area.”
The two surgeons, recruited to the OSUCCC – James from the University of Pittsburgh, joined Otto, who also trained in endoscopic skull base surgery at that University, to bring a unique perspective and skill set to the endoscopic procedure and place Ohio State at the forefront of endoscopic endonasal surgery worldwide. “There’s a lot of teamwork involved,” Prevedello says. “The neurosurgeon has the expertise to work around and inside the brain, while the head and neck surgeon has the expertise to work in the sinuses and skull base itself. We really complement, and learn from, each other.”
Often, the otolaryngologist first creates a space in the nasal cavity for two surgeons to work. Then 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. Tumors larger than the nasal cavity are either collapsed or removed piecemeal. If a patient’s eye is involved, the team will include a third surgeon, an ophthalmologist.
Carrau estimates that fewer than 10 centers in the United States provide comprehensive care for skull base tumors.
“One of the advantages here at the OSUCCC – James is that everyone on the skull base team—surgeons, nurses, therapists and support staff—is trained in both the traditional and endoscopic approaches,” Carrau notes. “We can treat any tumor and meet any need a patient may have. We have expertise in open and endoscopic procedures and have recently incorporated robotic surgery in our armamentarium. Through an international cooperation with surgeons from Rosario, Argentina, our team has pioneered reconstructive techniques that are now used throughout the world.”
Core members of the team are housed in one location. Patients can see their head and neck surgeon, neurosurgeon, reconstructive surgeon, and nurse practitioners, as well as endocrinologists, ophthalmologists, speech and swallowing therapists, and prosthetic experts if needed. A concierge service is available to arrange housing and other services for out-of-town and international patients. Ideally, Prevedello says, patients meet with their lead physicians on the same day to avoid multiple appointments.
Carrau says that the center’s surgeons have linked with Don Stredney, a research scientist in Biomedical Applications at the Ohio Supercomputer Center, to develop a realistic surgical simulation program that will help surgeons train for these intricate surgeries.
“Developing your skills requires doing many procedures, and these tumors are rare, so it’s not easy to acquire the needed practice in a timely fashion,” explains Carrau. “We’d like to create a simulation program that mimics the procedures we perform in the operating room—it would be like a souped-up video game that gives a surgeon the same sensory feeling that he or she would experience when cutting through tissue or bone with real instruments.”
The center draws patients from across the country and around the world, offering the opportunity for research to improve the procedures and post-surgical care—such as reducing the risk of swallowing problems that often follow skull base surgery—and to study the molecular events that drive these malignancies.
Otto, Old, Carrau and Prevedello are tracking patient outcomes to better define the tumor types and stages that the technique is best suited to treat. “We still need to prove that minimal-access surgery is as good as, if not better, than traditional surgery,” Carrau says.
Little is known about the genetic mutations and other molecular changes that fuel their growth, or how they might be treated with drugs in addition to surgery. “Acquiring enough tissue to study these tumors can be difficult,” Teknos says. “But with the center, we are building a bank of tumor tissue that will allow us to investigate potential therapies based on a tumor’s individual genetic characteristics.”
This research has already begun. OSUCCC – James cancer biologist Quintin Pan, PhD, research director for the Head and Neck Oncology Program, has shown that certain tongue and oropharyngeal cancers overexpress protein kinase C epsilon (PKC epsilon), a molecule important for tumor growth and metastasis.
Pan and Teknos are investigating whether PKC epsilon plays a role in skull base olfactory-nerve tumors called esthesioneuroblastomas. The team eventually wants to test a PKC-epsilon inhibitor developed by Pan as a potential treatment for esthesioneuroblastomas.
“There’s been little basic science done on these rare tumors,” says Pan. “We expect that the OSUCCC – James center will naturally attract these patients and provide tumor samples, which would enable us to produce cell lines and really look in depth to understand the genetic alterations that drive this tumor type.”
Carrau, Prevedello, Old and Otto look to robotic technology to raise skull-base surgery to the next level. Using robotic-assisted surgery, surgeons can execute fine movements that are impossible for human hands alone. “This means less collateral damage to healthy surrounding tissues,” Prevedello says.
Current robotic devices, however, use two or more arms that are too unwieldy for endonasal skull base surgery. “We will be working to develop a single-arm robot that is compatible with the endoscope and skull base characteristics,” he says.
Prevedello and Carrau both say that the commitment of the OSUCCC – James to a skull-base center of excellence drew them to Columbus. “Leadership at the University is fantastic,” Carrau says. “They are trying to provide the best care, with the best physicians available, supported by research to advance that care. Academically, professionally and philosophically, this matches my interests.
To refer a patient, please call The James Line New Patient Referral Center toll free: 1-800-293-5066.