Cranial Base Endoscopic Surgery
Endoscopic Neurosurgery Advances to Treat Rare, Complex Tumors
Growing among the nerves and blood vessels that crowd through the foramina, skull base tumors are among the most challenging of neoplasms to remove. But advances in endoscopic equipment, and constant honing of surgical technique, have radically expanded Massachusetts General Hospital (MGH) neurosurgeons’ ability to operate in these close quarters, allowing more complete resection and improving patient outcomes. “Endoscopy is less invasive than traditional microscopic approaches,” says neurosurgeon William Curry, MD, “but the most important thing is that it actually allows better access, and safer resections.”
Dr. Curry, who leads the skull base endoscopic neurosurgery program, part of the Cranial Base Center at Mass General, is an innovator in this young field. “As we look ahead, we are constantly pushing the limits of access, figuring out new corridors and getting to places and compartments that people haven’t been able to reach before.”
A generation ago, many skull base tumors were only operable through the roof of the skull, with all the limitations and morbidity that came with that approach. With advances in microscopy-guided intranasal approaches, the field of skull base surgery evolved in the 1990s into a true multidisciplinary field, combining the work of neurosurgeons, ear, nose and throat specialists, and plastic surgeons. In the late 1990s and early 2000s, the field took another major step forward with the spread of endoscopic instrumentation.
A Wider and Deeper View of a Complex Region
Unlike microscopy, with its narrower width and shallower depth of field, the endoscopic view of the structures in the skull base is both wider and deeper, and offers the surgeon a far more detailed view of the complex anatomy he or she must navigate around. “This makes it both easier and safer to access lesions of any sort,” Dr. Curry says. As a side benefit, recovery is faster and there are fewer complications than the same procedure done microscopically.
In both planning and execution, Dr. Curry works closely with ear, nose, and throat (ENT) surgeons. “This is always a team effort.” The rhinologists' deep familiarity with the internal anatomy of the nose, and with blood supply of the mucosa that is often diverted to heal the tissue at the skull base entry point, allows more extensive resections of intracranial tumors. “In the operating room, we are working together with four hands.” Dr. Curry says. “Some neurosurgeons do these cases by themselves, but the fact that we’ve always worked together allows us to do so much more, to explore a much wider topography at the base of the skull.”
While pituitary tumors are the most commonly operated-upon skull base tumor, Dr. Curry sees more of the harder-to-reach tumors, especially benign craniopharyngiomas, chordomas, meningiomas of the skull base, and anterior skull base malignancies of the sinuses. “Our goal is almost always to take the tumor fully out, which allows us to cure. But if the location prevents it, for instance because the tumor is involved with the carotid artery or the optic nerves, we may have to leave a little bit, and then treat with radiation.”
“We are always interested in the application of evolving technology,” Dr. Curry says. He is anticipating advances in both endoscopic visualization, with the arrival of three-dimensional high-definition cameras and monitors, and new strategies for tissue repair, including laser tissue welding—“space-age stuff!” says Dr. Curry—being developed by his ENT colleague, Benjamin Bleier, MD, of Massachusetts Eye and Ear Infirmary.
The application of robotics to skull base surgery is advancing, as well. “The instruments the robot can wield are not yet fine enough, but the potential is huge.” And Dr. Bleier is helping to develop preoperative three-dimensional simulations of the operation procedure, using high-definition MRI and CT images to create a “virtual patient” for exploring the anatomy and planning the approach. “This isn’t quite ready for prime time,” Dr. Curry says, “but we are working on it.”