Doctors use precise technology, unmatched skill - and a strong sense of what makes us human
by Tom O’Neill
Dr. Francesco Mangano is chief of the Division of Neurosurgery at Cincinnati Children’s.
The deeper neurosurgeons navigate into the human brain to remove complex tumors, the more a simple truth emerges: image is everything.
Advancements in imaging technology have transformed not only what neurosurgeons can do once they reach a tumor, but also how they negotiate the delicate pathways to get there. The slightest deviation in a “safe corridor” through brain tissue can forever change a child’s ability to move her eyes, move her toes, or move her parents to tears with a word or a smile.
Surgeons call these areas of the brain “eloquent” – one of medicine’s great understatements given that they control everything from movement to emotion.
The overlapping use of functional MRI, stereotactic navigation and intraoperative neuromonitoring allows brain tumor surgeons and neuroradiologists to see the impact of each surgical decision in real time.
Research at Cincinnati Children’s is driving a wide range of improvements in neurosurgery, including advanced diffusion tensor imaging (DTI) – a more detailed form of MRI – and surgical management of brain tumors and epilepsy.
“There’s no question that imaging technology and new surgical tools have given us a level of safety the pioneers of neurosurgery would have thought unfathomable,” says Francesco Mangano, DO, chief of neurosurgery at Cincinnati Children’s. “We are able to see slight gradations of gray, and tell if we are in an eloquent area we need to avoid. From that standpoint, I think imaging has revolutionized how we do things.”
Tumors in the deepest and most delicate areas of the brain, such as the thalamus and the brain stem, were once routinely considered inoperable. The brain stem is a neurosurgeon’s mine field. It provides sensory and motor stimulation to the face and neck. It controls heart rate, breathing, the central nervous system, pain sensitivity, sleeping and eating.
Approximately one in five brain tumors in children are gliomas in the brain stem.
Technology is crucial, but the success of brain tumor surgery relies heavily on the team’s intuitive skills, say Drs. Charles Stevenson, left, and James Leach.
“When Francesco resects a tumor near the bottom of the brain stem, near those critical areas, he’ll ask everyone to be quiet,” says James Leach, MD, a neuroradiologist at Cincinnati Children’s. “At that point he’s relying on many simultaneous cues. He’s listening to the patient’s heart rate monitor, seeing the neuromonitoring responses, and carefully assessing the ‘feel’ of the tumor and surrounding tissues. Those are amazing moments.”
The stakes are high. Within those eloquent regions lies the mind, which is invisible. No MRI can show a child’s sense of humor or creativity.
“There are ramifications for not only a child’s ability to walk or talk, but also his capacity to feel certain types of emotions,” says Charles Stevenson, MD, who leads Cincinnati Children’s brain tumor neurosurgery team. “Who they are. Their humanity.
“It’s hard to conceptualize but it’s critical to talk about that potential risk with families,” he says. “That’s the problem with the brain. None of our studies or scans tells us much about a person’s mind. So I think about that a lot when planning these surgeries.”
THE PATH OF TECHNOLOGY
Cincinnati Children’s became in 2007 the first pediatric hospital in the world to employ the BrainSUITE ™ concept in the operating room, with an integrated neurosurgical microscope, high-definition screens and a specialized bed with complete, multimodality MRI capabilities. Data from pre-operative tests is automatically and precisely aligned with the position of the patient’s head during surgery.
The three cornerstones of surgical imaging are layered: MRI, functional MRI and tractography are the map; stereotactic imaging reveals the safest routes to a tumor; and neuro-monitoring gives immediate results of every movement.
“The deeper you go,” Mangano points out, “the more difficult it is to remain oriented to where you are.”
Success between surgeon and radiologist is a function of teamwork and trust. Stevenson likens surgical navigation to a military laser-guided missile.
“You want to minimize the opening in the skull, come right down on that tumor, then get out like you were never there,” he says. “These tools allow us to do that.”
Mangano led a research team showing how DTI reveals the neural tracts in white matter by measuring the in vivo diffusion of water in tissue. It was published in July 2013 in the American Journal of Neuroradiology. He and his team have published several articles on these advanced imaging techniques. DTI is becoming increasingly important because it provides surrogate markers – like traffic cones – within the microstructure of white matter.
A LOOK AT THE FUTURE
The future of neurosurgery will bring less cutting. MRI-guided laser thermal ablation requires only a keyhole incision in the skull, through which surgeons thread a laser stylet and attack tumor tissue with light energy. It has been used primarily on adults since FDA approval for non-experimental use in 2007.
“We’re starting to see studies and my gut feeling is that it’s a good technique,” Mangano says. “We have the technology, we just need to identify the right patient. We could be doing it here within months."
Patients will also get younger. Cincinnati Children’s now performs brain surgery, including tumor resection, in children as young as several months. Swelling is a particular concern because a baby’s system hasn’t fully developed the ability to regulate itself. Blood transfusions are often required.
“You have to have your exit strategy,” Stevenson says, “and you have to manage it in an expeditious and safe way.”
THE UNBEARABLE LIGHTNESS OF SPEAKING
Leach says research at Cincinnati Children’s will lead to more detailed imaging and a deeper knowledge of anesthesia’s impact on brain activity in children. Language localization is elusive.
Words are, in a sense, invisible stop signs for neurosurgeons. And it’s hard to avoid what you cannot see.
“That’s a challenge,” Leach says. “It’s important to better understand how and where language is organized in children.”
Traditionally, language was thought to concentrate in two major areas in the dominant hemisphere called Wernicke’s and Broca’s areas. But it’s far more complex and affects children differently than adults.
One recent moment left Stevenson a bit speechless himself. He just happened to catch a TV news segment on a local cancer fundraiser, and recognized the young woman being interviewed.
“I operated on her when she was in high school,” Stevenson says. “She was a dancer, but one side of her body had grown weak, and in her class photo, half her face wasn’t smiling. It was a very large tumor. And now there she was, a bright college student, a young lady with enormous potential, giving an interview beautifully – with a perfect smile. I love that."
THE THREE PILLARS OF IMAGING TECHNOLOGY
|Functional Magnetic Resonance Imaging (fMRI)
uses a magnetic field and pulses of radio wave energy to capture images of the brain “in action.” Standard MRI shows the anatomy of the brain, functional MRI captures brain activity, and tractography outlines connections.
provides computer guidance for surgical procedures using magnetic resonance (MRI) or computerized tomography (CT) images. With it, neurosurgeons use imaging obtained prior to surgery to plan their opening and guide tumor removal.
captures circuitries in the brain by essentially intercepting the signal to various muscle groups, using electrodes. Any disruption, however slight, shows immediate reflexive responses that can indicate a potential functional disruption.
A BRIEF HISTORY OF BRAIN SURGERY
The Extraction of the Stone of Madness by Hieronymus Bosch, depicting trepanation (c. 1488-1516).
People have been drilling holes in skulls for a long time, to relieve everything from seizures to real or perceived mental illness.
At one burial site in France from 6,500 BC, archaeologists found 40 prehistoric skulls with trepanation holes. A trephine is an instrument that cuts a round hole, typically near the top of the skull. Remarkably, skull growth showed that many patients survived.
A thousand years ago, Peruvians treated head injuries with a series of holes. Patients depicted in European paintings from the Middle Ages look dire amid religious imagery.
In 1879, Scottish physician William Macewen performed the first documented brain tumor removal. “What a leap of faith that was,” Stevenson says. The teenage patient lived eight years tumor-free.
American Harvey Cushing is considered the “father of modern neurosurgery” for the many advances he led in brain surgery. After his death from a heart attack in 1939, an autopsy revealed a potentially fatal cyst in his brain.