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Personalizing Brain Surgery

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Richard Warme, a 67-year-old Long Island painter, was in the middle of a job when he suddenly didn’t feel well and had to sit down. As he stepped off a scaffold, half the world around him went black. “It was as if I suddenly turned blind on one side,” he recalls. “I could see from one eye, but not from the other.” His friends called an ambulance, and his primary care physician advised him to go to Stony Brook University Hospital.

After a series of brain scans, Warme learned that he had suffered a stroke because a blood clot had clogged an artery in his brain. Luckily, the stroke didn’t cause much damage or impairment, but bad news was yet to come. Warme was carrying a ticking time bomb inside his head that could kill him any day: a large aneurysm nestled deep in the back of his brain.

Aneurysms are little blood-filled balloons or domes that form on the walls of weakened cerebral blood vessels. When they rupture, they result in brain hemorrhages that can kill patients before they even reach a hospital. Modern surgical techniques fix aneurysms by stopping blood flow into them using one of two standard methods. The first is cutting through the skull and tying an aneurysm off with a device akin to a tiny clothesline clip. If the patient’s arteries are hardened or an aneurysm cannot be clipped, surgeons resort to what’s called an embolization procedure, threading a catheter through an artery from the groin all the way up to the brain to fill the aneurysm with tiny metal coils and sometimes a stent. Once the blood flow into an aneurysm stops, it essentially dries out.

Warme’s case was very complex. When Henry Woo, MD, a neurosurgeon and director of Stony Brook’s Cerebrovascular Center, saw Warme’s brain images, he instantly knew neither approach would work well. Burrowed deep within Warme’s brain, his aneurysm had a very large opening no stents and coils would ever be able to fill effectively, and his arteries were too hardened to clip. Warme needed a new cutting-edge embolization tool — a little spherical device made from thin fine mesh that would “plug” his aneurysm like a tub stopper. Woo could check whether it would work on Warme right on the spot by simulating a test surgery in his lab, without Warme even being present.

The ability to practice a surgical procedure before touching the patient was a surgeon’s fantasy. A few years ago, Woo, together with his colleagues neurointerventionalist David Fiorella, MD, PhD, and biomedical engineer Barry Lieber, PhD, turned this dream into a reality. They created a vascular simulation device that allows the physicians to perform test surgeries on exact replicas of patients’ brain structures.

The idea originated in 2009, when Woo saw a cardiac simulation device that mimicked the work of the human heart and aorta, the body’s main artery. It occurred to him that with a few additional features, the device would make a great training tool. “If we could add intracranial vessels to it, we would have a vascular system that would mimic human arterial anatomy, and it could be very helpful in training physicians,” Woo recalls. The team formed a company, called Vascular Simulations, and bought the necessary patents. They then began modeling and 3D-printing intracranial vessels and placing them inside a life-size plastic head.

Nicknamed Headley, the apparatus is computer controlled — its heart starts beating with a click, pumping around fluid that resembles the viscosity of human blood. Headley’s see-through head is filled with a special gel that causes the simulated arteries to behave as vessels in the brain would as catheters are pushed through. From the computer screen, the physician can control various parameters, including heartbeat and blood flow, to mimic real-life situations.

Headley quickly proved to be an invaluable personalized medicine tool. Vascular Simulations developed a process that allows 3D-printing replicas of a patient’s arteries and aneurysms based on his or her CT scans and MRIs. When placed inside the plastic skull, these artificial vessels simulate exact experiences the surgeons will have when operating on that patient, down to the pulsating blood flow and arterial resistance. “That lets them practice with different aneurysms and different devices,” says Marlene Baumeister, Woo’s clinical coordinator. “They can open up the head, snap in differently shaped aneurysms in different locations, close the head, and practice going in and out of the aneurysms with different devices.” Unlike a human patient, Headley doesn’t mind being operated on as many times as necessary.

There are other brain surgery simulators, but they typically allow surgeons only to visualize the procedure on a computer screen without delivering the true sensation of pushing a catheter against the blood flow, feeling the pulse and experiencing the resistance of the arterial walls. With Headley, surgeons can essentially practice an entire surgery without making a single cut on a human.

So while Warme’s brain was still recovering from the stroke, its replica was being prepped for a test surgery. Recreating a silicone aneurysm is a complex feat that takes about 36 hours, requires a lot of finesse and involves both physicians and material engineers. The staff members at Vascular Simulations loaded Warme’s brain scans on the computer and 3D-printed the blood vessels in plastic. Once the white squiggly structures hardened, they were coated with silicone and later sprayed with a special chemical solution to make them as slippery on the inside as human arteries typically are — otherwise the catheter threading experience would not be realistic. And when they were ready, Warme’s artery copies went into Headley.

After a few trials, Woo determined exactly the size of the device needed for Warme. He also knew that it was a perfect solution for the active Long Islander who still worked, fished, and prior to the stroke, captained a boat. However, the only way to get treated with the spheroid mesh was by joining a clinical trial, and Warme didn’t qualify because of a heart condition. There was one last thing left to try. Woo could ask the device maker to lobby the Food and Drug Administration on his behalf for a one-time compassionate use exemption. He would have to convince both parties that the mesh plug was indeed Warme’s only road to health, as opposed to a sudden hemorrhage and death. But he would also have to prove that it was the safest and most appropriate method to use. Lobbying for the exemption was a long and complex process, involving loads of letters and paperwork, but Woo was optimistic. He believed that the results obtained from the simulator would provide solid and convincing medical evidence for all parties involved.

Woo came to Stony Brook from the Cleveland Clinic in 2007. At the time Suffolk County, whose population totaled about 1.5 million people, had not a single surgeon who specialized in brain aneurysms. “This was probably the largest underserved metropolitan county in the United States,” Woo says. “There were no cerebrovascular neurosurgeons; there was no one who could perform an endovascular procedure, like coiling.” As a result, stroke patients had to travel two hours and sometimes longer to the nearest cerebrovascular center — a luxury people with strokes can ill afford. In an acute ischemic stroke, every moment counts, because 2 million brain cells die every minute, Woo says.

The establishment of the Cerebrovascular Center transformed healthcare standards for the entire region. ‘In just a few years we went from having no neurointerventionalists to having what probably is one of the largest practices for cerebrovascular diseases in the Tri-State area,’ Woo says.

In joining Stony Brook, he saw the opportunity to build a center where patients could be treated quickly, instead of traveling to faraway locales. After Woo launched the Cerebrovascular Center at Stony Brook, he recruited his former colleagues Fiorella and Lieber. “We enjoyed working together at the Cleveland Clinic, and the idea of working together again and building a new program sounded like a great opportunity,” Fiorella says, adding that he is grateful to Stony Brook for enabling the team to be as successful as they could be. The move worked out well for Woo also. “Stony Brook gave me an opportunity to start the program here, they invested money into it, and they let me recruit the right people,” he says.

The establishment of the Cerebrovascular Center transformed healthcare standards for the entire region. “In just a few years we went from having no neurointerventionalists to having what probably is one of the largest practices for cerebrovascular diseases in the Tri-State area,” Woo says. Today, the Center is known as a place where some of the most complex and dangerous brain aneurysms are successfully treated with minimally invasive techniques. As Woo and Fiorella take part in clinical trials, testing new embolization procedures and devices, they’re able to quickly offer them to a wider audience upon FDA approval. Fiorella says that one of the most gratifying aspects of his job is being able to treat patients with very difficult cases whose prospects would otherwise be quite grim. “I love coming to work every day,” he says, “and I love helping patients.”

The Center also quickly gained a reputation as a hub for training physicians from around the world. Not only does the simulator allow practicing cerebrovascular surgical techniques, but it has also proved to be a valuable platform for testing new embolization devices and methods when they first come to market. The endovascular field is constantly expanding, and new devices and technologies are being released all the time. But surgeons are a conservative bunch, and they often greet new inventions with extreme caution. They have good reasons for that — what if the new gadget doesn’t work as advertised, or worse, malfunctions during surgery? Headley takes the guesswork out of the procedures. It lets surgeons test-drive new equipment as many times as they want before using it on a patient. Woo estimates that hundreds if not thousands of physicians have already been trained on the simulator, and some institutions have acquired Headleys for their own use.

After months of writing letters and filling out forms on Warme’s behalf, Woo was finally granted a one-time compassionate use exemption by the FDA in the fall of 2015. As he expected, the results from the practice surgeries done on the simulator had clearly demonstrated that the new embolization device was perfect for Warme. His surgery date was set quickly — December 7, so he could be home for Christmas. Warme was calm and confident about the operation. “It’s a big decision to do a surgery like that and you have to consider a lot, but Dr. Woo explained everything so well, and he had practiced on that machine,” Warme says. “I trusted him, and I knew he was doing the right thing.”

Warme’s surgery went fast and easy because Woo had rehearsed it so many times, he knew every little twist of Warme’s arteries by heart. “He got out from under the anesthesia a lot quicker because the device was the right size and it went right in, thanks to all this preplanning,” Baumeister says, adding that Warme’s overall recovery was also quite speedy. “One month later he was going about his usual business.”

Warme recalls in amazement how well he felt when he woke up in the recovery room. “I had no pain, no complications, not even a headache!” he says. “Dr. Woo has truly magical hands.” Three months after the surgery, “I get compliments that I look better and younger than before.” His life is pretty much back to normal. He’s doing painting work again and is looking forward to the upcoming fishing season and being on the boat this summer. When he nets a big catch, he shares the fish with his friends and primary care physician. This year, he might bring some to Dr. Woo.

With Headley, surgeons can essentially practice an entire surgery without making a single cut on a human.

Lina Zeldovich lives in New York and writes about science, medicine and technology for publications such as The Atlantic, Psychology Today and Scientific American.


Neurointerventionalists treat delicate and dangerous conditions occurring within brain vessels, where even minor errors can have catastrophic effects. Yet, unlike other professionals, brain surgeons never had a safe test environment in which they could try a new approach or polish their skills. Until recently, building solid clinical judgment still came from surgeons’ experience with difficult scenarios and unexpected complications.

Vascular Simulations, a startup company launched by Drs. Henry Woo and David Fiorella with Barry Lieber in 2011 and based at Stony Brook’s Long Island High Technology Incubator, has changed that. Similarly to how pilots hone their skills on flight simulators, Vascular Simulations lets neurosurgeons practice operating complex, life-threatening cases before making a single incision on their patients. By replicating patients’ individual arrangement of blood vessels, the company creates a reliable test bed for every patient’s case, no matter how unique or complex. The old method of using the same technique on every patient no longer works, says Woo. “Every patient’s anatomy is different, and we have to account for that.”

Vascular Simulations creates silicone-based replicas of human blood vessels and aneurysms by reconstructing them from CT scans or MRIs. Surgeons from around the world can choose from a long list of off-the-shelf vessels, available on the company’s website, or upload custom images of their own patients. Within a few days the corresponding arteries and aneurysms arrive by mail. The surgeons can then “snap” them into their own Headleys and practice multiple surgeries. By using the simulator, surgeons can narrow their choice of embolization devices from a gamut of options to what fits each patient best.

Even a few years ago, such highly personalized treatment and testing was unheard of, but today it’s on its way to becoming the norm. In a field where an individualized medicine approach used to amount to thinking quickly on one’s feet and solving complications while the patient was still under anesthesia, Vascular Simulations is changing the way cerebrovascular diseases are treated around the world. With the level and precision of presurgical testing the company offers, it is quickly building a new standard of neurointerventional care, appropriate for the modern era of personalized medicine.

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