A minimally invasive approach to treating a mature teratoma brain tumor

How a new laser at Children's Hospitals and Clinics of Minnesota saved time, resources and most importantly, an 8-year-old patient's life

Gavin Pierson, 8, was running out of options. Even after repeated operations at Children's Hospitals and Clinics of Minnesota in St. Paul, the mature teratoma in the center of his brain continually grew back.

All told, in the first two years after his tumor was found, Gavin underwent more than 17 different surgeries, including five craniotomies, a procedure that requires a large incision in the scalp and excision of a section of skull so the tumor can be removed. He was at the point that further surgery of this type risked damaging tissue affecting not only vital motor functions, but the personality and cognition that make him the spirited boy he is.

Something needed to be done, because the relentless tumor was growing again.

That's the backdrop for the hospital's October 2013 acquisition of a new Visualase minimally invasive laser that proved to be not only an impressive surgical tool but the centerpiece of an approach that slashed Gavin's time in the pediatric intensive care unit and other post-operative costs. Gavin went home two days after his surgery in October and attended a birthday party two days later.

In contrast, after the preceding five craniotomies, Gavin endured painful recoveries, including several days each time in the PICU and up to two weeks in the hospital, plus weeks of physical therapy. The pain, recovery time and cost had become increasingly difficult for Gavin and his family to bear.

Adopting endoscopic and laser tools
Craniotomies are used successfully by neurosurgeons around the world. They are also the most invasive approach available. In recent years, however, neurosurgeons have adopted various minimally invasive techniques. But for situations like Gavin's, in which even the most advanced tools are unable to address hard-to-reach areas of the brain, neurosurgeons continue to eagerly await new innovations in endoscopy and laser techniques that have swept the rest of medicine.

For example, more than 95 percent of the 1 million-plus cholecystectomies per year in the United States are now done using a minimally invasive approach, according to a Thomson Reuters general surgery database. The same is true of appendectomies, more than 80 percent of which are done laparoscopically, according to Ethicon Endo-Surgery.

A new approach: minimally invasive laser ablation
The Visualase tool Children's acquired is a minimally invasive laser that combines MRI mapping and precise thermal destruction to ablate undesirable brain tissue. The procedure requires making a 3-millimeter pinhole in the skull, through which the surgeon threads an MRI-guided laser-tipped catheter directly to the active tumor site. It leaves surrounding brain tissue intact, unlike traditional surgery on tumors in relatively inaccessible sites.

Laser ablation occurs while the patient is in an MRI scanner, deploying light energy to heat and destroy lesions in the brain. Guided by real-time thermal MRI images, surgeons are able to pinpoint the exact target area without affecting the healthy surrounding tissue.

While the technology has historically been used in adults, Children's is one of only a few centers in the country where pediatric neurosurgery teams use the laser to treat epileptic lesions in children. However, Children's is the first center, and Gavin is the first child, ever to use Visualase to treat a mature teratoma brain tumor.

During Gavin's first laser ablation surgery in October 2013, the team successfully removed 25 percent of the teratoma. He was in the PICU for a mere 48 hours, and ready to go home on the second day. Pain and swelling were minimal, and most important, cognitive function was retained because the laser micro-ablated the tumor, and nothing else.

Today, after a second laser ablation using Visualase, Gavin's mature teratoma is more than 40 percent smaller than at its peak, and the parts that have been ablated are not growing back. With regular laser treatments, coupled with the experimental drug Palbociclib, which had previously only been used in clinical trials in adults, physicians anticipate the teratoma will continue to get smaller and not come back.

So far the negative side of the ledger has been fairly blank in Gavin's case. The biggest worry is that the laser simply cannot ablate enough of the tumor to completely cure patients. Post-operative swelling is another potential concern, yet to a far lesser degree than with major invasive surgery to the brain. This is why patients undergoing laser ablation are monitored overnight in the hospital before going home.

The takeaway
In addition to brain tumor patients such as Gavin, Children's has also successfully used the laser ablation procedure to treat children with epilepsy. The results have been excellent. For example, nearly eight months after using Visualase, one 14-year-old Children's patient, who previously needed frequent open surgeries when her medications failed to ease her chronic epileptic seizures, is now seizure-free.

Current laser ablation does not necessarily displace existing techniques. Each brain tumor and epilepsy case is unique and traditional treatment methods are well established and broadly efficacious. What laser ablation does do, however, is offer pediatric neurosurgeons and a handful of their patients access to minimally invasive options that did not exist just five years ago. Their great promise, realized in Gavin's case, is to enable surgeons to render the term "inoperable brain tumor" obsolete.

Procuring the Visualase laser was one of the best investments in the past five years for Children's neurosurgery team. Not only is it saving precious time and resources in one of the busiest pediatric hospitals in the Midwest, it's making a real impact on our patients' lives.

Joseph A. Petronio, MD, is medical director of pediatric neurosurgery at Children's Hospitals and Clinics of Minnesota. He is board certified in neurological surgery and pediatric neurological surgery, contributed to many publications, book chapters and presentations on pediatric neurosurgery, and has taught at several university medical schools. In addition, Dr. Petronio received a grant for his work for the Brain Tumor Foundation for Children. He is a graduate of Northwestern University Medical School.

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