A rare brain tumor in a previously inoperable area of an 8-year-old boy's brain remains dormant nearly four months after a second laser ablation surgery, Children's Hospitals and Clinics of Minnesota reported today upon the story being featured on the nationally syndicated talk show, The Doctors.

An MRI scan on May 20 of Gavin Pierson of Ramsey, Minn., showed that the formerly peach-sized tumor, a rare form known as a mature teratoma, has shrunk more than 40 percent from its peak, said Dr. Joseph Petronio, medical director of pediatric neurosurgery at Children's, who performed the minimally invasive surgery on Gavin.

He added that the hospital's new Visualase laser, which was threaded deep into Gavin's brain through a 3-millimeter pinhole, drilled just above his temple directly to the tumor site under guidance of an MRI-catheter system, appears to have destroyed the previously active part of the tumor.

That tumor tissue had regrown repeatedly after earlier attempts to address it with conventional brain surgery, or craniotomy, since Gavin's tumor was diagnosed two years ago. Another such operation would have endangered Gavin's ability to speak and walk because of the high risk of damaging surrounding brain tissue, Dr. Petronio said.

After both laser treatments, Gavin was able to return home the next day and back to school within a week − in contrast to a hospital stay of at least a week, including several days of intensive care, following open brain surgery.

Gavin is the first patient in the U.S. with a mature teratoma brain tumor to undergo this pioneering laser procedure since the Visualase laser system was approved for non-experimental use in the United States in 2007.

"The technology we've used to treat Gavin represents a first for pediatric neurosurgery and showcases the significant advancements that are possible," said Dr. Petronio of the Visualase system, which Children's acquired late last year. The purchase was supported by a fundraising campaign by Children's and Gavin's parents, Steve and Nicole Pierson.  

Children's and the family also successfully petitioned a pharmaceutical company to grant Gavin access to an experimental drug to help control the tumor's growth.

Dr. Petronio said that although Gavin's MRI results are encouraging, it's impossible to make a clear prognosis because Gavin is the first patient to undergo a Visualase procedure for a tumor like his. However, because of the non-invasive nature of the treatment, repeat procedures are possible if the tumor were to start to regrow.

"What's really exciting is the path this technology opens to areas of the brain that were for all intents and purposes closed to us because of the risk of collateral damage to nearby brain tissue," he said. "To think we may be reaching the day when the term 'inoperable brain tumor' is obsolete in children is extraordinary."

Children's pediatric neurosurgery program is the largest in the region, performing more than 450 brain surgeries per year.

Mature teratomas (Gavin dubbed his "Joe Bully") affect less than 1 percent of people afflicted with brain tumors and have long been viewed with fascination by surgeons. They have a dense consistency, likened to cement, and sometimes include odd material such as teeth, fingernails and eyeballs. If left untreated, they can be fatal.

"Every day is a fight: a fight for Gavin, a fight for our family and a fight against Joe Bully," said Nicole Pierson, Gavin's mother. "It's been a very long road to get here, but we're incredibly hopeful and grateful to the team at Children's. We hope that our experience will help other families in the same situation as us."

Gavin will continue to be monitored closely and receive surgical and pharmaceutical treatments as needed to reduce the size of his brain tumor.

The Visualase laser system was approved in the United States in 2007. It is in use at more than 40 centers, including 15 pediatric hospitals.  In pediatric patients, including at Children's Hospitals and Clinics of Minnesota, Visualase has primarily been used to address brain lesions causing epilepsy.