Pediatric-focused Cyberknife opens at Packard
Selene Greenway knew her 5-year-old daughter was dying when the emergency room staff asked if she had a camera. Unbelievably, Brenna, a previously healthy kindergartner who had complained that April evening of a headache, was now about to be airlifted to a nearby hospital for brain surgery in a last-ditch effort to save her life
"I could see Brenna slipping away in front of me," said Greenway. "I took her picture with my cell phone, and then they raced her to the helicopter."
Brenna was lucky. Although she had suffered a severe brain hemorrhage, the surgeons in the Las Vegas hospital were able to stop the bleeding and remove most of the abnormally tangled blood vessels—a congenital condition known as an arteriovenous malformation—that had caused the problem. But a small knot, and with it the risk of another bleed, remained deep beyond the reach of a surgeon's scalpel.
Although she recovered from that surgery, Brenna's parents knew she was living with a time bomb in her head. To defuse it, they turned to Lucile Packard Children's Hospital and its new pediatric-focused Cyberknife—the only such radiosurgery facility on the West Coast equipped for pediatric anesthesia.
Though Packard Children's and Stanford Hospital & Clinics have been treating patients with a Cyberknife for over a decade, the older system was located in a building that was not zoned for the anesthesia use that makes the new Cyberknife so unique. Located in the Stanford Comprehensive Cancer Center, the new Cyberknife offers two important benefits to patients and physicians: younger, more wiggly children or infants can be anesthetized for short periods to keep them still during the procedure, and patients of all ages can undergo treatment without being locked into the large metal head frame required by other radiosurgery treatments, such as the Gamma Knife.
"This is a huge advantage for kids like Brenna," said Michael S.B. Edwards, MD, Packard Children's chief of pediatric neurosurgery and director of regional pediatric neurosurgery. "Young patients in the past were usually required to wear a Gamma Knife head frame, and had to remain anesthetized during the entire, often daylong, procedure. Now we can treat newborn infants up to older children, who can hop off the table and go home or to school after the initial imaging step while we plan the treatment strategy."
The noninvasive process uses tiny, focused beams of radiation to perform radiosurgery on a patient's head or body. This technique allows doctors to attack trouble spots deep within the brain while minimizing the dose of radiation to surrounding healthy tissue. This issue is particularly important in children, whose brains are still developing.
A radiosurgery alternative to the Cyberknife, the Gamma Knife, is also used at the hospital. But the Gamma Knife relies on a rigid metal frame attached directly to the patient's skull to orient the radiation beams, making it difficult to treat infants or young children with small or fragile heads. Because the frame cannot be removed between the initial imaging and subsequent treatment, doctors also have to work fast.
"With the Gamma Knife, the clock is ticking," said Edwards. "We have to place the frame; perform the CT, MRI or other imaging studies; get everyone involved to meet and plan the treatment; and then treat the patient—all while the patient is intubated and asleep. It's not an optimal situation."
In contrast, the Cyberknife, which was developed at Stanford by John Adler, MD, uses a mesh mask to stabilize the head. The technology tracks any unintentional movements on the part of the patient and adjusts the radiation path as necessary. Children who can understand the importance of holding still can undergo the treatment while conscious; squirmy infants and younger kids can have short-term anesthesia for the approximately hour-long diagnostic and treatment sessions.
"The difference between the two technologies is pretty striking," said Anita Honkanen, MD, chief of pediatric anesthesia at Packard Children's. "Gamma Knife patients are usually anesthetized and intubated for hours, and often have a prolonged recovery. With the Cyberknife, recovery is usually quicker. And because they don't usually have to be intubated, we can often treat children with minor colds who would otherwise need to be rescheduled until they're healthy."
Finally, the Cyberknife's laser positioning technology makes it possible to treat tumors in other areas of the body.
On Dec. 19, Brenna received her Cyberknife treatment. Even thought it's too soon to draw a final conclusion about the procedure's effectiveness, Edwards is optimistic.
"Brenna's treatment went really smoothly," he said, "and her parents were very appreciative of the advantages of the Cyberknife treatment. She's doing great."
Despite her parents' relief, Brenna, an outgoing and social girl, likely had her mind on other things.
"One little girl told me 'I want to go to school'," said assistant professor of radiation oncology and Cyberknife co-director Iris Gibbs, MD, recalling one of the new facility's first pediatric patients. "That's what was on her mind. And that's what she did. She went to school immediately after her treatment. This made a tremendous difference to the family and to the child, and I was very happy to be able to offer this to her."