George Jallo, M.D., peers through the microscope and delicately guides his instruments near the teenager’s spine.

He methodically removes a tumor he has monitored for eight years from the spinal cord at the back of the girl’s neck. The work around pathways for neurons that travel to and from the brain is delicate. A mistake could impact the patient’s ability to speak, walk or breathe. Fewer than 200 of these types of spinal cord lesions are removed in the United States each year.

But in a field where millimeters matter, Jallo has built a reputation that spans the globe.

“Dr. Jallo is one of the world’s leaders in this field of spinal cord lesions and brain stem lesions,” says Nir Shimony, M.D., a surgical fellow at Johns Hopkins All Children’s Hospital in St. Petersburg, Florida, where Jallo is based. “He masters a unique technique.”

An International Expert

Jallo, who leads the Johns Hopkins All Children’s Institute for Brain Protection Sciences, has done surgery in Brazil, Mexico and other countries for the hospital, missionary trips or other special consultations.

The surgery on the 13-year-old involves a domestic patient, but two days later Jallo will give a presentation about it to the Sixth Annual World Course in Advanced Brain Tumour Surgery in London. The conference draws about 150 neurosurgeons from around the world and Jallo is one of about 20 presenters.

“They emailed and said we need your expertise for brain stem and spinal cord,” Jallo says. “I was a little nervous, but when you look at it, wow, it’s a very well-established program. Their reputation is unbelievable.”

Jallo described for the conference the case he had followed since the girl was 5. He discovered the lesion as he examined her for scoliosis. He tracked the issue through the years as she developed neck pain, dizziness and numbness in her fingers. She described a sensation of “walking on clouds” because of numbness in her feet. An MRI showed the lesion growing in size and changing shape.

Jallo recommended the surgery was worth the risk.

“These are rare tumors,” Jallo says. “The operation is very delicate and there are a lot of nuances to it. It’s a good teaching case for other surgeons who may not have as much experience with these particular types of cases.”

Shimony, who assisted, and neurosurgery resident Meleine Martinez-Sosa, M.D., made a 10-centimeter incision in the girl’s neck and work through procedures to expose the spinal cord, inserting an electrode that warns the surgeons when they are near the motor tracts where neurons send signals to and from the brain.

With the spinal cord covering, or dura mater, exposed, the surgeons opened the arachnoid layer, a spider-like membrane that cushions the central nervous system. This is where Jallo’s knowledge, skill and experience come into play.

“A very high skill and technique are needed to dissect the lesion and separate it safely from the delicate spinal cord,” Shimony says. “Every mistake, every extra tissue taken can end up in devastating results.”

After painstaking work and ongoing communication with the team monitoring the electrodes, vital signs and other sensors, the surgeons agree they have successfully removed the tumor.

Days later the girl shows no ill effects, walking, playing and getting stronger.

Unlikely Path

Starring at an international conference for neurosurgeons wasn’t always the obvious course for Jallo.

He was born in Bethlehem, moved to New Jersey at age 5 and wasn’t immediately a star student. But as he majored in Chemistry and minored in French at George Washington University, Jallo set a course toward becoming a doctor. But what kind?

“I think the brain is the most fascinating organ of the human body,” Jallo says. “I think it’s responsible for everything. When I realized I wanted to be a surgeon, I wanted to do something that was delicate, intricate. It was either going to be brain or heart because your margin for error was small.”

During a fellowship at New York University Medical Center, Jallo encountered the man who would become his mentor, the late Fred J. Epstein, M.D., who pioneered techniques in pediatric brain and spinal cord tumor surgery.

“I think that sparked my interest in pediatric neurosurgery and to do those types of operations,” Jallo says.

Jallo joined Johns Hopkins Medicine in 2003 and worked his way up to chief of pediatric neurosurgery at The Johns Hopkins Hospital in Baltimore, Maryland. He easily could have stayed there for years, but in 2015 he moved to Florida to become director of the Johns Hopkins All Children’s Institute for Brain Protection Sciences. Under his leadership, the hospital ranked in U.S. News & World Report’s pediatric Neurology/Neurosurgery specialty for the first time.

“I had a great job in Baltimore,” Jallo says, “but this job allowed me to bring together multiple disciplines, all focused to the brain. I get to partner and work much more closely with the neurologists, the psychologists, the psychiatrists, developmental pediatricians, everyone that has the same interest that I do in the brain. That’s what made it attractive.”

Not all aspects of the brain require Jallo’s precision. Even he performs more routine surgeries where the margin of error can be measured at what he considers a generous centimeter or more. But the cases that Jallo most loves are those like the one of the 13-year-old girl.

“The margin of error is under a millimeter,” he says. “I won’t get bored. It’s not the same operation every time. These types of operations are what keep me fascinated.

“Millimeters matter.”