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By pinpointing vulnerable skills necessary for reading, scientists can help improve quality of life for brain tumor survivors.

By Elizabeth Jane Walker; Photos by Peter Barta and Seth Dixon

The rattle of oak leaves under an angry sky.

The reassuring chirrup of crickets on a steamy summer night.

The rhythmic squeak of a rocking chair in a darkened nursery.

Many of us take these sounds for granted. But for a child recovering from a brain tumor, those noises can be muffled … or silenced.

That’s what happened to Lucy Krull, who lost her hearing after treatment for medulloblastoma, the most common childhood brain tumor. As Lucy’s mom can attest, academics can be difficult for a child who has undergone surgery, chemotherapy and high-dose radiation to the brain. Add profound deafness into the mix, and the challenges increase exponentially.


“Lucy’s extremely intelligent,” Kate Krull says, “but when she suddenly lost her hearing, she had not yet learned to read. She had learned a little phonics in advanced preschool, and yet she had a lot of trouble pronouncing words. She couldn’t decode words or spell them because she couldn’t hear the sounds in those words.”

The sounds of silence

Scientists at St. Jude Children’s Research Hospital have found about 75% of children treated for medulloblastoma experience some degree of hearing loss. That damage might occur because the tumor affects the cranial nerve that transmits information to the inner ear. High-dose irradiation to the brain can also cause hearing loss. Most notably, cisplatin, a chemotherapy drug used to kill tumor cells, can damage hair cells in the cochlea, the main organ of hearing. Despite receiving a drug designed to protect hearing, more than 30% of children in a recent study developed severe hearing loss.

As survival rates for childhood cancer have risen, scientists have redoubled their efforts to improve survivors’ quality of life. For Heather Conklin, PhD, chief of Neuropsychology at St. Jude, that means identifying the cognitive problems that accompany brain tumor treatment and developing ways to avert or eliminate those issues.

“We know these children are at cognitive risk, and we’re doing what we can to refine treatments to decrease that risk,” Conklin says. “Preventing or compensating for hearing loss is an exciting way to improve their functional skills and meaningfully impact their quality of life.”

Back to basics

Many childhood brain tumor survivors have problems reading, which contributes to poor school performance. Children like Lucy, who receive high-intensity treatment at an early age, are at highest risk. Although researchers assumed hearing loss contributed to those problems, no one had identified the specific cognitive skills that led to low reading levels. To find answers, Conklin, St. Jude postdoctoral fellow Traci Olivier, PsyD, and their colleagues studied 260 brain tumor survivors from the U.S., Australia and Canada. They wanted to target the specific language-based skills that contribute to poor reading levels.

“This is the first time anyone has drilled down to discover the key cognitive components leading to reading problems in these children,” Conklin explains.

In the first study of its kind, Heather Conklin, PhD, Traci Olivier, PsyD, and their colleagues discovered the specific language-based skills that contribute to poor reading levels in brain tumor survivors.


Patients in the study agreed to be tested for five years after diagnosis. The annual assessment included a hearing evaluation, as well as three hours of cognitive testing that spanned reading, math, attention, memory and IQ. The scientists concentrated on phonemic skills — the ability to identify individual units of sound and use those units to decode (or “sound out”) words. This ability is a basic skill in learning to read.

The team learned that hearing loss typically occurs within the year following chemotherapy, but the learning problems are most severe two to five years after completion of treatment. The combination of slower processing speed and phonemic problems appears to affect a child’s reading comprehension.

Heather Conklin, PhD, and Traci Olivier, PsyD

International collaborators:
Scientists had assumed hearing loss contributed to reading problems and poor school performance. But, no one had pinpointed the specific cognitive skills that lead to low reading levels. Heather Conklin, PhD (at left), and Traci Olivier, PsyD, led an international study to do that.

It’s a miracle, Momma

Lucy was one of 64 children in the study who had severe hearing loss.

“A kid with severe-to-profound hearing loss might not be able to hear a dog bark or a piano or a telephone, or even louder sounds, such as a motorcycle,” Olivier explains. “When you think of that in terms of what they might miss in the classroom, you can really see the impact.”

Lucy’s story began in 2011, when the little girl began vomiting and having balance problems. Immediately, her parents took her to the doctor.

“She had six brain tumors, as well as a sugar-coating of tumors all up and down her spine,” Kate recalls.

Surgery, chemotherapy and high-dose radiation were required to save Lucy’s life. About a year after treatment, she began having hearing problems. Hearing aids helped for a while, until she suddenly entered a world of absolute silence.

St. Jude provided Lucy with two cochlear implants. Now she can once again hear the voices of her friends, her teachers and her family. She can hear the whinny of her favorite horse and the clop, clop of his hooves during horse therapy.

“The cochlear implants changed her life,” Kate says. “The doctors said her brain would have to relearn how to process sound, which might take up to six months. But about six weeks later, she nonchalantly announced, ‘I can hear.’ I began screaming with excitement. Her little brother looked up at me and said, ‘It’s a miracle, Momma.’”

"The research into hearing and reading is all about quality of life. By helping kids regain cognitive function or protect it, St. Jude is providing a window to the world for their minds."

Kate Krull


Early diagnosis, early intervention

Although Lucy now has functional hearing, the sixth-grader still struggles with reading and writing. That is in keeping with results of the research by Conklin and Olivier, who found that children with severe hearing loss had more problems with phonemic skills, phonetic decoding, reading comprehension and processing speed than children with normal or mild-to-moderate hearing loss.

The work demonstrates a need for catching hearing loss as quickly as possible.

“It’s particularly important for the younger kids, especially those who are under 7,” Olivier says. “From a cognitive perspective, your brain is primed to absorb language at a really young age. That’s why young kids can easily learn other languages when they’re young, but the older we get, the harder it is. So, while those skills are developing, it’s crucial that our cancer survivors have access to sound as soon as possible after hearing loss is detected.”

Personalized learning interventions are also vital.

“The analyses we did — uncovering specific vulnerable reading processes — will help us better match interventions to children,” Conklin explains. “So, a child may need help with phonological decoding, or fluency or reading comprehension. We will be able to match the problem to the intervention because we now know the core processes involved. We can make recommendations to the child’s home school on how to intervene.”

Patient Lucy riding a horse

Back in the saddle: Lucy Krull (shown with her horse therapy instructor) lost her hearing after treatment for medulloblastoma. St. Jude provided Lucy with two cochlear implants. Now she can once again hear the whinny of her favorite horse and the clop, clop of his hooves.

A breath of fresh air

 “I always tell my children that the window to the world is reading. If you can read, you can learn anything; the whole world is open to you,” Kate says.

Now 13, Lucy enjoys creating art, riding horses and reading with the help of assistive devices. In addition to providing the cochlear implants, St. Jude helped the family obtain the best learning resources for Lucy.

“We’ve seen such an improvement in her ability to process language and learn words,” Kate says. “That might seem odd, because it’s a skill she struggles with, but she enjoys it.”

“The research into hearing and reading is all about quality of life,” Kate continues. “By helping kids regain cognitive function or protect it, St. Jude is providing, again, a window to the world for their minds.”

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Improving reading skills in brain tumor survivors video

Improving reading skills in brain tumor survivors

Heather Conklin, PhD, and Traci Olivier, PsyD, discuss the first known study to identify the cognitive components that lead to reading problems in pediatric cancer survivors.

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